STUDIES ON CERTAIN EXPLOITED MARINE FINFISH RESOURCES OF INDIA
V. SRIRAMACHANDFIA MURTK M.SC., Ph.D. Central Marine Fisheries Research Institute, Cochin
THESIS SUBMITTED FOR THE AWARD OF THE DEGREE OF DOCTOR OF SCIENCE IN MARINE SCIENCES UNDER THE FACULTY OF MARINE SCIENCES OF COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY COCHIN
AUGUST 1995 DECLARATION I, V. Sriramachandra Murty hereby declare that the research papers incorporated in this thesis represent the pbonapfide research work carried out by me independently and that they have not been previously submitted for any degree or diploma in this University or any other University in India or ab oad r . é8i£¥@L_ A ii \ggi$h6ir COCHIN V} SRIRAMACHANDRA MURTY PREFACE
After completing the postgraduate education and securing M. Sc. degree in Zoology from the Vikram University, Ujjain, in March 1965, I Joined the Central Marine Fisheries Research Itnstitute (CMFRI), in September 1965. Since then, I have been carrying out research in marine fisheries of India excepting a short period of three years when I was engaged in research in freshwater fish. During 197O—'73, I was on leave to work for the Ph. D. degree at the Andhra University Postgraduate Centre. Guntur and I worked under the guidance of Professor S. Dutt. The Andhra University awarded the Ph.D. degree to he in 1974 for my thesis entitled "Studies on the Taxonomy of Fishes of the Family cyprinidae and on some aspects of Biology of Barbus (Puntius) sarana (Hamilton-Buchanan, 1822) from lake Kolleru,.Andhra Pradesh, India". During the three-decade long career so;far, I conducted researches in Taxonomy, Biology and Population dynamics of several finfish species with emphasis on demersal finfish, besides conducting researches on some shellfish resources also. Initially, the work was carried out at Mandapam Camp and later at Kakinada, both along the east coast of India. The results of researches conducted were published in different journals in India. In 1976, a research project on biological characteristics of threadfin breams (gemipterus sPP) was initiated at the CMFRI and I took up the project as Principal Investigator; ii this project was carried out from eight centres along the Indian coasts. In 1978, I took up the leadership of the pro ject on silverbellies also which was implemented from four centres al¢ng the east coast of India. In addition to carry ing out researches myself, I organised and coordinated the research programmes in these projects on a continual basis till 1989 when these were closed. Further, I was involved in the research projects relating to sciaenids and carangids during this period. Besides, I was associated with team rese arch work. such investigations included studies on stock asse ssment of threadfin breams and silverbellies on an all India basis and, the monsoon fisheries of threadfin breams along the west coast of India. As Principal Investigator and Team Leader of these projects, my contribution covered the collection and analysis of data, pooling-and analysing the data collected from different centres by my colleagues, review of the work done, interpretation of data and the results and preparation of research papers for publication. I was also involved in a short term programme of resou rces survey of Lakshadweep in 1987. This was an indicative $urvey and covered ornamental fish resources, tuna live-bait resources and other finfish resources, among several other resources of the lagoons of Lakshadweep islands. In addition to my actual participation, the responsibility of collection of data by the first team, compilation of data collected by the colleagues in the second and third teams and their ana lysis and preparation of paper on ornamental fishes was given to me. Further, with the experience gained in working on the 141 stock assessment of exploited resources and exposure to the various issues connected with marine fisheries management, I prepared papers on marine fisheries management also. As a recognised guide of the Andhra University, I guided Ph.D. students. I was also appointed as an examiner for evalu ation of Ph. D. thesis of Bombay University. The submitted complex of thesis presents some of the papers published relating to the above mentioned groups of fish. The thesis is organised under four parts: Part I deals with papers on Taxonomy- new distributional records, nomen clatural issues and taxonomic revision. Part II deals with the results of studies on different aspects of biology, population parameters and stock assessment of different species of Nemip teridae, Leiognathidae, Sciaenidae and Carangidae. Part III embodies the results of studies in mixed fisheries assessments and the issues concerning such assessments. In Part IV, the papers pertaining to survey of ornamental fish resources of Lakshadweep and management of marine capture fisheries are included. The research results of these papers formed original contribution in the field of marine fisheries and had consi derably helped to enhance the knowledge on the taxonomy and dynamics of concerned populations which were essential prere quisites for formulation of measures for rational exploitat— ion of the stocks and management of the resources. The results of the works refered to the limits of fish production through biological investigations and documented and drew attention to iv the implications of increased exploitation of the valuable fish groups contributing to the marine fish resources of India. Noting the constraints encountered in multispecies stock assessment in the tropical regions, they provided a perspective on the fishery assessment strategies in the cu rrent situation and addressed the issues in fisheries manage ment. It is hoped that this humble contribution would kindle greater interest in comprehensive investigations on multi species fish stock assessment for maintaining the fishery on a sustainable basis.
ACKNOWLEDGMENTS
During the past thirty years, I had the opportunity\ and \ privilege to work under the stalwarts of Fisheries Science in India: Dr. S. Jones, D. Sc., F.N.G.S., F.A.sc., F.Z.S.I., F.M.B.A._, Dr. S. Z. Qasim, Ph. D., D. Sc., F.A.Sc., F.M.B.A., FONOAO’ D1‘. E0 G9 Do’ Do SC»; FoMeB¢Au Dr. P. S. B. R. James, Ph. D., D. Sc.. F.M.B.A., - the former Directors of CMFRI: they encouraged me and extended their whole~hearted support without which I could not have achieved what all I have, in my research profession. I am extremely gratefull to them. Dr. P. Vedavyasa Rao, Ph. D. F.M.B.A.. who was the Director of CMFRI for about an year during 1994 -1995, not only suggested to me to submit the published papers for the award of D.Sc. degree but also continuously inspired and encouraged me to complete the same quickly; I owe a deep sense of gratitude to him. Dr. M. Devaraj, Ph. D., the present Director of CMFRI, permitted and encouraged me to submit this thesis; I am grateful to him for this kind gesture. V
My colleagues at Mandapam Camp and at Kakinada, parti cularly Mr. P. Ramalingam, Technical Assistant at Kakinada, have helped me by extending their cooperation and assistance: I am thankful. to all of them. Dr. N. R. Menon, Director, gchool o£.Marine Sciences and Dean, Faculty of Marine Sciences, Cochin University of Science and Technology, Cochin, Kindly extended his support on several occasions: I am thankful to him. CONTENTS Preface Resumé of Research work Done References §§F_t I; Ia§9B9WX 1. On some interesting and new records of marine fishes from India. Q, mar. biol. Ass. lndig, 10(1): 126 132: 1968 (1969) 2. On the fishes of the family Platycephalidae of the seas around-India, Q. mar. bio}. Ass. India, 17 (3): 679-694; 1975 £1982) 3. Negipterus luteus (Schneider, 1801) (Nemipteridae, Pisces) the valid name for a threadfin bream from the Indo—Pacific region. Q, Q35. bi9l..Ass. indie, 19(2): 107-114;)l977 (1982); 4. ygpipterus mesopgion (sleeker, 1853) (Nemipteridae, (Pisces) a new record from the seas around India. Indian Q. Fish., 25(1&2): 207-213; 1978 (1981).
935? II Bsioslvszslld iR212\%s1sf-iiisasrnsfsiscs A. THRBADFIN BREAMS 5. Observations on some aspects of biology of threadfin bream Negipterus mesgprion (Bleeker) from Kakinada. Indian Q. Fish., 28(1&2): 199-207: 1981 (1982). 6. observations on the fisheries of threadfin breams (Nemipteridae) and on the biology of Nemipterug Jagonigus (Bloch) from Kakinada. ;ndian"J,;£isQ., 31(1)! 1-182 1984. 7. Estimates of mortality, population size and yield per recruit of ygmiggerus japgnicug (Bloch) in the traw ling grounds off Kakinada. Indian Q. Fish., 30(2): 255-260; 1983. vi vii 8. Further studies on growth and yield per recruit of gemipterug jgpgnigus (Bloch) from the trawling groun ds off Kakinada. gpdian J. §i§h., 34(3): 265-276 (1987). 9. Present status of exploitation of fish and shellfish resources: Threadfin breams. $3: Rao, P. V.,VLS.Murty and K. Rengarajan (eds) Monsoon fisheries of the west coast of India-Prospects, Problems and Management. miniBull Q. cent: it-. _ -—mar _ _ 'Fish Q” YT .Res — . 1Inst.,. 45: 154-168;1992. B. SILVERBELLIES 10. Observations on some aspects of biology of silverbelly peiggnathus bindgg (Valenciennes) from Kakinada. Indian £0 Fight) 30(1): 61“68: 19830 11. Studies on growth and population dynamics of the silverbelly Leiogngthus binggg (Valenciennes) in the trawling grounds off Kakinada. Indian_Q. Fish., 33(3): 277-284; 1986. 12. Population characteristics of the silverbelly geiogpathug bingug (Valenciennes) along west Bengal coast. gr gar. 919;. 533, India, 2s(1&2)= 41-47; 1986 (1988). 13. Biology and population dynamics of the silverbelly, Sgcgtor insidiator (Bloch) from Kakinada. Q; mgr. biol. Ass. lpdig, 32(l&2): 10-24: 1990 (1991). C O CROAKERS 14. Observations on some aspects of biology of the black croaker, Qtrpbpcca nibg (Jordan and Thompson) from KakinadaO Indian __ J. Fish0) 27(1&2): 66-75; 1980 (1981). 15. Observations on some aspects of biology of the croakers :?93!!!iJ¥$
D. CARANGIDS—SCAD 18. Observations on some aspects of biology and popu lation dynamics of the scad Deggpterus russelli (Ruppell) (Carangidae) in the trawling grounds off Kakinada. mar. biol India, 33 (1&2): 396-408 3 1991.
Pa£Ei§l¥seN$¥§deF1$h¢?}?§~A§§9§§m°EE 19. Multispecies stock assessment with particular refere nce to major demersal fish species in the trawling grounds off Kakinada._Q._gg£, biol . Ass, India, 27 (1&2): 39-48; 1985 (1987). 20. Mixed fisheries assessment with reference to five important demersal fish species landed by shrimp trawlers at Kakinada. p 69-86; in: Venema, s.C. and N. P. van Zalinge (eds) §gntribution§ to Iropical F19" 53993 5§$§§§m§“? in ln@12- PaPer5 Prepared bY the participants at the FAO/DANIDA/ICAR National Fo1low—up Training Course on Fish Stock.Assessment. FAO Rome, 1S7pp: 1989. 21. Stock assessment of threadfin breams (yemipterus spp) of India. Indian :g1Fpisn., 39(1&2)= 9-41; 1992 (1994). 22. Stock assessment of silverbellies of India with particular reference to Andhra Pradesh and Tamil Nadu. Indian Q. Fish., 39(1&2):'42-64; 1992 (1994) Psi; 12:9 w 9- “rv91__9“d£1a1=s99£fl§nspg _$gM_W _t_M I __ _ 23. Resources of ornamental fishes. in: Marine living resources of the union territory of Lakshadweep— 0an indicative E-920 surveyFish with op suggestions Inst433 for development. 6‘:
IQ 0
P U1 9 ix 24. Present trends in marine fisheries management and catch forecasting. Paper presented at the Interna tional workshop on application of Satellite Remote Sensing for identifying and forecasting Potential Fishing Zones in Developing countries;Hyderabad, India, 7-11 December,l993. National Remote Sensing Agency, Department of space, Hyderabad, India; Comm ittee on Science and Technology in Developing coun tries of the International Council of Scientific Unions, Madras, India, 25. Complexities of Management of Inshore Fishery Resour ces of India..§ishing_Qhime§, 13(8): 5-9; 1993. List of Research Papers Published by V. Sriramachandra Murty. Rssumé or RESEARCH woax nous RESUMé OF RESEARCH WORK DONE
INTRODUCTION one of the most important objectives of research in capture fisheries is to understand the state of exploited stocks and to suggest possible options for rational exploi tation, to ensure continued and sustained production of fish. To fulfill this, it is essential to understand the taxonomic identity of each species contributing to the fishery, its distribution in space and time, the various aspects of biology of the species that influence the fishery and enable making estimates of vital statistics and finally to estimate the parameters of growth, mortality and selection which are useful in stock assessment studies. Organised research on marine fishery resources of India was started during late forties. During that period, the fis hing used to be predominantly by artisanal craft and gear in the nearshore waters and the exploitation of each species was at a much-less—than-optimum level. During that period, the research efforts were mainly directed at describing the fisheries and in a few cases towards making preliminary stu dies on bionomics. The situation underwent tremendous change when mechanised fishing was introduced in sixties and then popularised. These and the location of lucrative fishing grou nds in the inshore waters together with the development of an export trade of fish and fishery products, paved the way for excellent growth of the fishing industry. and, consequently the total mrine fish landings increased from around half-a million tonnes in fifties to around 2.3 million tonnes in nineties. This development process not only brought to light 2 several resources which were not exploited or, exploited only marginally prior *0 introduction of mechanised fishing, but also their vulnerability to increased fishing pressure, necessitating scientific management of the resources through a reliable information base particularly on fishing effort, catch, seasonal variations in availability and abundance in relation to changes in environment and on the biological characteristics of the exploited species. There was considerable difficulty in identifying the spe cies accurately, because, in a large number of families of marine fishes, several closely-resembling species existed. Besides, many species came to light after the publication of the "Fishes of India" by Day (1878). More recently, the deli mitation of known species and introduction of nomenclatural changes have caused confusion and lead to use of incorrect scientific names or application of one name 'to more than one species. These have emphasised an urgent need for directed research in taxonomy of several exploited marine fish families. In the case of many species, there was practically no information on aspects of biology such as food and feeding habits, spawning and fecundity, growth and migration which were essential prerequisites for understanding spawning habits and seasons, deleniating spawning grounds, estimating recrui tment, understanding fluctuations in availability and abundance studying dynamics of the populations. As the fishery was still in a developing stage untill about a decade-and-a-half back, the effect of exploitation was not felt in respect of many stocks. Consequently, due consideration was not given to 3 the estimation of population parameters and to stock assess ments. The need for developing expertise in this major area of research also, was therefore, not considered. It was only after the catches of major exploited stocks started declining, that the imperative need to reorient the efforts towards stock assessment and management was realised. Accordingly, through the steps taken by the CMFRI and the training pro grammes arranged and organised by the Food and Agricultural Organisation of the U.N. and the Danish International Develop ment Agency jointly for the benefit of the fisheries Scientists in the tropical countries, that research work in fish stock assessment began receiving its due attention in India. The author had the opportunity to carry out researches in taxonomy, biology and population dynamics of major exploi ted fish stocks such as threadfin breams, silverbellies, cros kers, scad and others. The results of the studies;most of which happenned to be the first ones from the seas around India, contributed significantly to the enhancement of know ledge on the above aspects of the concerned fish species.
EAiRfI_T:__-l; E s'17AX°N91fiYt 1. on some interesting and new records of marine fishes from I ndia 0 This work reestablished the status of the two species of the family Drepanidae: grepane pungtgtg (Linnaeus, 1758) and Q. longimana (Bloch and Schneider, 1801). Several authors treated them as synonymous, inspite of their distinctness established by Lele (1924). Utilising the material collected from Palk Bay and Gulf of Mannar and examining them for both ‘ . morphological and anatomical characters, it was shown that the two species were indeed distinct and valid. A key to identify these two species was also given. For the first time, the presence of barbels in 3-4 rows below the chin in smaller individuals of Q. punctata and Q. longimana was reported. It was also reported that these barbels disappear in larger fishes over 270mm in total length. This paper also reported two species of fish, gggtholglig §D£g?¥Qp§§ (Bleeker, 1351) and Platycephalus igaganthug (Cuvier 1829) for the first time from Indian seas, along with detailed descriptions. §t§§hOjn}i§ integrnpta (Bleeker) of the family Labridae was known from western and eastern parts of Indian Ocean; the single specimen collected from the Gulf of Manner was the first report from the central Indian Ocean in general and from the Indian coastal waters in particular. Platycephalus isacanthus (Cuvier) (Family Platycephalidae) was known only from western Pacific and eastern Indian Ocean. The report from the Gulf of Manner and Pa1k.Bay was the first from India and Central Indian Ocean. 2. On the fishes of the family Platycephalidae of the seas around India. A taxonomic revision of the family Platycephalidae was made. This was the first comprehensive taxonomic work on the family from India after Day (1878). Studying the fresh material collected from along the Indian coast, the collections availa ble in the Zoological Survey of India, Calcutta and consulting the data on certain type specimens, a taxonomic revision of the family was attempted. In view of the confusion in assi gning the species to their respective genera, some earlier 5 authors (eg. de Beaufort and Briggs, 1962) preferred to include all the species under the single genus Blatycephalgs. This issue was examined in this work and the thirteen species were included under six genera tentatively. Detailed descri . \ ptions were given for the first time utilising the characters of ridges and spines on the head and keys for the identifica tion of genera and species were given. Of the thirteen species dealt with (against the seven species dealt with by Day, 1878), yahiyuss erratus (Cuvier, 1829) which was first described from Sri Lanka, was not report ed from any where else in the world though a mention of its name, that too erroneously, was made from a few localities. The description in this paper, on the basis of material from Lakshadweep sea, was the first from the region, in addition to the first adequate description of the species after its original description in 1829. glatycephalus carbunculus (Cuvier, 1829) was first descri bed on the basis of a few specimens from off Bombay and sub sequently there was no description of this species from any where else in the country. The material collected from the east coast of India, in the study, was the first report on its extended distribution from the east coast of India. 3. Nemipterus luteug (Schneider, 1801) (Nemipteridae,Pisces) the valid name for a threadfin bream from the Indo-Pacific region. After a critical review of the literature, studying the data of type specimens of relevant nominal species and examining specimens collected from Kakinada, along the east coast of India, it was shown that yemipterus luteug (Schneider, 1801) was the valid name for the species which was referred earlier as N.-- striatus’ ’ an ‘(Valenciennes ."f;.1'::*"-"-~—‘*t:'_:r~ 1830) N. filamentosus , " - .; (valenciennes, 1830), §. negatophorus (Bleeker, 1853 a) and Q, gecronemus (Gunther, 1859). A detailed description of the species was given for the first time from India. 4. §emipterus mesgprion (Bleeker, 1853) (Nemipteridae,Pisces) a new record from the seas around India, On the basis of collections made at Kakinada along the east coast of India, Nemipterus gesgprion (Bleeker, 1853 b) was first reported from the seas around India and adequate description was given. For the purpose of accurate identifi cation of the species, the data of the holotype of the species in the Leiden Museum was consulted and the original and sub sequent descriptions by Bleeker (1853 b, 1873, 1877) were also studied and details presented in the paper. To distinguish this species £rom.§. Japgnicus (Bloch), particularly in preserved condition, because colour is" the most important character in threadfin breams, a comparison of §, mesopgion and Q, igppnicus was made and the differences explained to enable accurate identification of the two species. 7
‘PPART —,__,‘_—'_:1._ II BIOLOGY ‘, 1%T':TQT__T AND H — POPULATION ,_,' .__ '_.l-Q _:I_ ' _ “_;"“ DYNAMICS '_' "'7' |_f‘ ‘ "‘ ‘
A. THREADFIN BREAMS The threadfin breams (N§@iptgrg§ BPP) which are exploited by trawlers are one of the major demersal finfish resources of India. In 1993, an estimated 86752 tonnes of threadfin breams were landed (Anon., 1994) which formed about 8.0% of total demersal fish landings and 4.0% of total marine fish landings of India, These fishes are known to be more abundant in rela tively deeper waters of 100-200 m (Silas, 1969; Silas gt 31,, 1976; Zupanovic and Mohiuddeen, 1973; Philip and Joseph, 1988: John, 1989: Sudarsan gt §l., 1990; Sivaprakasam_g§_gl., 1991) and are known to move into relatively shallower inshore waters \ during certain periods (Banse, 1959: Nair and Jayaprakash, 1986) particularly along the west coast. Among the maritime states, Kerala accounted for maximum catch which formed about 52% of total threadfin bream catch, followed by Maharashtra (l€%), Tamil Nadu (11%), Karnataka (9%). Gujarat (8%) and others. A total of six species contribute to the fishery of which flemipterus Jappniggg and §,‘Qg§gp£i2§ are most abundant, constituting the bulk of threadfin bream landings. The other species: Q.tolu , Q. delagoae,_§. luteu s and §. metgpias occur in the catches occasionally in small quantities. 5. Observations on some aspects of biology of threadfin bream qgmipterus mesgpriog (Bleeker) from Kakinada. After reporting the occurrence of ggmiptgrgs mesopriog in the Indian seas and publishing, a detailed description of the species from Kakinada (Murty, 1981), investigations on the biology of this species were carried out from Kakinada during January 1976-March 1980. This was the first original research 8 work on the biology of §. gesopriog from the Indian Ocean region: the lone earlier report was from east Malaysia (Weber and Jothy, 1977» on the basis of survey data obtained during March 29-May 1, 1972. The 1ength~weight relationship was calculated as Log w= -4.650901 + 2.877071 Log L. Examin ing 29S females of the length range 83-177 mm, the length at first maturity (50% maturity) was determined as 100 mm. By studying the ova diameter frequency distribution in mature and ripe ovaries, it was shown that §. mesopriog was a fractional spawner releasing the ova in two batches during the protracted spawning season. On the basis of occurrence of females in diff erent stages of maturation during different months and taking \ into consideration only the fishes of and above length at first maturity, the spawning period was determined as Decemberehpril with peak during January in the sea off Kakinada. Using the length data of 2386 specimens of the length range 32-215 mm and following the modal progression method, the growth of Q. mesoprion was studied: the parameters of von Bertalanffy growth equation were estimated as as LaC= 219 mm, K= 0.83248 per year and t°= —0.256198 year. The life-span in the fishery was estimated as three years. 6. Observations on the fisheries of threadfin breams (Nemipt— eridae) and on the biology of Nemipterpsyjaponicgs (Bloch) in the trawling grounds off Kakinada. Using the data collected by the author during 1976-'79 from the landings of small commercial trawlers operating off Kakinada, the fishery of threadfin breams and biology of yemdpterus japgnicus were studied. This was the first study in India on the basis of data collected from commercial vessels, 9 the earlier studies in the country being based on data of exploratory vessels operating off Andhra—0rissa coasts (Krishnamoorthi, 1973), off Cochin (Vinci and Nair, 1975; Vinci, 1983) and off Mangalore (Kuthalingam, 1971). During the study period, four species of threadfin breams contributed to the fishery. Qgmipterus japgnicus was the most dominant species supporting the fishery, followed by Q. ggsoprion, Q. andtolu _1§I_. luteus . It was shown that November-May was the period of abundance of_nemipterids in the trawling grounds off Kakinada. The reproductive biology of Q. japgnicus was studied. The testes were small even in mature fishes and it was not possible to quantify them into different maturation stages. The ovaries were, however, classified into six stages of mat uration on the basis of external appearance ( size in relation to body cavity, colour, nature of intraovarian ova as seen by naked eye) and structure and size of intraovarian ova under microscope. Fully spent fish were never encountered. The length at first (50% maturity) maturity was estimated as 125 mm in females. Like Q. meggpriog (Murty, 1982), §, japgnicus was also shown to be a fractional spawner, spawning in two spawn ing acts during the spawning period. The nature of ova diameter frequency distribution in mature and ripe ovaries and the non-occurrence of spent or spent rematuring females (over 1000 females examined during 1976-'79 period) were shown to be suggestive that the females once reaching ripe stage would not revert to "stage II" (rematuring adults or spent recovering adults) as was generally believed to be the case in Indian 10 marine fishes and in most temperate water fishes which were known to spawn during shorter periods, once a year. By cons idering females above length at first maturity and on the basis of frequency of occurrence of mature and ripe females in different months, the spawning was shown to extend from.August to.April with peaks during December and February. This conclu sion was supported by the occurrence of smaller fishes in the 35-85 mm length range over extended periods. For the first time in Indian marine fishes, an attempt to estimate total annual fecundity of a fractional spawner was made in the case of §. japgpicug from off Kakineda. The total annual fecundity in fishes of 134-199 m total length range was estimated as ranging from about 23000 to 139200. The relation ship between total length and fecundity was estimated as F= -116.56711 + 1.11909 L: (r=0.83) and between weight and fecundity as F= -0.75615 + 1.11380 wx (re 0.92). The sex ratio showed predominance of males; the largest length of males was observed to be 285 mm and that of females to be 215 mm. The possibility of faster growth rate of males as suggested by Krishnamoorthi (1976) and Eggleston (1973) was recognised in this study also (see Qasim, 1966 also). Using the length data of over 6600 specimens of the length range 35-285 mm collected during 1977-'79 and follow~ ing the monthly progression of modes in the length frequency distribution, the growth rete was estimated. The von Bertallanffy parameters of growth were estimated as La? 314 mm, K= 0.75 per year and to= -0.17 year. 11 Differential growth rate between sexes was observed in threadfin breams (Eggleston, 1973) and a possibility of such a situation occurring in.§. Japgnigus was also recognised in this study. Investigations made with scales and otoliths did not reveal growth checks of value in age determination in this species (some otolith sections were prepared when the author visited Lowestoft laboratory, U.K., but growth check of use were not discernible). As it was not possible to make length measurements of males and females separately in the field in the absence of external sexual dimorphism and in view of the practical difficulties in doing the work in the landing centre, the pooled data of males and females only were considered for estimating growth parameters. 7. Estimates of mortality, population size and yield per recruit of gemipterus japgnicus (Bloch) in the trawling grounds off Kakinada. For the first time in India, the mortality rates and stock size of yemipterus Japonicus were estimated on the basis of data generated from comercially exploited populations; the earlier study by Krishnamoorthi (1978) was based on data from vessels conducting exploratory surveys. Using the length frequency data obtained during 1976-79 from commercial trawlers at Kakinada and the values of growth parameters estimated earlier (Murty, 1984 a), the mortality rates were estimated and stock size determined. The values of total mortality rate (Z), fishing mortality rate (F) and natural mortality rate (M) were estimated as 1.86, 0.72 and 1.14 respectively. It was shown that the exploitation of §. igpggigug during the period did not have any adverse effect on the stock. 12 8. Further studies on the growth and yield per recruit of gemipterus Japonigus (Bloch) from the trawling grounds off Kakinada. Having studied (Murty, 1984 a) the growth using the modal progression method and recognising the bottlenecks in relia bly estimating the same using this method, another attempt to estimate the growth parameters of yemipterus Japonicus was made using the length data collected during 1980-'83 from off Kakinada and following the less subJective'Integrated Method‘ of Pauly (1980 a). The mortality rates, length at first capture and yield per recruit were also estimated. The von Bertalanffy growth parameters estimated were L QC-= 339m, K-= 0.52 per year t°= -0.16 year. The total (Z), natural (M) and fishing (F) mortality rates were estimated as 2.64, 1.11 and 1.53 respec tively. The length_at first capture (LC) was estimated as 120 m. The yield per recruit was estimated and it was shown that increased effort would result in decreased yield in the grounds under exploitation, if the cod end mesh size was not changed. It was also shown that yield could be increased if the cod end mesh size was increased by 70% without increasing the effort. The various issues relating to estimation of parameters were discussed in detail and the need to update the estimates, whenever stock assessment was attempted, was indicated. The values estimated in this work were compared with the earlier estimates. 13 9. Present status of exploitation of fish and shellfish reso urces - Threadfin breams- Monsoon fisheries of west coast of India, prospects, problems and management. [“As Principal Investigator of the project on threadfin breams, the author analysed the data collected by colleagues working at different centres along the west coast of India, interpretted the same, reviewed the literature and prepared the paper for publication. Additionally, the author was associated with the edito rial work of the publication_7 Due to the ban imposed by the government on trawling during monsoon period along the Indian west coast, particularly along the Kerala coast, the fishing industry expressed appre hensions on the validity of such a ban. As part of the Insti \ tute's efforts to examine whether such a ban was indeed nece ssary, the data on threadfin breams- a resource of consider able magnitude taken in large quantities during monsoon period by the trawlers- collected during 1984-'88 were analysed and the results reported in this paper. The data on total catch, species composition, length com position of catch and maturity condition of fishes exploited during different seasons were examined critically. The study revealed that while the ban on trawling was not essential so far as threadfin breams were concerned, the need for-continu ous monitoring of the exploited stocks was emphasised because: the trawl fishery was multispecies in nature, the inshore grounds were known to be nursery grounds for many species of fin- and shellfish, the yields of threadfin breams in the inshore fishing grounds of 0-50 m depth range reached near optimum levels and because the cod end mesh size of trawl nets 14 was reduced in the shrimp-oriented trawl fishery.
B. SILVERBELLIES The silverbellies (Leiognathidae) are known to be abun dant in shallower regions of the sea upto about 40 m depth (James, 1973: Pauly, l977 a, b; Pillai and Dorairaj, 1985; Sudarsan gt gls, 1988; Sivaprakasam.2t gl.,l991) though they are known to occur in depths of 100-150 m.also (Sudarsan_g§ §l., 1988). An estimated 62304 tonnes of silverbellies were landed in India in 1993 (Anon,, 1994) which formed 5.5% of total deme rsal fish catch and 2.7% of total marine fish landings of India. Maximum landings (71% of total silverbelly catch) of these fis hes were obtained along Tamil Nadu coast, followed by Andhra Pradesh (9%), Kerala (8.4%), Karnataka (6.0%) and other maritime states. Though these fishes were taken by artisanal gear as well as trawl, the latter accounted for the bulk of the landings. silverbellies were known to undertake diurnal vertical migrat ions (Venkatraman and Badrudeen, 1974: Murty, 1988) staying at the bottom during day time and rising to surface and sub surface watersduring night time. A total of about 20 species were known from india but only a few species: Leiognathgg jonesi, Q. bindus, Q. dussumieri,brevirostris Q. and secutor insidiator contribute to the fishery significantly. 10. Observations on some aspects of biology of silverbelly peiognathusy _i_ b nd us (Valenciennes) from Kakinada. Leiognathusigindus was one of the mst dominant components of silverbelly catches along east coast where no attempt to study the biology was made. The present paper from Kakinada was 15 the first one from this coast as the single earlier work (Balan, 1967) from the country was from the west coast of India. The aspects of biology pertaining to maturation and spawning and length—weight relationship were presented in this paper. The length at first maturity (50% maturity) was estimated as 80 mm. The ova diameter studies showed .that bindus Q was a fractional spawner, each fish spawning twice during a year. The spawning period was found to be continuous throughout the year with peak during DecembereApril. The length frequency distribution of the species in the fishery was presented. The length-weight relationship was calculated as: Log w - -4.77709 + 2.96182 Log L
11. Studies on the growth and population dynamics of silvers belly Leiognathusybindug (Valenciennes) in the trawling grounds off Kakinada. After completing a study of the spawning biology of Leiggnathusybindus (Murty, 1983 a), the von Bertalanffy growth parameters, mortality rates and yield per recruit were estimated utilising the length frequency data collected from the trawl landings at Kakinada during 1979—'8l. This also happenned to be the first work from the east coast of India as Pauly and David's (1981) estimation of growth parameters using the data of Balan (1967), was from off Calicut (west coast). The growth parameters were estimated as hx:= 158.4 mm, K = 0.58 per year and t°= -0.024 year. The mortality rates were estimted as Z=5.2, M=l.5 and F=3.7. The study on yield per recruit indicated the need to increase the cod end mesh size by about 50% to be able to harvest the maximum yield 16 without affecting the stock adversely.
12. Population characteristics of the silverbelly peiognathus bindus (Valenciennes) along west Bengal coast. This paper was based on the data collected during a midwater trawl survey conducted between long. 200- 21° 03.8 and lat. 87°15. - 88°55. E along the coast of west Bengal. The data on L. bindus during the survey showed that larger fish inhabit relatively deeper waters and, confirmed the earlier study of Venkatraman and Badrudeen (1974) that silver bellies stay at bottom during day time and migrate to surface and subsurface waters during night. The length-weight relation ship of the stock was estimated as Log W= -5.38217+3.28637 Log L The mortality rates estimated showed that total mrtality rate was equal to natural mortality rate indicating that there was no exploitation of this species in the region: this was supp orted by the landings also. It was suggested that maximum yield of this species could be obtained at a fishing mortality rate of 3.6 with the 42 mm cod end mesh size of trawl net.
13- Biology and population dynamics of the silverbelly" Beggtor insidiator (Bloch) from Kakinaua. In the silverbelly landings by commercial trawlers at
Kakinada. f secutorh '.§,.__ :____'_'f_.7" insidiator H ' iii’ was one of the most dominant species. On the basis of data collected during 1979-'83, a study on the biology and population dynamics of the exploited stock was made. This happenned to be the first report on the above aspects of the species from India; earlier, Pillai (1972), briefly dealt with the spawning habits and fecundity of this species from Tuticorin. 17 Maturation, spawning and sex ratio were studied and it was shown that this species spawned throughout the year with a peak during January~March in the sea off Kakinada. The length at 50% maturity was estimated as 90 mm. Though the maximum length of males and females was the same, females were predominant in larger lengths. The length—weight relatio nship was calculated as Log w= -5.73713 + 3.43654 Log L. The von Bertalanffy growth parameters were estimated as L“? 123 mm, K= 1.2 per year and t°=--0.01 year. ) The total mortality rate was estimated using different methods and the value was taken as 6.1052. Similarly, the natural mortality rate was estimated by four different appro aches as 1.8, 2.3, 2.4 and 2.6. The age at first capture was estimated as 0.86 year. Using all these values, the yield per recruit was estimated. The yield as a function of fishing mortality showed that it did not attain maximum within the values of F considered. The yield as a function of age at first capture (to) indicated the need to reduce the tc from 0.86 to 0.70 year. The reduction in tc was, however, not reco mended because the same would result in increased exploitat ion of still smaller fishes which did not have any commercial value. The difficulties encountered in the analysis of data for estimating growth parameters, mortality rates-and yield were discussed. 18 C. CROAKERS The fishes of the family Sciaenidae (croakers, jew fish) represented over thirty species in India, contributed signi ficantly to the exploited demersal finfish resources of the country. In 1993, an estimated 161105 tonnes of croakers were landed along the Indian coast (Anon., 1994) which formed about 14% of total demersal fish catch and 7% of total mrine fish landings of India. Maximum catches were obtained from Gujarat, followed by Maharashtra, Tamil Nadu, Orissa, Andhra Pradesh, Kerala and other maritime states. of the species known from the ¢°\""=1'Y- Prstseibss 9£s¢s=1fl3P§- Qtslithvs 9‘!!1§!~T:1- -Jsmise
!29l2££@42- m€E£2FhXQ¥§',£' an°“5= E‘ §i22'.Q~ I \carutta and Atrobpcca nibe were most abundant at different regionsa some species like Q. dlacanthqs which used to form dominant components in the landings along north west coast of India, registered declining yields in recent years. 14. Observations on some aspects of biology of the black cro aker.§trobnpca nibg (Jordan and Thompson) from Kakinada. The paper represented the second report on biology of gtrobuccg gibe from anywhere in the world and the first one from Indian Ocean region in general and from the Indian coastal waters in particular: the only earlier report was from Japan (Matsui and Takai, 1951). Q, gigg formed a seasonal but major component in the mnltispecies (about 20 species from off Kakinada) sciaenid catches taken off Kakinada by trawlers: during 1975~'77, this species formed 27% of the average annual sciaenid catch of 1500 tonnes. The length-weight relationship was 19 estimated as Log W = -5.524308 + 3.213476 Log L. The length at first maturity was estimated as 145 mm; through the study of ova diameter frequency distribution, it was shown that Q, nibe spawned twice during the spawning period which exte nded from February to July in the sea off Kakinada. 15. observations on some aspects of biology of the croakers Qohnius (QohnieoB§)_QussuQieri (Cuvier) and Johnius (Johnius ) Bloch carutta from.Kakinada. This paper was the first report on the biology of Q. Qussumieri and Q. carutta (excepting the study on spawning of Q. Qaruttaby Rao, 1967) from the Indian seas. The length weight relationship, relative condition factor, length at first maturity, spawning habits and spawning seasons were determined. In Q. Qgssunigri, the spawning season extended from March to August. The length at first maturity was esti mated as ll0 mm. The length-weight relationship was calculated as Log W = —4.845l1 + 2.96347 Log L. The changes in relative condition factor were found to be associated with gonad cycle. In Q. caru t a,t the length at first maturity was found to be 155 mm. The spawning season extended from January to June. The length-weight relationship followed the equation LOg W a + LOg L0 16. Growth and yield per recruit of Johnius (Johnius) carutta Bloch in the trawling grounds off Kakinada. A After studying the maturation, spawning, length-weight relationship in Q.carutta (Murty, 1984 b), the estimation of growth parameters, mortality rates and yield per recruit was made on the basis of data collected from trawl landings 20 at Kakinada during 1980—'83. The parameters of growth were estimated as bX:= 333.3 mm, K = 0.44 per year and toe —0.0002 year: the mortality rates as Z I 5.07, M = 1.0 and F = 4.07. At the prevailing levels of to and F during 1980-83, the yield per recruit as a function of F had already declined. The yield per recruit as'a function of tc showed that Ymax could be obtained at tc= 1.7. The study lead to the suggestion of the following options to maximise and then sustain the yield: ——-——-to decrease the fishing effort by 51% without modifying the cod end mesh size, to increase the age at first capture by 50% (i.e. cod end mesh size) without changing the fishing effort, or ————— to increase both effort and cod end mesh\ size of trawl net 0 17. Observations on some aspects of biology of Johnius (gohniegps) vogleri (Bleeker) and Rennahia macrophthalmus (Bleeker) in the Kakinada region. ['The author was responsible for planning the work, collection, analysis and interpretation of data and for preparing the paper for publication. The junior author rendered assistance in aquisition and analysis of data.7 Among the several species contributing to the sciaenid fishery by trawlers at Kakinada, Johnius______vogleri and nPen h a ia macrophthalmus were important among others. From.off Kakinada, there was no information on the biology of these species; in the case of Q. ggglggi, there was no information on the biology from east coast of India. The earlier studies were restricted to those by Rao (1967, 1983) in Q. macrophthalmus from Visakha patnam and by Muthiah (1983) in.Q. vogleri from off Bombay. The present paper dealt with the results of a study on the 21 length-weight relationship and spawning biology. It was shwn that these two species spawn in two batches during 0ctober/ November-June in the sea off Kakinada. The length at first maturity (50% maturity) was estimated as 147 mm. inmacro §_ 'phthalmps and 190 mm in‘Q. vogleri. The length—weight relatio nship was estimated 888 Q. macro*_ hthalmns: 7 P Lo L_iifi_ W = -4 63735 + 2 g89703 0 0 Q. vogleri: Log w = -s.0s923 + 3.07931 Log L
The fishes of the family Carangidae comprising of horse mackerels, scads, leather jackets and others, constitute an important pelagic finfish resource of India represented by nearly sixty species belonging to about16 genera. In 1993, an estimated 129064 tonnes of carangids were landed in India (Anon., 1994) which formed 11.3% of pelagic finfish catch and 5.6% of total marine fish landings of India. of the diffe rent species, the scads represented by about four species cont ribute to over 46% of the carangid catches. Degapggggg russelli is the most dominant species of the scads and is exploited in large quantities by trawlers during certain periods. 18. Observations on some aspects of biology and population dynamics of the scad Qgcapterus ssssslli
I The length-weight relationship followed the equation: Log w = -5.93433 + 3.40764 Log L. The von Bertalanffy growth parameters were estimated as Ldzn 232.3 mm, K = 1.08 per year and t°= —0.08 year. The length and age at first maturity were assessed as 150 mm and 0.88 year respectively. The spawning period off Kakinada was determined as extending from.December to.August. The different mortality rates were estimated as Z = 6.65, M = 1.90 and F =-4.75, The yield per recruit ana lysis showed thatiif the age at first capture was above 0.6 year, the yield increased with increase in F without attaining maximum. studying the earlier literature on experimental fishing and taking into account the fishing practices, the possible reasons for the seasonal fishery ofrusselli Q. were explained. The spawning season determined was explained to be realistic taking into account the earlier studies on exploratory and experimental fishing and larval and spawner surveys (Raoiii et al Q 1977) and the review of Qasim (1973) on spawning of Indian mrine fishes. The reasons for the difference in the estimated 23 values of growth parameters given by Sreenivasan (1983) and this study were examined and explained, though it was expre ssly stated that these values could be different in different stocks of the same species and also innthe same stock between different periods (vide, Gulland, 1983) for various reasons. In the estimation of natural mortality coefficient, the available methods, including the methods recently developed (Pauly, 1980 b, 1983; Alagaraja, 1984) were critically exa mined and finally the method adopted by Sekharan (1975) was followed with Justification. The problem of estimating length at first capture (LC), in the absence of selection experiments, was discussed and justification deduced for the estimate obtained taking into account the known distribution pattern of the species and fishing practice. Yield per recruit analyses were, however, made using different values of LC (and hence to) and the yield curves compared and the strategy of exploitation suggested noting the limitations. 24
_PART V 7'“7" V _'tIII , , '—_MIXED , '_,___‘—_“;__ FISHERIES _:___I‘_‘Il'7T:L _"‘——‘_ ASSESSMENT i‘ ‘I “ _ ]‘—_—_ ‘ f 19. Multispecies stock assessment with particular reference to major demersal fish species in the trawling grounds off Kakinada, The Indian marine fisheries, like any comparable tropical marine fisheries, exploit a large number of species in any l Q'gear. . The classical models of fish stock assessment of exploited stocks (Beverton and.Holt, 1957) only deal with single species assessments. The author made a few single species stock assessments and found that though such assess ments did provide useful insights into the state of the expe loited, single species stocks, they did not help to palnning a strategy for rational exploitation and management of multi species stocks. Besides, methods of assessing multispecies stocks in the tropical context were also not available. The author, therefore, attempted the multispecies stock assess ment using the data obtained from trawl landings at Kakinada, This was the first attempt in India to do multispecies stock assessment and it primarily demonstrated the methodology using four demersal finfish species. The theoretical and practical issues, in making the assessment, were discussed in deta.;i1 0 In the higher latitudes, particularly in the north sea, multispecies stock assessment model (nultispecies Virtual Population.Analysis Model-—-MSVPA) was developed (Helgason and Gislason, 1979; Gislason and Helgason, 1985; Pope, 1979: 25 ICES, 1984, 1986, 1987: Gislason and Sparre, 1987) taking into account the species interactions, particularly in regard to mortality generated by predation, and following the age-based methodology. While this approach was still under trial, in the tropics, the age—based methodology could not be implemented because of the inability to determine the age of individual fish (even after the discovery of daily growth rings in the otoliths of tropical fishes, as this methodology was not successful in ageing fishes older than about one year-——— see Gjosaeter g§y§l,, 1984). Necessarily, therefore, the length-based methodology appears to be the only answer
to tropical fish stock assessment until a more efficient\ model is developed. In the present paper, the methodology of multispecies assessment using the data of one speices of threadfin breams, one species of croakers and two species of silverbellies, using the Beverton-Holt model was demonstrated. It was also shown that with existing gear under operation, the effort had to be reduced by about 6% to ensure maximum yield of the four species or, the cod end mesh size had to be increased by about 28% without increasing or decreasing the effort. The latter option was explained to be the most desirable one as the lengths at first capture of the species were less than the lengths at 50% maturity. 20. Mixed fisheries assessment with reference to five impor tant demersal fish species landed by shrimp trawlers at Kakinada. After attempting an assessment of multispecies stocks in the tropical context, another assessment of five exploited 26 species in the sea off Kakinada was attempted using the length-based Thompson and Bell analysis developed by Sparre (1985). This approach, similar in concept to the one attempted earlier (Murty. 1987 b), was also given primarily to demonstrate the methodology for assessment of a mired fishery. Additionally, this approach considered pooling the values (prices) instead of the yields themselves so that it became more meaningful in the mnagement. The theory of length-based Thompson and Bell (1934) model was also presented This was the first stock assessment study of the kind in tropical waters and it was shown that this approach could be followed for the assessment of a large number of species exp loited by the gear.
21. Stock assessment of threadfin breams (gemipterug spp) of India. [7As principal Investigator of the project and team leader, the author analysed the data supplied by colleagues from all centres and interpretted the same, reviewed the work done and prepared the paper for publication, in: addition to generating data from Kakinad§7 Though some isolated attempts on stock assessments were made,during different periods from different localities, of single species (Krishnamoorthi, 1978: Murty, 1983 b, 1987 a; Vivekananda? and James, 1986; Devaraj and Gulati, 1988;.John, 1989: Kasim_§t_gl., 1989), concerted efforti to study the population dynamics from all along thea coast taking into account the principal species, was not made. This paper dealt with the mixed fisheries assessment of the threadfin breams 27 wsairssxrs Japonisvs and E» mss¢;>ri<>s> from east and "est coasts of India. All necessary parameters were estimated, stock assessment made and optimal yield levels in the exist ing fishing grounds indicated. The various scientific_issues relating to the assessments in the tropical context using length data were discussed, particularly the widely-differing values of growth parameters estimated using data of different years and the consequent'difficulty in using_g particular set of growth parameters for estimating mortality rates and yield. The choice of selecting two sets of values of growth parameters, the smallest and largest gxivalues and their related K values from among the several sets of reasonably satisfactory values obtained, for proceeding further with the assessments and then considering the average values of yields (of the two obtained using two sets of growth parameters) corresponding to each effort level (F-level) as representing the realistic estimates, was believed to be the best under the existing situation. Besides, the conflicting options for rational exploitation of different species in the same fishery were pointed out and the strategies to be followed, in the given option, were indicated. 22. Stock assessment of silverbellies of India with particular reference to.Andhra Pradesh and Tamil Nadu. ['In addition to generating data from Kakinada, as Principal Investigator of the project and team leader, analysed the data from all four centres and interpretted the same, reviewed the work done and prepared the paper for publication‘? Though silverbellies were known to occur in the catches all along the Indian coast, about 80% of the silverbelly catch 28 was landed from off Tamil Nadu and Andhra Pradesh: of these regions, Tamil Nadu's contribution was the highest forming 70% of silverbelly landings of India. Bulk of the silverbelly catch in the country was obtained from trawlers. Of the species contributing to the fishery, geiggnathug bindus and §e§uto£ insidiator were the most dominant along Andhra Pradesh and northern Tamil Nada coasts and_§. jonesi and Q. Qussumieri along southern Tamil Nadu coast. Though work on stock assessment of silverbellies was carried out earlier (Venkatraman gt 35., 1981: Murty, 1986, 1988, 1991 and .Karthikeyan g§_§l., 1989), it was restricted to single species from restricted areas. T0 have an overall view of the status of the exploited silverbelly stocks from the region of greatest abundance in the country, two mst dominant species (Q. bindus and §, ingidiator) from Andhra Pradesh and Northern Tamil Nadu and two other dominant species (Q. jonesi and Q. dugsumigri) from southern Tamil Nadu were selected for the present assessment. The available information on the biology of different species from different localities along the Indian coast was reviewed. Parameters of growth and mortality rates of the selected species were estimated. Stock assessment was done for each species separately from the regions and then mixed fisher ies assessment was carried out. Along Andhra Pradesh, the effort leveli was found to be greater than the one yielding maximum catch in the existing fishing grounds: in northrn Tamil Nadu, scope for marginally increasing the yield by increasing the effort was indicated.In southern Tamil Nadu also, scope for increasing the yield bv increasing the effort was indicated. Regulation of cod end mesh of trawl net was also explained. 29
PART IY RESOURCES SURVEY AND MANAGEMENT 23. Resources of ornamental fishes of the Lakshadweep islands ['The resources survey was carried out by three teams covering thirteen islands. The author participated in the first team. The responsi bility of analysing the data and preparation of paper on ornamental fishes was given to the author who analysed the data and prepared the paper for publication, using the data collected by the second and third teams also;7 A In recent years, the demand for live ornamental fishes is increasing and a strong export market is developing. Though a comprehensive account of the fishes of Lakshadweep (Jones and Kumran, 1980) was published, information on spec ies available for exploitation, their relative abundance and the areas of abundance in the lagoons and reef flats of different islands was lacking. For the first time in the region, a survey was conducted during January—March 1987 in 13 islands of Lakshadweep, which resulted in collection of 139 species of ornamental fishes belonging to 33 families. Of these, it was shown, the fishes of the family Pomacentridae were the most dominant in terms of numerical abundance and number of species (22 species collected) followed by 'Labridae (21 species). Apogonidae (10 species), Mullidae (9 species), Chaetodontidae (8 species), Callyodontidae (6 species), Acanthuridae (6 species) and others. The number of species known from Lakshadweep region and the number of species comon in the area were given. The distribution and abundance of diff erent species of ornamental fishes in the reef flats and lagoons 30 during the survey period were explained and a few suggestions for rational exploitation were made.
24, Present trends in marine fisheries management and catch forecasting, [TA£ter discussion on the subject and the format of the paper, the responsibility of survey of literature, consolidation of informtion and preparation of the paper was taken by this author? The Indian marine fisheries were facing a near crisis in that, the catches from the presently exploited inshore waters reached optimal levels in respect of majority of stocks and the region beyond 50 m depth in the Exclusive \ Economic Zone which was estimated to support a potential yield of 1.7 million tonnes, was yet to be exploited commer cially. While technologies for increasing production from the seas were available and the investigations on several exploi ted stochs were carried out aiming at stock assessment, it was felt necessary to bringout a comprehensive account of the available methds of marine fisheries management and catch forecasting under the Indian context and to make suggestions on the future course of action to be taken. After describing the current marine fisheries scenario briefly, the various methods of short and long term forecasts of the yields, the management strategies and the information requirements were indicated, 31 25. complexities of management of inshore fishery resources of India. [“The author was involved in the preparation and finalisation of the paper;7 In the context of declining yields from the inshore fishing grounds along the Indian coast, the prevailing social and economic conditions of the resource users and the various complexities, controversies and conflicts among the different sectors of fishing industry in the country, the imperative need to enforce regulations and manage the fisheries was discussed. In consideration of the various issues, it was suggested that: -—- increased role might be provided to the local or regional fishing communities in the formulation of regulatory measures and their managerial responsibilities, —-—- positive access might be ensured in favour of local fishing communities, regulatory measures should be formulated with a strong conservation policy through careful regulation of fishing effort and restrictions on gears, and a system of fishing within the regional management scheme transmuting the conflict to coexistence or even symbiosis might be incorporated in the management system. 32
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1' ON SOME INTERESTING AND NEW RECORDS OF MARINE FISHES FROM' INDIA J. Mar. biol. Ass. India, I968, 10 (1): 126-132
ON SOME INTERESTING AND NEW RECORDS OF MARINE FISHES FROM I'NDIA"“
' By V. SRIRAMACHANDRA MURTY Central Marine Fisheries Research Institute, Mandapam Camp
WHILE examining the fish landings by shore seines and trawl nets at various fishing centres along the Palk Bay and Gulf of Mannar in the vicinity of Mandapam the author came across several specimens of Drepane longimana (Bloch and Schneider) which is little known and Drepane ptmctata (Linnaeus) which was recognised as the only valid species of the genus Drepane. A study of these specimens has shown that these two speciesare distinct as shown by some authors (vide Text). A brief com parative account of these two species is given in this paper, along with a few remarks and key to distinguish the two species. The author has also been able to collect specimens of Platycephalus isacanthus Cuvier from the above catches, and a single specimen of Stethojulis interrupta (Bleeker) from the inshore waters of Gulf of Mannar caught in dragnet, whose occurrence, in Indian seas, is so far not known. Brief descriptions of these two species are also given, in this paper.
Family: DREPANIDAE ~ Drepane longimana (Bloch and Schneider) This species was first described by its authors from Tra.nquebar. Cuvier and Valenciennes (1831) studied the specimens of the genus Drepane, both morphologi cally and anatomically and distinguished the two species D. longimana (Bloch and Schneider) and D. punctata (Linnaeus). Cantor (1850) also recognised the two species as valid. But subsequently Gunther (1860), Bleeker (1877) and Day (1878) recognised D. punctata only as the valid species. Lele (1924) revised the genus Drepane and established both anatomically and morphologically, the distinctness of the two species. However Weber and de Beaufort (1936) considered D. punctata as valid and relegated D. longimana -to its synonymy. Smith (1949) believed that, the Genus Drepane consists ‘ possibly two species’. I-Ierre (1953) pointed out the value of Lele‘s (op. cit.) work and stated that ‘ the dissection of numerous specimens in conjunction with a study of this paper showed that D. longimana is a valid species ’. Munro (1955) refers only to D. ptmctata without any mention of the other species. In spite of its common occurrence in trawl catches and first description from south-east coast of India and the latter revision of the genus Drepane by Lele, D. longimana is not well known especially in India. Since the species of the genus Drepane are commercially important, a brief comparative description is given along with a key to distinguish the two species. IIII ' - ._ * Published with the permission of the Director, Central Marine Fisheries Research Institute, Mandapam Camp. NEW RECORDS OF MARINE FISHES FROM INDIA 127
Thirty specimens of both males and females of D. longimana (Plate I, A ) ranging from 97-180* mm. in total _length and fifty specimens of both sexes of D. ptmctata (Plate I, B) ranging from 88-502 mm. in total length collected during November 1965 to October 1966 have been examined in this study. It has been found that sexes are alike as regards the colour pattern, external form and other anatomical characters in both the species. The specimens are deposited in the Reference Collec tion Museum of Central Marine Fisheries‘ Research Institute, D. Iongimana No. C-MFRI-F79/506 and D. punctata No. CMFRI-F79,'l88a. The meristic characters of both the species are given below. D. Iongimana,rakers14-I5. D. VIII, 21-22; A. Ill, 17-19; P 1. 17 ; P2. I, 5 ; Ll. 50-55;‘ Gill D. punctata,15-l6. D. IX, 21-22; A. III, 18-I9 _ ; P I. l7 ; P 2. I. 5; L l. 50-55, Gill rakers The most important morphological and anatomical differences between the two species, which also agree with Lele’s observations, are given in Tablel and certain body proportions in per cent of total length are presented in Table II. TABLE I , Morphological and anatomical differences between D. longimana and D. punctata Character D. longimana D. puncrata __ .___ #4 ~~- _ ' - _ __ _-11'.-.. - -i ---_-1.... — ___——» _ 4- .... _ 1,: :____—_—- -.i—-— ——~—__ _— ~ __ I. MORPHOLOGICAL (a) Dorsal spines Always 8. Always 9. Radial between first two verte- Radial between first two verte brae supports the first dorsal brae supports the first two spine only. 3rd_ spine long dorsal spines. 4th spine long CSI . 6St. (b) Colour 4-9 vertical dark bands on each Each side with 4-ll vertical side -or bands absent and rows of dark spots or with body silvery. rows of spots with underlying bands or with both rows of spots and dark bands. ' (c) Lateral line. Makes a strong upward curve. Makes a low symmetrical arch.
ANATOMICAL (0) Air-bladder. Two short anterior and two long Two short anterior and two long tubular‘ osterior horns tubular posterior horns. .About l5 pshort and variously. At each of the anterior cor branched caeca on each side ners two lateral caeca, the Three pairs of caeca on the posterior long and sends out inner margins of the posterior lateral flattened branches. A horns. pair of caeca on the inner margins of ‘the posterior horns. (b) Pyloric caeca Three. Two. (c) Liver. Bilobed, long and thin. Bilobed, short and thick. The dorsal side is produced into \ irregular prominences.
* Since the manuscript was sent to press the author examined two specimens of D. longimana from Colachel (S.W. Coast of India), measuring 277 and 360 mm., and a single specimen of the same species 2ll mm. long from Cape Comorin which agree in all details with the specimens OF the lower size range of this species studied in this work. 128 V. ' SRIRAMACHANDRA MURTY
TABLE II Body proportions of D. longimana and D. punctata in per cent of total length (Number of specimens in each case : 13) Morphometric D. longimana D- Plmffa? 11 S. N0. character Range of T. L. 97-180 mm. Range of T.L. 88-251 mm. (139.3 mm.) (147.5 mm.)
Height of body 66.00-70.75 (68.44) 65.33-75.00 (69.54) Length of head 24.32-28.88 (27.26) 24.56-30.09 (27.69) Length of caudal 21. 17-25 .77 (23.48) 21.05-26.21 (23.86) Length of Pectoral _ 42.26-49.08 (46.80) 44.80-51.39 (43.17) Diameter of eye 8.24-10.34 (8.93) 7.39-11.36 (9.25)
Parentheses indicate the mean.
From the above comparison it is clear that although the two_ species show o\fer lapping body proportions they differ strikingly in the morphologlcal and anatomleal
1 t9 O‘¢_sI._.-r 0 i "3 I 4
FIG. 1. Head of Drepane pzmctata (Linnaeus) (T.L. 133 mm.) showing the position of bafbelg characters mentioned. Based on the above diiferenees a key to distinguish the two species IS given below.
Ur:hUJl-I-— J. Mm. m0I.. Ass. ?l\m,\. X (I) V.SRIR/\IW\LiI?1ANl)RA Mumy, PL»\'lT:]
I
1
PLATE I, A. D:-eparw /
PLATE I1, Plar_vcepha1u.s" isacanrhus Cuvier. A. Lateral view [note the subopcrcular flap) B. Dorsal view of head. NEW RECORDS OF MARINE FISHES FROM INDIA 129 KEY T0 "ms SPECIES
1. Spinous dorsal with 9 spines, 4th spine longest ; vertical rows of dark spots with or without underlying black bands on sides ; pyloric caeca 2 ...... Drepane punctata 2. Spinous dorsal with 8 spines, 3rd spine longest; no dark spots ;with or without dark bands on sides ; pyloric caeca 3 ...... Drepane longimana Remarks: In this connection it may be worthwhile to mention the presence of small barbels (Fig. 1) measuring 3-5 mm in length, below the chin in both the species, which seem to have hitherto remained unnoticed by the earlier authors. These are arranged in 3-4 transverse rows ; those of the succeeding rows shorter than the preceding. In D. punctata their number varies from 2-10 and they appear to get reduced as the fish grows; and beyond 270 mm in total length, they are altogether absent. In D. Iongimana the number varies from 4-10 in all the specimens examined. The barbels are longer and thinner in D. longimana when compared to those of D. punctata. Dzlrtribution : The distribution of D. longimana extends from the west and east coasts of Africa through Red Sea, seas of Indiato Australia and that of D. puncfata from Red Sea and the east coast of Africa through seas of India to Australia.
Family : LABRIDAE Stethoujlis interfupta (Bleeker) (Fig. 2) Material : A single specimen from Gulf of Mannar near GMF RI jetty, 79 mm., deposited in the Reference Collection Museum of Central Marine Fisheries Research Institute No.I CMFRI. " F" 69/ 583.‘I .. %i§§¢»s.i",. 'gy'etsi$ '°”é;‘g,"'?"'>”4ct A IQ I » ~ " "-"1"Hi;-~ _~53.-.i'i _ " h-7',’ ” .‘-'1' ,‘.”;';f"“.’.'-f.'.'_- -7:: s,1'; ~.i‘-‘if-'_' I-LIZ:-‘—2 A* --is . ' n _,_._._,-.,-, "'.-. '- -h' ' '5'" ‘¢¢? '~i5 at Q‘ 93 0“ ’ ’__| )3}, I - \~_& _ » \ "FIG. 2. Srethojulis interrupta (Bleeker) 79 mm. ' D. IX, 11 ;A. 111, 11 ;Pl. 14 ; P2. I, s ; Ll. 28,; Ltr. 2/1/9. Height of body 3.8, length of head 2.7, length of pectoral 4.4, snout vent length 1.5 and snout to dorsal origin 2.7 in length without caudal and 4.6, 3.3, 5.6, 1.8 and 3.3 respectively in’ total length. Snout 3, eye 6 in length of head. Eye 2 in snout and 1.5 in interorbital space.
"3'
-X _\ P “Q
"t$3 is fieear \\ 3'"0 ’=§§$?1» ‘*3 \
. . ‘-3 \ I H ‘I 130 ' V. SRIRAMACHANDRA MURTY Head naked except near the occiput where the scales are small when compared to those on sides of body and scales on thorax slightly larger than those on sides of body. Mouth small, horizontal, teeth in jaws incisiviform in a single series with a well developed canine at the corner of the mouth. Lateral line continuous but bent obliquely after _the 18th scale running on two scales and thereafter runs horizon tally on 8 scales to the middle of caudal. Dorsal spines stiff and pungent. Pectoralsi about as long as head without snout. Colour: In fresh condition reddish brown above and creamy below. The body with longitudinal red colour bands on sides. A longitudinal band, beginning from nape runs closely below the base of dorsal fin to the upper caudal rays. Another from middle of snout runs backward and downward through the upper border of eye to the dorsal edge of gill opening and ends just above the dark brown spot dorsal to the pectoral fin base ; another from tip of snout extends along lower edge of eye to the preopercular border ; a short band from gill opening to upper base of pectoral and below this another band runs parallel to this from gill opening to the anterior border of pectoral, interrupted here, but continues further after five scales to the middle of caudal. A dark blotch at pectoral axil. All the colour bands turn dull white on formalin preservation. Distribution : Previously known from the Red Sea and east coast of Africa as far south as Bashee (cape province) and from Singapore, Indonesia, Coast of China, Philippines and New Guinea. The present report is the first from the central Indian Ocean.
Family: PLATYCEPHALIDAE
Platyeephalus isacanthus Cuvier (Plate II, A)
Material : Thirty specimens from Palk Bay and Gulf of Mannar in the vicinity of Mandapam ranging from 144-211 mm T.L. Two specimens deposited in the ReferenceCMFRI. Collection MuseumF. 144,/573. of Central Marine Fisheries i Research Institute No. D. IX, 12 ; A. 12.; Pl. 19-20; P 2. I, 5 ; -L l. 55-57 ; Ltr. 8-I0/1/l4-l7; Gill rakers 5-6. Head 2.9-3.1 in standard length, 3.4-3.8 in total length. Height 7.4-10.1 in standard length 8.9-12.2 in total length. Body elongate dorsal side convex and ventral side flat. Head depressed (Plate II, B) its width 1.6-1.9 in its length. Maxilla reaching to below front border of eye. Eye 4.1-5.1 in head; 1.2-1.6 in snout. The iris extending on the pupil is divided into a number of cirri. The supraorbital ridge serrated posteriorly with 6-9 small spines, the last one bigger than the preceding ones forming the beginning of the superior postorbital ridge. The superior postorbital ridge smooth ending in two small spines. The inferior postorbital ridge with 5-6 small spines, the last one somewhat larger than the others, terminating near the beginning of the lateral line. The suborbital ridge with a spine below the middle of eye, another below hind border of eye, and some times a third spine indistinct, at the base of the upper preopercular spine. Lateral line smooth, except for 4-5 anteriormost. scales provided with small spines. A well developed triangular skinny flap present on the subopercle- The first dorsal spine NEW RECORDS OF. MARINE FISI-IE-S FROM INDIA I31 about as long as eye ; the third spine longest. Pectorals rounded, length of pectoral 5.1_6-6.12 in standard length and 6.24-7.76 in total length. Ventrals not quite reaching anal. Caudal rounded. Colour: In fresh condition reddish brown dorsally, light yellow ventrally. Dorsal spines and rays with small dark spots. Pectorals with small dark spots. Caudal with dark spots on rays as well as on membrane. Sometimes three to four broad dark brown cross bands on the upper side of the body which may disappear on preservation. Distribution : The known distribution of the species extends westwards from Northern Australia and Waigeu through Philippines, Macao (South of Hong Kong) and Tourane (V iet Nam) to Singapore and the present record from the east coast of India is of interest. Day (1878) described seven species of platycephalids from the seas around India. The description of the flat head given by him under the name Platycephalus carbunculus Cuvier and'Valenciennes was found similar to that of P, carbunculus Cantor by Bleeker (1878) who described the same as a new species, P. canton‘. P. carbunculus Yalenciennes (1838) was reported from Bombay on the western coast of India, but Rao (1966) while giving a key to the known Indian.species of Platycephalus in his paper ‘ Platycephalus bengalensis sp. nov. from Bay of Bengal’ did not include P. carbunculus Valenciennes. He included P. pristfger Cuvier and" stated that it occurs in the Bay of Bengal off Waltair. Thus the number of species of Platycephalus (seven by Day including P. canton‘, P. “carbunculus Valenciennes, P. bengalensis eleven.Rao, P. pristiger Cuvier and P. isacanthus Cuvier) ' occurring in Ind_ian seas becomes
SUMMARY
The distinctness of Drepane longimana (Bloch and Schneider) is corroborated, from the study of L the specimens from Gulf of Mannar and Palk Bay. The occurrence of Stethojulis iriterrupta (Bleeker) and Platycephalus isacantkus Cuvier in the I11dian seas (from the east coast of India) is reported for the first time.
ACKNOWLEDGEMENTS The author is thankful to Dr. S. Jones, for guidance and comments, and to Dr. E. G. Silas for going through the typescript and suggesting necessary improve throughments. Thanks are also due the to Mr. K. V.N.typescript. Rao and Dr. P. S. B. R. James for' going Rarsneucns
BLEBKER, P. 1851. Bijdrage tot de kennis der ichthyologische fauna van de Banda-eilanden. Nat. Tzjdschr. Ned. Indie, 2 : 252. -———-—. 1862. Atlas Ichthyologique. 1 : I33. ———-—.Akad. 1877. Amsterdam, Revision des especes Insulindiennes 17 : 21. De I la Famile Des Chaetodontoides. Verh. 132 V. SRIRAMACHANDRA MURTY
BLEEKBR, P. 1878. Revision Des especes Insulindiennes Du Genre Platycephalus. ]bid., 19 : 1-31. BLOCH AND Scruamona. 1801. Syst. Ichrh. :229.
CANT0g49';‘.(1 . 1850. Catalogue of Malayan Fishes. J. Asiar. Soc. Bengal, 18: 1021, 1143-1145 Cuvuaa AND VALENCLENNES. 1829. Hist. Nat. Poissons, 4 : 246 Paris. " -——--. 1831. Ibid.,7: 129-136. -—---. 1833. Ibid., 9 : 461. DAY, F. 1878. The Fishes of India. 2 : 116, 274-278. Barnard Quaritch, London.
Giiugfisgé 1860. Catalogue of acanthopterygian fishes in the collection of British Museum, HERRE, A. W; C. T. 1953. Check list of Philippine fishes. Res. Rep. U.S. Fish. Wildl. Se:-v., ° 20 : 489. __ / LELE, S. H. 1924. Studies in Bombay fish. 1. Revision of the genus Drepane Cuv. 8:. Val. J. Proc. Asiar. Soc. Bengal, 20 : 274-288. ' LINNAEUS, C. 1785. Systemma narurae : 273. British Museum (N.H.) Lohdon. Muuao, [AN S. R. 1955. The Marine and Fresh Water Fishes of Ceylon : 169, Canberra. RAO, V. Vrswsswmm. 1966. Platycephalus bengalensis sp. nov. from Bay of Bengal. Ann. Mag. Nat. Hist., Ser. 13, 9 : 123-127.
SMlTH,fA rica. J. L. B. 1949. The Sea Fishes of Southern Africa: 232, Central News Agency Ltd., S. WEBER, M. AND DE BEAUFORT, L. F. 1935. The Fishes of the Indo-Australian Archipelago, 7: 180-183. Leiden. EQONTRIBLYPION 2}
MURTY, V. SRIRAMACHANDRA. 1.982. On the fishes of the family Platycephalidae of the seas around India. g_. mar. 1391. Aas. Igdia, 17 (3): 6'19-694 (1975). LC0NTRIBU'I‘ION 2
J. mar. bio! Ass. India, 1975, 17 (3): 679 — 694
ON THE FISHES OF THE FAMILY PLATYCEPI-IALIDAE OF THE SEAS AROUND INDIA*
V. SRIRAMACHANDRA MURTY**
Central Marine Fisheries Research Institute, Cochin-682 018
ABSTRACT
The fishes of the family Platycephalidaei popularly called “Flatheads” widely distri buted in the Indio-Pacific region are of some commercial importance. Thirteen species of flatheads are so far Known to occur in the Indian Seas as reported byDay (1878), Munro (I955), de Beaufort and Briggs (1962) and others. As to their taxonomy, especially at their generic level, opinions vary among ichthyologists who studied the group. In view of their fishery importance along some parts of the Indian Coastfand because of the paucity of any detailed information on the species, a comprehensive study of the group has been made, based on the collections made by the author from different parts of the Indian Coast and the material available in the Indian Museum, Calcutta. These have been compared with the descriptions of the type specimens available in the Museum National d ‘Histoire Naturelle, Paris and Rijksmuseum van Natuurlijke Historic, Leiden. Detailed descrip tions, distribution, synonymy and key to identification of genera and species of fiatheads occuring along the Indian Coast are given in this paper.
INTRODUCTION
THE Ftsnizs of the family Platycephalidae (flatheads or crocodile fishes) are dis tributedthroughout the tropical Indo-West Pacific region. Day (1878) recorded seven species from the coasts of India and Ceylon. Munro (1955) recorded eight species from Ceylon; de Beaufort and Briggs (1962) described eight species as occurring in Indian Seas. Rao (1966) described a new species from Visakhapatnam and Murty (1969 a), George (1970) and Jones and Kumaran (1971) reported one species each as new records from the Indian Seas. Some species contribute significantly to the groundfish catches especially along the southwest coast of India. As pointed out by Schultz (I960) it has been extremely diflicult to make accurate identifications 01 these fishes because the available descriptions are inadequate; the cranial ridges and spines which are shown to be taxonomically important were not given due importance. Further, there is no up-to-date comprehensive information on these fishes from Indian Seas; the available keys for identification of species are either inadequate or do not include all the known species from the region. Studies on this group from outside India include the works of Bleeker (1878), Jordan and Richardson (1908), Jordan and Hubbs (1925) and Matsubara and Ochiai (1905). "‘ Presented at the ‘Symposium on Indian Ocean and Adjacent Seas—Their Origin, Science and Resources’ held by the Marine Biological Association of India at Cochin from January 12-18, 1971. "Present address: Kakinada Research Centre of Central Marine Fisheries Research Institute, Kakinada-5 33 002. T The platyoephalids dealt with in this paper do not include members of the families Bembradidae, Bembridae and Parabembridae which have recently been incorporated in the family Platyoephalidae by Greenwood et al. (1966). [ll 680 V. SRIRAMACHANDRA MURTY
In view of the fact that the available species descriptions are inadequate and the consequent difficulty in identifying them correctly, it was felt that a detailed account of these fishes from this region giving adequate descriptions based on examination of fresh material, key for identification and their distribution, is neces sary to provide a basic reference for more comprehensive fishery biological studies of some of the species. The present study deals with thirteen species that are known to occur in the seas around India. There is considerable confusion in assigning species to their respective genera. Some authors (de Beaufort and Briggs, 1962) preferred to include all the species under the genus Platycephalus Bloch. Schultz (1960) gave a tentative key to the genera. In the present paper an attenpt is made to assign the species to their respective genera; since there are several nominal genera and the type specimens of the type species could not be examined, the present arrangement can only be treated as tentative. The author is thankful to Dr. S. Jones, former Director, Central Marine Fisheries Research Institute (CMFRI) for the encouragement and for the facilities and to Dr. E. G. Silas, Director, for going through the manuscript and olfering suggestions for its improvement; late Dr. K.V. Sekharan and Mr. S. Reuben of the CMFRI Substation, Visakhapatnam; Mr. M. S. Muthu of CMFRI unit, Kakinada and Dr. K. C. George of CMFRI, Cochin have kindly sent material from their respective areas and the author is very much obliged to them for their help. The author is also thankful to the Director, Zoological Survey of India for permitting him to examine the collections of platy cephalids in the Museum of Zoological Survey of India and to Dr.A.G.K. Menon, Superintending Zoologist, Zoological Survey of India for the help rendered. Thanks are due to Dr. J. Guibe of Museum National d’Histoire Naturelle, Paris and to Dr. Boeseman, Curator of fishes, Rijksmuseum van Natuurlijke Historic, Leiden for kindly sending data on certain Types. Dr. F. H. Talbot of the Austra lian Museum, Sydney, has kindly arranged to send some relevant literature.
MATERIAL AND METHODS
The specimens for this study were collected from Visakhapatnam, Kakinada, Madras, Pondicherry, Tuticorin and Mandapam on the east coast and Bombay, Cochin and Neendakara on the west coast. In addition to these, the collections of this family in the Zoological Survey of India, Calcutta (ZSI) and National Museum, Sri Lanka were also examined. Morphornetric and meristic data of the relevant type specimens in the Museum National d’Histoire Naturelle, Paris and Rijksmu seum van Natuurlijke Historic, Leiden also have been utilised for comparison. In taking measurements, total length (TL) was measured from tip of snout to the tip of caudal fin and Standard length (SL) from tip of snout to base of caudal fine. Head length was taken from tip of snout to the posterior margin of the operculum and head width between the bases of the upper preopercular spines of the two sides. Eye diameter is the horizontal diameter of bony orbit. L. tr. includes the count of scales from origin of first dorsal obliquely backwards to lateral line, the one in the lateral line and from origin of anal obliquely forwards to lateral line. Vertical rows of scales above lateral line are counted from above the lateral line from its origin to the end at the base of caudal fin. The nomenclature of various ridges on head is taken from Schultz (1960). No attempt has been made to include all the synonyms under each species; only the original reference and all the references
[2] PLATYCEPHALIDAE FROM SEAS AROUND INDIA 681 from the area under study are included. The species for which adequate descri ptions are available from this region, are not described in this paper. Specimens of the species collected by the author and utilised in this study have been deposited in the Reference collection Museum of the Central Marine Fisheries Research Institute (Murty, I969 b).
KEY T0 GENERA or PLATYCEPHALIDAE FROM INDIA 1. Teeth on vomer in a continuous crescent-shaped band ...... Platycephalus Bloch Teeth on vomer separated medially into two subovate patches by deep edentulous furrow ...... 2 2. Suborbital ridges finely serrate ...... 3 Suborbital ridges not finely serrate; with distant spines or entirely smooth ...... 4 3. Preopercle with strong antrorse spine on lower side ...... Rogadz'us Jordan and Richardson No antrorse preopercular spine, preocular with 2-3 spines ...... Wakiyus Jordan and Hubbs 4. Eye with a dermal cirrus (tentacle) ...... Thysan0phrys Ogilby Eye without a dermal cirrus ...... 5 5. All lateral line scales spiny ...... Gramnoplires Fowler Only first few scales or anterior half of lateral line spiny ...... Suggrundus Whitly Genus: Platycephalus Bloch 1975 Platycephalus Bloch (1795). Nat. Ausland Fische, 9: 76 (Type species : Platycephalus spathula Bloch = Callionymus indicus Linnaeus). Platyeephalus indicus (Linnaeus) Callionymus indicus Linnaeus (1758). S_vst. Nat. ed. ,l0: 250. Platycephalus insidiator Day (1878). Fish. India, 276. Thysanophrys indicus Munro (1955). Marine and freshwater fishes of Ceylon, 253. Misra, (1962). Rec. Indian Mus., 57:304. Platycephalus indicus de Beaufort and Briggs (1962). Fish. Indo-Ausr. Archipel., ll. Material examined: 1 specimen 363 mm from Tuticorin (Gulf of Mannar); 4 specimens 191,207,243, 312 mm from Mandapam iPa1k Bay); 2 specimens 156, 188 mm from Athankarai Estuary (Palk Bay) l specimen 362 mm from Madras (Day’s collection) ZSI No. ll2—115; 1 specimen 180 mm from Chilka Lake ZSI F. 11086/1; 4 specimens 216, 166, 373, 386 mm from Akyab, ZSI Dup. Cat. Nos. 47, 272, 398, and F. 1510/ 1; l specimen 215 mm from Burma ZSI F. 12079/1; 1 specimen 175 mm from Namkhana ZSI F. 4981/2; 1 specimen 175 mm from Philippines, ZSI F. 4222/2. Description: D. IX, l3;A. 13; l8~l9; V. 1, 5; Ll. pored 61-74; Vertical rows of scales above lateral line 105-136; L. tr. ll-15/1/25-38; G. R. 2 +1 + 5.
[31 682 V. SRIRAMACHANDRA MURTY Head 3.04-3.85 in SL, 3.50-4.02 in TL, body depth 9.17-17.18 in SL, 10.58-19.63 in TL. head width 1.24-1.63 in its length. Eye 5.00-8.08 in head; 1.37-2.25 in snout, head strongly compressed, maxilla reaches to below middle of eye. Interorbital space rather flat and wide, 0.62-1.26 times wider than eye diameter. Teeth villi form, those on upper jaw at the symphysial region pointed, in a cresent shaped band on vomer and in two narrow longitudinal bands on palatines; some on vomer and palatines slightly pointed (on vomer the pointed teeth are at the end of the crescent). Ridges between nostrils smooth, run parallel backwards up to middle of interorbital space. A short but strong spine on anterior orbital rim. Supraorbital ridge completely smooth, superior postorbital ridge also smooth, but in large specimens with single spine posteriorly; inferior postorbital ridge with a spine anteriorly and with two to four spines posteriorly, last one longer and in line with lateral line. Suborbital ridge, smooth sometimes with single spine below hind border of eye. Two strong sub equal preopercular spines, upper one at an angle to suborbital ridge. Opercular ridges flat and smooth, lower ridge not very prominent. A prominent triangular subopercular flap present. Head completely scaly. First lateral line scale keeled. First dorsal spine short, second and third spines more or less of same length, nineth spine not connected with eighth one; first ray of soft dorsal longest. Pectoral more or less rounded, 6.00 to 7.31 in SL; 6.92-8.31 in TL. Pelvic sometimes reaches anal origin; 4.83-5.90 in SL; 5.80-6.75 in TL. Caudal truncate. Colour: Brown above and pale yellow below. Sometimes two cross bands on posterior dorsal side. Pectoral, pelvic and dorsal fins spotted. Caudal yello wish with two oblique black bands with white borders. Distribution: Extends westwards from coasts of New Guinea, Philippines, seas of Japan, through Celebes, Borneo, Java, Sumatra, Burma, Andaman Coasts of India, and Sri Lanka to east coast of Africa and the Red sea. Remarks: Cantor (1850) and Matsubara and Ochjai (1955) reported ten dorsal spines in this species and according to them first spine is very small or rudimentary and hidden. All other authors have reported only eight spines in first dorsal fin. In all the present specimens the author counted only nine spines. First rudimentary (Cantor, 1850) or isolated reclining spine (Matsubara and Ochiai, 1955), however, could not be seen even with a lens.
Genus: Rogadius Jordan and Richardson Rogadius Jordan and Richardson, 1908. Proc. U. S. Nat. Mus., 33:630. Type species: Platycepbalus asper Cuvier.
f Rogadius pristiger (Cuvier) (Pl. I) Platycephalus prisriger Cuvier (1829). Hist. nat. Poiss., 4:260; de Beaufort and Briggs (1962). Fish. Indo-Ausrer. Archipel., 11:139-140. -Regadius asper Munro (1955). Marine and freshwater fishes of Ceylon. 251. (nec. Cuvier) Material exemined:2 specimens 105 and 111 mm SL from Sri Lanka (collected at-34 fathoms) ZSI No. 11745; 3 specimens 97, 102 and 118 mm SL from off Ganjam Coast (Bay of Bengal) ZSI Nos. 12951, 12952, 12953; 1 specimen 56 mm SL from Andaman Sea (6 m) ZSI No. F. 424/2; l specimen 58 mm SL from Nicobar Island; ZSI No. F. 424/2; and 2 specimens 94 and 105 mm SL from Andaman Sea, ZSI F. 81211 and 813/l.
[4] PLATYCEPHALIDAE FROM SEAS AROUND INDIA "683
Description.‘ D. IX, ll; A. ll; p. l9-23; V. I, 5; Ll pored 52-54, vetical rows of scales above lateral line 54-58; L. tr. 6-7/1 /20-21; G. R. 1 + 1 -3- 5-6. Body depth 5,6-6.9, head 2.5-2.6 in SL. Head width 1.6-1.9, eye diameter 3.0 3.5 in head length, eye 1.0-l.l in snout. Body width at the insertion of pelvics 5.00-5.60 in SL. Teeth in jaws villiform, on vomer in two distinct oval patches, on palatines in two narrow bands. Teeth on vomer and palatines pointed. Anterior nostril with a flap. Interorbital space narrow, 5.0-7.0 in eye diameter. Two completely serrated longitudinal parallel ridges between nostrils on both sides. A strong spine on anterior orbital rim. Supraorbital ridge smooth anteriorly, serrated posteriorly and continued to behind eye as superior postorbital ridge which also serrated ending in two spines. Anterior portion of inferior postorbital ridge serrated, posterior portion with two to three strong spines, last one in line with beginning of‘ lateral line; suborbital ridge completely serrated ending in a long pre opercular spine. Three to four spines below upper preopercular spine and a strong antrorse spine below. Opercle with two smooth ridges each ending in a spine. Opercle and preopercle with ctenoid scales. Lateral line smooth excepting anterior 4-6 scales which are spiny. First dorsal spine small, third spine longest equal to postorbital part of head. Pectoral rounded; pelvics reach anal origin. Colour: Specimens preserved in alcohol brown above, light below. Spinous dorsal dark on distal. half; rays of soft dorsal with faint longitudinal rows of spots. Pectorals with dark spots, pelvics and caudal dusky. Cross bands on body not clear. Distribution.‘ Known from Queensland, New Guinea, Philippines, Indonesia (Batjan), Ternate, Menado, Makassar, Lombok, Bali and Singapore in the Pacific; Andamans Islands, Sri Lanka, Visakhapatnam and Ganjam Coast (Bay of Bengal), Seychelles, Gulf of Oman and Gulf of Aden in the Indian Ocean. g Remarks: This species was described by "Cuvier (1829) from Sri Lanka; Day (I878) did not include this species. To date there has not been published account of this species from the Indian Coasts except for a mention by Rao (1966). Hence the present description of this species happens to be the first from the Indian Coast. '.-v'-_ Genus: Wakiyus ' Jordan and Hubbs, 1925 'osWakiyrls Tmm'k Jordan and Hubbs dShleel). (1925). Mem. carnegz'e'Mus., l0:286 (Type species :PIatycephalus spmSorsogona Herreus (I934). _e= Fish. Zool. Mus.mc Stanford an Um'y., 1:67c (Typeg species_ Sorsogona serrulata Herre = Platycephalus tuberculatus Cuvier). KEY TO Smacnzs. or Genus. WAKIYUS _I FROM INDIA1. I D. IX, ll; A. ll-12; ridges of head finely serrated, 21-22 anterior scales of lateral_ lineI spinyI ...... 1. .... _ ...... - ...... _ ...... W.'_ tubercu-Iatus (Cuvier) __ D,‘ IX‘, 12; A. I2; headridgesserrated butdestitute of spinesjionly 3-5 scales of the lateral line spiny ...... W. serrgatus (Cuvier) .'.Wak_iyus tuberculatns (Cuvier 1329) (Pl. 11 SA, B) Platdvcephalus tuberculatizs Cuvier (I829). Hist. nat. ..P0iss., 4; 258-259; Day (1878). Fish. India,Misra, 275; (1962). de Beaufort Rec. and Briggs Indian ( 1962). Mus, Fish. 57:304.Indo-Aust. Archipel.,' - -' ' 11:l42-1432
[51 684 V. SRIRAMACHANDRA MURTY
Sorsogona serrulata Herre (1834). 67. Suggrundus tuberculatus: Munro (1955). Marine and freshwater fishes of Ceylon, 252. Material examined: 21 specimens ranging from 51-125 mm from Palk Bay and Gulf of Mannar near Mandapam; 3 specimens 105-124 mm from Madras; 3 specimens 72-81 mm from Pondicherry; 1 specimen 135 mm from Madras, ZSI No. 1856 (Day’s collection); l specimen (length not recorded) ZSI No. 1857 Day’s collection; and I specimen 94mm from Sri Lanka, Ceylon National Museum No. F.M.94. Description: D. IX, 11; A. 11-12; P. 19-21; 6; vertical rows of scales above lateral line 53-59; L. tr. 5,! 1/ 1 -6. Body depth 6.1-8.0 in SL, 7.2-9.6 in TL. Head 2.5-2.9 in SL, 3.11-3-46 in TL. Head width 1.35-1.77 in its length. Eye 3.37-4.40 in head, 1.00-1.40 in snout Inter orbital space 3.2-5.0 in eye. Anterior nostril with aflap. Villiform teeth in jaws; in two oval patches on vomer and in two elongate bands on palatine. Some teeth on vomer and palatines pointed. Two longitudinal serrated ridges between nostrils. Two to four spines on anterior orbital rim; Supraorbital ridge completely serrated. Superior and inferior postorbital ridges denticulated former with last two spines slightly elongate and ending at origin of lateraline. Suborbital ridge finely serrate ending at base of strong preopercular spine which is short and not reached gill opening. Two to three smaller spines below upper preopercular spine. Lower opercular ridge finely serrated ending in a spine. 21-22 anterior scales of lateral line spiny. Opercle and preopercle scaly, rest of head naked. Some scales on opercle and preopercle tuberculate and small. First dorsal spine short, third spine longest as long as or just shorter than second ray of soft dorsal. Pectoral rounded, pelvics reach anal. Colour .- Brown above, light below. 2-5 broad transverse bands on upper side, region between pelvics and at anal origin pigmented black. Dorsal spines and rays with back spots. Pectorals and pelvics with black bands. Caudal black. Distribution : Red Sea, coast of Natal, coasts of India, Singapore, Philippines and Queensland. Remarks: Cuvier (1829) stated “La lingne laterale est presque aussi epineuse qu au scaber” but unlike in scaber the type of tuberculatus in the Paris Museum has only 25 spiny scales in lateral line, and in present specimens only anterior 21-22 scales of lateral line are spiny. Cuvier (1829) gave a dorsal fin count of D. 9-1/11 and Day (1878) gave it as 1/7-8/1 1-12, but in all the specimens examined (including those of Day in the Indian Museum) the present author could count only 9 spines and 11 rays. De Beaufort and Briggs (1962) considered Sersogona serrulata Herre as a doubtful synonym of tubercularus Cuvier. In the present description it is consi dered as a synonym of W. tuberculatus. Schultz (1960) recognised Sorsogona Herre as a valid genus with S. serrulata as its type. However, since there are 2-4 preocular spines and suborbital ridge completely serrated in tubercuIatus——the chara cters of Wakiyus Jordan and Hubbs (1925), genus Sorsogona Herre is considered as asynonym of Wakiyus Jordan and Hubbs. Ridge of lower opercular spine dis tinctly serrated in tuberculatus. This character also found in serratus belonging to Wakiyus; in rodericensis which is assigned to genus Suggrundus Whitly here, the
[6]
‘-”.<115 053-‘ Q8‘ Fug *0 T9. +8. |-Akh +01‘P U1 PLATYCEPHALIDAE FROM SEAS AROUND INDIA 685 author found this ridge spiny at least anteriorly. Hence it is felt that this character does not provide a ‘decided gap’ (Mayr, 1969) of generic significance. Wakiyus serratus (Cuvier 1829)
PlatyceplhalusBer in. serratus Cuvier (1829). Hist. nat. P0iss., 4:259-260; Peters (1876). Akad. Wiss. M0natsb., 839 (1876); Day (1878), Fish. India, 276. Sziggrundus serralus: Munro (1955). Marine and freshwater fishes of Ceylon, 252. Material examined: 6 specimens 115-124 mm from Laccadive Sea ZSI F. 896/1; 901/1-904/l and F. 906/1. Description: D. IX, 12; A. 12; P. 19-20; V. 1, 5; Ll pored 42-50; vertical rows of scales above lateral line 55-65; L. tr. 6/1/17-19; G. R. 1+1 +7—8. Body depth 5.8-6.7 in SL, 6.6-8.8 in TL. Head 2.6-2.7 in SL, 3.0-3.2 in TL. Head width 1.8-1.9 in its length. Eye 3.3-3.9 in head and equal to snout. Interor bital space 2.7-3.5 in eye diameter. Body subcylindrical and head depressed. Teeth in jaws villiform, a few pointed; those on vomer slightly pointed and curved, arranged in two oval patches; similar teeth on palatines in two longitudinal banks. Two longitudinal serrated ridges on either side of median line between nostrils, which extend back to interorbital space. Anterior orbital rim elevated, preocular with two to three spines. Supraorbital ridge and superior postorbital ridge serrated completely the latter ending in a spine. Inferior postorbital ridge serrated with two moderate spines posteriorly at beginning of lateral line. Suborbital ridge serrated completely ending at beginning of strong preopercular spine which is 1.9-2.2 in eye; 3 moderate spines below upper preopercular spine, no trace of an antrorse spine below. All serrated ridges are destitute of spines. Anterior part of lower opercular ridge serrated, posterior part smooth ending in a spine; upper ridge com pletely smooth. Opercle and preopercle scaly. First dorsal spine short 1.3-1.6 in eye; third spine longest and 2.2-2.3 in head. Lateral line smooth except first 3-5 scales which are spiny. Colour: Specimens preserved in alcohol - body brown above and light below; spinous dorsal with a dark blotch; second dorsal with dark spots on rays. Pectorals with dark irregular spots on rays; pelvics dark. Distribution.‘ First described from Sri Lanka (Trincomale) and subsequently recorded from New Ireland. The present description from the Laccadive Sea is first from the seas around India. Remarks: Cuvier (1829) described this species from east coast of Sri Lanka and subsequently Peters (1876) reported it from New Ireland. There does not seem to be any other authentic record of this species from anywhere else. De Beau fort and Briggs (1962) did not include this species. None of the available descri ptions is adequate for correct identification of the species. The present specimens conform the description of Cuvier (1829) except that -according to him there are ll rays in anal fin whereas in all present specimens there are 12 rays. It appears that Cuvier had a doubt with regard to the presence of at least very small antrorse preopercular spine but in present specimens there is no trace of such a spine.
[7] 686 V. SRIRAMACHANDRA MU RTY
Genus: Thysanophrys Ogilby, 1889 Thysanophrys Ogilby (1889). Proc. Linn. Soc. N. S. W., 23; 40. (Type species: Platycephalus cirronasus Richardson).
KEY TO SPECIES or Genus THYSANOPHR YS FROM INDIA Anterior part of the supraorbital ridge smooth, posterior portion serrated; vertical rows of scales above lateral line 82-97 ...... T. carbunculus" supraorbital ridge completly serrated; vertical rows of scales above lateral lines about 68 ...... T. canton‘.
Thysanophrys carbunculus (Valenciennes) (Pl. lI C) Platycephalus carbunculus Valenciennes (1833). Hist. nat. P0iss., 9: 461; De Beaufort and Briggs (1962). Fish. Indo-Australian Archipe1., ll. Suggrundus carbunculus: Munro (1955). Illarinc and freshwater fishes of Ceylon, 253. Material examined: 13 specimens 82-162 mm from Pall<' Bay and Gulf of Mannar near Mandapam; 1 specimen 102 mm from Bay of Bengal, ZSI F. 421 /1; 6 specimens 77-139 mm SL from Arakan Coast (Burma), ZSI cat. 123. Description: D. IX, ll-12; A. 12-13; P. 18-19; V. I. 5; Ll pored 51-55; vertical. rows of scales above lateral line 82-97; L. tr. 9-ll/1/25-29; G. R. l+l+3-4. Body depth 7.0-9.6 in SL; 9.1-10.1 in TL. Head 2.8-3.2 in SL; 3.4-3.9 in TL. Eye 3.4-4.2 head; 1.0-1.1 in snout. Teeth villiform, in two distinct oval patches on vomer, in two narrow bands on palatines. Maxillary reaches to below anterior border of pupil. Anterior nostril with a flap. A ridge on either side of median line between nostrils, bearing 1-2 spines. Anterior orbital rim with a shorl spine. Supraorbital ridge smooth anteriorly and serrated from above anterior border of pupil, serrations more prominent posteriorly; superior postorbital ridge with 3-4 spines, last one generally at a distance from others and slightly longer; inferior post orbital ridge with 5-6 spines, last one longer than others and in line with lateral line. Suborbital ridge with a spine at its beginning, one or two below middle of eye and three to four spines behind this, last one at the base of upper preopercular spine which is short, not reaching gill opening. Two small spines below upper preopercular spine. Opercle with two smooth ridges ending in spines. Opercle and preopercle scaly. A small simple tentacle on eye above middle of pupil. Lateral line smooth except for anterior 2-4 spiny scales. Subopercular flap not prominent. First dorsal spine small, 2.00-2.30 in eye, third spine longest and equal to or slightly smaller than.postorbital part of head. Pectoral rounded, 4.7-5.6 in SL; 5.7-6.7 in TL. Pelvics reach anal, 4.2-4.7 in SL; 5.1-5.6 in TL. Caudal rounded. Colour: Body dark brown above and white below. F our broad dark brown bands on dorsal side: one near posterior end of spinous dorsal, another near beginn ing of second dorsal; third near posterior end of second dorsal and fourth one on caudal peduncle. These bands extend to sides also but divided into irregular blotches there. Two cross bands from eye over check, posterior broader than anter ior, another band from preopercular angle below. Spinuous dorsal with abroad brown band distally; second dorsal and anal rays with brown spots. Pectoral with small spots on iays forming irregular crossbands. Pelvics with three or four rows of spots on rays and caudal with 4 cross bands.
[31 J. MAR. BIOL. Ass. INDIA, 1975, I7 (3) V. SRIRAMACHANDRA MURTY, PLATE I
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PLATE ll A. Wakiyus tuberculatus (Cuvier) - lateral view, B. W. tubercuiatus — dorsal 'view of head and C. Thysanophrys carbunculus (Valenciennes) — lateral view.
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PLATE IV A. Suggrundus isacfam‘/zu.s' (Cuvieri) — lateral view, B. S. isacanthus — dorsal view of lhéad, C. S. bengalensis (Rao) —lateral view and D. S. benaglensis ~ dorsal view of head.
_- -.. 4 -»-o-aw H “0QQ~¢-¢vv PLATYCEPHALIDAE FROM SEAS AROUND INDIA 687
Distribution: Known from Singapore, Bintang, Banka, Java, Borneo, Celebes, Aru Islands, Tonkin and Bombay. Remarks: Valenciennes (1833) first described this species from Bombay. So far there is no other report of this species from Indian Coast; present report is the first from Bay of Bengal and south east coast of India. Also this happens to be the first record for coast of Burma (ZSI Cat. 123.) Of twenty specimens of this species examined only two specimens (199 mm SL from Arakan Coast,and 115 mm SL from Mandapam) have 13 rays in the anal and one specimen (137 mm SL from Mandapam) has 12 rays in the second dorsal which are different from counts given by Valenciennes for this species (D. IX, ll; A. 12). None of the authors gave any range for these counts, but for Bleeker (I878) who gave “ll (l2)” and “l2 (l3)” for second dorsal and anal respectively. However, present specimens agree with carbunculus Valenciennes in all other essential characters.
De Beaufort and Briggs (1962) did not include carbuncuius described by Munro (1955) under synonmy of this species. The description given by Munro is inade quate to come to any conclusion since it does nct give the essential characters: tentacle on eye, serrations on head ridges, etc.
Thysanophrys cantori Bleeker Plarycephalas canrori Bleeker, (1878). Verh Akad. Amsterdam (Revision Platycephalusj, .19:26. De Beaufort and Briggs. Fish. Indo-Australia Arc/n'peI., ll :l49-151. Platycephalus carbunculus: Cantor, 1849. J. Asiatic Soc. Bengal, 18: 1021; 1850. Valen ciennes Day (1878). Fish. India. 278 nec. Valenciennes. Piatycephalus malabaricus: Gunther. Cat. Br. Mus, II: 181 (proparte) (nee. Cuvier). Plarycephalus carbunculus described by Cantor (1850) from Pinang was con sidered as a new species P. cantori by Bleeker (1878). Day (1878) followed Cantor in giving the description of what he called P. carbunculus Cuvier and \/alcnciennes and gave the distribution of this species as western coast of India to Malay Archi pelago. De Beaufort and Briggs (1962) in a note under the description of P. canton‘ remarked that “It is not known whether Day saw the specimens of what he called carbunculus but his description resembles that of carbunculus of Cantor and hence referable to cantori.” They gave the distribution for this species as western coast of India, Madras and Pinnang. The present author could not collect at least one specimen of this species from the Indian Coasts. It is possible that Day (1878) followed Cantor (1850) for the description of carbunculus and that on the basis of the report of carbunculus by Valenciennes from Bombay and that of Cantor from Pinang, gave the distribution as western coast of India to Malay Archipelago for his Carbunculus There is however no authentic report of canton‘ from India and its occurrence in the area is doubtful especially since “it is not known whether Day saw specimens of what he called carbunculus”. Hence the occurrence of camori from India needs confirma tion.
Genus: Grammoplites Fowler, 1904 Grammoplites Fowler, 1904. J. Acad. nat. Sci. Philadelphia, 12:550. (Type species: Cotrus scaber Linnaeus).
[9] 688 V. SRIRAMACHANDRA MURTY
KEY ro SPECIES OF Grsrvus GRAMMOPLITES FROM INDIA Upper preopercular spine long and strong reaching to gill opening; a black blotch posteriorly on the distal half of the spinous dorsal between 6th and 9th spines; the spines on the lateral line not very prominent especially posteriorly ...... Grammoplites maculipinna (Regan) Upper preopercular spine short not reaching gill opening, the distal half of spinous dorsal completely dark; the spines on the lateral line very prominent more so posteriorly ...... Grammoplites scaber (Linnaeus) Grammoplites maculipinna (Regan) 1905 Platycephalus maculipinna Regan, 1905. J. Bombay nat. Hist. S0c., 16: 318-324; George, 1970. J. mar. biol. Ass. India, 10: 355-356. Thysancphrys scaber: Flower, 1928. J. Bombay nat. Hist. S0c., 33: 117. Material examined: 12 specimens 175-270 mm from Neendakara (Kerala Coast); 2 specimens 127 and 175 mm from Bombay 1 specimen 240 mm from Alleppey Coast, ZSI F. 5352/2. Description .' D. IX, 12-13; A. 13; P. 21-23; V. 1, 5; Ll pored 53-56; vertical rows of scales above lateral line 91-101; L. tr. 10-11/1/31-38; G. R. 1+1 —i—6—7. George (1970) gave a detailed description of this species. Remarks: The specimens examined conform to the original description by Reagan (1905) in all characters; in only one specimen (175 mm from Bombay) the soft dorsal has 13 rays as against the count given by Regan (12) and in all the specimens examined by the present author. Distribution : From Muscat (Gulf of Oman) through Bombay to Kerala Coast. Grammoplites scaber Linnaeus (Pl. HI A, B) Cottus scaber Linnaeus (1785). Syst. nat., ed. 10, 264. Platycephalus scaber Day (1878). Fish. India, 275; De Beaufort and Briggs 1962. Fish. lndo-Aust. Archipel, ll: 140-142. Grammoplites scaber Munro (1955). Marine and fresh-water fishes of Ceylon, 251. Material examined: 10 specimens 105-182 mm from Palk Bay and Gulf of Mannar near Mandapam; 4 specimens 127-280 mm from Neendakara (Arabian Sea); 2 specimens 137, 180 mm from Madras; 2 specimens 152, 161 mm from Laccadives, ZSI F. 898/ 1, and 899/ 1 ; 3 specimens from Madras, ZSI 1858; ZSI 1852 55 (Day’s collection); ZSI 1181/2 from Karaikal; ZSI F. 5146/2 from Cochin; ZSI F. 2208/1, 2210/ 1 from Orissa Coast; ZSI F. 532/2 from river Hooghly; ZSI 9121 from Pinang; ZSI 11217 from Orissa Coast; ZSI F. 1180/2 from Sankuppam and ZSI F. 1183/2 from Karaikal. Description: D. IX, 12; A. 12-13; P. 19-22; V. I, 5; Ll pored 52-55; vertical rows of scales above lateral line 99-108; L. tr. 10-11/1/29-32; G. R. 1+l+4-6. Body depth 9.33-13-87 in SL, 10.55-15.87 in TL. Length of head 2.97-3.42 in SL, 3.42-3.96 in TL. Head width 1.66-2.31 in its length; eye diameter 4.14 5.38 in head, 1-12-1.57 in snout. Interorbital space 1.80-3.50 in eye. Maxillary
[10] PLATYCEPHALIDAE FROM SEAS AROUND INDIA 689 reaches to below middle of eye; anterior nostril with a flap. Teeth villiform in two distinct oval patches on vomer and in two elongate bands on platines. Ridges between anterior nostrils with a spine on each, between these two ridges from pos terior part, two smooth ridges extend parallel upto anterior part of interorbital. A strong pointed spine on anterior orbital rim. Supraorbital ridge smooth in its anterior half, serrated posteriorly and continued as fan-like diverging low ridges, central one forming superior postorbital ridge which has 3-6 spines. Inferior postor bital ridge with 5 spines at its beginning; 3 spines below anterior half of eye, one spine below middle of eye, one spine below posterior border of eye and 2-3 spines behind it, last one at base of upper preopercular spine which is short and does not reach gill opening, 1.16-2.50 in eye and 6.16-10.00 in head length; two small spines below it. Opercle with two smooth ridges ending in spines. Opercle and pre opercle scaly. First dorsal spine small, third spine longest and equal to or slightly smaller than first ray of second dorsal. Height of anal slightly less than that of second dorsal. Pectorals rounded 6.93-8.51 in SL, 7.93-9.65 in TL. Pelvics 4.94 5.68 in SL, 5.58-6.56 in TL. Caudal rounded. Lateral line completely spiny, spines strong and very prominent posteriorly. Colour: Brown above and light below, about 4 dark vertical bands on dorsal side which extend to sides also. First dorsal with minute dark spots and black on distal half. Second dorsal, anal, caudal and pectoral with small spots; pelvic dark with minute black pigment spots. Distribution: Coasts oi Natal and Zululand, Madagascar, Reunion, coasts of India, Sri Lanka, Singapore, Sumatra, Nais, Banka, Java, Borneo, Celebes and Sulu Islands. Enters estuaries also.
Genus: Suggruntlus Whitly Suggrundus Whitly (1930). Mem. Queesland Mus., 10:26 (Type species: Platycephalus rudis Gunther = Platycephalus meerdervoorti Bleeker). KEY TO Sracnas or Genus Suacxwvovs rnou INDIA
18-24 anterior scales of lateral line spiny ...... Suggrundus rodericensis (Cuvier) Only 3-5 anterior scales of lateral line spiny vertical rows of scales above lateral line 62-67. D. IX, 11; suborbital ridge with 4-6 spines ...... Suggrundus malayanus (Bleeker) D. IX, 12; suborbital ridge with 3 spines ...... Suggrundus isacanthus (Cuvier) Vertical rows of scales above lateral line 72-81, no black spots on body, D. IX, ll; A. 12 ...... Suggrundus bengalensis (Rao) Vertical rows of scales above lateral line 92-109, several black spots on head and body, D. IX, 11-12; A. ll ...... Suggrundus crocodilus (Tilesius) Suggrundus roderieensis (Cuvier) (Pl. III C, D) Plarycephalus rodericensis Cuvier (1829). Hist. nat. Poiss., 4:253. De Beaufort and Briggs (1962). Fish. lndo-Asutralian Arch:'peI., 11:144-145. Platycephalus timori’ensz's Cuvier (1829). Hist. mt. Poiss., 4:254. Platycephalus macracanthus Bleeker (1878). Verb. Akad. Amsterdam, 19, (Revision Platycephalus); 22-23. Day (I 878). Fish. India, 276.
[111 690 V. SRIRAMACHANDRA MURTY
Platycephaius scaber Gunther (1868). Cat. Br. Mus, 2: 187 (nee. Linnaeus). Thysanophrys macracamhus Fowler (1929). J. Bombay nat. Hist. S0c., 33 :1 17." Suggrundus macracanthus Munro (1955). Marine and Freshwater fishes of Ceylon, 252 Material examined: 9 specimens 184-212 mm from Visakhapatnam; 6 spe cimens 130-183 mm from Kakinada; 10 specimens 100-188 mm from Madras; 1 specimens 155 mm from Madras, ZSI F, 2351/2; 1 specimen 156 mm SL from Karachi, ZSI F. 422/2 and 1 specimen 160 mm from Porto No'vo, ZSI F. 1179/2. Description: D. IX, 12-1.3; A. 12-13; P. 21-23, V. I. 5; Ll pored 51-57; Vertical rows of scales above lateral line 78-93; L. tr. 7-l0/ 1/ 17-20; G. R. l+l+5-7. Body depth 7.50-10.85 in SL, 8.85-12.57 in TL. Head 2.86-3.68 in SL, 3.40 4.3l in TL. Width of head 1.09-1.85 in its length. Eye 3.15-4.54 in head, 1.11 l.27 in snout. Interorbital 2.33-3.76 in eye. Maxillary reaches to below anterior part of eye. Teeth villiform in two oval patches on vomer and in two elongate bands on palatines. Two spines one on either side of median line between anterior nostrils. A strong spine on anterior orbital rim. Supraorbital ridge smooth anteriorly with 4-5 spines on posterior portion. Superior postorbital ridge with two spines, one immediately behind eye and another at end of ridge. Inferior postorbital ridge with 4-5 spines. Suborbital ridge with a spine at beginning, one below middle of eye and 2-4 behind this ending at base of long and strong preoper cular spine which reaches gill opening. Two short spines below longest preoper cular spine. Inferior opercular ridge with 4-5 spines anteriorly, remaining portion smooth ending in a spine. A triangular skin flap on subopercle. Head com pletely rugose, with scales on opercle and preopercle; otherwise head naked. 18-24 scales of lateral line spiny. First dorsal spine short; thirds spine longest as long as or slightly longer than longest ray of the second dorsal. Pectorals rounded 6.58 7.63 in SL; 7.64-9.09 in TL. Pelvics 4.68-5.72 in SL; 5.48-6.45 in TL. Caudal more or less rounded. Colour: Body dark brown above» and light below. Four faint cross bands one near posterior region of spinous dorsal another near middle of second dorsal, a band near posterior side of second dorsal and a band on caudal peduncle. Spinous dorsal dark with small scattered black spots. Second dorsal with black spots on rays. Pectoral black with small spots on rays. Pelvics dusf v, anal pale, caudal black. Distribution: Reunion, coats of India, Sri Lanka, Singapore, Ambon, Timor, Sulu Islands, Philippines and Formosa. Remarks: Of 28 specimens examined, in only two of them (ZSI F. 2351/2 and 1179/2) there are 13 rays in the second dorsal fin. Type specimens of roderi censis, timoriensis and macracanthus have 0111)? 12 rays in second dorsal; all authors gave 12 rays consistantly for rodericensis. i'In two other specimens of rodericensis examined (196 and 202 mm from Visakhapatnam) there are 13 rays in anal whereas description and type specimens of rodericensis and timoriensis show only twelve rays. Type specimen of macracanthus, however, seems to have 13 rays in anal as also given by De Beaufort and Briggs (1962). ‘ '
Suggrlmdus malayanus (Bleeker) l853_.-, Platycephalus malayanus Bleeker (1853). Not. Tij. Ned. Indie, 5:498. 'Verh. Akad. Amsterdam, 19:27-28; 1879. Atlas Ich1h., 9, tab, 419, fig. 2. De Beaufort-and Briggs (1962). Fish. lndo-Aust. ArchipeI., .11 : 152-153; Jones and Kumaran, 1971. J.-mar. biol. Ass India, 12:187-196.
[121 PLATYCEPHALIDAE FROM SEAS AROUND INDIA 691
Material examined: 9 specimens 64-169 mm from Kavarathi (Laccadives). Description: D. IX, 11; A. 12; V. I, 5; Ll pored 52-56; vertical rows of scales above lateral line 62-67; L. tr. 8/l/28; G. R. I + 1 + 4-5. The description is given by Jones and Kumaran (1971). Distribution: Known from Queensland, New Guinea, Banda, Ambon, Philippines, Borneo and Java in the Pacific and from Padang (Sumatra) and Lacca dives in the Indian Ocean.
Suggrundus isacanthus (Cuvier) 1829 (Pl. IV A, B) Platycephalus isacanthus (Cuvier, 1829). Hist. nat. Poiss., 4:246; Murty (1968). J. mar. biol. Ass. India, 10(1): 126-132. Material examined: 30 specimens ranging from 144-211 mm from Palk Bay and Gulf of Mannar on the southeast coast of India. Description: D. IX, 12; A. 12; P. 19-20; v. 1,5; Ll pored 55-57; L. tr. s-10/1/ 14-17;G.R.l +1+ 3-4. Distribution: West wards from Northern Australia and Waigeu through Philippines, Macao (south of Hong Kong) and Tourane (Vietnam) to Singapore and further west wards to the southeast coast of India (Mandapam). Suggrlmdus bengalensis (Rao) 1966 (Pl. IV c, D) Platycephalus bengalensis (Rao, 1966). Arm. Mag. nat. His., Ser. 13; 9:123-127. Material examined: 25 specimens 123-194 mm from Visakhapatnam and Kakinada I specimen 141 mm from Madras, 2 specimen (caudal fin broken) 89 mm S.L. from Tannesse rim Coast of Burma. Description: The following meristic data were taken (Table 1). CharacterTABLE 1. Meristic data ofLocalities specimens from diflerent localities I H Visakhapatnam Madras Burma and Kakinada PelvicfinAnalPectoralDorsalfin finIX, fin 1, 11 19-20I2 5IX, 1, 1211 519 IX, 1, I219 ll5 L1Vertical poredrows of scales above54-57 lateral line 53 77-83 5381 81
Distribution: First recorded from Visakhapatnam. The present report extends the distribution southward to Madras and eastward to the Tanasserim Coast of Burma.
Remarks: The specimen of this species in the collections of Zoological Survey of India contains a label with the following details: Platycephalus malayanus
[13] 692 V. SRIRAMACHANDRA MURTY F. 423/2 off Tenasserim Coast of Burma “Endeavour” (Indian Survey) Sta. No. 396; 9-11-1911. Rao (1966) described this species for the first time on the basis of his collections from Visakhapatnam. Although the specimen from Burma was colle cted 55 years before the species was first described, the present report happens to be the first from Burma because the specimen was registered under a different name (P. malayanus) in the Zoological Survey of India. Suggrundus crocodilus (Tilesius) 1812 Platycephalus crocodilus Tilesius, 1812. Krusenstemk Reise, Pl. 59, fig. 2. Platycephalus punctatus Cuvier, 1829. Hist. nat. P0iss., 4:243. Platycephalus malabaricus Cuvier, 1829. Ibid, Day, 1865. Fish Malabar, 45. Thysanophrys crocodilus Munro, I955. Marine and Freshwater fishes of Ceylon, 253. Material examined." 2 specimens 96, 189 mm from Tuticorin, 2 specimens 267, 268 mm from Visakhapatnam; 1 specimens 185 mm from Madras; 3 speci mens 121, 241, 262 mm from Malabar (Day’s collection) ZSI, Reg. No. I849, 1850, 1851; 1 specimen 139 mm from Pillai Bay, Mergui Archipelago, ZSI No. 10946. Description: D. IX, ll; A. ll; P. 18-22- V. I 4-58; vertical rows of scales above lateral line 92-109; L. tr. ll-13/l/24-33; . . + 1 + 4-5. Head length 2.91-3.16 in SL; 3.42-3.70 in TL; body depth 7.9-10.4 in SL, 9.25 12.1 in TL. Head width 1.66-2.18 in its length. Eye 3.84-4.85 in head; 1.22-1.50 in snout. Maxilla reaches to below anterior border of eye. Teeth villiform, arranged in two ovate patches on vomer and in two elongate narrow bands on palatines. Anterior nostril with a flap. Two spines between anterior nostrils. Two smooth ridges run parallel from between anterior nostrils upto beginning of interorbital space and then becomes indistinct. A strong spine on anterior orbital rim. Supra orbital ridges serrated posteriorly from behind middle of eye and end in a fan-like low radiating ridges behind eye and one of them on either side continued as superior postorbital ridge with a single spine. The inferior postorbital ridges with 5 spines each, last two elongate and last one ends at beginning of lateral line. Suborbital ridge with a spine in its begining, a spine below middle of eye and another below hind border of eye; behind this ridge is smooth, sometimes about three spines present ending in a long spine on preopercular angle. A single spine below this. Sub opercular flap rather feeble. Opercle with two smooth ridges each ending in a spine. Preopercle and opercle scaly. 14-16 rows of scales before dorsal. First dorsal spine short and third spine longest; second dorsal higher than anal. Pectorals rounded 5.66-6.57 in SL, 6.61-7.65 in TL. Pelvics 4.25-5.34 in SL, 4.84-6.23 in TL. Colour: Body reddish brown above, light below. Dorsal side of head and body with several black dots which extend to sides also. 2-3 broad dark bands on dorsal side. Outer three fourths of spinous dorsl black. Rays of soft dorsal with small black spots; pectoral rays with black spots which form irregular bands; pelvics black; anal whitish; caudal dark with two or three longitudinal black bands. Distribution: The known distribution of this species extends from coasts of New Guinea westward through Japan, Philippines, Ambon, Timor, North Celebes, Borneo Java and Banka to Singapore in the Pacific and from Nias, Andaman gea,cean. coats of Sri Lanka and India,Madagascar, Natal and Zululand in the Indian Remarks : The present specimens conform to the original descriptions of Platycephalus punctatus Cuvier and Platycephalus malabaricus Cuvier in all respects
[14]
Q}? will ,_,LI1 PLATYCEPHALIDAE FROM SEAS AROUND INDIA 693 but differ in the soft dorsal and anal fin rays. Counts of these fins for above two species as given by Cuvier 12 and 12 respectively whereas in all the present specimens ll and ll. Day (1878) gave D. 1/8/12; A. ll-12, while there are ll rays each in second dorsal and anal fins in specimen of his collection in the Zoological Survey of India.
All the meristic counts of the specimens in the present study agree with Matsu bara and Ochiai (1955) but according to them the “interopercular flap” is absent which character they have utilised even to distinguish genera; in all the present specimens this flap is present though rather feeble. Other than the thirteen species dealt with in the present paper the following twelve species (not so far recorded from the Indian Seas) are known to occur in the Indian Ocean region. No attempt was made to study the descriptions of these species so as to refer them to different genera; they are given under the generic name Platycephalus. Platycephalus longiceps Cuvier (Singapore, Java, Delagoa bay, Mozambique, Zanzibar and Red Sea) P. bataviensis Bleeker (Singapore) P. sundaicus Bleeker (Singapore, Sumatra, Java) P. boschei Bleeker (Singapore) P. nematophthalmus Gtinther (Singapore, western Australia) P. nigripinnis Regan (Muscat) P. towensendi Regan (Karachi, Muscat) P. subfasciatus Gilnther (Muscat) P. pristis Peters (Mozambique) P. grandideri Sauvage (Madagascar, Durban) P. portuguesus Smith (Mozambique) P. borboniensis Sauvage (Madagascar)
Rmanewcus BLEEKER, P. 1878. Revision Des espécés Insulidiennes Du genre Platycephalus. Verh. Akad. Amsterdam, 19:1-31. CANTOR, T. 1850. Catalogue of Malayan Fishes. J. Asiatic Soc. Bengal, 18 (2) 983-1443. DAY, F. 1878. The Fishes of India, 2:274—278. Barnard Quaritch, London. -i——-— 1889. The Fauna of British India including Ceylon and Burma, Fishes, 2:1-503. DE BEAUFORT, L. F. AND J. C. BRIGGS 1962. The Fishes of the Indo-Australian Archipelago, ll: 127-165. E. J. Brill [Ed.], Leiden. Fowusn, H. W. 1904. A collection of fishes from Sumatra. J. Acad. nat. Sci. Philadelphia, 2 (12) 495-560. Gizonoa, K. C. 1970. Note on two species of flatheads rPlatycephalidae : Pisces) from the trawl grounds of the southwest coast of India. J. mar. biol. Ass. India, 10 (2):l87-196. GREENWOOD, P. H., D. E. Rosew, S. H. WEITZNAB, AND G. S. Mynns 1966. Phyletic studies of Teleostean fishes with a provisional classification to living forms. Bull. Am. Mus. nat. Hist., 131: 241-455. Jonas, S AND M. KUMARAN 1971. New records of fishes from the seas around India J. mar. biol. Ass. India, I2: 187-196.
[15] 694 V. SRIRAMACHANDRA MURTY
JORDAN, D. S. AND C. L. HUBBS 1925. Record of fishes obtained by David Star Jordan in Japan in 1922. Mem. Carnegie Mus., 10: 93-94. iii AND R. E. RICHARDSON I908. A review of flatheads, gurnards-and other mail checked fishes of the waters of Japan. Proc. U. S. Nat. Mus., 33 (I581): 629-670. MATSUBARA, A. AND K. OCHIAI 1955. A Revision of the Japanese fishes of the family Platy cephalidae (The Flatheads). Mem. Coll. Agric. Kyoto Um'v., Fish Se:-., 68, 4: l-I09. MAYER, E. 1969. Principles of Systematic Zoology, TMH Edition, 428 pp. MUNRO, I. S. R. I955. The Marz'ne and Freshwater Fishes of Ceylon, l-349. MURTY, V. SRIRAMACHANDRA 1968. On some interesting and new records of marine fishes from India. J. mar. bio]. Ass. India, 10 (1): 126-132. ———-i, 1.969. Catalogue of fishes (excluding from the Laccadives) in the Reference Collections of the Central Marine Fisheries Research Institute. Bull. cent. mar. Fish. Res. Inst., 10: 1-36. RAO, V. VlswEswARA 1964. Platycephalus bengalensis sp. nov. from Bay of Bengal. Ann. Mag. nat. Hist‘., Ser. I3, 9': 123-127. SCHULTZ, L. P. l960. Platycephalidae. In: The Fishes of Marshall and Marianas Islands. Bull. U. S. Nat. Mus., 202; 3: 45-62.
[16] lcowraxsvrlou S |
MURTY, V. SRIRAMACHANDRA. 1982. Neggptgrpg lu§gg§ (Schneider, 1801) (Nemipteridae Pisces) the valid name for a threadfin bream from the Indo-Pacific region. Q, Q35. biol. A§g.Ind1a, 19(2):107-114 (1977) 11-icoirramvrxoni ..s._,s__ sl J. mar. biol. Ass. India, I977, 19 (2) : 107 - 114
NEMIPTERUS LUTEUS (SCHNEIDER, 1801) (NEMIPTERIDAE, PISCES) THE VALID NAME FOR A THREADFIN BREAM FROM TI-IE INDO-PACIFIC REGION
V. SRIRAMACHANDRA MURTY Central Marine Fisheries Research Institute, Cochin-682 018 Aesruacr
Neznipterus Iuteus (Schneider, 1801) is shown to be the valid name for a threadfin bream from the Indo-west Pacific region and that N. striatus (Valenciennes, 1830), N. filamenrosus (Valenciennes, 1830), N. nematophorus (Blocker, 1853) and N. macronemus (Gunther, 1859) are its junior synonyms. A detailed description of this species, on the basis oi‘ specimens collected from Kakinada is given.
INTRODUCTION
DURING the course of investigations on the biology and fisheries of nemipterid fishes in the trawler catches off Kakinada (Lat. 16° 15' N to l?° l0’N and Long. 82° 22' to 82° 35’ E), the author collected several specimens of a Nemipterus species which agree with Day’s (1875) description of Synagris striatus Jerdon, 1851 and also with the description of Nemipterus nematophorus (Bleeker) given by Weber and de Beaufort (I936). The fact that these two specific names were not treated as synonyms by these authors and neither of them had even referred to the other specific name, prompted the author to probe into their taxonomy. It has been found that these two species are junior synonyms of Nemipterus Iuteus (Schneider, 1801) and that the latter is the valid name for the specimens mentioned above. Most of the recent authors (Weber and dc Beaufort, I936; Fischer and Whitehead, I974) recognise N. nematophorus (Bleeker, 1853) as valid, which is also shown to be a junior synonym of N. Iuteus in the present paper. The name Nemipterus luteus has almost become a forgotten name (though the name is ‘available’ in the meaning of the Code) and some authors (Fisher and Whitehead, 1974) have even treated it as a doubtful species. The nomenclatorial status of this species is discussed and adequate description on the basis of specimens collected from off Kakinada, is presented in this paper. I am thankful to Dr. M. Boeseman, Curator, Rijksmusseum van Natuurlijke Historic, Leiden for sending data on holotypes of Dentex filamentosus Valenciennes and D. nematophorus Bleeker. I am also thankful to Dr. Martine Desoulter of Museum National D’ Histoire Naturelle, Paris for kindly sending data on the specimen of Dentex luteus Valenciennes and for sending relevant literature. Dr. P. K. Talwar, Superintending Zoologist, Zoological Survey of India, Calcutta has kindly sent the original description and figure of C. Iutea Schneider; Iam thankful to him for this help. 108 V. SRIRAMACHANDRA MURTY
HISTORICAL Resume Schneider (1801) described Coryphaena Iutea on the basis of a specimen from Tranquebar. The description is very brief; the figure shows: D. X, 9; A. Ill, 7 and caniniform teeth in upper jaw. Valenciennes (1830) described Dentexlureus from Pondicherry on the basis of a 7 inches long specimen. He described the species as: *suborbital very high, teeth decrease in size towards interior of the mouth in such away that it is difficult to notice the canines which are eight in number. The scales are large and there are forty scales in the lateral line. Valenciennes (1830) considered Coryphaena Iutea Schneider as a doubtful synonym of his Dentex Iuteus and slated: “We have found this species in the Berlin Museum among fishes of Bloch. First he had confused this fish with his Spams jap0m'cus because we have seen it written as such by his own hands. However, he appears to have recognised it afterwards and it seems that the figure given by Bloch in tab 58 of the of edition of Schneider and also the short description on p. 297 under the name Coryphaena Iutea were made after the same one. Some traces of reddishness could also be seen on this specimen which Bloch had mistaken for bands in his painting. His specimens more entire than ours shows that the third ray of caudal is prolonged into a filament. It is 7 inches long from the tip of snout to the end of caudal lobe; the caudal filament is one inch long. Gunther (1859) recorded Synagris Iuteus (Cuv. and Val.) and treated Coryphaena lutea Schneider, as a doubtful synonym of it. He did not give the description of this species in detail except for a few meristic data and stating that “teeth nearly equal (Val)”. Day (1875) stated “There are two of Bloch’s specimens marked Dentex Iuteus at Berlin; one evidently the skin from which Bl. Schn.’s figure has been taken, the artist not having reversed it whilst he had delineated the eye too small and the (?) elongated dorsal spines are broken. On the second specimen which has no elongated dorsal spine is Val’s label, “C’est le vrai C. Iutea Bl. Schn”. Valenciennes (I830) described Dentex srriatus on the basis of an 8-inch long specimen from Tranquebar in the Berlin Museum (fide: Bauchot and Daget, 1972). He named the species as striatus following the unpublished manuscript description of Coryphaena striata by Bloch. He described the species as: suborbital very high, scales slightly longer, ciliated; the limb of preopercle strongly striated, the canines are feeble; the body with lontgitudinal lines. Caudal lobes in the specimen are not complete and so it is not possible to say whether they had filaments. Jedon (1851) recorded Dentex striatus C. V. from Madras. He described only the colour of the species as: alternate longitudinal bands of rosy and yellow, dorsal purple beneath, yellow in the middle and rosy externally. Anal blended with pale rosy, others tinged with rosy. *Here and elsewhere in this paper, the English translation of Valenciennes’ French text is“ quoted. THE VALID NAME FOR A THREADFIN BREAM 109 Day (I875) described Synagris striatus (Jerdon) from Madras but figured species as Synagris luteus in plate VIII, figure 5. Among others, the description shows that there are 8 canines in the upper jaw, the vertical limb of preopercle serrated, the first two dorsal spines and upper caudal lobe are produced and filamentous. Day (1875) who stated that “Bl. Schn.’s figure (of Coryphaena Iutea) is probably coloured from a description in which it was said to have been striated or banded; and instead of placing such longitudinally he has given them as vertical”, treated Coryphaena lutea Schneider as a doubtful synonym of Synagris striatus (Jerdon). Valenciennes (1830) described Demfex filamentosus from Surinam (Sumatra). The description shows that the first dorsal spine (actually the first two dorsal spines in the holotype), upper caudal lobe and pelvic ray are produced and filamentous; canines L8 in number, preopercular border finely serrated. Bleeker (1853) described Dentex nematophorus from Padang (Sumatra). Gunther (I859), Weber and De Beaufort (1936) and Fisher and Whitehead (1974) described Synagris (or Nemipterus) nematophorus (Bleeker). These accounts among others, show that the first two dorsal spines and the upper caudal lobe are produced and filamentous and that there are canines in the upper jaw. Gunther (1859) described Synagris macronemus from Surinam. He treated Dentex filamentosus Valenciennes, 1830, as a junior synonym of his S. macronemus apparently under the erroneous impression that the name D. filamentosus Valenciennes, 1830 was preoccupied by Dentex filamentosus Valenciennes 1841 in : Webb. and Berthelot, Hist. nat. canaries. Ichthy., pl. 6, though the former has priority and the latter is a synonym of Dentex gibbosus (R.afinsque, l8l0) (Vide, Bauchot and Daget, 1972) but at the same time stated that “lt is not certain from the imperfect description of Valenciennes whether the fish D. filamentosus Valenciennes. 1830, should be referred to Synagris or to Dentex; according to the figure it has the habit of Synagris but the scales on the preoperculam are arranged in more than three series, as in Dentex”. It has since been confirmed (Weber and De Beaufort, 1936) that there are only three rows of scales on preoperculum of the holotype of Dentex filamentosus Valenciennes, 1830 which is also the type species of the genus Nemipterus Swainson. The important taxonomic characters of all the above species taken from the available descriptions and in some cases from types, are presented in Table l.
DISCUSSION It is clear from the above that several earlier authors described Nemipterus Iuteus under five different specific names evidently being uncertain ofthe nomenclatorial status ofthe nominal species they described. This is because : 1. the original description of Coryphaena Iutea Schneider is most inadequate 2. Bloch prepared a description of Coryphaena striata but never published it and deposited a specimen in the Berlin Museum under this unpublished name, and 110 V. SRIRAMACHANDRA MURTY 3. the type specimen of Coryphaena lutea Schneider and the specimen labelled C. striala in the Berlin Museum are apparently damaged. The earliest published account for the species under discussion is that of Coryphacna lurea Schneider, 1801. Since the efforts made by the present author to get the type specimen of this species in the Berlin Museum re-examined were not fruitful and since the original description (including the figure) is not adequate on whether the first two dorsal fin spines and upper caudal lobe are produced in this species (these two being the most important diagnostic characters), it is, however, inferred that the first two dorsal spines and the upper caudal lobe were produced and filamentous in the holotype because (1) Valenciennes (1830) stated that he came across a specimen of C. Iutea in the Berlin Museum and that he believed that the description and figure of C. Iutea Schneider were made after this specimen. He further stated that “...montre que le troisieme rayon ia caudale se prolonge en un long filament” (the third ray of caudal is prolonged into a filament) in C. imfea Schneider in the Berlin Museum, and (2) Day (l875) stated that in a specimen marked Dentcx luteus at Berlin Museum, “...fr0m which Bl. -Schnfs figure (of C. {urea} has been taken”, “...the (?) elongated dorsal spines are broken”. It is clear from the above statements that though Valenciennes examined the specimen in the Berlin Museum quite before Day had examined it, the former did not even notice the possibility oi the first dorsal filaments being broken. Valencicnnes only noticed the caudal filament and by the time Day examined this specimen, the caudal filament also was, perhaps, brokens There is a specimen ofDent»ex lureus (examined by Valenciennes, 1830) in the Paris lvluseum, the data ofwhich are presented in Table l. This agrees well with Coryplzaena lzztea Schneider. The description of Denzex srriatus Valenciennes, .1830 (based on the specimen of Bloch: Fide Bauchot and Daget, 1972) is inadequate to relate it to C. Zutea Schneider. The subsequent description ofthis species by Day (1875), however. shows the important characters clearly and this agree well with C. [urea Schneider. The original description of 1)ente.\; _/'ifanzem‘o.sz1.r ‘\/alenciennes, 1830 shows, among others, that only the first dorsal spine is produced and filamentous. An examination of holotype ofthis species shows that the first two spines of dorsal are produced and filamentous, as against only one as described by Valcnciennes (1830). The data on the hoiotype of De.-'2te.\: ::e.'r1a;c-phi:-ms Bleeker, 1853 (Table 1) indicates that it agrees closei'yn-'1tt~ C. [urea Schneider, 180i. The original description Synagris mrzcronermrs Gunther, agrees with D. filame/zlosus Valenciennes, 1830. Gunther (1859) obviously repeated the same mistake as Valenciennes (I830) in stating thatonly theiirst dorsal spine is produced. However‘, since he treated _D._fz'i't;'nzers!0szrs of Valen ciennes (I830) as asynonym of his S. macronemm" itis believed that his macronemus also is a synonym of Nemipterus lutezis (Schneider). It is, thus. clear that Der-ztcx srri.az‘us Valenciennes. 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SRIRAMACHANDRA MURTY The name Nemiprerus luteus (Schneider, 1801) cannot be suppressed on the ground that it is a nomen oblittum since Article 23 (b) which providse for this, is repealed (vide Declaration 43 in Bull. Z001. N0men., 27 (3 & 4) : 135-163, 1970). A detailed description of N. lure-us along with its synonyms is given below. Nemipterus luteus (Schneider, 1801) (Fig. 1) Coryphaena Iurea Schneider, 1801, p. 297, tab. 58; Tranquebar. Demex Iureus Valenciennes, 1830, p. 250; Pondicherry. Denrex srriatus Valenciennes, 1830, p. 252; Tranquebar. Denrex filamentosus Valenciennes, 1830. p.254; Surinam(Sumatra). Demex nematophorus Bleeker, 1853, p.500; Padang (Sumatra). Synagris macronemus Gunther, 1859, p. 380; Surinam. Synagris srriams Day 1875, p.90, Madras. S'yrragr:'s luteus Day, 1975, pl. VIII, fig. 5. Nemiplerus nematophorus Weber and De Beaufort, 1936, p. 366. Fisher and Whitehead, 1974. Material examined : 20 specimens ranging from 140 to 216 mm TL* from Trawler catches of Kakinada. Meristic data: D. X, 9; p. 16—18 (16 in 1, 17 in 18, 18 in 1; N : 20); V. 1, 5; A. III, 7; L. 46-49 (46 in 5, 47 in 7, 48 in 6, 49 in 1; N: 19); L. tr. 4/1/9-10: G. R. 10-12 (10 in 2, ll in 7, 12 in 8; N117).
Fig. 1. Nemiprerus Iuteus (Schneider, 1801). Body proportions as percentage of standard length: Body depth at dofgalorigin 30.1-34.1 (3l.7)**, head length 32.0-35.8 (33.6), predorsal length 28.0-34.5 (33.3), prepelvic length 31.6-35.5 (33.4), preanal length *‘ Total length is measured from tip of snout to tip of lower caudal lobe. "’* Values in paranthesis are mean values. THE VALID NAME FOR A THREADFIN BREAM 113
60.6-66.1 (63.9), lengthof dorsal fin base 50.5-57.5 (54.0), length of anal fin base 15.9.-21.2 (19.7), pectoral length 29.0-34.1 (32.0), pelvic length 27.3-32.9 (30.3), depth of caudal peduncle 10.3-12.2 (11.2). Body proportions as percentage of head length : Depth of head behind preopercular border 78.8-90.0 (82.7) horizontal eye diameter 28.8-38.9 (32.7), snout length 23.7-31.6 (27.6), interorbital length 16.3-2l.2(l8.9) height of suborbital 10.5-20.0 (15.0). Other characters: Mouth termial, oblique; maxillary reaches to below anterior border of pupil. Teeth in several rows in both jaws; in upper jaw 3-4 canines on the outer row on either side, canines absent in lower jaw. Height of suborbital equal to about half vertical diameter of eye; suborbital surface rugose. Vertical border of preopercle finely serrated. Scales ctenoid; 3 rows of scales on preopercle. The first two dorsal spines are produced and filamentous, when folded they extend beyond posterior border of dorsal fin upto nearly base of caudal; spinous dorsal (excepting filaments) shorter than the soft, pectorals falcate, reach upto above 2nd or 3rd anal spine, the first ray of pelvic produced reaching 3rd anal spine, spinous anal ‘shorter than soft portion. Caudal forked;the second branched ray of upper caudal lobe produced into a filament. Colour: Body pink above and silvery below. A yellow blotch below lateral line near origin. A longitudinal band on either side of the base of dorsal fin with irridiscent shine. Similar band on lateral line. Three longitudinal yellow bands below lateral line but above pectoral base. One yellow band on either side, on ventrolateralsides. The two dorsal filaments and upper border of dorsal deep yellow; the remaining portion of dorsal fin pink. Pectoral and pelvic light pink. Anal pale witha longitudinal yellow band above middle of the fin. Caudal pink except the tips of upper rays in the upper lobe and the filament which are deep yellow. Distribution: East coast of India, coasts of Sumatra, Borneo, north Celebes and Philippines. Remarks : Nemifpterusluteus occurs in the trawler catches off Kakinada in fair quantities when there is fishing at depths of over 55 metres. The peak period of abundance for this species at Kakinada is January-March. During 1976 an estimated 35.3 tonnes of this species where landed forming 6.7 % of the total nemipterid catches of the year.
R EFERENCES Bxucrror, M. L. /mo J. DAGE'T 1972. Catalogue critique des types de poissous du Museum national d’l—Iistoire naturclle. Bull. Mus Nat. Hist. Nat, ser. 3,24: 99. IBLEEKFR, P. 1853. Niewwe tientallen diagnotische beschrijving van nieuwe of Weining bekende Vischsoorten van Sumatra. Naruurk. Tijdschr. Ned.-lndie5: 500. —— 1873. Revision des cspeces de Dentex, Synagris, Gymnocranius. Verh. Akad. Amsterdam, 13 : 23.
1-~ 1877. Atlas Ic/zthyologique, 7 : 90 DAY, F. 1875. Thefishes of India (Ist part) : 1 - 168. 114 V. SRIRAMACHANDRA MURTY
FISCHER, W. AND P. J. P. wHITEHE.AD (Eds.) 1974. FAO Species Idemification sheets f0r_f:'s/zcry pm'p0SeS. Eastern Indian Ocean (Fishing area 57) and Western Central Pacific (Fishing area 71). Vol III, FAO, Rome. GUNTI-IER, A. C. 1859. Catalogue of fishes in the Britsh flluseum, 1 : 377 - 380. JERDON, T. C. 1851. Ichthyological glcanings in Madras. Madras J. Lin. Sci., 17 : 128 - I51. SCHNEIDER 1801. In : Bloch and Schneider (Ed.) Systerna Ichthyologiae. VALENCIENNES, M. 1830. In : Cuvier, M. B. and M. Valenciennes. Hist. Nat. P0:'ss., 6 : 559 pp, pls. 141 - 169. Reprinted 1969, A. Asher 8 C0., Amsterdam. W1za1=.R, M. AND L, F. DE BEAUFORT 1936. The fishes oflndo-Australian Archipelago, 7 : 1-607. ‘CONTRIBUTION 4 1
MURTY, V. SRIRAMACHANDRA. 1981. §§m1BtQgu§ mggqpgiqg (Bleeker, 1853) (Nemipteridae Pisces) a new record from the seas around India, lgqéaq Q, £isQ., 25 (1&2): 207-213 (1978). ]CONTRIIT“—“j_,____ DUI‘ ; —_~ IOTJ- K‘ —*? 41 Reprinted from Indian J. Fish., Vol. 25, N05. 1 8: 2, I978, pp: 307-313
NEMIPTERUS MESOPRION (-BILEEKER 1853) (NEMIPTE-Rl:DAE PISCBS) A NEW RECORD F-ROM TH-E SEAS AROUND INDIA
V. SRIRAMACHANDRA MURTY Kakinada Research Centre of C.M.F.R. Institute, Kakinada.
ABSTRACT
Nemipterus mesoprion (B-leeker) is reported for the first time from the Indian seas. This spec-ieg -resembles “N. japoizicus (-Bloch) closely bu-t differs from it i-n eolou-r. snout length, head length, height of suborbital bone and pelvic fin length. A description of the species is presented-.
INTRODUCTION During the course of investigations on the fishery and biology of hemi pterid fishes in the trawler catches off Kakinada, the author collected specimens of N€i'fli'[JI€rHS tolu (Valenciennes), N. japonicns (Bloch) and ;N. .mes0prz'on (Bleeker). The -last named species-has hitherto not been reported from the seas around In-dia (vide: Day 1878, Weber and De Beaufort l936,;.Munro 1955).. Since the present report of.N.= mesoprion is the first from the Indian-seas, a des cription of the same is presented here. It is observed that N. mesoprion resembles N. japonicus very closely and in preserved condition it is difficult to distinguish between the two species with reasonable accuracy. An attempt is made in this paper to bring out those cha racters that would help distinguish these species.
MATERIAL AND METHODS
Specimens under st-udy were collected from trawl catches -ofi Kakinada from depths of 1-5-70‘ m. Colour and pigmentation were noted in fresh speci mens, but detailerdobservations were made on specimens preserved in 5% for malin. The morphometric data are presented ‘as percentage of standard length or head length. Frequency distribution of meristic characters is given in paran-' thesis following‘ therange: eg." p. 16-I8'(16 in 20, ...... etc.) meaning 16 tiprays in of'20specirnens lower andso caudalon. Total length lobe.is measured from.- tip' of snout to 208 MURTY
._ ;.'..~‘_, " "‘ ,' -“pf .- " - ' '_'. /I/B/'I/filing i I ‘i'-.55"i.--'- " ' '~;f_:.i..3,1 '-~_\-_'>-.' _.I’: ' _' -.T'l',»'_.-. _ _ _'_--._" .,.', ~._ “'4!: E.‘-!_‘I |__;‘_--" I _ _ '‘ _ I‘w-.j- ' , -. _ 3; H '5 '5;-. _._\\ -- -.3-,\~ ‘ -. \
F10. 1. Nemipterus mesoprion (Blceker) 175 mm x 1%
NEMIPTERUS MESOPRION (Bleeker) (Figure 1) Dentex mesOpri0n Bleekcr, Nat, Tijdschr. Ned. Indie, 1853, IV,_'255 (Priaman) Material examined: 30 specimens (18 males, 12 females) ranging from 10] to 185 mm total length. Meristic Dara: D. X, 9; P. 16-18 (16 in 20, 17 in 9, 18 in 1); V. I, 5; A. III, 7; C. 17; L1. 45-49 (45 in 3, 46 in 6, 47 in 11, 48 in 9, 49 in 1) L.tr. 3—3%[1§9. Body Proportions: a) As percentage of standard length: Total length 127.6-134.6 (l31.8*), body depth 31.6-37.5 (33.6), head length 34.5-40.0 (37.5), predorsa-1 length 31.5 36.4 (33.6), prepelvic length 32.5-36.9 (35.1), preanal length 62.5-70.5 (65.8), dorsal fin base length 50.0-57.3 (52.9), anal fin base length 16.9-21.8 (18.8), Pectoral length 32.4-39.0 (34.5), pelvic length 27.6-37.8 (31.6), least height of caudal peduncle 9.6-11.5 (10.3). b) As percentage of head length: Head height (measured behind preopercular border) 71.1-85.2 (77.0), eye diameter 27.6-37.5 (32.1), snout length 20.8 28.3 (24.4), interorbital length 18.8-24.4 (21.6), height of suborbital bone 10.0-17.0 (13.3). Other Characters Mouth oblique, maxillary reaching to below anterior border of pupil, Teeth in jaws in several rows, ‘pointed; upper jaw with 3-4 caniniform teeth anteriorly in each ramus, but such teeth are absent in lower ja-w. Scales ctenoid; three ‘rows of scales on preopercle. Height of suborbital nearly half of vertical dia meter of eye. Hind border of preoperculum crenulate. Dorsal spines strong, first spine shortest, fourth to tenth more or less of same length; softdorsal deeper than spinous one. First anal spine shortest, third longest. Soft anal less deep Figures in pnrant-heses are mean values.
-\r NEMIPTERUS MESOPRION 209 than soft-dorsal; the last -two rays of anal long-er than. the preceeding ones. Pecto rals falcate, extend to above first or second anal ray. -Pelvics with the first ray produced, reaching to first or second anal rays. The second_branched ray of upper caudal lobe produced into a long filament th-e length of which is more than the caudal fin itself. Colour (fresh): Body pink dorsally and on upper half of flanks, lower flanks and -belly silvery. 3-4 longitudinal yellow bands on sides below lateral line; thick yellow longitudinal bands one the ventrolateral borders. Dorsal fin with closely packed yellow pigment dots on the lower three-fourths of the fin forming a longi tudinal yellow band which divides into 3 s-mall ba-nds on the last few rays; upper margin pink. A reddish Iblotch below lateral line near its origin. Pectoral pink; pelvic pink but with the first ray whitish all along its length. Anal whitish with a distinct narrow lon-gitudinal yellow ba-nd in the middle. Caudal pink includ ing the elongated filament on the upper lobe. Distribution. Known from Sumatra (east and west coasts) and Singapore. T-he pre sent report extends the range of distribution westwards towards the east coast of India. Remarks The present specimens, agree well with the original description by Bleeker (1853), with the holotype and also with the description of Weber and De Beau fort (1936) in several characters (Table 1) but diff-er in the following: Accord ing to Bleeker (1853) and Weber and De Beaufort (I936) the height of sub orbi-tal is equal to vertical diameter of eye, whereas in the holotype and the specimens examined by the present author it is about half vertical diameter of eye. According to Weber and De Beaufort the hind border of preoperculum is denticulate but in the holotype and the present specimens it is crenulate. The tip of upper caudal lobe appears to be broken in the holotype (Dr. Boeseman in litt., vide Table 1); in the original description of this species Bleeker (1953) described the caudal fin as mutilated, presumably with the tips broken off [“valde ema-rginata lobis (ex parte abruptis)]. Therefore, in the subsequent descriptions (1873, 1977) Bleeker did not describe a produced upper caudal lobe in this species. Weber and De Beaufort (1936) stated that they examined “typical specimens” in Leiden Museum and that “In three specimens from Malacca the upper caudal lobe is produced in-to a long filament.” These authors did not how ever state whether the upper caudal lobe is not produced in other specimens they examined (if at all). As stated above in all the present specimens, the second branched ray of the upper caudal lobe is produced into a filament. The description and figues of N. mesopriosn presented by FAO (1974) clearly show that the upper caudal lobe is produced into a filament which is short; in the 210 MURTY TABLE 1. Nemipterus rnasoprion: Comparison of specimens from Kakinada with the holotype and with the description by Weber and De Beaufort (1936) . Sl.No. Character Specimens from Description Kakinada * Holoty-pe of Weber and De Beaufort . Dorsal fin count x, 9 x, 9 x,9 . Anal fin count I»II,7 III,7 I'I'I,7 Pectoral fin rays 16-18 16 16 . Lateral line scales 45-49 45 45-47 . L. tr. 3-3%ll—|9 3%l1|8 or 9 3-3%l1[1l . Standard length/head length 2.5-2.91 3.0 3.2-3.5 . Standard length/body depth 2.8-3.1 3.3 3.2-3.5 . Head length/eye 2.7-3.4 3.3 3.1-3.4 . Eye/Interorbital length 1.2-1.7 2.2 1.5-1.6 10. Hind border of preopercle Crenulate Crenulate Dentic-ulate 11. Canines in upper jaw only in upper in upper jaw only Jaw only 12. Suborbital -height equal to half of Slightly more Equal to vertical diameter than half vertical ofless. eye orslightly diameter of vertical of eyediameter of eye. 13. Upper caudal lobe producedspecimens Produced in all Doubtful three Produced speci in men-s from Malacca.
* -Holotype No. 5684 of Leiden Museum, 94.5 mm Standard length; type locality: Priam-an (Sumatra). present -specimens the filament is long and longer than the caudal -fin. There is no difference in the length of caudal filament between sexes in the present specimens. Colour is the most important character in distinguishing species of Nemi pteridae: (Eggleston 1973). The colour of N. mesoprion is described (FAO 1974) among other things as: head with yellow strea-ks from eye to middle of upper jaw, dorsal fin with a broad -median yellow longitudinal band which sub
\Ooo~1O\<.n-I=§-?l\J>— NEMIPTERUS MESOPRION 211
Ii '-‘-~__-_ FIG. 2. Nemipterus fa-ponicus i(*B-loch) 2711 mm X 1. divides towards tail into three yellow -bands separated by blue lines. Pelvic fins pink with elongated first ray d-eep red; caudal fin reddish, median rays yellow, outer rays and filament red. In the present specimens yellow streaks on head absent, the median band on dorsal fin narrow anterior-ly and broad posteriorly, it divides posteriorly into three bands; pelvic fin pink except the first elongated ray which is white; caudal fin pink including the median rays and the filament. The difierences in the colour pattern may be due to differences in the habitat. TABLE 2. Distinguishing characters of N. japonicus and N. mesoprion
S] .No. Characters N. japonicus N. mesoprion
1. Head length Equal to or less than body More than body depth depth. 2. Snout length Equal to or more than Less than horizontal eye horizontal eye diameter diameter 3. Suborbita-I height Equal to or slightly less About half of vertical eye than vertical eye diameter diameter 4. First pelvic ray Not produced and does Produced and reaches be not reach anal origin. yond anal origin up to 2nd anal ray. 5. Colour: a) on anal fin A longitudinal yellow Only one longitudinal band near base with yellow band in the middle. three irregular or broken yellow bands below. b) On upper caudal Tip of upper caudal lobe Tip of -upper caudal lobe obel and filament yellow, and filament pink. 212 MURTY Among In-dian Nemipteridae N. -mesoprion resembles N. japonicus (Bloch) (fig. 2) in several characters andd-ifiers mainly in colour, but when preserved specimens are examined, colour is no-t of anyvalue and one has to necessarily depend -upon other characters most of which show overlap in distin guishing between the two species. The avai-laibl-e description of these two species do not help in distinguish-ing them satisfactorily. An examination of 30 speci mens of N. japomicus ranging from 92 to 280 mm in total length and comparison of these specimens with those of N. mesoprion, both collected from the trawler catches off Kakinada, have revealed differences in certain characters (Table 2) which are of use in distinguishing these species in fresh or in preserved condition. To show the extent of variation in the relative proportions of head length, snout length, height of suborbital bone and pel-ivc fin 1-ength in each of these two species and to show differences in these characters between them, head length and pelvic fin length expressed as percentages of standard leng-th are plotted -against standard length and height of suborbital -bone and snout length ex-pressed as percentageso of ohead length, ___e against head length (-figure 3). Though o D 0 TO0 _'9 0°00 . Io,L @ -~= °==0° . . . e "ea ""1 sY " s “s. "> = oul'1n:ru$lIl‘Iu\0ul0-0 ' 0OII‘N!&Ifl'lI'II1-QIB O0!, "3 00% 'tf.O1‘ .. 00° ivItQ “R ;' °o ‘ >.0go rg 0 0 0 o
_<9 ‘____ j T - -- "- . - -,_ _.‘~ _- ~;‘ - - ~‘® - - :-—+ ll v*J-—~-f 3—L° Soulwuuuiwlcvtn 3 I 2 00081: l ::n.uIn:u1Io 2 : Flo. 3. A. Relationship -between he-ad length expressed -as percentage 0-f standard length and standard -length; -B. Relationship between pelvic fin length expressed as per centage 'of_ stand-a-rd length and stand-a-rd length; . C. Re-1-a-tions-hip between height. of sLtb0rb1_t-a-l' bone ex-pressed as percentage of head -length and head length; D. R€l3.Il'OI]S-hl-P be-tween $n01.lt length expressed as percentage of -head length and head len-gt-h. N.' mesoprion Q Nf jaiponicus O a definite relationship in the different body proportions with standard length or head length is not perceptible, it may be seen that:
60
0 o 0 ° 0on o 00 0 v0O°'°. O O O0 o0°g°$Q
O
0 O o°° O Oo 0 Q % o '0 0 U o _ ' U 0 Q <5‘ " " ‘ii "'10 ii» “IQQI-l‘1'}! IIDLIISYN i NEMIPTERUS MESOPRION 213
1. head is relatively shorter in N. japonicus and relatively longer in N. mesoprion. 2. pelvic fin is relatively shorter in N. japomicus and relatively longer in N. mesoprion, 3. height of subonbital is relatively more in N. japonicus and relatively less in N. mesoprion, and 4. snout is relatively longer in N. japonicus and relatively shorter in N. mesoprion.
ACKNOWLEDGEMENTS I am thankful to Dr. E. G. Silas, Director and Dr. K. V. Sekharan Sci entist S-3 of CMFR Institute, Cochin for the encouragement and for suggestions. I thank Dr. M. Boeseman, Curator of fishes, Rijksmuseum van Natuurlijke Historie, Leiden for kindly sending -data on holotype of N. mesoprio-n and for sending the original description of this species. I also thank -Mr. Y. Manikyam, Lecturer in Zoology, Ideal degree college, Kakinada for drawing the figures of fis-hes presented in this paper. Rerenertces BLEEKER, P. 1853. -Diagnostische beschrivningen van view of weining bekende vissch~ soorlaen van Batavia. Nat Tiidschr. Neder.-Indie. IV: 255-256. BLEEKER, -P. 1873. -Rev-ision des especcs dc Denrex, Synagi-i.r, G_vmn0cram'us. Verh. Akad. Amsterdam, XIII: 30-31. BLEEKER, P. 1877. Atlas Ichthyologique. VIII: 92, Tab. 328, fig. 4. DAY, F- 1373- Fiflles Of "1450, 778 pp, William Dews-on and Sons Ltd. EGGLESTON, D. 1973. Patterns of Biology in the Nemipte-ridae. J. mar. biol. Ass. India, 14: 357-364. (1972). FAO. I974. F A0 speCi€.s' identification sheets for fishery purposes, Eastern I-ndian Ocean fishing area 57 and Western Central Pacific Fishing -area 71. Vol. Ill, FAO Rome. MUNRO, I. S. R. I955. The Marine and Fresh-water fishes of Ceylon. 169 pp. Canberra. WEBER, =M. AND L. F. DE BEAUFORT. 1936. The Fishes of.lrrd0-Australian Archipelago. 7: 607 pp., E. I. Brill, Leiden. PART II BIOLOGY AND POPULATION DYNAMICS A. THREADFIN BREAMS v@@-»Rm~sj
MURTY, V. SRIRAMACI-IANDRA. 1982. Observations on some aspects of biology of threadfin bream Ngmip_t:Fem}§ ;1)esQp;i% (Bleeker) from Kakinada. Indian §_.1=‘ish., 28 (1&2): 199-207 (1981). ~la",' 1-.:~" =.-. _. -— i-~ ~ it- '~— ‘— -—" — ' ICONTRIBUTION..|I| 5 mm mam J. Fish, Vol. 28, Nos. 1 at 2, 192:1. pp: :99 201
I2.
9' ' Io
I
-OBSERVATIONS ON SOME ASPECTS OF BIOLOGY OF THREADFIN BREAM NEMIPTERUS MESOPRI ON (B-L-EE'K=ER) FROM IQXKINADA
V. SRIRAMACHANDRA MURTY Kakinada Research Centre 0)‘ C.M.F.R. Institute, Ka"kl'naa'a.
ABSTRACT
The 1eng=1:h—weight -relamiomhip Of N. mesop-rion Cain be desonlbed by the equation log W * -4.650901’ + 21877071" log :L. 'Fe|n1a‘les =a-teafiin first masturlity at a Ilengfth of I00 mm. Tlhiis species -is Ea fmctiiomll Slplillw-.fl£t1‘, the ripe ova rtwo spaw-nri-n-g -acts d*u~ri:ng -the single spawning season: Deoemberr-A¢p~ri'l.. It is es\‘.iin1-a|ted- that -the species altrtaiins 1140, -1-85 and 205 mm alt the comrple*t:i~orn- of first, secondl and third yea-rs, respecwtsivcly. The estimated gno-wrtlh 'p3JI‘-3!I‘l1¢l€-1"-S ane: L ct = 2-I9 mm, K ‘—= 0.8-3248 and" to = -0.2-56-I98 yeanis. ~
INTRODUCTION
As -par-t of i~nvest*ig"a=tion~s -on Ithc 1'~e.source characteristics of uh-readfin breams, studies on the ‘biology -of N emwipfeius mesoprio-n (Blocker) were initiated at Kaki-niad=a in 1976. The species was finst reported from India only in 1976 (Murry MS) -and 1:h-ere is -no published @inl:'t*orr-n1+a=t.ion on any aspect orf biology of this spec-i-es from India. This speici-es form-s a seasonal fishery at Kakina-da and the data collected firom the trawl catches du-rin-g January 1976-March 1980 are utilised for the study. MATERIAL AND METHODS Sampl'~e.s were obtai-nod at weekly interval-s rfirom the catch-es of trawlcrs operating off Kaki-nrada. Since this Isrpecies -foims =a seasonal fishery at Kakinada, samples -were collected as and whcn it occurred in the catches. Samples were brought to the rltaboratory -for data -on total lenglih-.* Wffii-g*h*'£, -sex and stage of maturation-. Data we-re -taloen -from fresh specimens only. The l~en-gth-w-eitght re la-tionship was carlcu-lat-ed by the method of II-east -sqlu ares using it-he formula W = aL" or -log W = log a + n log L (Le Cren 1951), where W =rweigh1: in g, L = length in mm, -a = -a constant and n = exponent. W-h-ile the ma-tux‘-ation sta-gas were .a-llott-ed‘ on -the basi-s of macroscopic -exainrimationi of fresh ovaries, ova
* As -the upper caudal lobe of this species is pnodluced and some times the filament is -bvoken-. the tot-a-I length ‘is m-cl:-surcd f-nom the flip -of snout to
TABLE 1. Comparison of regression line-s of Length-w-eight relation-ship of males and females of N. me-séoprion. x Reg. CohDev»iati.on- from Reg=res.sio11 df 2 >< 2 Z >< y 2y? '~ effi-eienjt d-f SS MSS
With-in Mall-es 310 1.422756 4.097065 12.007835 2.87966 309 0.209648 Females 294 1.207296 3.468791 10.304630 2.87319 293 0.338134 602 0.547782 0.000909 Pooled 604 2.630052 7.56585-6 22.312465 2.87669 603 0.547809 0.000908 Differences -be-tween slopes 1 0.000027 0.000027 Between 1 0.333072 0.959265 2.762693 _ Total 605 2.963124 8.525121“ 25.075158 2.877072 6014 0.547771 Between -adjust-ed mean-s 1 0.000038 0.000038 it‘? ——_ _ ——~ _7__ _ ———~ __ ' - — _ _ ._ r 7 .. _7" ‘ ' ‘ Slopes F = 33.666, df = 602, l Not s-ignifica-nrt at 5% E-leveatti-ons F = 23.89, df = 603, 1 Not sign=ifican.t at 5% BIOLOGY or THREADFIN BREAM 201
MATURATION AND SPAWNING
As -in the ea.-se of N. japonicus (~M=U1_1ty' MS) =nhe testis in N. mesoprion is very -small even in mature -fishes thus making it diffioult to study -the process of maturation in males. Hence, only temailes are considered for this A total of 295 tr‘-email-es raing-ing Ifirom 83 =to 177 mm were examined. The stages of malruration -are fixed fo11ow=i-mg those fixed 4301' N. jalponicus M-S) from Kakiniaida. i. Length at first maturity: Fishes in the stages III-VII of ma.-tut-aition are taken -as mature -for this -purpose. The peroennage-frequency d-iJSt[l'iib'U¢'iOI1 of mature fem-at-eis in each lengrth group -are shown -i-n1 fiig-use 1. Fish-es above 90 m-m showed mature ovaries. The data show that 50% of the fish are mature at 100 mm. Henroe 100 mm is taken as the length at first maturity of !f6I[l'3Jl'6 N. mesoprion aat Kakilnada. In this connection it -may ibe mentioned that the smallest female With ripe ovary obmai-nod ti-n the present study measured 110 mm. i.i. S paw ning: The nova-diam-eter-frequency distribution i-n mature and ripe ovaries tare presen1ted in fi-gu-re 2. I|t -may ‘be seen that the ova are dirst-ributed around two mod-es (Fig. 2; A & B) -in mature ovaries (st. V): one mode at 0.152 mm (7-8 m.d.) and the other at 0.418 mm (21-22 m.d.); the former group consti tutes maturing U1"3!I1lSh1C€Hit ova and the 1-amber oonstiuntes mart-une opaque ova. In mnming ripe -females (fig. 2, C & -D) za group of ova are separated and form
so-4Q\ kw
"W
1 ' I —
. ,____ _ ,__ , i " "‘ * as asunern flows usin FIG. -1. Pemcenmaige-frequency9l‘°‘l1P5- of mature female N. mesoprion in du‘fi'ement F length
IIRC-EN M6! rnmuzucv Q L1Lm%? ,__j___ ? I I l I if ” I
5.1 202 MURTY modes at 0.722 mm (37-38 m.d.) or 0.760 mm (39-40 m.d.). "Dlwswe constitute -Ifho ripe ova with translucent yolk amt]; -distinct oial globule. In fact, 11h-ore is ovi— donoe of being almost complete (fig. 2, \D) by the poor -representation of ripe ova in -the ovary. Appamenmly, the malzume ova forming -a mode at 0.418 M r - M U no iéiil‘ 0
W \ 5-6 B-O ZS-ll ll-I5 45.45 OVA DLAMQTEQ Ill RIG. Z. 0va~d1i1amooar-fnequeoy drisrtmibrwtflon in mature and owasriesl of N» me-$’0P"*°"I A & -B. iM*a'11urc ovacries (st V) coillelctedi on 12-1-7-9~ 7-Iii-79. C & I). Rliipe (st VI) ovaries ooilileotsevd" on IQ;-1-79.. MT: Mama-ning orransfluoont ova», M0": Mature opaque ova, RT: Ripe translucent ova wimh oil -gflwbulc.
' - 2 - -...--P:-¥‘_A._.;-.?PERCENTAGE FREQUENCY _ _. 1' ~ __n>-.___“_M fi -'. "_'_"'—""_~..L'$‘_'.i-’_'.?"ii1.O O1 ll r \ \ O5 ‘i 1 _" ‘i ‘*-" ’““_]r ii "“"‘—- ‘i I“— *°"- -'— ——~ —-- --—- ~Iv'--II 1- --;L—--— -1- i —-— —--—.---—I~—ol Q BIOLOGY or‘ THREADFIN BREAM 203 mm in -mature ovaries (fig. 2, A & B) have undergone she process of maturation and re-ached the modal diameters of 0.722 mm and 0.760 mm (Fig. 2 C & D) in ripe ovaries. I-n ripe ovaries (st. VI) -a mode can also be seen in the mature opaque ova -at 0.418 mm (21-22 m.-d.) (Fig. 2, D) or at 0.342 -mrm (17-18 m.d.) (Fig. 2, C). These modes are the same as those representing matu11'e ova in stage V (Fig. 2A & B). S AGE AND GROWTH For purpose of study of §ag»c- and growth, data on -the -length-fr-equ-ency di-st=r.ibution collected id-uriing Jan-uary 1977-September 1980 are used. A total of 2386 -specim-ens ranging from 32 to 215 mm were ex=am*i-ned. The monthly length fmequency =d-i.stri|bu'tion of N. mesoprion in different years are shown in figure 3. It may -be seen "that data are =avlai-table for only -a few months in 'difie»1‘-ent years. T‘ih'i-s is mainly due to -the -fa-ct that this species forms _a seasonal fishery duri-ng P5w@ @CD*Ol‘-7 mum .*'9‘?’§° QC)-PC) PF“) 9°!” tum OO\ N O00!»P99 l""lQ U-l‘JI 204 MURTY J anu=a=ry-March and during other months -irt becomes soaroe in the camehes (M-urty MS). Even duri-ng shont -periods for which data are availafbl-e, the modes 1111-e monthly 1-emgllh-fmequenlcy dzistriibrution do -not show ol-earr~cut progression matk-i"-riag the -estimation of age However, -an attempt i-s made here to esti-matte -the g,-row-th rate and age by following the modal progression (wherever possilbl-e) during short inmemvals of one to four months. This has been done deli berately, in spit-e of the -lim-irtaIti=on»s involved because there is no information on age and‘°’ growth1 . of this. -speciesL3 from Q78 I-n-dia-. I-t may be seen from figure 3, -that I.0 ,¢/ M _ Z nlm. now 30 ,Q,‘ —— MAGIC»:I '° \(¢,| B ISQa //\\an V 4AM-I OI- *C1 A/¥Z - - ‘~ — ,‘ an I "'I91 \_ mafin ‘:0: .... -._/\ " ‘ A Alli}:1_';-'l ‘j1\T9e.'>' ¢/ "H 1 H .-/\\ \\ 5: \' -4 1;.-1\ . \>; -_ APGR.W-2 io‘O "nu‘ -omen _f.-.'-.ii- Ce Qka-noon-ni 6 ' 5 .._ 4 MARCHH F "ll Q J_ ‘Q1 1 | . fin J' ‘e_“ . 1W y —v____* ‘— ' —u 1_+-— | v——' q v v U 1 1 $ 10 no‘ ‘KI ">0LENGTH J0 690095 *0 van "0 ‘m .9 Q FII-G. 3. Monthly length-ftrequeinicy drismnflbutzion of N. mesoprion i.-n diiffenent years. -the -mode (a) at 50 mm in March 80 can be traced to 70 mm in April 80 giv ing ea -growth of 20 mm in one month. The mode (lbl) at 70 mm in M-arch 77 is ¢»l'!&O68ib1'€= to 80 mm .in April 77 giving a -raite of 10 mm per month; another mode (b2) =3I1'S0' at 70 mm in May 79, can be traced to 100 mm in August 79, in three m-oniths, gi=vi-ng an average growth rate of 10 mm per month. T-he mode at 100 -mm (ol) -i-n~ F~ebruamy_ 78 can be traced to 110 mm in March 78; similarly, the mode -at 100 mm (cl) i-n December 79 can ‘be t-naoed to Pl RCENTAGE FREQUENCY 8 O \' -i..-_;._ .._;__'._....'_-E 6 -_. BIOLOGY 01= THRBADFIN BREAM 205 110 mm in January 80 thus giving a -growth name of 10 mm per month-. The mode at 110 (d) in February 80 has to 120 mm in March 80 Wilth "a growth hate of 10 mm per month. The mode (el) art 120 -mm in February 77 can "be traced to 130 mm in Mairoh 77 and -the mode (e2) -at 120 mm in February 77 to 130 mm -in April 77, thus -gi-vi-nig -a 'mon»t-hily growth rate of 5 mm. The mode at 130- mm -in December 79 (If) is traceable to 140 mm in Feb!"-wary 80 giving a- growth of 10 -mm in two m*on|th;s. Similarly the mode at 150 mm (g) in January 77 can Ibe traced -to 160 mm in 77 giving a monthly growth rate of _5 mm and the mode (h) at 150 mm in. september 78 is trace-aibl-e to 1. 70 mm -in Januar-y 79 (in four month-s) with a- growth rate of 5 per m=on~th. Beyond I70 mm, the modal progression is not trace-able. From -the above ObSC~I‘VI3.'lZl‘OI1lS -it may be summari-sed that the monthly g-now-th rates are 20 m-m =betw-e-en 50 and 70 mm lecngith, 10 mm between] 70 and 120 mm, and 5 m-m ~between- 120 and 170 -mm 1-e-n-gth. Simoe a growth of 20 man i.s observed‘ between 50 -and 70 m-m in one month, the -fishes forming a mode at 50 mm can be reasonably -1:aken as two months old (at a growth rate of 25 -m-ml-m'onith). I.t may .thus ~'be taken -that N. mesoprion off Kaki-nada obtains a length of 140 -mm at the COII1ap1€*ti0II1= of one year and 170 mm at the compl-etion of -one-an-d~h.a'lf yeazr. Weber "and J ot-hey (1977) beliieved @th»at- -this speoi-es la-t=tai=ns 50-60 mm, 125 mm and 15 6 mm at -the com-piletion of finsrt, second and third years, respec -tively. The data for the above eonolusions ca-me from the survey of dem-ersal fish resoumces cainri-ed out in the coastal watens of the South Chi-ma sea bordering east Malaysia ( Sa-r-awak -and Sabha) inom 29th M'3JfCh to lst May 1972. The l-ength data of N. mesoprion olbta-ined adoring the above period -were (analysed with -the help of -probability paper (Harding 19-49, Cassie 1954) and the resultant normal dimribwtions of different 'Len-gith groups were taloen as belonging to diff-eren-t age groups. These auth-ors, ‘how-ev-er, did not take the growth rate of the esp-eoi-es znfto account nor did they have data. -over exiten-ded rperiods to -fa:ci'lietate- the study of age and growth. Th-e von Bertallanfiy -equation -for growth in length (Bev-erton and Ho-It I957) which is of the form: Lt = L¢(1-°'K(t't°)) W1-mire Lo: = as-yntp-to~ti.c length of the fish, Lt = length at age t, K = a con stant -eqeua-l -to 1/3 of caltabolic coeffici-enit, t = age of fish and to = a:T'b-irtfa-1'y origin of g-row=th curve, was fitted to the age-l-ength data-7 of N. mesoprion from Kaki-neada. The Loc. was eestimated from the |Fomd-eWalf-ord plot (Food 1933, Walford 1946, Beverton an-d Holt 1957) of Lt + 1 Iagalinst Lt on the =bas"i=s of lengths a@tta I 2|0-1 0-i .4 1 I2 + u J I ~04 30+‘ o ‘iii30 '3.-1 so it; ' ? —*0 -~0 -~I2 _o ]:'~_i~'-—'—- :50‘x 3° ' ' H?" L: me. 4. 'I=T0md~Wa‘1If0IrKii {flint otf gmwflll in 3 ~ \ 4 10+,1 ‘ Ie ‘ { ‘O-2‘ O V— -77- V;-—‘iW' ' ' ' _|—U 5 -_ _~~'——]*_ """ "-¢“- - '7‘§f‘-' I "'15; ' 'IQ‘ Ytmls3 1 4 FIG. S. growth curve of N. mesoprion I LENGTH on O flfri _i:,_O 1 3,, Qi?-—-1 '__ 17- ___ __~— -—— i BIOLOGY OF THRBADFIN BREAM 207 V Th-e palram-eter-s K a1hd to were eestiim-ated from the efiuation (Beverton 1954) =lo=g e (Lo:-Lt ) = log e (Lac —|— kto) -Kt and va.1-ues obltained are K = 0.83248 and to = -0.25619s yeams. The l-e-rngths at difiemenm =a¢ge:s cahcuhated fnom 1ihc von .Bc-rt-aianffy growth eq-u-amiorn are pl-otilaeld in figure 5 which mdicave 11h-at observed -and calculated lenglth-s at d=i-fferen=t ages agree closely and -th|a=t N. mesoprion at K=a.kin~a.-da attains 140, 185 and 205 -mm ia-t the O01I1'pl'€1l3i'0l'l' of firm, second a-nd third years re1spe~ctive]y. REFERENCES BEVERTON, PR. J. H. .1954. =N~o1cs1 on -‘the -use orf .nh1eo¢r'.’it1icafl m1o-dels aim the stu-diy odf dynaa.m-ics of ex-p10i.1:e¢d fislh |p0p1Il'arti.'o|ns. U ..S'. Fish. Lu-b Beaufo:-'1 N.C. Misc. con-tr., 2: l5I9- pp. BEVERTON, R. J. H. AND S. J. I-101.1". l-957. On -the dJy.n-amics of ex'pl0:i|ted- fish pop'uJ~at.im1s-. Fish, Invest. Ser. London, Min. Agric. Fish U.K. 2"(1-9): 53~3 pp. ~ CASSIE, R.. -M. l'954. Some uslsts of -pnolba-bl]-ilty -p-asp-ar in the nallysis orf Sli-Z6 frcqueclcy distri -bu.ti|o-ns. Ausr. J. Mar. Freshwater Res. 5(3): 513-5'22. CLARK_ F. N. 1-934. Mu~t|.m"-jlty of |th|c C-zullirf-o|nni.i=a. S..=.rdeLn|e (Sardina caemlea), d.e1termincd -by ova (Mame-te;r me.a-"sI11.=1~.=:"1n~e|n|ts.. Fish. Bull. Calif. Div. Fish. Game, 42: 49 pp. F0111), E. 1933. -An a-ccso-um of. -the l-Ircmnitrrg jrrrvc9t1g‘ati|01f1-'.S condu-oted at Pl*yim0~u-th du-ring the _vea:r-.s I924-1933. J. mar. hiol. Ass. U.K._, 1'9: 305-3'84. HARDING, J . P. I-949. The we ocf .prob;=.1b~i"l-iety paper =fior the gr-aphlic-.a£I -a*n|a=1ys-is of pol y m0'd=al f=rcque.ncy d*is'tr=irbuIt-iionvsl. J. mar. bfol. Ass. U.K., ZI8: -141-1153. LE -CREN, -E. D-. 1'95!1. The l»:¢n.gth~wc=E;gfl1t -I1el'a1t-i-0nslh|i*p and season-afl cycle gonad '.\"e=ig.ht and ¢.Q=11;dfi|[=i.Q4n in the -Perch (-Perm fluviatilis). J. (lnim, EOOL, 202 2014,19. Suamscon, G. W. AND W. G. COC-HRAN. II967. Statistical Methods. Sixlhh -Edit-iron Oxford and iLB1I-I .p-ubl'1s*11.i|n-g 00., New -Dellhi. 59-3 pp. WALFORD, L. A. 19456. A new gr-aphdx: mewhaod of cbesc-nilhing -the growth of amima-ls. Biol Bull Woods Hole, 90: 1'41-14-7. WEBER, W. mm A. A. IOTHY. 1977. Obsre-rwamhoms: on the fish Nemipterus bpp. (I-‘amil-y: Ncm\i!pne11id'a:) i!n- -the coast-all wastem of =e1a-at Mlaiaysaiial. Arch Fisch Wiss., 2-8 ( 2/ 3): 109-122. [corwraxaurxou 6 l MURTY, V. SRIRAMWCHANDRA. 1984. Observations on the fisher ies of threadfin breams (Nemipteridae) and on the biology of Nemégpgrgo j8E9Di¢Q§ (Bloch) from Kakinada¢ ;§d;agl§,?F1sQ., 31 (1): 1-18. .17cowrareurrou - - —— 7 _,";1. 6 , I Reprinted from Indian J. Fish, Vol. 31. No. 1.1934; PP- ['13 OBSERVATIONS ON THE FISHERIES OF THREADFIN BREAMS (NEMIPTERIDAE) AND ON THE BIOLOGY OF NEMIPTERUS IAPONICUS (BLOCH) FROM KAKINADA V. SRIRAMACHANDRA MURTY Kakinnada Research Centre of CMFR Institute, Kakinada 533002. Aasrmxcr Of the four species of threadfin breams occurring, N. iaponicns is the most dominant at Kakinada. Peak landings are obtained during first and last quarters. There is significant difference in length-weight relationship of males and females. Peak values of Relative condition factor are associated with accumulation of fat. This species is a fractional spawner releasing the ripe ova in two batches during a protracted spawning season: August-April. The -length-. at first maturity is esti mated as 12$ mm in females. The estimated fecundity ranges from 23049 to 139160 in fishes of 134-199 mm length; in this length range, there is linear relation ship between length and fecundity and between weight and fecundity. Generally males outnumber females and attain larger length. N. japonicus attains 185 mm, 255 mm and 285 mm at the completion of the first, second and third years, res pectively, at Kakinada. The various growth parameters are estimated as: L CI: 314 mm, K = 0.75142 and to = —0.I7309 years. INTRODUCTION ffhreadfin breams constitute an important portion oft the demersal fish catches at Kakinada: an estimated 394 tonnes were landed by the Lrawlers dur ing April l968~December 1970, forming 9.7% of the total trawl catches (Muthu et al 1977). With increase in the fishing effort in recent years, the catches of these fishes increased considerably, though showed decline in 1978 and 1979. The present account deals with the fisheries of threadfin breams and biology of N. Japonicus. MATERIAL AND Mernons The study is based on data collected during 1976-1979. Estimates of monthly and annual effort and catches were made following Muthu et al (1977). Three types of boats were engaged in fishing in the area, using two-seam bottom trawl nets (see CMFRI 1981 for details). The effort (number of units) was standardised taking Pomfret (the total number of units of this boat is maximum in the fleet) as the standard unit, following the procedure of Gulland (1969). The catch rates (C/ E) mentioned in this paper refer to catch per unit of standard efiort. 2 'MURTY Samples for the study were obtained at weekly intervals. Data on length,* weight, sex and stage of maturation were taken from fresh specimens. The length data obtained on each observation day were raised to the day’s catch and these data were further raised to get monthly length composition of the catch. For the ~present study, these data were -scaled down to percentages. The length weight relationship ‘and Relative condition =factor were calculated following Le Cren (1951).; Ova-diameter measurements were taken from formalin-"preserved ovaries: small pieces from the middle of the ovaries were taken and all the ova in the piece were measured.-with the help of-an ocular micrometer at a magni fication where each -micrometer division was equal to .0.019 mm, following the procedure of Clark (I934). Fecundity was estimated taking stage V ovaries. Ftsmanras The catches of nemipter-ids were highest in 1977. In 1978 and 79 the catches were low, when both the eflort (Table 1) and the catch rates were also in decline. The period from November to May was the season of abundance with peaks during January, March, May and December (fig. 1). TABLE l. Estimated catches -(kg). eflort (standard units)" and catch rates of Threadfin breams during 1976-’79. (Values in parantheses indicate per centage increase or decrease over each previous year)". Particulars [976 1977 1978_ 1979 Effort 33777 58450 53645 50125 (+731)) ('8.2) (_6.6) Catch 527767 1336945 393361 271386 C/E 15.6 (+1-53.3)22.9 (-70.6)7.3 (‘3l.O)5.4 Four species of nemipterids contributed to the fishery. N. japonicus was the most dominant species contributing to over 50% (by weight) of nemipterid catches in most months, followed by N. mesoprion, N. tolu and N. luteus (Fig. 2). N. mesoprion formed a seasonal fishery, particularly during January-March. D_uring certain years this species dominated over even N. japonicus. N. tolu occurred almost round the year, but in poor quantities. N. luteus was also represented by poor catches, but occurred in considerable quantities during January-March. Determination of depthwise distribution of different species was not possible on the basis of the present data. According to Narayanappa et al (1968), * Total length, measured from tip of snout to tip of lower caudal lobe. FISHERIES on THREADFIN BREAMS 3 Nemipterus spp. were predominent -in ‘depths beyond 50 -m.q'The data on experi mental trawling, by Satyanarayanai et a1 (1972), also -showed that threadfin breams were more abundant in the area beyond 50 m depth. ---_._( -_. . _- ‘ __1 -:_ ,I. - - H79 ..\ .‘l'$£ L’ ‘nae1 e" "2 = I = 1 llli 1 ll W 1 I 1 00¢ IOU 1 J\ .-2 -_ -u 1 _ -11 1-— § 1 _ Q 1 "* Zk 4 i 1'Q. -_ i3 IiQ 1i iL ll Z1 1 %i3 i- ll ‘-“ _iI-— -:2-1 - Fri it 1 "-2' 1=2 VT‘ 1' Z1 5 ~ ~ E 5?; 2 2-1 E1 is -4 '“ ill 5 gE a .1; 1 l l 1 4i—1—-—+J F M A. M r‘—_-1 _ A_-_ S "1 O rérrN D 1-'. 1 1- 4 F 'U 'A H J J A S O h D FIG. I. Seasonal abundance of FIG--. 2. Monthly percentage com-' Threadfin breams during 1976 position (by weight) of nemi 1979. pterid species during 1976-1979. Silas (1969) showed that, in the depth zone 75-100 In along the west coast, N. japonicus predominated ind exploratory and experimental fishing opera tions, often forming 75% of the trawl catch. Zupanovic and Mohiuddin (1975) also reported similar abundance of this species in the 50-125 m depth zone along the northeastern Arabian ‘sea. A BIOLOGY o1= Nemipterus japonicus Length-eweight relationship The study was based on 27.9 females ranging from 69 mm and 5 g to 218 mm and 139 g and 168 males ranging from 71 mn1eand6 g to 251 mm and 184 g,-5 collected during April 1-976-March 1977. The relationship was calculated separately for the sexes and the equations obtained are: Pt?-\€.Lr1iTAGE _. __ u J _<_>_n_§. .._i s>_;..<2._ ,1 3 0 8» 9'1" I -..‘l Y Q“PIUCCHIWCC J B'lfl.|.§.'|ll. mansion-Eu-m1.u.@un.|.zm 4 MURTY Males: log W 2 —3.65045 + 2.43025 log L Females: log W = -4.78737 + 2.95688 log L The significance of difierence between the Regression coeflicients of sexes was tested by Analysis of covariance following Snedecor and Cochran (1967) (Table 2). The difference is significant at 5% level. TABLE 2. Comparison of Regression lines of length-weight relationship of males and females 0)‘ N. japonicus from Kakinadu. D Ex? Exy Eyl Regression Deviation from coeflicient DfRegression SS MS Within Males 167 2.77689 6.74856 20.03178 2.43025 166 3.63104 Females 278 2.82427 8.35101 25.15722 2.95688 277 0.46435 4-43 4.09538 0.00924 Pooled 445 5.60116 15.09957 45.18900 2.69579 444 4.48368 Difference between. slopes I 0.38830 0.38830 Comparison of slopes: F = 42.02; Df = 1,443; Significant at 5% level. Differences in length-weight relationship between sexes in nemipterid fishes are known; Eggleston (1970) recorded the difference in N. virgatus and Krishnamoorthi (1973) in the case of N. japonicus ofi Visakhapatnam. Vinci and Nair (1975) and Hoda (1981), however, did not find difference in the length-weight relationship of males and females of N. japonicus from Cochin on the west coast of India and from Pakistan coast, respectively. Relative condition factor The Relative condition factor (Kn) values of females were less than unity in January, April and June and more than unity in other months. In males, the values were more than unity in all the months. lt was also observed that the Kn values of males were more than those of females in most months. Fat accumulation started in lune, became heavy in August-October, and traces of it were present in November-December. During January-May there was no fat. The high Kn values in July-October (fig. 3) were thus due to fat accumulation. For comparing the Kn values of different lengths, data of March-May 1977 only were considered, to eliminate any possible influence of different factors (e.g.. maturation, fat accumulation, etc.). on Kn values. The Kn values of males up to 155 mm were less than those of females, but from 165 mm on ward these values were more (fig. 4). In females, there was a peak at 75 mm, rrsnsarss or THREADFIN BREAMS 5 followed by a gradual fall till a minimum at 125 mm, increasing again to a peak at 145 mm; there was another fall at 165 mm and another peak at 195 mm. l I TS J 1 .5. / Mao; -—~wu.£s 1t ~F£wu.Es V L32$€ 1 . I ||15-\I‘ MA L £' a g5 Qrmx_|iil . 1-O75-. -—¢'£MAtEs | -01511 \‘ omsi-oz. s<‘f °'”°‘_l-I 5}\ \\ II:ii ous . \ ‘—”r“—-Tr--~*Q $7 #*’*——+T_—i"_ 75 - K0 VALUCS 6 MURTY Stage V (gravid): Ovary occupies about 2- the length of the body cavity, whitish, with numerous blood capillaries, ovarian wall thin; ova spherical, opaque with narrow translucent outer border. Stage VI (ripe): Ovary occupies from % to entire length of the body cavity, cream-coloured. Ripe ova, which are translucent and with a distinct oil globule, are already released into the lumen of the ovary; along with these ova are several mature (opaque) and maturing (translucent) ova. (In several instances, -the ovary extended to about half the length of body cavity, with a few ripe and a majority of opaque ova. Obviously the majority of ripe ova were released. Such ovaries were also included under stage VI.) Stage VI]: Completely spawned ovary was never encountered. 2. Length at first maturity: Only females in stages III-VI were taken as mature for this purpose; The data of August-April (spawning period) alone were con sidered. Fishes of 100 mm and above showed mature gonads and there was an increase in the number of mature fishes with increase in length. About 50% of the fish were mature at _a length of 125 mm .=(fig. 5). Hence this length was taken as the length at first maturity at Kakinada. According to Krishnamoorthi (1973), the length at first maturity of females of N. japonieus ofi Waltair was 165 mm. ‘ti . ll~l _\‘l\_ r Le ~— _ _—a —III 1 a—~-1»:---—_— ' 1* , .» ,1i______r;___,l ,, .. __ __ .-Q4»-QUIQ-Q _ l'_ _g__/\/\/'\ ;_i :__l ______;I U ___¢__g_g_._ _ '. T______,______.___._,..___ ;, _,__—i gem e,_,,*_' . ._; ,Fe; :1 *1 ~1 'we-—!—>.' ‘—~I'_“l"""‘I"‘P"'*v--'r'.'~'I'°_-"'ll. I03 '°'v1 n ¢_ esL£"(’m as -es GROUPS’ - I“ _,.__j_,_; H“ 4 HoI ovaI7-II DIAMal?'£R ,T__, 0 7,i.__, mg' I no FIG. 5. Pel'centage- frequency dis- FIG. 6. Ova-diameter frequency tribution of mature females of distribution in ovaries of differ groups.N. japonicus in different Japonicus. length ent stages of maturation in N. PIQC [N TAG! Psnccnuoe rnzoucucv Oi‘ : ‘F ,6 _e 9.. r. .2 as jig . __ FISHERIES OF Tl-IREADFIN BREAMS 7 3. Spawning habits: The ova were distributed around a modal value of 0.08 mm ‘in -stage II (fig. 6). In stage III, a batch of ova was released from the parent stock and formed a mode around 0.27 mm (mode ‘a’). This mode pro gressed to 0.76 mm in stage VI. In stage IV, another batch of ova was released from the parent stock and it formed a mode around 0.19 mm (mode ‘b’). This mode could be traced to 0.38 mm in stage VI. Two batches of ova were, thus, released from parent stock and underwent the process of maturation. While the ova at mode ‘a’ in stage VI were ripe and to be released, the ova at mode ‘b’ in stage VI were opaque and were yet to become ripe (figs. 6-7). Also the mode ‘a’ in stage V and mode ‘b’ in stage VI were more or less at the same diameter, indicating that the ova at mode ‘b’ in stage VI probably took the same _._ _-M]'_ _--r----MO ---,- -I----—»--MT --——-MO "---'—"'RI“"“""""_ I5] tL‘q7m ‘S. 7‘2~lq7o; fmsakmi <2-|- mo. r:..|s8""“ 15 '2"°7°' "" zoom ?" 5‘ , lio-a-n1vr|_|s2mm ~-. 1‘/‘_\ I 1-‘ /&-_ '5 | .' 'W /*\ :27_Q_’Q7q fL|55mm is 8""-I979; |$mm ~----'1' —-'.r§a'ow-"rrc"s§rm| \5 __ . ‘, "T e— "'1" r ._, - ..,-\\ '5 :I 2o-1;--um. ~ TL-l7Omn| /3rs—~‘-¢.»_T¢wwta.e-sin J \ 5 /xi/\\' ' ,'""""_ _J . iii '_ . _ ZI \I t ‘-'5‘> , I ._26-l2-l979.TL‘T Q 1 _| _'Z -uozmjnI. i .' '_-— (H4 j-f—y-'*1'*rLU'iP*'r"_' 312; ' 5-6 GM 322I l 29931 TF5 . “ ova DIAMETER (ma:1I ~5I . . | FIG. 7._ Ova-diameter frequency distribution in (A) stage {V and I B) stage VI ovaries collected during different -months. Diameter ranges' of Immature ova. (I); Matur ing translucent ova (MT); Mature opaque ova (MO), Ripe translucent ova with an oil globule (RT). time to become ripe and spawned as the ova at mode ‘a’ in stage V. Thus, it appears that N. japonicus is a fractional spawner, releasing its ripe eggs in two batches during the spawning season. Eggleston -‘('1973)“ancl Dan (1980) have obtained similar results. The process of maturation also suggests that once the fish reaches stage VI and release the batch of ripe ova, it may revert to stage V and again undergo ripening and reach stage. VI. This is possible, because P5RCENTAGE FREQUENC Y .a*__t " _§" - uv X,__\£ 1 ;-,€E_,.,-r_,‘{'_L_.:.:I.;._ 2 F ,,___--_.i 2.’) I/' L _ _ __ I-|'1. \ an-#QiIIlIlI@¢‘_-' _.~._ ._ .. ._ "I E5 S MURTY TABI. E 3. Month-l_1'" percentage frequency distribution of adult females of N. japonicus in different stages of maturation (Data of 1977-1979 pooled) No. of specimens % of maturation, _. sta.-g cs _ ,_.o ,2 examined II IV v VI Jam 8'1 8.6 18.6 45.7 12.8 14.3 F ch 37 16.2 5.4 5.4 73.0 M at 117 42.7 17.1 17.1 6.8 16.3 Apr 55 69.1 18.2 9.1 1.8 1.8 May 27 85.2 14.8 4 it .1 un 9 100.0 4 I9 J u1 55 36.4 40.0 23.6 — i Aug 35 11.4 2.8.6 8.6 11.4 40.0 Scp 76 9.2 19.8 28.9 14.5 27.6 Oct 67 3.0 23.9 26.8 44.8 1.5 Nov 91 53.8 38.5 7.7 Dcc 71 1.4 2.8 12.7 40.8 42.3 ">01 1 1 1 11 1 1 1 1 \ /\ 1 1 .1 1 \ . 1 1 1 1 \_1 1 1 20 1 " / 1 1 1 “-1_I977an v—— JAwv 1 —= 1 4 59> FSEF -1"-16-6 I978 1N *"'*“—*“"r""|"-"'1 MAYJAN "1'—"r"I979 MAY"I '"*' #'-"@"fi""*?»"T“"!"_1“_Y'"'1"' SEP 1“'1""1—"" HG. 8. Percentage-frequency distribution of grav-id and ripe (st V + st VI) females of N. }'ap0m'cus in different months. PERCENTAGE - FREQUENCY .15 019-18,? 0 ,_42.? \ / .1 J -~____ FISHERIES OF THREADFIN BREAMS the modal sizes of mature opaque ova in stage V and VI were more or les same. There was also a group of maturing translucent ova forming a mod (fig. 7) in stage V. which seem to mature and become opaque by the tim the ovary reached stage V1. Thus it appears that the ovary, on reaching stag VI, and releasing ripe ova, does not go back to stage II, as is generally known but only returns to stage V. Supporting evidence is available from the fact tha fully spawned and spent rematuring adults were never encountered in thl catches. James and Baragi (1980) observed similar situation in some marim fishes of India. 4. Spawning season: For the purpose of determining the spawning period, onlj individuals above the length at first maturity were taken into account. Though there were difierences in the occurrence and abundance of gravir and ripe females in difierent years the spawning season of N. japonicus at Kaki nada may be taken as extending from August to April (Table 3) with (peak! during February and December (fig. 8). The occurrence of juveniles of the length range 35-85 mm over an extended period (vide infra) supports this conclusion. Krishnamoorthi (1973) stated that N. japonicus spawns off Waltaii during September-November, and Dan (1980) observed that this species spawns twice a year, during December-February and June-July, at Waltair. This species in the south China sea spawns during May-October (Eggleston, 1973). Fecmtditv For estimating fecundity, 30 stage V ovaries, of fishes ranging from 134 to I99 mm TL (32 to 105 g weight), were taken. Since N. japonicus re leases ripe ova in two batches, the fecundity estimates from stage V ovaries pertain to the first batch only. To facilitate estimation of the number of ova produced for the second batch, the total number of maturing-translucent (0.17 0.30 mm) and mature-opaque ova (0.31-0.57 mm), from the ova-diameter frequency distribution of stage V and VI ovaries (Fig. 7A & B), were taken and their percentages determined (Table 4). While the percentage of mature opaque ova in stage VI ovaries ranged from 51.5 to 69.7, with the average at 59.2, the percentage of mature-opaque ova in stage V ovaries ranged from 30.1 to 57.5, with the average at 45.4. Hence, the ratio of ova produced for the first spawning act to those for the second was taken as 45:55. The first and second batch fecundities range from 10372 to 62622 and from 1.2677 to 76538, respectively, and the total annual fecundity from 23049 to 139160, in fishes ranging from 134 to 199 mm TL. The average values are given in table 5. Fecundity against total length as well as weight (fig. 9) of fish shows a linear relation. The equations obtained arc: a) F = -116.5671} + 1.11909 L and b) F = *O.756l5 + 1.11380 W 10 MURTY TABLE 4. Maturing translucent ova and mature opaque ova in ovaries of stages VI‘ and V in N. japonicus (percentages). Maturing-Stage Mature- VI Maturing— Stage V Mature translucent opaque translucent opaque OV3 OV8 OV3 ova 461; 53.2 55.8 44.2 30;; 69.7 54.6 45.4 45;; 54.7 69.9 30.1 48;; 51.5 58.5 41.5 39;: 60.8 53.2 46.8 34.1 65.9 50.4 49.6 .4'I_.5 58.5 42.5 57.5 Pooled 40.8 59.2 54.6 45.4 Where F = total fecundity in thousand eggs, L = length in mm, and W = weight in grams. The'C0rrelati0n 6668161661 (1') for both the equations are 0.83 and 0.92 respectively. According to Dan (1980) the average fecundity ranged from 13.9 to 58.4 thousand eggs in N. japonicus, with the range of 138 to 205 mm, from Waltair. The estimated fecundity for the first batch spawning in the .pre sent study agrees well with the fecundity estimates of Dan (1980).. Sear ratio Females outnumbered males in January, March and May-June 1977 and in January, March-July, September and November I978 (Table 6). In 1979, TABLE 5. Estimated average batch fecundities and total fecundity in difierent length groups (cm) of N. japonicus Average Average I Batch II Batch Average length (mm) Wt. "( g) N Average Average‘ total fecundity 134* 32 10372*12677* 923049“ if 146 .44 25149 30738 55887 9»1s3 41 23064 28189 51253 .163 A59. A 30514 31294 67808 _.174. "63 30152 36851 67003 183 19" 35904 43883 79787 195 105 56064 68522 124586 * Actual values. IQ!A 4 "OijI .0 1 .1/. ~+I. O »O 0 I l1 0,/ '/ ‘ - : 0 0/ 0 ,| O I‘C .. /O0. . .. '_O , s "1|>I A.1 l I |O-4",1| 04 0 L‘f""v30 vSO + i__1-” 70 ‘I 90 ”T——I"' HO ' 1:30 ¢ {—-y-T1 no we ; ;—, Weight (91 Tom Iengthlmml FIG. 9. Relation between fish weight and fecundity and between fish length and fecundity ' in N. japonicus. At 5% probability level the'XZ- values for 91977 and 1978 showed that the observed differences in the monthly sex ratios were statistically significant, whereas they were not significant for 1979. In this connection, it may be noted that data were not available for all 12 months in 1977 and 78. The data on the sex ratio in relation to length (Table 7) showed that in most length groups males outnumbered females and females were not repre sented in groups beyond 215 mm. Also the mean length of males in the catches was always greater than that of females. The present observation therefore supports that of Krishnamoorthi (I979) off Waltair that females were generally smaller in siize than males and males grew quicker and to a larger size. Age and growth A total of 6654 specimens, ranging from 35 to 285 mm, were measured for age‘- and growth during the years 1977-1979 (figs 10-12). Mode ‘f’ at 65 mm in January I977 could be traced to 85 mm in February 77, with a growth rate of 20 mm per month (fig. 10). Mode ‘a’ at 75 mm in April 1977 could be traced continuously to the mode at 275 mm in May 1978; the mode at 75 mm in April 1977 showed a progression up to 115 mm in June (2 months) at a growth rate of 20 mm per month; the mode at 115 mm in June 1977 x {XU Fecundity 0 2 _-l_-_L_&_.l_.._|___..._._;...._.L_. O \ \‘\ 12 MURTY TABLE 6. N. japonicus: Proportion of females and sex ratio in monthly samples during 1977-1979. Proportion N Females of females M: F ratio X2 test [97 7 Jan 63 39 0.619 Feb 23 13 0.565 Mar 131 83 0.634 Apr 99 39 0.394 May 72 40 0.556 0/ Jun 19 'l 0 0.526 X =59. 524 J ul -— No data Df=9 Aug 42 10 0.238 Significant Sep 92 27 0.293 Oct 110 38 0.345 Nov 85 26 0.306 Dec -- No data Pooled 736 25 0.442 l.0:0.8 .1 978 Jan 49 43 0.673 Feb 43 19 0.442 XXL 2.».-aw Mar 42 31 0.738 Apr 144 55 0.382 May 15 5 0.333 b¥ Jun -— No data =- a Jul 84 46 0.548 Aug . 9 2 0.222 &p 25 14 0.560 Significant Oct -- No data Nov I31 72 0.550 1.0: 1.2 Dcc 43 16 0.372 1| .0:0.6 Pooled 585 93 0.501 .1 .0: 1| .0 I 979 hm 93 39 0.419 Feb 100 47 0.470 Mar 120 56 0.467 Apr 50 [6 0.320 Ma)" 47 20 0.426 ':P$Loo Jun 20 8 0.400 ll Jul 24 H 0.458 Aug 48 27 0.563 Scp -83 38 0.458 Oct 90 36 0.400 3M¥ww¢ Nov 5 3 .l4 0.264 Dcc I134 71 0.530 Pooled 862 38 3 0.444 _'::?:>'ob 99¢:-w-U--» Qqobb1--\b--Ir-¢|-Ira I-I\)n-lp-r-— s=rP¢9~&éé5ééé 7'59?‘ ??b? Qgbbbb 0° --‘-Is-1oowbo'~1'~.1i.n§oZ¢;; Mum PPPPPU'lC7\0O®u-~ ¢@¢@ -6L;; -§LJ"l-{>03 ;uQh@¢ §-_%> TABLE 7. N. japonicusz Sex ratio in relation to length. groupsLength I97 7 I978 pooledI979 1977-79 (mm) M F M F R4 'F L4 'F 65 o—i» I 75 2 I 3 3 S 85 9 7 9 7 4 5 22 19 95 14 I5 I6 15 ll I2 41 42 I05 I8 29 21 25 34 31 73 85 I15 32 39 34 41 48 40 I14 120 I25 23 37 39 37 44 51 I06 125 13$ 27 58 24 48 40 37 91 143 I45 57 52 25 35 43 50 12$ I37 I55 42 34 32 47 33 $9 I07 140 I65 55 22 13 23 33 51 101 96 I75 47 8 18 4 31 26 96 38 I85 20 ll I6 2 35 12 71 25 I95 22 6 I4 5 22 7 58 I8 205 23 1 I6 27 I 66 2 215 6 3 8 I 22 I 36 5 225 2 Qniflr 3 34 -2 39 _l 235 9 i 16 ii 245 5 i 8 ii 255 2 3 i. 265 __._ ...._‘ cu-~_ 275 ti 2 ii 285 i ii bl 411 325 292 293 479 383 1182 I001 mean length 155.34 135.74 145.75 133.46 160.05 141.40 154.88 137.24 (mm) Sexrafio L26 : L00 L00 : L00 L25 : L00 .Ll8 1 LOO could be traced to 145 mm in August 1977 (2 months), with an average growth rate of 15 mm per month. The mode at 145 mm in August 1977 could be traced to 165 mm in October (2 months), with a growth rate of 10 mm per month. From 165 mm in October 1977 the growth was not traceable but this could be connected to the mode at 205 mm in March 1978 (fig. ll) (5 months) with an average growth rate of 8 mm per month. The mode at 205 mm in March 1978 was traced to 215 mm in May (2 months), with an average growth rate of 5 mm per month; this mode was not further traceable but the mode ‘b’ at 205 mm in November 1978 could be traced to 235 mm in May 1979 (in 6 months) (figs. 11 & 12), with an average growth rate of 5 mm per month. Similarly, the mode ‘e’ at 215 mm tin January 1977 (fig. 10) could be |-sh-In-s}~J—oQ\ [Qn-A Nut Lgjhd n-so--oh 14 -=M"UR'i'Y traced to 235 'Il‘l.lTl‘".iI1 May (4 months), with an-average growth-—-. rate of 5 mm per month. The progression of this mode was not traceable further. The mode ‘c’ at 245 mm in October 1979 was traceable to 255 mm in December 1979 io"Li ______/XW77 N occ-M1 2I6 ~21 ' ' a oer-mv N-I99 ;~ l I Ir.’ ____, , _ ~ ~ 4,-- ; . _._ .! ¢ 19. 77 N-236 ! is--0- . i AUQ Q77?-I42 JUN 1977 N.4$ \_I ' __.- _ _ _ Q|§'|'i _. __ ' -"i ._ _ ...___--i ”~ \\ ‘-*-MAYA“ I| 0";.-"’ / 1077 u=24s i . _'. _%L 1- _.-—_._ _ _ __¢-I-"a,__ ' - -IN‘5ii____iii_... -"P hI- "—— I- ll i - _ -—---..___.... W -i_.._. --_ ,0; m _ Mag:-n17 an-303 ,0-i1___.." :__4“_‘_;L , . _i.__ FE8- . . -._.__ H‘I911 .?._";‘."_"_‘__;:.-,'_'-:—_.__ u=7o '0‘35 ’-, -//’__/§______-*1-'““’"'. 7Sfi—-1 ITS .1— . . , = ISS7- ,2---A._. 1 air I95iauuavv 7--T-_”““T—-TT —r—Y—T‘ 235 wars 275 i ‘=* LENGTH GROUPS mm FIG. IO. Monthly length-frequency distribution of N. japonicus in 1977. (2 months), with a monthly‘ growth rate of 5 mm. Since the growth rate from 215 mm to 235 mm and from 245 mm to 255 mm was the same (5 mml month), the same growth rate" could be taken from 235 to 245 mm. The mode ‘d’ at 255 mm in March 1977 could be traced to 265 mm in June ’77 (3 months), with an average growth rate of 3.3 mm per month. My Since the growth rates from 65 mm to 85 mm and from 75 mm to 115 mm were estimated at 20 mm per month, a still higher growth rate can be expected for fish up to 65 mm (the smallest modal length the present study period was 65 mm, vide_ figs. 10'-12) and an age of 3 months (at a growth rate of 21.7-mm per month) could be reasonably allotted to fish of 65 mm. On the basis of the estimated growth rates for different lengths, the lengths attained at different ages (months) are shown in figure 13A.“ The points on the graph are the modal lengths obtained from the data- (figs. 10-.12) and the curve indicates the authors interpretation of modal progression. PCENTAGE— 8-I FREQLJEIQCY _. U _ _4L_ 9__a.a<;> ._L<;» 2_1._...,.._.&1_. FISHERIES OF THREADFIN BREAMS "-It ‘J.: -,1/X 45/ _ _-.. l DE.c_|°_,‘- “'tif::T:;"_" ‘t"___ ~‘2£_. .__ . .._.. -C \_— — i e..-Q____ ~ ~ we --- . . _...... _i.-_.-‘-___‘_'f-. NOV ...... i_._ i---_ _. ._ a _._ ._~=_-.. . =o-_;{ /A\/\ we// I976\/ N 20 :0-7_ JUL +978 / N |45 -.: ..-_/\\ MAY '- — |¢7'e --__ N '00 ’\. . ,- :1 -,,_.____._:-'17}.-.1'”::.—/ \ APR-19'-‘B —.--.N 5:0 — ._ . Z_ ,MAP _, _.B P978 , __ N77_ __ _ Fag“,-,8______""-_—&\i- —;_i—=_____i_a.i.i "'77 JAN 197'. N Q4 .o.l"_I‘—v"—- I . . -or '~ _xi_-e-1 '1 1'" v-*—; —v—7-F-=1--1-"-1"-1---1 _ --r""1%—Y—Y"'— I so 15 us =55LEPKBTH nos GROUPS 23$ "TH >75 RIG. 11. Monthly length-frequency distribution of N.' japonicus in 1978. The von Bertalanlfy equation for growth in length is of the form: Lt = Lot (l-—e"K (Flo) ) The Ford-Walford plot (Beverton\ and Holt'\ 1957; Ford. 1933; Walford 1946) on the basis of lengths attained- at intervals of 6 months. is shown in figure 14. It was observed that the points were well represented by a} straight line. The asymptotic length (Lo; ) obtained in this-' study is 314 The values of K and 10 were estimated on annual basis from the relation: I log c< Loc—lt ) = (log eL°¢ +a K to )1- Kt _ and the values obtained are K = 0.7514 and to =i'-0.1731 year (fig. 15). The von Bertalanify growth equation for-sN. japonicusi"-from Kakinada can be written as: Lt 2 (]_e_0.7Sl4 The lengths at different ages, calculated from the above growth equation (figure 13b), show that N. japonicus attains 185, 225 and 285 mm at the completion of first, second and third years respectively. Since the maximums length obtained in this study was 285 mm, the fishable life span is 3 years. PERCENTAGE. -D eousncv — I.» ~ U 6 I.» U-I _§_._.._9. t_9__q_s2+t... .bs> ., . .. O I6 MURTY 05¢ 1070 N O12 F? '"'"*" "_* ' "'* F56?-"|§1'€'§+_ F4316: |- - '_;~_____~__ _ Hi ______:__‘_'.“.r:'..""'.i. -- ‘O4:-"/I - ._.. W-~\_ _.._?_._:- _.'_'ocr ""-—.-""L'“:- :91}: N130 -v .:'.._ Hi-.. _ / %,*._ saw. mm N-227 __il-;:'/__ii.-_. .“::*—-""'“ ----T :.'_'.i.?i-. D ‘U6 1Q.7§ N J5 _—-1--n \\_5 fl I_ IZ/ ._-. ...¢\ i-_i_ .__ . —._.- k _i.. .. _.. .1’. ---_r _ \ ___/\~. JUL-W79 \./ //‘Ix\\/ \\ ~ as - -_.. ___.i_____.___. _. ..-__...... 0 ...... \ JUN Ni‘? N 45 I \/L um 1919 N 2'0 . »—-——~____--—-"_X- - --..- .. . _. .._ . - ._. ..ii_.-.__..-..---___-i--.-.-. &Q bAPI I9 79 N 417 IQ '---+—".‘Z4 1 ——-. ’//’\‘ UK997q K 177 |.° /‘\—/X/\._..- _./_.___..._.___....ii___"'l*_—_.-;-_'-‘TI’. FEB W79 N I23 ...... -...-_. -i I _'/_/\/\’__\1 I_ 1w*~ __ ‘ . . i ~—~|—r*'r"r'-1*:--r__b'iAun~:-0-.‘ 7': - -mm 1 v—w— 3 65 I35 155LENGTH GROUPS235 mm "FIG I2. Monthly length-frequency distribution of N. iaponicus in 1979. i .A -11.3I _ MO :00?'x 8 IOO ~<> ~~.§,.,ii "t i i 1? 1 “ '° 1not 2an vans 3 0 . 7v‘vvrvIIu..~-______>__-__‘ Q _ __ . _ 'l'nII\"II'"Il'IlIU a ‘ 1 w'*-“- v IONTHS PIG. 13. A. Growth in length of N. iaponicus on the basis of modal progression; B. Von Bertalanfiy growth curve. PERCENTAGE FF2E.OU|iNCY 1014; LENGTH ._<'Li _2' .é_ iri- _9 LUITM IMI 0N O €_|__ 444'-—+ /, FISHERIES OF THREAD!-"IN BREAMS I7 According to Krishnamoorthi (1973) N. japonicus attains 1.50, ZIO and 240 mm at the completion of first, second and third years, respectively, in the sea off Visakhapatnam. Ben Tuvia (I968) presented the length data of N. japonicus obtained during November-December 1957 from the Ethiopian coast and assumed that the modes obtained at 13 and I7 mm ac belonging to ‘(Y 1201i /77 111- _ 130-1 h . -IIf ET 2‘0- . ’. ____ "_ 5 __ |-._ , F. :'J2o°i_ "'//,. /// —~, .T mo!~" /" /or' ‘— /v I_, __0| 1'1 I -I O-75102-_ I / 4I . |rzo1'—|—-v—| in goo 1—|-'1' Q49 : 1-—r---- 3» r-'1.pg --|.—r--|'"'r'--1- -O6 " 0 1C-5 ' t '_——“—i +0 1'5 fii_ 91.0 T B97" 2 ” 5F Ltlhfll Ace |~ vents FIG. I5. Plot of lot!“"\_. I-~ '~4\- - L. '. I-‘IG. I4. Ford-Walford plot of against ‘t‘ to determine ‘to’ gra growth of N. japoniczrs. phically. and ‘I’ age group respectively. Eggleston (I973) and Fischer and Whitehead (I974) observed difierential growth rate in sexes of N. japonicus. In the pre sent study it was observed that males attain longer length than females (vide section on sex ratio), but it was not possible to determine the age and growth of sexes separately by length-frequency method. in the absence of external sexual dimorphism in this species. REFERENCES BEVERTON. R. ]. H. 1954. Notes on the use of theoretical models in the study of the dynamics of exploited fish populations. U. S. Fish. Lab. Beaufort. N. C., Mi.s'c.. Comr., 2: I59 pp. BEVERTON. R. J. H. AN!) S. J. HOLT. I957. On the dynamics of exploited fish popul ations. Fislz. Im'('.s'I Ser. London. Min. Agric. Fish. 2 (19): 533 pp. BEN Tuvm, A. 1968. Report on the fisheries investigations of the Israel South Red Sea Expedition I962. Bull. Sea Fish. Res. Sm. Haifa, 52, 21-55. CLARK, F. N. I934. Maturity of the California sardine (Sardina caerulea), determined by ova-diameter measurements. Fish. Bull. Calif. Div. Fish. Game, 42:49 pp. CMFRI. I981. Commercial trawl fisheries ofi’ Kakinada during I969-I978. Mar. Fish. in for. Serv. T & E Ser. N0. 31:1-6. DAN, S. S. 1980. lntra ovarian studies and fecundity in Nemiprerus iupomeus (Bloch) Indian J. F4's'h., 241 48-55 (1977). TH II: ‘R0; 4- .2 ;.. ‘. p, _ OQQ - 1. _ L‘ 4 j.._. ._4._---4. ._._.. '~r' I ‘“_l I; _ _-;_.. ' ' '. ’_. '0 I‘. / FJ I I 4 K 1 _/H 1. / 18 MURTY EGGLESTON, D. 1970. Biology of Nemipterus virgatus in the northern part of the South China Sea. in: Marr, I. C. (Ed.). ‘The Kuroshi; A symposium on the Japan current. 417-424. EGGLESTON, D. 1973. Patterns of biology in nemipteridae, J. mar. biol. Ass. India, 14: 357-364 (1972). FORD, E. 1933. An account of the herring investigations conducted at Plymouth during the years 1924-1933. J. mar. biol. Ass. U. K., I9: 305-384. GULLAND, I. A. I969. Manual of methods for fish stock assessment part. I. Fish popul ation Analysis. F/IO Mammls in Fi.s'lzeri€s Scieitce N0. 4: 154 pp. Hom, S. i\1. S. I981. Length-weight and volume relationship in the threadfin bream, Nemiprcms iuponicns from the Pakistan Coast. J. mar. bioi. Ass. India 18: 421-430 (1976). }'AMF.s. P. S. B. R. AND V. K. BARAGI. I980. Ovary as an indicator of frequency of spawning in fishes. Pmc. Indian nam. Sci. Acad., B 46: 479-489. KRISHNAMOORTHI, B. 1973. Biology of the threadfin bream, Nemiptems japonicus (Bloch). Indian J. Fish., 18: 1-21 (1971). H. KRISHNAMOORTHI. B. 1976. A note on the size difference between males and females of Nemiprerus japonicus (Bloch). Indian J. Fislz., 21: 608-609 (I974). LE CREN, I-_'. D. 1951. The length-weight relationship and seasonal cycle in gonad weight and condition in the perch -(Pcrca fiuviatiiis} J. Anim. Ec0l., 20: 201-219. MUTHU_. M. S., K. A. NARASIMHAM, G. Sunmxamt Rao, Y. APPANNA Sasrmr AND P. RAMA LINGAM. 1977. On the commercial trawl fisheries off Kakinada during 1967-70. lnrlian J. Fish., 22: 171-186 (1975). NARAY.AN.\PPA, (3., D. A. N. R.-mu mu A. V. V. SATYANARAYANA. 1968. Certain observa tions on the otter trawl operations carried out in the inshore and deep waters ofi Kztkinada. Proc. Incio-Paci/ic Fish. C0zm.. 13 (Ill): 45O~455. SATYANARAYANA, A. V. V., G. NARAYANAPPA AND D. A. N. RAJU. 1972. On the com parative fishing experiments with a four-seam and a two-seam trawls on the east coast. Fish. Technok, 9 (2): 169-179. $11..-\S, l-_'. G. 1969. Exploratory fishing by R. V. Varuna. Bull. Cent mar. Fish. Res. Inst, 12: 1-86. SNEDI-LCOR. G. W. AND W. G. Cocnam. 1967. Srasrisricai Me!/10d.s. Sixth Edition. Ox ford & IBH Publishing Co., New Delhi. 593 pp. VINC1. G. K. AND A. K. K. NAIR. 1975. Length-weight relationship in the threadfin brearn. Nemiprerns japonicus, along the Kerala coast. Indian J. Fis/1., 21: 299-302 I974). WA|.1=0Ro. L. A. 1946. A new graphic method of describing the growth of animals. Biol. Buil. Woods Hole, 90: 141-147. ZUPANOVIC S. AND S. Q. MOHIUDDIN. I976. A survey of the fishery resources in the northeastern part of the Arabian sea. J. mar. biol. Ass. India, 15: 469-537. FONTRIBUTION -,1 MURTY, V. SRIRAMACHANDRA. 1983. Estimates Of mortality, population size and-yield per recruit oft‘. léppgicqg (Bloch) in the trawling grounds off Kakinada. I%n Reprinted from Indian J. Fis-h., Vol. 30, No.2. 1983; pp. 255-260 ESTIMATES OF MO.RTALI'TY, POPULATION SIZE AND YIELD PER RECRUIT OF NEMIPTERUS IAPONICUS (BLOCH) IN THE TRAWLING GROUNDS OFF KAKINADA V. SRIRAMACHANDRA MURTY Central Marine Fisheries Research Institute R»C., Kakinada ABSTRACT The mortality rates of N. japonicus are estimated from annual age com position of fish caught by trawlers. The estimated values are Z" = 1.86. F'= 0.72 and M = 1.14. The exploitation rate (U) is estimated at 0.33 and the total annual stock at I181 tonnes. The yield curve shows that the fishing mortality can be increased from the present level of 0.72 to 1.75 to get increased yield. INTRODUCTION For rational management of. fisheries resources a knowledge of various mortality rates (total, natural and fishing) of fish populations is necessary apart from the knowledge on various aspects of biology of the concerned species. In an earlier paper (Murty MS), the author presented the details of some aspects of biology of N. japonicus from Kakinada. The present paper deals with the mortality rates, population size and yield per. recruit of this species in the traw— ling grounds oil Kakinada. The account is based on the data collected during 1976-79 from the trawlers operating ofi Kakinada. The methods of collecting data on catch and etlort are given in the earlier paper (Murthy, MS). The length data collected on, each observation day was raised to the day’s catch and the monthly length composition of the .catch was obtained by raising the pooled. days’ catch to the month’s catch. The monthly data were pooled to get the annual length compo sition of the catch (i.e. the number of fish caught in each length group). In the region off Kakinada (16° 35'-17° 25’ N Lat. and 82° 20’-82° 55' E long.), N. japonicus is caught almost exclusively by trawlers, though it occurs in stray numbers in the catches of the indigenous gear operating in the same area. Hence, the fishing mortality can be taken as having been generated by trawlers only. OBSERVATIONS AND Resurrs Estimation of Mortality rates: Fishes of the length range 35-285 mm occur in the catches. A preliminary analysis of data on length composition of the catch 256 MURTY indicated that fishes of the length range 35-75 mm are not fully recruited to the fishery. According to Rieker (1975), it is impossible to find out anything definite about the actual mortality rate of fishes which are not fully vulnerable to the gear, because representative samples of these lengths cannot be obtained. It is apparently for these reasons that Gulland (1977 ) states, “. . . .that it is both simpler, and in many ways more realistic to omit fish below some chosen size (or age) from most of the analyses.” (p- 77). In the present study, hence, only fishes of and above 85 mm are taken into account for estimating mortality rates. Estimates of total Mortality are obtained by using the equation: log C Nt = loge NO —Zt Where Nt = number of fishes in ditleret age groups; t = age of fish, uum— ber of fish when t = 0 and Z = total instantaneous mortality rate. Estimate of ‘Z’ are obtained separately (by the catch curve). for each year using the age groups represented in the catch of that year. For this purpose, the length com position of the catch is converted into age composition on the basis of age determined earlier (Murty MS), and the numbers of fish in each age group are scaled down to number of fish per 1.00 units of efiort since the effort expended in difierent years was different. The annual age composition of catch in different years is shown in Table 1 and the values of ‘Z’ for different years are shown in Table 2. It may be seen that the ‘Z’ values range from 1.58 to 2.03 in different years, with an average value of 1.86. TABLE l. Number of fish in each age group (catch per 100 units efiort) and their natural logarithms in N. japonicus during difierent years. Age 1976 1977 1978 1979 groups CIE loge C;'E C/E loge C/E C/E loge C_/E C/E loge C/E .___~.-;- _ _ — __ '_ —_; 0 851.5 9.0496 23056 10.0458 18203 9.8091 6784 88224 I 3410 8.1345 10005 9.2103 I338 7.1989 1627 7.3944 ll 645 6.4693 1514 7.3225 312 5.7430 634 6.4521 III 77 4.3438 94 4.5433 — — 12 2.4849 YearTABLE 2. Estimated Brien eflort and ‘Z’ values(units) during different years. T7 1976, 33777 1-57826 1977 58450 1.83953 1973 53645 2.03305 1979 50125 1.99548 Average 1.86 rs? ESTIMATES OF MORTALITY 257 Natural mortality rate (M) is estimated from the relation: Z = M + qt following Gulland (1969 )7 and Ricker (1975), where, q = catchability co etficient, and f = fishing eilort. A plot of ‘Z’ against fishing efiort is shown in figure 1. The estimated value of natural mortality is 1.14177 (value of Y-intercept in fig. 1). According to Gulland (1969), “A fish which approaches its ultimate length quickly —- i.e., has a high value of K -—- is likely to have a high natural mortality, whereas a fish that grows slowly ( a low K) is likely also to have a low M.” (p. 70)- The K value obtained for N. japonicus from Kakinada is 0.75142 (Murthy MS), and the high natural mortality rate obtained now (M = 1.14177) is in conformity with the theoretical concept outlined by Gulland (1969). In this connection it may be mentioned that, according to Krishna moorthi (1978), the natural mortality rate of this species off Visakhapatnam is 0.5037, which is very low when compared to that from Kakinada. However, Krishnamoorthi (1978) did not take age composition of catch into account for estimating mortality rates. Fishing mortality rate (F) for the 1976-79 period is estimated as 0.71981. IP12 O 53 \ w'= 0-55 EC_ I tp':0-33 I _| , to 012$ IQ: 0125 1 ea‘. o-azs 1 Mn-:42 M»-042 ' "=0-9'1’ 1 1 1 > 0-2 ifi_r_—;I;’ SIS +i'*iI* ‘SO ‘I’-T‘iI Q” 0 ‘ft:-.4—;'F::;Iq 0.5 |.5 2-5 g ‘V O ' *O-5 _ ,, I _l'5 ---;----, 2'5 , ,0 . —0'5 , - ,*|'5 r. .2'5 ~ . "M" I mo um" Fishing Mortality Rate FIG. 1. Plot of instantaneous total F|G- 2- Yield Per Ycquit {Yw/_R) cfiortmortality rate(F) (Z) at against fixed fishing ages in relation of exploitation to fishms morlallty (Tpl) and natural mortalities (M). Estimation of poulation size: The estimates of exploitation rate (U) are made using the equation: “"*iTiT*<‘"°_ F ~<1=~~~M> I ) (Beverton and Holt 1957; Bicker 1975), and, from this, the total annual stock (Y/U) and average standing stock (Y/F) are estimated (Y * annual esti mated catch). 70%|. MOITAL Tv can 90 1 6.pm;if?‘ -it H Yitl For Inn — Oman II S N 258 MURTY The exploitation rate (U) is calculated, keeping the value of Z constant, at 1.862 (The 1976-79 average value) and using difierent values of ‘F’. The details are shown in table 3. TABLE 3. Stock estimates of N. japonicus based on dijferent 1-'alues of ‘F ’. 2 F rqz [J *Y|U *Y[F (kg) (kg) 1.862 0.42 0.2256 0.191 2022539 919774 0.52 0.2793 0.236 1636885 742894 0.62 0.3330 0.281 1314151 623073 0.72 0.3867 0.327 1181361 536535 -0.82 0.4403 0.372 1038454 471104 0.92 0.4941 0.417 926391 419897 1.02 0.5478 0.463 834352 378730 * Y = The estimated annual average catch of N. japonicus for 1976-79 period is 386305 kg. The estimated catches of N. japonicus at Kakinada range from 196 t, in 1979, to 862 t, in 1977, with an annual average of 386 t, for the four year period 1976-79. Since the maximum estimated landings of this species in any one year were at 862 t, the average annual stock should be above 900 t. This means that the value of F against Z = 1.862 can be at 0.92 (Table 3). It is observed that the present ‘F’ is at 0.72, and it may be concluded that the present trawling efiort will not have any adverseatfects on the stocks of N. jatponicus. Estimation of yield per recruit: The yield-in-weight perrccruiit (YWL/R) was calculated from the equation of Beverton and Holt (Beverton 1953) as modified by Jones (1957), which states: YW -_= E R*w6< 61961-6) {1-> X, X;, P and Q where X = e—K(tp I-to). X, -- e "K09 _t=),P = ZIaand,Q= one + exponent in the length weight relationship. In the above equation (1), R’ =_ Re -M (tp 1 —tp ) where R = number of fish first entering the fishing ground, ESTIMATES or MORTALITY 259 The above yield equation can be rewritten as given below, after account ing for natural mortality during pre-exploited phase and by dividing both sides byYW R (Krishnan Kutty F and IQasim I 1967): I T __. R W¢¢Z(1pl—1..)-M(1pl —1p) {B (,XPQ)— ,r (XiPQ)} ...... (2) The parameters of von Bertalanfiy’s growth equation for N. japonicus from Kakinada were estimated as K = 0.75, to = -0.17 and W = 320 g (Murty MS); it was shown that maximum age attained (t) in the population is 3 years. The yield per recruit at natural mortal_ities (M) 1.142, 1.042 andL0.942 and at two different ages of exploitation (lip I), against fishing mortality rate (F), are shown in figure 2. Since in the present work M is estimated as 1.142, it was felt reasonable to consider lower values of M as given above for calcula tion of yield per recruit, because the life span of the fish being 3 years a value higher than 1.142 for M is not expected: the value of M estimated on the basis of life span is at 1.0 (assuming that about 95% of the fish would die before they attain 3 years of age if they are not subjected to exploitation). In the present work, the age of exploitation of the population (tp 1) is estimated at 0.33 year, according to the growth rate and age determined earlier (Murty MS). Since the commercial trawlers are engaged in fishing almost ex clusively for prawns (Silas et al 1976), and since there is reduction in the cod-end mesh size of trawl nets at Kakinada (Rao et al 1980), tofacilitate catching even smaller prawns which have a lucrative market, it is felt that the industry will not increase the cod-end mesh size in the coming few years. Hence, there is no possibility of getting an increased age of exploitation for N» japonicus from the present 0.33 year. Keeping this point in mind, the yield per recruit is calculated taking the present age of entry (1P ) of N. japonicus into the fishing ground as the age at recruitment to the fishery (i.e._. tpl = tp) and also taking the present age at recruitment. (fig. 2). It is observed (fig. 2) that, attpl = 0.125 and at different M values, maximum YW/R is reached at F = 1.50 and decreased thereafter with further increase in F. When lpl -= 0.33 and at different values of M, maximum yield is obtained at F = 1.75 (fig. 2). It is also observed that, with decreasing M, the yield per recruit is increasing. Since the value of M obtained for the period of investigation is at 1.142, and the present F is estimated at 0.72, there is scope for increasing the yield of N. japonicus from the present fishing ground by increasing the fishing effort and 260 MURTY without changing the cod-end mesh size. As stated above, even if there will be change in the mesh size, it will only be towards decreasing it, and even then the yield can be increased by increasing the effort (i.e.. at tp I = 0.125. vide fig. 2). ACKNOWLEDGEMENT I am thankful to Dr. E. G. Silas, Director, for encouragement and to Mr. K. V. Narayana Rao, Scientist S-3 and Dr. K. Alagaraja, Scientist S-2, for going through the manuscript and suggesting improvements. REFERENCES BEVBRTON,Cons. R. J. int.H. 1953. Explor. Some observations Men, on the 19:principles 56-68. of fishery regulations.l I. BEVBRTON, R. I. H. AND S. I . HOLT. 1957. On the dynamics of exploited fish populations. Fishery Invest. London, Series 2, 19: 553 pp. GULLAND, I. A. I969. Manual of methods for fish stock assessment. Part I., Fish popula tion analysis. FAO Manuals in Fisheries Science. No. 4:_ I54 pp. GULLAND, I. A. 1977. The Analysis of data and development of models. In: Gulland. I. A. (Ed.). Fish population dynamics. John Wiley and Sons, London, 372 pp. Jones, R. 1957. A much simplified version of the fish yieldequuation. Joint meeting of /CNAF ICES/FAO, Document No. 21, 8 pp. Knrsmmmoonrm, B. 1978. A note on the mortality rates and yield per recruit in Nemi pterus japonicus (Bloch). Indian J. Fish., 23: 252-256 (1976). Knrsnmuxurrv, M. mu S. Z. Qssnvr. 1967. Theoretical yield studies on the large-scaled tongue sole, Cynoglossus macrolepidorus (Bleeker), from the Arabian sea. Bull. Nat. Inst. Sci. India, 38: .864-875. PEARSON, K. 1948. Tables of Incomplete Beta-Function. “Biometrica” oflice, University college, London. Rao, G. Sunrmouut," C. Susseum AND S. LALITHADEVI. 1980. Impact of mesh size re duction of trawl nets on the (prawn fishery of Kakinada in Andhra Pradesh, Mar. Fish. Infor. Serv. T & E Ser. 21: I-6. RICKBR, W. E. 1975. Computation and interpretation of biological statistics of fish popu lations. Bull. fish. Res. Bd. Canada, 191: 382"pp. SILAS, E. G., S. K. DHARMARAJA mu K. Rnuosruum. I976. Exploited marine fishery ' resources of India—a synoptic survey with comments on potential resources. Bull. Cent. mar. Fish. Res. Insr.. 27: 25 no. lcouraxauwxon e ‘ MURTY, V. SRIRAMACHANDRA. 1987. Further studies on the growth and yield per recruit of Qemigterug Jgponiggs (Bloch) in the trawling grounds off Kakinada. ;pdi§pJ,;§}Sh., 34 (3): 265-276. ‘CONTRIBUTION 6 I Reprinted from Indian 1- Fish., Vol. 34, No. (3). 1,987: pp. 2.65-276 FURTHER STUDIES ON THE GROWTH AND YIELD PER RECRUIT OF NEMIPTERUS JAPONICUS (BLOCH) FROM THE TRAWLING GROUNDS OFF KAKINADA V. SRIRAMACHANDRA MURTY Kakmada Research Centre of CMFRI, Kakinada 533002. ABSTRACT On the basis of data on N. japonicus from trawl landings at Kakinada, the von Bertalanfiy parameters of growth in length are estimated as Lulu 339 mm, K = 0.52 per year and t-.. = --0.16 year. The mortality rates are estimated as Z 2.64, M =- 1.11 and F 1.53. The length at first capture is estimated as 120 mm. The yield per recruit analysis shows that increase in effort from the pre sent level results in reduced yield from the present fishing ground if the cod end mesh size is not increased. INTRODUCTION Nemipterus japonicus (Bloch) is the most dominant species in the nemi-pterid landings along both coasts of India and some information is available on various aspects of biology and population dynamics of this species from Visa khapatnam (Krishnamoorthi 1973, 1976, 1978; Dan. 1980) and on biology and fishery from Cochin (Vinci and Nair 1975; Vinci 1983). On the basis of data collected during 1.976-79 from the landings of small commercial trawlc-rs at Kakinada, the author (Murty 1983, 1984) reported on various aspects of biology and yield per recruit of this species. The results of the study u-sing the data collected during 1980-83 on the growth and population dynamics of N. japonicus in the trawling grounds off Kakinada are presented in this paper. l\/IATERIAL AND Mernoos Data on effort and catch were collected from the trawlers for 18-20 days in each month; these data were weighted to get monthly estimates of efiort, catch and species com-position. Boats of three difie-rent sizes are engaged in trawl ing in this region (see CMFRI, 1981, for details) and the effort (no. of units as well as trawling hours) was standardised taking Pomfret as the standard effort and all demersal groups together were considered as one species for this purpose. The length data of N. japonicus collected on each observation day (at weekly intervals) were weighted to get the day’s and then the month’s length 266 Mums’ composition of estimated catch. The length data were grouped into 10 mm-class intervals and the mid points in these groups were considered to s-tudy the growth. Parameters of growth in length were estimated following the ‘integrated method’ of Pauly (1980) and using the well-known von Bertalanfiy growth equation: Lt La ( 1-¢'K("‘-> l) Ecstimatcg of Lw and K were obtained using Ford-Walford plot (Ford 1933, Walford 1946) as adapted by Manzer and Taylor (1947); the growth data of N. iaponieus of diiferent lengths at intervals of six months were used for the purpose. lnstamaneous rate of total mortality (Z) was estimated using the data of annual length-frequency distribution of catch and following: l. the length-converted catch curve method of Pauly (1982), 2. Cumulative catch curve method of Jones and van Zalinge (1981) and 3. Beverton and Holt (1956) method. The coefficient of natural mortality (M) was estimated using the relation Z =- ;\'l -%— qf where q is the catchability cocliicicnt and f the fishing effort. It was also estimated using the equation of Pauly ( l98()): Log M =1: -.n.nor~6-0.21<> log Lm -l- 0.6543 log K + 0.4634 log T where Len is in cm, K per year and T in °C. For the purpose of this equation the value of T was taken as 272°C from Ganapati and Murty (1954) and La Fond ( I958}. Length at first capture (Le) was estimated following the method given by Pauly (1984). The yield in weight per recruit was estimated from the equation of Bever ton and Holt (1957). ESTEMATION OF GROWTH PARAMETERS The monthly modal lengths of N. japonicus during January l98O-Decem her 1983 and the growth traced through them are shown in figure 1. While draw ing the growth curves. the points that are likely to fa-ll in a curve were joined first and then the curve was extended further both upwards and downwards. A total of nine curves, each of them passing through several modal points, were thus drawn (Fig. 1). The lengths attained at intervals of six months, starting from the smallest modal length in each curve, were read from these growth curves for estimating Lt» and K using ‘Manzer-Taylor plot’. (Fig. 2). From the origins of GRO\VTll AND YlEl-D Pl-LR RECRUIT OI: N. J./\l3’ONlCUS 267 ._...i 270+ 9 E i0 no.0’/0A C ../'/-/I.00 _ .F EE3130 hog". .0I 0/1"» I ”-I 0 " /~'u ° 00 /./'// 0 //0 v-.-w v<‘wv-' ,..v----V,’ -:'...-.-'v__ J |9§OA J-J OA195: H O J A|9§2 ' '/J 0 J HAt9§3 O' FIG. l. Estimation of growth in length through growth curves in N iaponicus. the curves D and G (Pig. 1.), the age of smallest modal length at 65 mm was read as three months and, taking this into account, the lengths at successive half years were estimated using values of slope and elevation of Manzcr-Taylor plot, for purpose of estimating no (Fig. 3). The von Bertalanfiy parameters of growth in length were, thus. estimated as I_.a.> = 339 mm, K --- 0.52 per year and to =-- -0.16 year. Since the maximum length observed in the catches is 305 mm, the life-span of N. japonicus in the trawling grounds is 4.26 years. sao36¢320 __- - _____]/’ _.¢".' soo2001 1/ * //‘II : ,_--no} 200- 34° ,../, /._/* - t IG mo /ggq i if / % “W -t Z0401/’2'0_’ ;____A______;?_;____‘_so as asI.| 2'io'z¢o‘s'oS6'i‘S<>' lmtnl°'°".J i ;_ -_'-IP21; .' ~-/~<> ‘fly.’ _""4Il‘-‘~§*‘l—”“ ~ 2 = ~ = e 'A*’7’—+ FIG. 2.in Manzer N. japonicus.and Taylor plot FIG.japmzicus. 3. Estimation of I. in N. ESTIMATION on MOR'I'Al.lTY RATES Total mortait't_v rate (Z): The points that represent the straight descending part of the length-converted catch curve (Fig. 4) and the points that fall in a straight line of cumulative catch curve (Fig. 5) were taken into account to estimate the total mortality rate. For Beverton-Holt method, the mean length was calculated taking fish of and above length at first capture. TOTAL. LE . I O ‘?.__f.’_.-__.___‘:’ ‘Z.__.._. \\ \ O .>\‘_.: &\\\\\\ "\_\‘\_ _ 0 pr K; - .. \\\\\Q \“.‘\\. 6 '&K\\\\ \\ \ \. \&\s.\ \ -\\< -\ '9 ' \ \. ‘ _ _1'_._ ~t \ ~.\ \ \ 268 MURTY ta a.-sro IO - ~01’Q.Q_@. useo ~ 409; us£O 1983 v. Q Ot fin. O. Q__ 01/'6" usw if 4__.. -.-. _._._. j Q ._®%O _ _ , ______i. -u_-u 9 U ._0e D I-J . "B2 ,,./'“ Q ll H ) | ,.-r°'°, :' h____._.__.| I 6 .. _ _ ._._ ' . \ _Or ..-'>\3iQQeU —1Z -' .-> . I 9wee ma:I. ' I M‘ .- .a\ -'5' Methods of 1980 1981 1982 1983 Average Pauly 2.2964 2.2571 3.8364 2.5427 2.7332 Jones and van Zalingc 2.5606 2.0901 3.4288 2.4281. 2.6269 Bcverton and Holt 2.2027 2.1450 3.6742 2.2402 2.5655 Average 2.3532 2.1641 3.6465 2.4037 2.6419" Estimated catches of N. japonicus 261 201 632 365 364.8 —v 1, .,--‘._-._h I . 2}-+i CvMuLA FEOU NCY *.-'_ _Q._ __5_.._..-.L.--L-40- N) _- _.__._.Lr - 0 Z onowru AND YIELD man RECRUIT or-' N. JAPONICUS 269 Natural mortality rate (M): An attempt was made to estimate the value of M with the help of regression of Z against effort. For this purpose, the values of Z obtained by diiferent methods were used separately and the effort was taken as number of units as well as trawling hours. The estimated values of M are negative in all cases indicating that they are unrealistic. Using the formula of Pauly (1980), the M value was calculated as- 1.11. Assuming the value of tmax in the population to be the one in the unexpoited phase and also assuming that 99% of the fish by numbers would die by the time they reach this age in an unexploited phase (Sekharan 1975), the M value can be estimated as 1.08 which is almost the same as that obtained by Pauly’s formula. For the present study this value was taken as 1.11. The various mortality rates in N. japonicus during the period of study, thus, are: Z 2.64. M =-" l.ll, F -- 1.53 ESTIMATION OF LENGTH AT Fmsr CAPTURE The data on length composition of catch of the four years were pooled (because the mesh size of the gear was the same during different years) and a length-converted catch curve was obtained to estimate Z value for this purpose and also to obtain an estimate of the number of fish in the first length class that is fully selected —- i.e. the estimated number of fish corresponding to the first point in the straight descending portion of the length-converted catch curve (number of fish against the 135 mm group in table 2). Using these two values and also the value of M obtained above, the length at first capture was estimated as 120 mm (Table 2 and Fig. 6). Using the data in table 2 and varying the values of M, several values of L3 were obtained to see whether they would be difierent. For different values of M ranging from 0.1103 to 5.0 and 25.0, the estimated values of Le are not quite different (Fig. 7). ESTIMATION OF YIELD PER RECRUIT The value of Wm corresponding to La, was calculated as 389.7 g. The smallest length in the catch at 50 mm was taken as the length at recruitment whose age (tr) is 0.15 year. The age at first capture (te) is 0.68 year on the basis of the estimated value of length at first capture. The yield in weight per recruit (YW|R) with the value of M at 1.11 and with five values of lc ranging from 0.43 to 0.77, (corresponding to Lc rang ing from 90 to 130 mm} against F (Fig. 8A) shows that for higher values of tc. maximum YW|R is obtainedat greater values of F, and that the YW|R is greater 270 MURTY TABLE 2. Derivation of selection curve of N. ja-ponicus caught by zrawlers at Kakinada (Data of 1980-83 pooled). ofMid points 10 mm Numbers Numbers P length caught mid point to Mortalityl Mortality II available Ni---— Cumulative classes (Ni) mid point (M Z) (means) (Ni|Pi) (Ni]P‘i) P _ —_:»— —— —— _ _ —--.2-V-—-—a. 45 (0) M=_l.l.103 (0) (0) 55 I0] 1.2978 179564 0.00056 0.00056 0.069 1.3916 65 1027 1.4853 163124 0.00629 0.00685 0.0715 1.5791 75 5348 1.6728 145708 0.03670 0.04355 0.0742 1.7666 85 6139 1.8603 127807 0.04803 0.09158 0.0773 1.9541 95 15711 2.0478 109889 0.1.4297 0.23455 0.0804 2.1416 105 27968 2.2353 92507 0.30233 0.53688 0.0840 2.3291 115 38884 2.4228 76069 0.51 1 17 1.04805 0.0879 2.5166 125 36620 2.6103 60973 0.60059 1.64864 0.0920 2.7041 135 * (47544) (2.7978) *(47544) ( 1.00000) 2.64864 _-_-_.—-—+,-~ - ______i—— ; , _ W, __ -ii —i *.'??_ - " - -: r :_'_:._. '~-V I-~ I , ,_ _ ___ V, * Camputed from the equation of the length-converted catch curve. when tc its higher. Under the current value of it: (0.68), the yield per recruit attains its maximum when F its 1.6 and declines slowly thereafter with further in crease in F. It may be noted that the present F is 1.53. The yield per recruit as a function of lc under the present rate of fishing mortality (Fig. 8B) shows that maximum YW|R is attained when te is 1.1 and with increase in Ic thereafter the yield per recruit declines. DISCUSSION The models dealing with fish stock assessment assume the growth pattern, natural mortality and recruitment in ea species to be constant. However, accord ing -to Gullaznd (1923, p. 165), “This is obviously not true; in a year of good food supply, growth is likely to be unusually good, while in unfavourable years GROWTH AND YIELD PER RECRUIT OF N. J APONICUS 0051I‘! |3Ql-__.._2P££§.§3_m_°_..¢ -—r_‘. . : ~ -9-""" _ _ _ __,,d -i; 1| — 1 4 14L-¢;,,_i.-Q-,->i,_..v1¢.-¢-_¢?4 " | Q1 °l 4 1 0351 l < _ _ - _ .E9"!£_“_ P9919 _ l.1 1' ::I o-est‘|Q 40 7O ~e~1-:""‘t__ too Q _ -;~-., |3O 'Y; - E '1“I emreemmr" 2 3 4 Y’ -5 \I\/\<;’ 25 e. LENGTH mm NATURAL MORTALITY RATE FIG. 6. a. Results of division of numbers caught by num bers available, represent FIG. 7. Results of analysis of ing selection pattern and b. cumulative curve to sensitivity of Le estima estimate the length at tes to changes in natural first capture, in N. japa mortality input in N. ja nicus. ponicus. natural mortality may be high”. On the basis of the data obtained during 1976 79 at Kakinada, the parameters of von Bertalanfiy growth equation were estimated as: La: 314 _tmn, K 0.75 per year and to ---- — 0.17 year (Murty 1984) whereas in the present study from the same area, these parameters were esti mated as 339 mm, 0.52 per year and —-0.16 year respectively. In the earlier study, growth was estimated by following (for shorter intervals) the modes 1n the monthly length frequency distribution in the succeeding months whereas II] the present study, the integrated methods of Pauly (1980) was followed. While the observed diflerences (though not very great)Lin the methods used, it is als £4 fl) possiblefor the differences that the ingrowth the estimated rate has values really of changeparameters, , whatever the fact that may there be arethe reasons Q QA differences between them (assuming of course, that the methods used give reliable results) indicates the need for updating the parameter estimates, whenever attempts at saock assessment are made The values of total mortality coeflicient (Z) obtained by difierent me thods (Table 1) in any one year are close to each other. The choice of taking the average (at 2.64) of the values obtained by all meth ds of all four years to represent the Z during the four-year period can therefore fie taken as reasonable a The estimated values of Z (Table 1) during 1982 are much greater than those PROBAB L rv OFcgerune Q O‘ —~:-“tU! -0 I LENGTH AT F RS1’ Ul C$PTUR£ _<'>__+-_-4'-‘Pg 272 MURTYit ,9-77 ‘J’L. .__€.,-¥%~$,__/ p® *9__Q:s£ 9 o ea _,_p— g rI. give“ I .OSI "tl‘.1 _-....,_. \\—R_ i_~_.%— " _- R‘ -§[ . ‘r .. l 1-> - B ‘.-‘L.1 rfl2.\, 1‘ ‘l. 2»4‘_ . A . _,L 1.~L ._ Q I _1| |'. .4; I 1_4i. V. _ fa, A_ 1. -___ 1{L O2 OAGE _ at 1'»'a§_,1l cnpalae‘ M __.‘._\ e L, *_.4 L1 ~ I ~' L'_._';_ ' —g —':'~;"*‘_-‘i Jr; ' **L— 4 U0' FISHING "O MORTAL!" ' RATE "9 FIG. 8. Yield per recruit of N. japonicus: A. as a function of fishing mortality rate (nume rals indicate the age at first capture and the broken vertical line the present fish ing mortality rate). B. as a function of age at first capture (vertical line indicates the present age at first capture). of the other three years: the average during this year is 3.65 whereas during the other three years the averages range from 2.16 to 2.40. The estimated catches of N. japonicus during 1982 were 632 tonnes -- the highest during the four year period — whereas the same during the other three ranged from 201 to 365 tonnes (Table 1). It is known that the estimation of coeflicient of natural mortality in ex ploited populations is difiicult (Cushing 1981). It is particularly difficult in the case of tropical demersal fisheries which exploit a large number of species simul taneously, with the result, information o-n effective effort with reference to a particular species cannot be obtained. Hence the regression of Z (of a particular species) against multispecies effort is likely to result in unrealistic values of M including negative ones (Ricker 1975, Pauly 1982). Obviously because of this reason, the values of M obtained by regression in the present study are negative and naturally the MIK value is less than unity, whereas this ratio in fishes is known to range from 1 to 2.5. (Beverton and Holt 1959). The value ( 1.11) obtained by using the formula of Pauly gives an MIK value which is within the above range; for this reason and for reasons mentioned above, this value was taken as M in the population of N. japonicus at Kakinada. In the earlier work, however, the author (Murty 1983) obtained an-M value of 1.14 on the basis of We/R 0 . 2-,: -_ ?__ ..__5{’:. L ~;._ Yw/'1 9 _ GROWTH AND YIELD PER RECRUIT Oli N. JAPONICUS 273 regression of Z on multispecies effort which is almost the same (obviously acci dentally) as that obtained by using the Pauly’s formula in the presen-t work. With the parameters of growth estimated earlier (Murty 1984, vide supra) and with the Pauly’s formula, the M value can be calculated as 1.44 which is slightly more than the one obtained in the present study. It may be mentioned in this connection that the author has also studied (Murty 1986a, b) the growth and mortalities of sciaenid and silverbelly species from Kakinada and realiable esti mates of M could not be obtained by the regression of Z on effort. Length at first capture { LC) is an important p-arameter in yield equation and has to be estimated through selection experiments, for each type of gear separately. In the absence of such a study, some authors have resorted to select ing a value arbitrarily (Krishnamoorthi 1978) or to considering the smallest modal length (Banerji and George 1967; Murty 1983) in the monthly samples as the Le. If the value of Le (and l'lCIlCCl(?) is taken like this for computing yield, the yield curve cannot be taken as representing a true situation because, even when the same values of M and F are used, the values of yield per recruit will be different when te is different; further. the value of F again-st which Ymax is attained can also be different when different values of te are considered. This is evident from the present study also (Fig 8.A). Thus any arbitrarine-ss in considering the Lt; values is likely to result in incorrect advice for the manage ment of a resource. Pauly (1984) developed a method with the help of which “the selection curve of the gear can be inferred from the shape of the ascending arm of a length-converted catch curve and the growth parameters" (p. 17). if the natural mortality rate is known. Further according to him (p. 19), “the values of Le obtained through this method are indeed close to those obtained from selection experiments” in Mediterranean hakes and sardines. However, three assumptons have to be fulfilled for the estimate by this method to be accu rate (Pauly 1984). One of them is that the gear in question is a trawl or a gear where it is only the smaller fish that are selected aga.inst. Obviously, this assump tion is fulfilled in the present work. In N. japonicus, the fact that gravid and ripe fish occur in the trawling ground in considerable numbers during the spawning period August-April and that smaller fish of the length range 35-85 mm also occur in the fishing ground (Murty I984) suggest that spawning take-s place in the usual fishing ground and this ground itself serves as nursery area also. Hence, there is no question of smaller fish reaching the fishing ground from a separate nursery ground (recruitment) in this species, as opposed to penaeid prawns or some temperate fish species. Hence the smallest fish caught can be safely taken as fully recruited, thus fulfilling the second assumption also. The third assumption is that the M value used for fish below the smallest recruited length and the mortalities generated by interpolation between M and the Z 274 MURTY value of the fully selected fish are accurate. This assumption was verified using sensitivity analysis and it was observed ( Fig. 7) that the Lc is not very sensitive to changes in the input value of M. The yield per recruit analysis shows that any increase in efiort (F) in the present fishing ground will result in reduced yield, if the present cod end mesh size is retained (Fig. 8A}; if the cod end mesh size is increased, effort can also be increased to get increased yield (Fig. 8A) or even if the effort is no-t increased, increasd yield can still be obtained by increasing the cod end mesh size (Fig. 8B). The length at first maturity in this species is 120 mm (Murty 1984). Since the length at first capture is also 120 mm, increasing the cod end mesh size will be beneficial in the sense that there will not be any problem of recruitment overfishing brought about by continuous removal of prospective spawners. The private trawlers at Kakinada fish in depths up to 50 m most of the time and go up to 80 m depth only during certain months of the year (November February). During these latter months the catches are generally good (Murty i984). Further, it is known (Silas 1969; Zupanovic and Mohiuddin 1975) that N. japonicus is abundant in 75-125 m depth zone. Hence there is need to fish in such depths at Kakinada to get higher yield of this species. Acxuowraocemuurs I am thankful to Dr. P. S. B. R. James, Director, for encouragement and to Mr. C. Mukundan, Head of Demersal Fisheries Division, for the useful criticism. REFERENCES Bevenrou, R. I. H. AND S. I. HOLT. 1957. On the dynamics of exploited fish popula tions Fish. Invest. Ser. London, Min. Agric. Fish., (19): 533 pp. Bevunrou, R. I. H. AND S. I. Hon". I959. A review of Life spans and mortality rates of fish in nature and their relation to growth and other physiological characteristics. Ciba Foundation Coiloquia on ageing. G. E. W. Wolsenholny and M.O.’. Connor. (Ed.) The life span of animals, 5: 142-I47. CMFRI. 1981. Commercial trawl fisheries off Kakinada during 1969-1978. Mar. 1'-‘ish. Cochin).Iufor. .§'.'?:".>. T & E Se:-., (31): I-6. (Central _ Marine Fisheries Research Institute, CUSI-IING, D. H. 198]. Fisheries Biology: A study in population dyna-nuss. Second edi tion. The university of Wisconsin press, 295 pp. DAN, S. S. I980. lntra ovarian studies and fecundity in Nemipterus japonicus (Bloch). Indian I. Fis/1., 24: 48-55 (1977). Four), E. 1933. An account of the herring investigations conducted at plymouth during the years 1924-1933. .-'. mar. biol. Ass. U.K., I9: 305-384. (iRO\V'l'll .~\-ND YUZLD PER RECRUIT Oi" N. JAPONICUS 275 GANAPATI, P. N. AND V. S. R. MURTHY. 1954. Salinity and temperature variations of the surface waters off Visakhapatnam Coast. Andhra Univ. Mem. Oceanogr. I: 125-142. GUl.I../\ND_, J. A. I983. Fish stock Assessment: A Manual of Basic Methods, John Wiley and Sons, 223 pp. Jomzs, R. AND P. N. VAN ZALINGE. 1981. Estimation of mortality rate and population size of shrimps in Kiuvait Waters. Kuwait Bull. Mar. Sci.. 2: 273-288. KRISHNAMOORTHI, B. 1973. Biology of the threadfinbream, Nemipterus japonicus (Bloch). Indian J. Fish., 18: 1-21 (1971). KRISHNAMOORTHI, B. 1976. A note on the size differences between males and females of Nemipterus japonicus (Bloch). Indian J. Fish., 21: 608-609 (1974). KRIS!-INAMOORTHI. B. 1978. A note on the mortality rates and yield per recruit in Nemi pterus iaponicus (Blochi. Indian J. Fish., 23: 252-256 (1976). LA Form, E. C. 1958. Seasonal cycle of sea surface temperature and salinity along the east coast -of India. Andhra Univ. Mem. Oceanogr. II: 12-21. MANZER, I. I. AND F. H. C. TAYLOR. 1947. The rate of growth in lemon sole in the straight of Georgia. Frag Rep. Fish. Res. Board Pacific Coast Stn., (72): 24-27. MUR'fY, V. SRIRAMACHANUR.-*.. 1983. Estimates of mortality. population size and yield per recruit of Nemigslerus japonicus (Bloch) in the trawling grounds off Kakinada. Indian J. Fish., 30: 255-260. Mmrry, V. Sntrusmscwnsnaa. 1984. Obscrvatiions on the fisheries of threadfin bl'C3I1'lS (Nemipteridae) and on the biology of N€fl1ipl8J'US japonicus (Bloch) from Kaki nada. Indian J. Fish., 31: 1-18. MURTY, V. SRIRAMACHANDRA. 1986a. Growth and yield -per recruit of Johnius (Johnias) carutta Bloch in the trawling grounds off Kakinada. Indian J. Fish. 33: I63-170. MURTY, V. Sntiumacmmonix- 1986b. Studies on growth and population dynamics of the silverbelly Leiognathus bindus (Valenciennes) in the trawling grounds off Kakinada. Indian J. Fish., 33: 277-284. PAULY, D. 1980. A selection of simple methods of for assessment of tropical fish stocks. FAO. Fish. Circ. (729): 54 pp. PAULY, D. 1982. Studying single-species context. pp 33-70; In: Pauly, D. and G. 1. Murphy (eds.) Theory and management of tropical fisheries. ICLARM Conference Proc. 9. 360 pp. ICLARM. Philippines and CSIRO Australia. PAULY, D. 1984. Length-converted catch curves: A powerful tool for Fisheries Research in the tropics. Part Il. Fishb_vIr', 2(1): 17-19. RICKER, W. l.-L. I975. Computation and Interpretation of Biological statistics of Fish populations. Bull. Fish. Res. Board. Can. 191: 382 pp. SILAS, E. G. I969. Exploratory Fishing by R. V. Varuna. Bull. Cent. mar. Fish. Res. Inst., 12:1-86. VINCI, G K. 1983. Threadfinbream (Nemipterus) resources along the Kerala coast with notes on biology of Nemiptems iuponieus. Irzdimi J. Fish. 29: 37-49 (1982). 276 MURTY VINC1, G. K. AND A. K. K. NAIR. 1975. Length-weight relationship in the threadfin bream, Nemipterus japonicus, along the Kerala coast, Indian J. F:‘sh., 21: 299-302 (1974). WALPORD, L. A. 1946. A new graphic method of describing the growth of animals. Biol. Bull. Woods Hole, 90: 1.41-I47. Zummovrc,S mo S K MOHIUDDIN . . . 1976. . A survey of the fishery resources in the north eastern part of the Arabian sea. J. mar. biol. Ass. India. 15: 469-537. _,‘. r.’—.,*__;';"‘ _ _ _,T1_‘f__%%_§ ‘CONTRIBUTION 9] MURTY} v. SRIRAMACHANDRA, K.V.SOMASEKHARAN NAIR, P. A. THOMAS, S. LAZARUS, S.K. CI-IAKRABORTY, S,G. RAJE, C. GOPAL, P.U.ZACHARIA AND A. K. VELAYUDHAN.1992. Present status of exploi tation of fish and shellfish resources: Thread fin breams. £3: Rao, P;V., V. S. Murty and K. Rengarajan (eds)Monsoon fisheries of the west coast of Ind1a- Prospects, Problems and Manage me"=- §“1l;_9?"§s_m§Fx.F%§P-_§£§:_l9§t- 45: 154-168. LCONTRIBUTION 9 C M F R I Bulletin 45 MONSOON FISHERIES OE THE WEST COAST OE INDIA PROSPECTS, PROBLEMS AND MANAGEMENT October 1992 ‘Hill ICRR CENTRAL MARINE FISHERIES RESEARCH INSTITUTE lndlan Councll of Agricultural Research Post Box No. 2704, Ernakulam Cochin 682 031, India Limited Circulation Bulletins are issued periodically by the Central Marine Fisheries Research Institute, Cochin to interpret current knowledge in various fields of research on marine fisheries and allied subjects in India. © Copyright reserved Published by : Dr. P. S. B. R. James Director Central Marine Fisheries Research Institute, Cochin. Edited by : Dr. P. Vedavyasa Rao Dr. V. Sriramachandra Murty Dr. K. Rengarajan Central Marine Fisheries Research Institute, Cochin. Citation LUTHER, (3., K. V. Nanmmm RAO, G. Sm/t Rao, C. Murmm, G. Gomxumn, N. Gomuuousnua PILLAI AND PRATiliBtlA PUITIRAN 1992. Present status of exploitation of fish and shellfish resources : Whitebaits. Butt. Cent Mar. Fish. Res. Inst, 45 : I'll - 120. Cover Photo : Fishing activities and fish landings. Cover Layout : Dr. K. Rengarajan. DTP Typesetting and Printing by Modern Graphics, Cochin 682 017 CONTENTS Preface Introduction : P. S. B. R. ]AM1=5 Oceanography of the Arabian Sea with particular reference to the Southwest Monsoon RA0, C. P. RAMAMIRTHAM, A. V. S. MURTY, S. MUTHUSAMY, KUNHIKRISHNAN AND L. R. KHAMBADKAR Productivity of the Arabian Sea along the Southwest coast of India : M. S. RAJACOPALAN, P. A. THOMAS, K. I. NIATHEW, G. S. DANIEL SEQ/ARA], RAN1 MARY GEORGE, C. V. MATHEW, T. S. NAOMI, P. KALADHARAN, V. K. BALA CHANDRAN AND GEETHA ANTONY Present status of exploitation of fish and shellfish resources Marine fish production of maritime States of the west coast of India : "K. ALAGARAJA, K. BALAN, K. S. SCARIAI-I, K. V1]AYA|.A1 Tunas and Billfishes : P. S. B. R. ]AM1=.s, P. P. PILLAJ, A. A. IAYAPRAKASH, N. G. K. PILLAI, G. GOPAKUMAR, T. M. YOHANNAN, C. MUFHIAH, G. M. KULKARNI AND S. KEMPARAJU Indian mackerel : A. Nosua, M. H. Dnuuouao, T. M. YOHANNAN, G. GOPAKUMAR, N. G. K. PILLAI mo G. M. KULKARN1 Oilsardine M. KUMARAN, K. V. NARAYANA RAo, G. G. ANNIGERI, MADAN MQHAN, P. N. RADHAKRISHNAN NAIR, PUTHRAN PRATHIBHA, M. ABDUL NIZAR, V. K. IANAKI AND UMA S. BHAT Whitebai ts : G. LUTHER, K. V. NARAYANA RAO, G. SYDA RAo, C. MUTHIAH, G. GOPAKUMAR, N. GOPALAKRISHNA PILLAI AND PRATHIBHA PUT}-IRAN Z51? 1'°s1> Ribbonfishes Catfishes: S. LAzARus, K. S. ScAR1An,i M. Z. KHAN AND A. K. VELAYUDIIAN : N. GQPINATHA MENON, V. N. BANDE, C. NIUTHIAI-I, S. G. RAJE, P. U. ZACIIARIA AND K. BALACHANDRAN Threadfin breams : V. SRLRAMACHANDRA Mum, K. V. SoMAsE| Croakers : T. APPARAQ, K. V. SOMASEKHARAN NAIR, S. K. CHAKRABORTY AND S. G. RAIE Lizardfishes : K. V. SOMASEKHARAN NAIR, VINAY D. Desnmuxu AND S. G. RAJE Flatfishes and Flatheads GRACE MAmEw, M. FEROZ KHAN AND K. NANDAKUMARAN Prawns : C. SUSEELAN, G. NANDAKUMAR, K. K. SUKUMARAN, V. D. DESHMUKH, K. N. RAJAN, M. ARAvINDAKsHAN AND P. T. SARADA Squid and cuttlefish : K. PRABHAKARAN NAIR, M. M. MHYAPPAN, S. SYDA RAo, K. SUNILKUMAR MOHAMED, KUBER VIDYASAGAR, K. S. SUNDARAM AND A. P. L1RroN Socio-economic aspects of the monsoon fisheries of the west coast of India : D. B. S. SEIIARA, K. K. P. PANn<1 Impact of fishing along the west coast of India during southwest monsoon period on the finfish and shellfish resources and the associated management considerations = P. s. B. R. IAMES Bull Cent. Mar. Fish. Res. Inst, 1992, 45 : 154 - 168 PRESENT STATUS OF EXPLOITATION OF FISH AND SHELLFISH RESOURCES TI-IREADFIN BREAMS' V SRIRAMACIIANDRA Muimr, K. V. Somnsmomzm NAIR, P. A. THOMAS, S. Lazmzus, S. K. Cnaxanaonrv, S. G. RAJE, C. COPAL, P. U. ZACHARIA AND A. K. VI.-ZLAYUDHAN Central Marine Fisheries Research Institute, Cochin 682 031 Aasrmcr Threadfin breams, an important demersal fishery resource along the Indian west coast, are mainly exploited by small commerdal trawlers in depths upto about 50 m. These fishes are more abundant in relatively deeper waters beyond S0 m and are known to move into shallower areas during monsoon period along southwest coast. Along Kerala Coast, maximum catches and catch rates are obtained during monsoon period. There is no significant trawling along Maharashtra and practically no trawling along Karnataka and Gujarat Coasts during monsoon period. Two spedes viz. Nemipterus japonicus and N. mesoprion, contribute to the fishery and along Kerala Coast, the latter species is the principal one during monsoon period and the former in other period. Along the coasts of other States in the west coast, the principal species is N. japonicus in all seasons. Fishes of larger lengths are caught in monsoon period and of smaller lengths in postmonsoon period at Cochin. At Bombay, the average length ls highest during the postmonsoon and lowest during monsoon in N. japonicus. Nemipterids spawn over longer periods and in N. japonicus peak spawning takes place during monsoon at Cochin and Bombay, during postmonsoon at Veraval and partly during post and pre monsoon periods at Mangalore. In N. mesoprion, peak spawning takes place during postmonsoon period at Cochin and Veraval and during monsoon period at Bombay. The available information and data on distribution during different seasons, on various aspects of biology and on present exploitation of stocks of threadfin breams along the west coast are considered for a detailed discussion and suggestions on different management options are given. Inrnooucrtou zone during February-May and in comparatively shallower waters during July-September. There The fishes of the Family Nemipteridae, are wide seasonal fluctuations in abundance of popularly called Threadfin breams (Kilimeen in Ma threadfin breams particularly in the trawling layalam, Madhumal meenu in Kannada, Rani in grounds of the eastern Arabian Sea. Along the Marathi, Lat machala in Gujarati) form an important southwest coast of India, in the trawling grounds component in the exploited demersal fishery off Sakthikulangara and Cochin, very heavy catchs resources of India. An estimated 67,677 tonnes of are obtained during the monsoon months of lune these fishes were landed in 1989 (CMFRLI989; August, the catches during this period accounting Anon., 1990) from Indian Seas, which formed 7.7% for over 80% by weight of total annual threadfin of total demersal fish landed and 3.0% of total bream landings at these centres. For various marine fish landings of India. Though they are reasons such as conflicts between the fishermen of presently exploited in depths of about 50 m and less artisanal gear and trawlers, apprehensions of over by the small commercial shrimp trawlers, the fishing of spawners and destruction of spawns, threadfin breams are more abundant in 75-100 m particularly of some important pelagic fishes, depth along the Indian west Coast (Silas, 1969) and caused by mechanised fishing during monsoon in the depth range of 50-125 m in the north eastern months and safety of fishermen, some States on the Arabian Sea (Zupanovic and Mohiuddin, 1973). west coast of India have prohibited mechanised According to James et at. (1987), the threadfin fishing during monsoon months. This has led to a breams constitute a promising resource having great deal of resentment among trawler operators good potential for exploitation along both the and exporters. According to them "the ban will not coasts; according to them, further, large concentra produce better catches after the ban period, but the tions of these fishes are located in 75-225 m depth stoppage of trawling will affect the future catches -1I_r also” '1./‘\i\. quarter forming 32-42% of total annual catch in quarter in yet another year (1985). The effort is 1983, 1985 and 1987. (e) At another centre in minimum in second quarter (17-25% of annual Maharashtra (Sassoon Docks at Bombay) (Fig. 1 E) effort) in all years; the catch, however, is highest in ‘ T, ._. 5°; 1 [JEFFQRT ICATCH . @ 1 J-P r X “I. 1-*,_ “(gmLm @ *l.l.rLr|.m.fL~.llI1.rLILll.r\.r|_I“..,II.l1.F|.l3 T-'1 l.lL-rlFL 28] @ ._T ._-t 1 |I I |"_"‘ 4;; .._1-1 ||l|.|| 4.1 i, ||..||.|ll i T1ll . aj®J l Tl Ir I‘ II .I.,I I . ? I-I‘I \i‘ . n l1IT i L 1' it -1 , . . l 4—1- li‘ ‘ l‘' ‘ -’; , I .i'.1 | 1‘ II982 3 I 3 I 3 II987 3 .I 3 I 3 I Fig. 1. Quarterly estimated effort and threadfin bream catch in different years at important trawl landing centres along the west coast of India. A. Sakthikulangara, B. Cochin, C. Mangalore, D. New Ferry Wharf, E. Sassoon Docks and F. Veraval. the effort is highest (27-29% of annual effort) in second quarter in all years excepting one (1984) fourth quarter in four years (1983, 1984, 1986 and when the same is highest in fourth quarter. (f) At 1987), first quarter in one year (1982) and in third Veraval in Gujarat (Fig. 1 F), the effort is minimum E F FOQT >< OOOUNTS CATCH x5O O TONNES é. t Hlr Q 1 J W ._' _ (J j I 31 9_ 1 to 1.57 in ttnsti tiiiarii" 2-. all years teaming .-it?"/ii or -L-.-"10 a'::i£.;Z §‘=.-'i;izc1':, jt..y /\1igt1;'~';t i’e.'=.k ?1‘a 2 [Ll1u.fL;“‘1 I986" 87 @ 6*. tlttltfl. U. 12° I985‘ 86 8-in J40 U. J lliittlhti" M M ll iii at it Fig. 2. Monthly estimated effort and catch of threadfin breams by hooks and lines at Vizhinjam during different years. Monthly effort and catch at selected centers : At very poor or absent during September-October. Vizhinjam, hooks and lines contribute to over 95% Though there is considerable trawling effort in of threadfin bream landings and this gear is in November and December there is either no catch or operation round the year. Maximum effort is the catch of nemipterids is very poor. expended (Fig. 2) in July-August 1984, October At Mangalore, there is no trawling during 1985, December 1986, January, July, August 1987 June-August period; there are no landings or poor Effort x 00Ounts N" 1_ E | EE-F’ ha.-. E? LT; 1 4» O5 0 O souuo; — |-13$93 V. SRIRAMACHANDRA MURTY ct al. e,._|9aa-as 2'? I987" 88 2-. _i-v I986“ 87 255° I-»w-" .2332 A é 8I 8: 1985- as -[L “'2 EIEFFORT H[L 1:984-as I M- | ICATCH -F “W 2L F M A M J J A S O N D J Fig. 3. Monthly estimated effort and catch of thrcadfin brcams by trawlers at Cochin during different years EFEORT x 000unt s/CATCH -§ N N .1 J 1 Ii» ‘ "Ii : li ti" 1 "1;-'>' :\;-f ‘ii’-2+’: * ‘ ‘Q landings duririg 5eptembcr anci uctober and breams is obtamed in i‘."".-i1i‘:S00fl period of alt years maximum catch of over 400 t is obtained in March except 1984-'85 when the peak catch is obtained in and May. postmonsoon period (Fig. 6). At Cochin (Fig. 7 A) the average effort is highest during premonsoon At New Ferry wharf landing centre in and lowest during postmonsoon except during Bombay (Fig. 4), the trawling effort and catch of 1985-86. The nemipterid catch, however, is the nemipterids are very poor from June to August. highest during monsoon fomiing 71-97% of total Consistently good catches are obtained in October nemipterid catch obtained in each year. At and in some years the catches are maximum in Mangalore (Fig. 7 B) both the effort and catch are April. The effort is generally at its peak during highest in premonsoon period and there is no September-December period. fishing during monsoon. At Bombay (Fig. 7 C), the effort and catch are minimum during monsoon and At Veraval (Fig. 5), there is no trawling maximum during postmonsoon. At Veraval (Fig. 7 during lune-August. Though the months of peak D) there is no fishing in monsoon period and the effort and catch are different in different years, effort as well as catch are higher in premonsoon in generally the catch and effort are good during some years and in postmonsoon period in some March, September and October. other years. 6: I9 ee- as C1 EFFORT I omen QI 3 Jill] - _):1-_|:u -. TI 2}_l_987‘88 l k19as'- s"/I I I 5 I I & J N ' ‘ 2“ifTl§6i1|._ -- ._. -v .... IL IL 11. U. ll. *|984-B5 1 27 FM-A MJ J A S O N D J Fig. 4. Monthly estimated effort and catch of threadfin breams by trawlers at New Ferry Wharf (Bombay) during different years. Seasonal variations in effort, catch and catch The catch rates during the three seasons rates : As mentioned above, the premonsoon (Fig. 8) show that they are highest during monsoon period consists of four months, the monsoon three period at Cochin and during premonsoon at months and the postmonsoon period five months. Mangalore. There is no consistency in the periods Therefore, for comparison of effort, catch and catch of peak catch rates at Bombay and Veraval in rates between different seasons as well as between different years. At Vizhinjam, peak catch rates are the same season in different years, monthly average obtained in monsoon period in all years except in catch and effort in each season are calculated. At 1984-'85 when the same is obtained in postmonsoon Vizhinjam, peak effort of hooks and lines is seen in period (Fig. 6). monsoon period in two years (1984-85, 1987-'88) and in postmonsoon period in two years (I985-'86, The effort (Fig. 9) is highest during premon 1986-'87) (Fig. 6), but peak catch of threadfin soon period at Cochin, Mangalore and Veraval and EFFORT X OOOU/CATCH X l60 v. SRIRAMACHANDRA MURTY at oi. during postmonsoon period at Bombay. There is the three seasons in different years (Fig. 10) shows no fishing during monsoon at Mangalore and that at Cochin, N. mesoprion is the most dominant Veraval and the effort is lowest during this period species during monsoon period forming over 70% at Bombay (Fig. 9). of threadfin bream landings in this period and 4 7£90 _ 89 Tl ..l9BT' B8 6, .L 2*. Nl986'87 c: l'hf'* -.1 L tees-86’% QiIlI ~——-l984‘B5 8: ul llF an A N[L M J? J “Kl sf 0 N 0 u Fig. 5. Monthly estimated effort and catch of threadfin breams by trawlers at Veraval during different years. Srscms Courosmous’ about 55% of nemipterids obtained in the annual landings. N. japonicus is the dominant species Along the west coast centres four species during pre and postmonsoon seasons. The three contribute to the fishery. These are N. japonicus, N. species contributing to the fishery at Vizhinjam are mesoprion, N. delagoae and N . metopias. Of these, N. N. metopias, N. delagoae and N. japonicus, the first one japonicus and N. mesoprion are most dominant, being the dominant. Peak catches are obtained in together forming over 95% of threadfin bream monsoon period and N. metopias forms about 95% landings. N. delagoae does not form any significant of nemipterid catch during this period. proportion in nemipterid catch and N. metopias is principally encountered at Vizhinjam only. The At Mangalore N. japonicus is the most abundance of N. japonicus and N. mesoprion during dominant species in the premonsoon and postmen EFFOR T It 00Ounts CATCH xD0t 8 t~ -%? "*$’; ql F‘ &"l."'“\ ?)"fi\.lr* soon fishery aitimtigh N. mcsoprion is also caught in period (Fig. 3 At Mangalore, the length range of small quantities during the period. the species in the catch is 60-289 mm. At Bombay, it is found to be 70-329 mm during the entire period; At Bombay where the fishing during mon the mean lengths are (Fig. 11) the highest during soon is very poor (Fig. 9), N. japonicus is the postmonsoon period and the lowest in the monsoon predominant species in all the seasons (Fig.10) months. At Veraval, the length range during the forming about 70% of the thrcadfin bream catch. At entire period is 30-309 mm; the average lengths are Veraval there is no fishing during monsoon and N. larger in premonsoon period during first two years japonicus is the most dominant species during both and in the postmonsoon period during later period pre and postmonsoon periods forming around 80% (Fig. ll). of threadfin brcams catch in each year. 1! 7'I -1" [:|Effort ‘ 22-» -so ‘ .Cotch 01% IT ~—¢CpU6 i &l -L IO-_+,l ‘ " -= +78- T‘ ujPr:MCi Po ref MNNPOHi Pr* M Po Pr MuCCPo;P'r M 1984-asW 1985-86 uses-av 1987-asall tsaa-es Fig. 6. Estimated effort, catch and catch per unit ot effort of threadfin brcams during premonsoon (Pr), monsoon (M) and postmonsoon (Po) seasons in different years at Vizhinjam. It is thus clear that the monsoon fishery is N. mcsoprion: At Cochin, as in the case of N. largely supported by N. mesoprion at Cochin japonicus, the highest mean length is recorded in the whereas at other centres the dominant species is N. monsoon period and the lowest during postmon japonicus during all seasons and at Vizhinjam the soon months, the length range in the catch in all dominant species in monsoon is N. metopias. years being 30-269 mm (Fig. 12). At Mangalore, the specimens in the length range of 70-205 mm Lmom Comvosmon constitute the fishery of pre and postmonsoon periods. At Bombay, the length range in the catch The distribution pattern of length range and is 70-259 mm and there is no definite pattem in the mean length of N. japonicus and N. mesoprion in the distribution of mean lengths in different seasons catch in each season during different years is during different years and the mean lengths show depicted in Fig. ll and 12 respectively. a very narrow range (Fig. 12). At Veraval, the length range in the catch is 40-299 mm; the highest N. japonicus : At Cochin, the length range of catch mean lengths are at 168 mm during premonsoon is 30-309 mm with variations during different period in 1984-'85 and at 139 mm during postmon seasons. Larger fishes are caught during monsoon soon period in 1985-'86. ln 1986-'87, the mean in all years and the mean length is the highest lengths are more or less same during both pre and (except during 1984-'85) during monsoon period; postmonsoon periods, but larger fishes are caught the mean length is lowest during postmonsoon in the latter period. Effortx OOun0 s ‘.1’;;i1 .i’-f ; ‘fl°’ .2 QL Lg I Q63 E; _. .L- l~___tat ck... I I _d5 ~L as fat ands iif 0_-1; NF0 ‘1'_'I=_-nmfi OIo A0 OI of FT Q P_‘FQ -4 o|-— T SQUUO —t.[3tDQ 162 V. SRIRAMACHANDRA MURTY ct al. Smwmwc off Mangalore extends from November to April It is known that the spawning period of with peak during December-February. As there is nemipterid species of India is protracted and that no fishing here during monsoon there is no these fishes are fractional spawners (Murty, 1982, information on spawning during this period. In the 1984; Vivekanandan and James, 1986) like several sea off Bombay, mature adults are available round other Indian marine fishes. the year, but peak spawning appears to take place ?“!\/OFGVOI D U Effgrj .C0tch _. r l “i |l 41|~ ‘ ~, A C — Bombay oO~1..lin._.. ‘__._ - t X7-I Mungolore B T_ I,-_q I—r0 e<11 1 04-‘ ¢U1 _ A - C0ChlI't|67ot~ I ii-Inszsi 1 4i. ‘f '*Pr WM£1. WPQ Pr M P0 _MPr LM it Po ‘pr M Poi Pr WM I984‘ 85 i985‘ 86 I9 86" 8 7 I9 87’ 8 8 I988‘ 89 Fig. 7. Estimated effort and catch of threadtin breams during premonsoon (Pr), Monsoon (M) and Postmonsoon (Po) seasons in different years at different centres. N. japonicus (Fig. 13) : At Cochin gravid adults are during monsoon. At Veraval there is no fishing observed during monsoon and postmonsoon during monsoon and spawning appears to take periods; peak spawning appears totake place in place during pre and postmonsoon periods with monsoon period. The spawning season in the sea peak during latter period. EFFORT it OO Oun 7‘ pi; P -"F L F *1 "~?F?.1\DF!N vw.1=»\ vs 163 HI veanvne 100 4 1 _ W s _-M; 1 f so M __ __Q e s_ 1‘‘Gib?--i w0.. aousmr - V’ MANGALORE N 0°4cocH|N BOOT i ‘*1-'35 “ ‘T —se s“1e*‘ |se$'— r; Fig. 8. Estimated catdw rates of threadfin breams during different seasons in different years at different centres (Pr : Premonsoon, M : monsoon, Po : Postmonsoon). 6* VERAVAL A BOMBAY Hf t ii ii" " it W *1 MANGALORE + Ii-vi it _C0‘CH|N 1 ” it it it j “ it L ‘ s >fi— ‘i 1* ‘*1 * —~ r~ : I 1 -1- ~1 ="i* =_i * 684$ e5Po Pr M #0 Pr o lgr K Po 'F3'88_§9 Fig. 9. Estimated# fishing effort by htrawlers during differentP seasons in different years at different centres. (Pr : Premonsoon, M : Monsoon, Po : Postmonsoon). EFFORT (Number of units X i000) e9,sf J;I_O‘ CATCH PER UN T EFFOR L ‘ } 9 bl ii 533* Q 45 T O —~|1-1 £0 Q (II Q O "U -Q vi-1 —-Q ID Q N 164 v. SRIRAMACHANDRA MURTY et af. N. mesoprion (Fig. 13) : Off Cochin, this species exploited stocks with varied success (Naamin, 1984; spawns during monsoon and postmonsoon periods Garcia, l986)- Similarly, closure of selected trawl with peak in the latter period. In the sea off ing grounds is resorted to protect fish on spawning Bombay the spawning appears to take place round grounds, those migrating through areas of the year with a peak during monsoon period. At restricted extent where they are especially vulner Veraval there is no information during monsoon; able to capture, to protect young fish on nursery spawning takes place during pre and postmonsoon grounds or to prevent or reduce conflicts between periods with peak during the latter period. fishemen of artisanal and mechanised gears. IN']oponicus []N'rnasoprlon 0° Hcrngbm"'. .| I. - ii-‘T’ , , r“ -—v'-rT‘B‘°mb*u""‘"-"rawiti\|;.. i Jeri“ H 34%| .~ii E. iiitii!|‘t ii4 | |I1 i | I .,'I , I i I ' \ i., l V 1 | |i 1 68. ii i I | | I .|;iiti i 2 V I | 4' l=Premonsoon Zzmomoon 3:p°;gmon,°°n Fig. 10. Percentage composition of N. japonicus and N. mesoprion in each season in different years at different centres (two more spedes also occurred, but in very small quantities and therefore ignored in this graph). DISCUSSION The neritic areas in the sea are known to be nursery grounds for a great majority of fishes. Closure of certain areas in the sea for fishing According to Rounsefell (1975), though this "area and banning fishing during certain seasons are is small in comparison to the area of the waters among the important and wellknown methods of overlying the deeper ocean, it is the scene of greater management of exploited resources. In the tropics, share of the world's fisheries and this ranks high total or seasonal bans on trawling are known to in importance" and Garcia (1986) states that in have been implemented for rebuilding the most tropical areas, the fish production originates Perce...as " ".1:tN THREADFIN BREAMS 165 in the littoral areas where fingerlings become relatively deeper water into shallower areas due to benthic before starting to migrate towards deeper upwelling (vide infra). Thus the littoral areas serve water, growing in size and decreasing in numerical as nursery grounds for majority of fish including abundance". According to Nagabhushanam (1971 ), threadfin breams. Therefore trawling in these areas the juveniles of larger fishes which inhabit deeper (even with nets having larger cod end mesh size) waters, are most abundant in the shallower regions destroys large number of young fish which congre less than 20 m forming 70% of total catch from gate in these areas. Rounsefell (1975) states that within this area. james and Adolph (1971) also closure of such areas is an effective way to prevent made similar observations. ln the case of threadfin destruction of young fish. Further, an undesirable breams, particularly N. japonicus, Nagabhushanam consequence of indiscriminate trawling in the (1971) and Nair and Iayaprakash (1986) observed nursery grounds is that, in the long run, the fish larger fish in deeper waters and smaller fish in become progressively smaller and exploitation shallower regions. Weber and Jothy (1977) and tends to be limited to shallower inshore regions as Pauly and Mortosubroto (1980) found in the relatively deeper waters do not offer scope for any nemipterid fishes of South China Sea, a positive viable activity. These considerations prompt en correlation between size of fish and depth in which forcement of ban on trawling in shallow inshore they are caught indicating again that the larger areas. 330 BOMBAY 3 VERAVAL cocnm :mmcA1_onE ‘T ‘ll’ l 3 I 2 T | ~; 2.l 2.. Q l Z_ 3.. I 3 ll ‘T’ 3 I ll \4 .l | 210 ‘l ‘r l -' -— H ~— 1"’ l l \ 3 2. 4 l ~ "1" \ l,. ‘ l ‘l * ‘l -. ‘r gr3T l _ l l ZIO Ii ‘ r t l l 2 .1 it T| l t ‘ '137". l 3? 1'‘L it-T 2 2 ‘l l l i 4if -\‘- i~*,‘\iL‘l L \ ll*‘T l‘*‘+ ll5 4 l,7’ -Q- l ll I rl E150E ___ A U 7. ‘gi v|+ J ‘l fwt» -qp Il lg. ‘id 11 -$ ~ I\ lll ‘l I . . 1 i i +V mt“L L1 y ‘l pl | l‘ N3 . l ‘lpd r lat‘ #_i l l l .._0 3H; l t as‘g J. +. .I‘ l.._._ ' _L[_,.h..L; \ \ _a_ "390 A -L aL_.._ Q -Ll t l ‘ 4L a s.fl.._¢l* . .:_J._ 1‘ _l_ i 30 44 -L|_ Pr omomoon M onsoon 3= Postman: oon l984‘85 l987'8B I987" B8 I984" B5 I98T'O8 l9B4'B5 l98?'8B Fig. ll. Length range and mean length of N. japonicus during different seasons in each year at different centres (The vertical line shows the length range and the closed circle with a small horizontal line on the vertical line, the mean length). Implementation of closed seasons in the fishes inhabit deeper waters and the smaller fish the tropical waters is also an established method of shallower regions. The mean lengths of N. jap0m' management of resources. According to Garcia cus and N. mesoprion off Cochin are larger during (I986), closed seasons "are easily enforceable and, monsoon months (Fig. ll and 12); this apparently if implemented at the appropriate time of the year, is due to the movement of relatively larger fish from usually produce good results". onqth P + s so # g 40! _. __ f _¢ __ F s as s 4» :|U N l 4-. F F 4. 4» F i ¥ PF44 - 4*1» 4 :i' F @4194 Ti. a 4 166 v. SRIRAMACHANDRA MURTY et al. 300 COCHIN MANGAL OR E BOMBAY I VERAVAL ‘T "‘2 2 :'"-.3 "-' -1'-— 9. 2 ' in qq-g 240T __2 ‘TH 5‘I 5 5’ 3| sE .“Br~‘" p ll *Ts’-,--l i . 5.0 I 3 _. i__ \,‘p p | +i rs _‘_W -0 -\* i = 4 I i '&' *t'.¢@ ‘ti l + '20]"] l 3_¢_pIi A ‘+1? ' ‘ \AH i 1 ll TA'9' ‘' + 1 E4 i .J * Ll -I-1-Q. l ‘ii _,*_~5— I T. i 9 l A T i 1-6 . I I _._ ‘ I ' __,___I i -1, ‘I -l— --__r; -I-4-it ¢dJ— n-l-L 4& ' A _1._ . | .1.. ' .1... . I‘-Premonsoon Monsoon P ostmonsoon I 14,1I96-4'65 | L'_J—l |_,..r 198?-as -__I run 1901-sell?‘ _ . r_ 1985-66. | _l___ l_r_l_?£_'_lll_,_l l ,____user-as $84-as _ _lwI-Y-l—‘A H1986-er ___ l1L_ Fig. 12. length range and mean length of N. mesoprion during different seasons in each year at different centres (The vertical line shows the length range and thePR5 closed circle 0N$0Wwith a small horizontal lineN_ on the vertical line, the mean length). According to Banse (1959) strong upwelling takes place ”fr0m 8° to at least 15° N" during the whole southwest monsoon season along the west BOMBAY coast. Further, Banse (1959) observed "towards north the upwelling certainly reaches 15° and 2] cocum.F._.._._ perhaps 18° N . . .". ‘According to Rao and Ramamirtham (1976), upwelling takes place in the region between Kanyakumari and Karwar during VERAVAL-_L______J___ _ , Z3 monsoon period. Thus, upwelling region extends from off Kanyakumari to off southern Maharashtra. E somamr g This upwelling influences the distribution of demersal fish population along the southwest coast .11 “ of India (Banse, 1959; Nair and layaprakash, 1986). an ANG ALORE __ _ _ As stated elsewhere in this paper, the threadfin breams are more abundant in relatively deeper waters along the west coast and move into shal cocum‘—+ 9+ 9 1 —~r—I as 9 ‘r ca +~1 lower depths of 35-40 m during monsoon to avoid F M A M J J A S 0 N D J oxygen deficient areas (Nair and Iayaprakash, Fig. 13. Spawning periods and peak spawning periods of N. japonicus and 1986). Thus the threadfin breams are available in N. mesoprion at different centres (Peak spawning period indicated by black bars; bars with broken lines indicate absence of fishing). large quantities in intermediate depth zones during ITIB SO YOU To TO rig or O t . : -__‘-L _4 +is ’i . ;__ 7;, F¢ _ if as 99+ L r_ + . |‘\J l'\) t_____.___. Oi {OI _|._ Jr -P’ ¢ __ N _,,o N F sail is 401 10-I THREADFIN muzams 167 monsoon. The upwelling off Kamataka Coast also pattem of threadfin breams during different sea is likely to result in such abundance of nemipterids, sons and there is also no fishing during monsoon, but there is no fishing in this region during along this coast. However, "most species in Indian monsoon. waters, with the exception of a few inwhich seasonal breeding has been clearly established, are Along Maharashtra Coast the fishing is poor continuous breeders . . . ” (Qasim, 1973). This is and so also the catches and catch rates (Fig. 4, 8, 9). a positive feature and there does not seem to be any If there is any movement of threadfin breams into cause for concern about recruitment overfishing the fishing grounds during monsoon period as [provided the condition that the length at first comparable to the one off Kerala Coast, one would capture (LC) is maintained above or close to the expect the catch per unit of effort during monsoon length at first maturity, is met], because of trawling to be very high here also, whereas the same is during a particular season (monsoon). actually less than that in the other periods, indicat ing poor abundance of threadfin breams in the Seasonal trawling bans in overfished areas fishing grounds during monsoon. There is no are known to give useful results as in the case of trawling along Gujarat Coast during monsoon demersal fishes along the coast of Cyprus (Garcia, period. 1986). There is no trawling along Karnataka and Gujarat Coasts during monsoon period and the It has been shown that Nemipterus japonicus poor fishing activity during this period along and N. mesoprion are the two species that contri Maharashtra does not offer any scope for concern bute to the bulk of the catches and N. mesoprion is on whether monsoon trawling should be permitted most dominant at Cochin during the monsoon or not. Along Kerala, the considerable activity period (Fig. 10) and its contribution is very poor during monsoon can be the cause for concern, but during other periods. A similar distribution can be the poor exploitation of threadfin breams during expected along Karnataka Coast also, because of the pre and postmonsoon months and fractional spa wn upwelling in that region during monsoon. ing habits and protracted spawning periods in these fishes can nullify any (if at all) adverse effect It is known that Indian threadfin breams are of fishing during monsoon on the stock of thread fin fractional spawners having extended spawning breams. This, however, should not lead to complai periods (Murty, 1982, 1984; Vivekanandan and sance among managers of fisheries resources James, 1986). In the sea off Cochin, N. japonicus and because : N. mcsoprion spawn during monsoon and postmon soon periods with peaks during monsoon in the 1. The Indian marine fishes as also the thread fin former and during postmonsoon in the latter breams, spawn over extended periods and species (Fig. 13). Since N. mesoprion is the principal the inshore areas are nursery grounds for species during monsoon (Fig. 10), there may not be majority of fishes andl continued trawling in any problem of recruitment overfishing for thread the littoral waters can lead to undesirable fin breams off Cochin, because of trawling during consequences, monsoon period. The information from Mangalore 2. as in the case of majority of Indian marine is rather inadequate. Off Bombay, spawning takes fisheries resources, the yields of threadfin place in all the three periods (Fig. 13) with peak breams also have reached levels where during monsoon in both the species. As the exploi further increase in the same does not seem to tation is very poor (Fig. 4 and 9) during monsoon be possible from the presently fished areas; there is no cause for concern. In the sea off Veraval, both the species spawn during pre and postmon 3. the demand for even smaller shrimps in the soon periods with peak during postmonsoon period lucrative export markets has led, in almost all (Fig. 13). Though there is no fishing during areas, to the reduction of the cod end mesh monsoon, there is every reason to expect spawning size of trawl nets, the consequence of which to take place during monsoon also. It is not possible is the reduction in length at first capture (LC). to state anything about the impact of trawling This in its tum can cause recruitment over during monsoon on stocks of threadfin breams off fishing and collapse of demersal resources Gujarat as there is no information on distribution over a period of years. I68 V. SRIRAMACIIANDRA MURTY et at. Though the data on hand do not indicate not possible) and prevent clashes between fisher adverse effects of trawling during monsoon on the men of artisanal and mechanised gears. stocks of the threadfin breams along west coast, ACKNOWLEDGEMENT closed season for trawling during monsoon can still be considered for implementation, because, in The authors are grateful to Dr. P. S. B. R. addition to the above reasons, it is known that such James, Director, CMFRI, Cochin for suggesting this a practice will help rebuild the exploited stocks work and to Dr. P. Vedavyasa Rao, Principal (most of which have almost reached a level where Scientist for his constructive criticism on the additional production from the present grounds is manuscript. REFERENCES Anon, 1989. The seafood exporters of India : Face to Face with NACABHUSHANAM, A. K. 1971. A survey of the offshore demersal a calamity. Seafood Exp. ]., 21 (8) : 3. fisheries of the Andhra and Orissa Coasts, with special reference to the biological data collected during 1960. --——, 1990. Annual report I989-90. CMFRI, Cochin, 95 pp. Indian I. I~'ish., 13 : 359-379. Bmsa, K. 1959. On upwelling and bottom trawling off the NAIR, K. V. SOMASFKIIARAN AND A. A. JAYAPRAKASII 1986. A note southwest coast of India. I. mar. biot. Ass. India, 1 : 33 on the monsoon fishery for threadfin breams off Cochin. 49. Ibid., 33 : 106-112. CMFRI 1989. Marine Fish Production in India - 1985-86. Mar. I‘/tum, D. mo 1’. Monwosumztrro 1980. The population dynamics Fish. Infor. Serb. T 8 E Ser., 91 : 1-32. of Nemipterus marginatus (Cuvier and Val.) off western Kalimantan, South China Sea. Fish. Bi0I., 17 : 263-273. Cancun, S. 1986. Seasonal trawling bans can be very successful QASIM, S. Z. 1973. An apprisal of the studies on maturation and in heavily overfished areas : The “Cyprus effect". spawning in marine teleosts from the Indian waters. Fishbyte, 4 (1) : 7-I2. Indian Fish, 20 : 166-181. jamss, P. S. B. R. mo CLEMENT Ar>o1.r~n 1971. Observations on Rao, D. S. mo C. I’. RAMAMIRTHAM 1976. Seasonal variations trawl fishing in the Palk Bay and Gulf of Mannar in the in the hydrographic features along the west coast of vicinity of Mandapam. Indian I. Fish, 12 : 530-545 (1965). India. Ibid., 21 : 514-524. -—, K. /\l.A(ZARSWAMi, K. V. NARAYANA Rm, M. S. Muruu, M. ROUNSIiFEt.l., G. A. 1975. Ecology, utilization and management of S. Ralacovauw, K. Al./tcanai/\ mo C. MUKUNIJAN 1987. marine fisheries. The C. V. Mosby Company, Saint Louis. Potential Marine Fishery Resources of India. CMFRI Spi. 516 pp. Pub, 30 : 44-74. SILAS, E. G. 1969. Exploratory fishing by R. V. Varuna. Butt. Cent. Mum, V. SRIRAMACHANDRA 1982. Observations on some aspects Mar. Fish. Res. Inst., 12 : 1-86. of Biology of threadfin bream Nemipterus mesoprion VIVHKANANDAN, E. mo D. B. James 1986. Population dynamics (Blocker) from Kakinada. Indian I. I-'ish., 28 : 199-207. of Nemipterus japonicus (Bloch) in the trawling grounds —- 1984. Observations on the fisheries of Threadfin breams off Madras. Indian I. Fish., 12 : 145-154. (Nemipteridae) and on the Biology of Nemipterus Wsssn, A. mo A. A. Iornnr 1977. Observation on the fish faponicus (Bloch) from Kakinada. ibid., 31 : 1-18. Nernipterus app. (Family : Nemipteridae} in the coastal waters of East Malaysia. Arch. Fish. Wise, 28 (1) : 9-122. NAAMIN, N. 1984. The banning of trawl fishing in Indonesia. Paper presented at the FAO/Australia workshop on ZUPANOVIC, S. mo S. Q. Momuoom 1973. A survey of the fishery management of penaeid shrimps/pranms in the Asia resources in the northern part of the Arabian Sea. I. mar. Pacific regions. Mimeo Rept., 19 pp. bioi. /iss. India, 15 : 496-537. B . SI I.-VERBELLI ES ‘CONTRIBUT ION 1 0] MURTY, V. SRIRAMACHANDRA. 1983. Observations on some aspects of biology of silverbelly peioggqphug bindus (valenciennes) from Kak1nada..Indian Q, Fish., 30 (1): 61-68. nomismou.___.._ ._-_.. __ __, £0] Reprinted from Indian I. Fish., Vol. 30, No. 1, 1983 DP- 61-63 OBSERVATIONS ON SOME ASPECTS OF BIOLOGY OF SILVERBELLY LEIOGNATHUS BINDUS (VALENCIENNES) FROM KAKINADA V- SRIRAMACHANDRA MURTY Kakinada Research Centre of Central Marine Fisheries Research Institute, Kakinada. Ansrmcr The length—weight relationship of Leiognat/ms bindus can be described by the equation log W = -4.77‘/'09 + 2.96182 log L. The length at first maturity is estimated as 80 mm. This species is a fractional spawner and appears to release the ova in at least two spawning acts during the course of one year; it appears to spawn in almost all months, with a peak during December-February. Based on length frequency distribution, the species attain 65 and 90 mm at the completion of first and second year respectively. INTRODUCTION Along the Andhra coast. an estimated annual average of 4073 tonnes of silverbellies landed during the 11-year period 1969-79 (CMFRI 1980), forming 9.5% of all India silverbelly catches. The studies on the resource charac teristics of silverbellies were taken up at Kakinada in 1979, as part of investi gations on the major demersal fisheries resources, and the present paper deals with some aspects of the biology of Leiognathus bindus, which is one of the important species in regard to abundance, in the trawl catches at Kakinada. Reports dealing with biology of silverbellies in general are afew from India (Arora 1951; Kuthalingam 1958; James and Badrudeen 1975) and, but for the paper of Balan (1967), there is no information on the biology of L. bindus. MATERIAL AND Marnoos The study is based on the data collected during the years 1979 and 1980. Samples were obtained at weekly intervals from the catches of commercial trawlers. On each observation day, samples of all silverbellies were collected from 3-4 boats for species composition and biology. The length data on L. bindus obtained on each observation day were raised to the day’s catch and these were further raised to get monthly length composition of the estimated catch- It is only on the basis of these data that the estimation of age and growth rate were made. For detailed biology the specimens were examined in fresh condition; the data on weight" of each fish were taken to 0.5 g accuracy. The various maturation 62 MURTY stages were fixed arbitrarily following those fixed for L. brevirosrris by James and Badrudeen (1975). Ova-diameter measurments were made from ovaries fixed in 4% formalin, following the procedure of Clark (1934). From each ovary about 300 ova were measured at a magnification, at which 10 md equals 0.097 mm. The length-weight relationship was calculated by the method of least squares using the formula W = aL" or log W = log a '1' n log L, where W = weight in grams, L = length in mm, a = a constant and n = exponent. LENGTH-WEIGHT RELATIONSHIP The study is based on 183 males ranging from 54 to 113 mm length and from 2 to 24 g weight and 182 females ranging from 56 to 122 mm length and from 2 to 38 g weight. The relationship was calculated separately for sexes and the equations are: Males: log W = — 4.74861 + 2.94179 log L Females: log W + — 4.81952 + 2.98912 log L The significance of difference between the regression coefiicients of sexes was tested by analysis of covariance foliowing Snedecor and Cochran (1967), and the results are given in Table 1. It is observed that the difference is not signi cant at 5% level. Hence the data of sexes were pooled and a single equation was calculated for the species from Kakinada which is: log w = _- 4.77709 + 2.96182 log L In the parabolic form the equation can be written as W= 0.0000167 L1-96182. According 16 Balan (1967), the equation for the length-weight rela tionship of this species from Calicut is W= 0.00002452L2'8641. TABLE 1. Comparison of regression lines of length-weight relationship of males and females of L. bindus from Kakinada. df EX’ EXY 291 Re g. co Deviation from Reg. eflicient art MSS Within Males 182 0.99866 2.93786 11.44379 2.94179 1s1 2.80119 Females 181 0.70836 2.11739 8.76149 2.98912 180 2.43230 361 5.23349 0.01449 Pooled 363 1.70702 5.05525 20.20528 2.96144 362 5.23442 0.01445 Difference between slopes 1 0.00093 0.00093 Between l 0.00002 0.00072 0.04198 Total 364 1.70704 5.05597 20.24726 2.96182 363 5.27231 Between adjusted means 1 0.03789 0.03789 Comparison of slopes F Q 0.1449|0.0o093 ”= 15.58. Df ¥ 36111 9 7 Comparison of elvation F = 0.03s910.0144s = 2.622, Df =.1,362 Mxrunsrrou AND SPAWNING The study is based on 540 specimens (288 males and 252 females) ranging from 60 to 122 mm total length. nroroov OF Sl'LVERBEl.LYr 63 Length atsfirst maturity: For the purpose of determining the minimum length at first maturity only females were considered, and fishes in stages III-VI of matu ration were considered as mature. The data of the two years were pooled. The percentage of the mature fish in relation to immature fish in different lengths are given in figure 1. It is observed that mature fish occur from 72 mm and that until a length of 102 mm the percentage of mature individuals show gradual increase. Above 102 mm all are mature. It may be seen that at a length of 80 mm, 50% of the fish are mature and this length is taken as the length at first maturity of L. bindus from the sea off Kakinada. It may be stated in this connection that according to Balan (1967), the length at fiirst maturity of this species at Calicut is 87 mm, almost the same. ""09" "F'":"no_“ "_'“ Qqgmi /'\ ..1 /"— T‘ ‘\ ., Afip IV -m““\./ /'/\ IO‘ S-1‘ ILincfn #71 ‘UL’?Q‘! _Gxups 7 0'-F .. N7ll U7 II I0‘ E I" Kl UITII FIG 1- Percentage-frequency dis- FIG. 2 L. bindus: ova-diameter tribution of mature female. L. frequency distribution in ovaries bindus in relation 10 immature of Stages III-V of maturation. females in different length groups. MP ; lkiaturing partially opaque ova, M0 = Mature opaque ova. Spawning: For-purpose of detremining the spawning season only females above the length at first maturity were taken into account. The frequency distribution of females in stages II-VI of maturation during 1979 and 80 and in the data of two years pooled are shown in Table 2. It is observed that fishes in stage IV of maturation occurred during March, May, September, November and Decem ber 1979 and January, March, July and August 1980.. StageVI females occurred only in small numbers in January and July 1980. On the basis of the occurrence of fishes in stages IV-VI of maturation in different months, it appears that in the sea ofi Kakinada L. bindus spawns in almost all months with a peak during December-February. Supporting evidence is obtained from the le ngth-frequency distribution: smaller fishes in the length range 15-34 mm occur in the catches in almost all months (fig. 3). It may be stated in this connection that mature L» bindus were recorded throughout the year wih peak during February-April at Madras (CMFRI 1978). PEQCENTAGE _.-.3 FIIQIQQ III euucv . I on * \4 4 _1 _ _.__ _\. \_ \ 1 0 l /)1 / 64 MURTY TABLE 2. L_:. bindus: frequency disrizibution of adult females in different stages of maturation (Data of 1979 and 1980 pooled). No of Months No- of females % of maturation stages females above examined length at Ist 1 naturity. 11 III IV V VI ,__,,__ ,_._,. . ai__..._ .-- -- . ..~¢--i. .__, January 43 33 —~ 33.3 51.5 9.1 6.1 February 49 33 18-2 66.7 15.1 ii ii March 19 5 20.0 20.0 50.0 gm if April 7 5 100.0 1-— Iii May ll 6 16.7 50.0 33.3 gm 5..-i June 4 3 1.00.0 gm pi July 10 9 ___ 55.5 33-3 my 11.1 August 12 12 16.7 58.3 16.7 8.3 Q-uni September 32 31 9.7 45.2 45.2 gm October 23 l7 52.9 47.1 — November 7 7 .-_. 14.3 85.7 - December 35 44.0 20.0 _.__-_—_ li; —~_ _ 25~ V-é__ 12.0 -V .— _—' _‘ ;i _ _ —~_ .m _ _. 24.0_ —-i-.__. According to Balan (1967) the spawning season of L. bindus at Calicut is very short, extending from December to February only. The ova-diameter frequency in ovaries of stages III-V of maturation are presented in figure 2. Three types of ova are present in the ovaries of stages III-V: one representing immature stock with the diameter extending up to 9 md; these ova are translucent with irregular shapes with the nucleus clearly visible and with yolk in some only. These ova were not considered for measurement of diameters. The second group represents the maturing ova, the diameter ranging from 10 to 24 md; these ova are more or less spherical and partially opaque heavily yolked and nucleus not visible The third group represents the mature ova with diameter ranging from 25 to 51 md; these are spherical and opaque vitellinewith yolk deposition space. complete. These H ova in stage V show the distinct peri It is observed (fig. 2) that there are two modes in the diameter-frequency dstribution in stage III: one at 32 mdi (mode a) and the other at 14 md (mode b). These modes show progression to 35 md and 17 md in stage IV respectively and 41 md and 20 md in stage V ovary. The ova forming a mode at 41 md in stage V may be released in one batch after a short time since they are already mature. The -ova forming a mode at 20 md in stage V have already undergone about half the maturation process, and they may take only less than _.@ BIOLOGY OF SILVERBELLY half the time required for the immature ova to undergo the process of maturation and release, since it is generally known that the growth of ova in maturing condition is faster than those in immature condition. In stage V, a new mode appeared (mode c) at llmd; these ova forming t.he early maturing. This mode is almost the same as that at 14 md (mode b) in stage Ill, which indicates that this mode reaches to about 20 md by the time the ova forming a mode at 20 md in the same ovary reach about 32 rnd. This situation indicates a possibility that once the ovary reaches stage VI (ripe) it may revert back to stage III and again undergo ripening and reach stage VI- It may be mentioned in this connection that James and Baragi (1980) have indicated that in some fishes the ovary after attaining stage VI (ripe) and releasing a batch of ova may revert to stage V, IV or III. It may be questioned as to how stage VI ovary reverts back to stage Ill after releasing a batch of ova instead of to stage II as is genearlly known in fishes. The ova forming a mode at 4] md in stage V may further increase in size by the time the ovary passes on to stage VI and the ova forming a mode at 20 md in stage V may grow further and pass on to a modal size of 32 md — the modal diameter of mature opaque ova in stage ll] (fig 2) -— judging from the progression of ova in different modes in stages [II-V. Thus, it appears that L~ bindus in Kakinada is a fractional spawner releasing the ripe ova in at least two batches in the course of one year. Balan (1967), however, states that each adult female releases the ripe ova in one spawning act during a short spawning season at Calicut. The conclusions made here get support from the occurrence of stage IV females in almost all months (Table 2) and also from the similar observations made at Madras (CMFRI 1.978). LENGTH-F R EQUENCY DISTRIBUTION Data on length-frequency distribution collected during the years 1979 and 1980 were used. A total of 5626 specimens ranging from 17 to 122 mm were measured. The monthly length-frequency distribution is presented in figure 3. It is observed that the modes in the length-frequency ditribution do not show regular monthly progression and in some consecutive months the distribution shows modes at the same length- There are, however, some modes whose pro gression could be traced for shorter periods ranging from one to five months. An attempt is made to estimate the growth rate and age on the basis of the progression of these modes. lt may be seen from figure 3 that there is a mode (a) at 32 mm in December‘ 1979 which can be traced to 37 mm in January 80. This can be further traced to 57 mm in May 80. Thus a growth of 25 mm is obtained in 5 months from December 79 to May 80 at a rate of 5 mm per month. The modes at 47 mm (b & c) in September 79 and February 80 can be traced to 52 mm in October 79 and March 80 respectively, which also give n monthly growth of 5 mm. There is a mode (d) at 52 mm in August 79 which can be traced to 57 mm in September 79; this mode can be further traced to IA 66 MURTY 62 mm in November 70. Thus a monthly growth of 5 mm is observed between 52 and 57 mm and 2.5 mm between 57 mm and 62 mm. The mode (e) at 57 mm in September 80 can be traced to 62 mm in November 80 which gives a growth of 5 mm in two months. Similarly the mode (f) at 57 mm in March 79 has shown n growth of 5 mm in months and reached 62 mm in May 79. The progression of 1979 I980 _.,,iI020 oaccvnrv urctmn"I LoL ‘O4'°1_=n1-s‘ mvsunra ll}i==c1===.. ' novcnnrn __ ' |Q-1' _.__L".4:.‘.J_In gen ! l I I. !|~r7d ' I ,' ‘O sol—— ecvoua ._ _.. _.1-_'r.:.'."ri'.\lt~_. i l in-2|: °¢ 7°55’ 5 O 4 II - an_.__cCU it ,0 '15|;____._[': :1 .1"'11.". 1 1...}-!.“h_"'n.n—\_ '_£U 1'" .. ;-q‘ ' :':;¢z"'1-‘ I .o_,_-__._..rTl. I-if: (41[...:._L ‘n ~no .§TL'f1_J:1:c1.:':x_. $01 ‘ qsggp '9 do-1 IF, a-mm JULY E5 ._I0‘ __" ‘_)_'_ F in-to E _loss! I0 I.) ,0:1" 411 A rill L ' _- '0-'1.__ __- < ._li'JIfri.s;_[1 - F‘'FI I-,' 7‘n- ,_-) tr .I» __ a :4" . lr -.__’4; _H5 5 ‘ r— an lo not III I0 (07 ° '. KL I ’ 1"" 1 1... ,!"1-l_Jij:z.J*_ ,9?.1' .|_9‘ -- _H,1 IPML II-:43 H AIILI 1-| . an1 ,0 'I '1___L= ..Ll:r:__'- 'nun __._.___.__ -LI I -_.' "I"!Q ‘ “, 0 .¢__i. ._1,- z can __,_Hi‘la-an ' . I ' ‘° ,.__= "0- E n °I049! MIMI? 0 .-¥ 4-1 rr :57w-rY*1-Y'*' 17 47 71' l I01 . ' ' ggporn lmurs tan! FIG. 3. Monthlylength-frequency distribution of L. bindns during I979 and I980. mode at 62 mm (d). in November 79 can be traced to 72 mm in March 80 (4 months) giving a monthly growth of 2. 5 rmn; this can be further traced to 82 mm in August 80 (5 months from March) which shows an average growth of 2 mm per month- Similarly the mode (g) at 72 mm in July 80 can be traced to 82 mm in December 80 giving a growth of 10 mm in five months with an average monthly growth of 2 mm. The "mode at 82 mm in September 79 (h) can be traced to 92 mm in February 80 which gives a monthly growth rate of 2 mm; this mode can be further traced to 97 mm in May 1980 with a growth of S mm (l.66emm[month) in three months. rg nee umc _ FR :2EN or 5 ..'-.-.- -- !.._. ...l.... --_1.. L... ._ -.‘;.*"3 "."'"'_'?'“_ -,.:* t?;'3_ . '1" T J‘ “.13 0_ W 6» T-Ir '3 O 6 PERCENTAGE rnaoucncv BIOLOGY OF Sll~.VERBEl..I.'Y 67 It can be inferred from the above observations that in the sea oil‘ Kakinada L. bindus grows at an average monthy rate of 5 mm between 32 and 57 mm length, 2-5 mm between 57 and 72 mm length, 2 mm between 72 and 92 mm length and 1.7 mm between 92 and 97 mm. The growth is not traceable beyond 97 mmthough fishes up to 122 mm length are recorded in the catches. Since a growth rate of 5 mm per month is obtained from 32 to 57 mm and since a reduced growth rate is observed from 57 mm onwards, the smallest modal length obtained in the present study at 32 mm (from which growth rate could be traced) can be reasonably taken as 4 months old with an average growth of 8 mm per month. It may thus be stated that L. tbindus attains average length of 65 mm at the completion of first year and 90 mm at the completion of second year in the sea off Kakinada, It may be mentioned here that the catches. of L. bindus at Madras range from 33 to 124 mm length and it appears that the species attains 70 mm at the completion of first year (CMFRI 1978) Balan (1967) studied the length-frequency distribution of L. bindus in the catches obtained at Calicut during 1956-1959. Though he did not arrive at any con clusion regarding growth rate and age he stated that “. . .. there is an overall increase in the size of the fish from 50 mm in April to 90 mm in November i.e., showing a growth of 40 mm in the course of 7 months each year (in 1957 and I958) in general.” James and Badrudeen (1975) studied the length-frequency disribution of Leiognathus brevirostris from southeast coast of India. According to them the fish grows at a uniform rate of 5 mm per month throughout its life and attains 60 mm and 120 mm at the completion of first and second years respectively. It is possible that the longevity of L- bindus is more than two years because the estimated average length at the completion of second year of life at Kakinada is 90 mm and because the maximum length recorded is 120 mm. In view of these observations and also since growth rate could not be traced beyond 97 mm (which is 28 months old), the estimation of growth parameters has not been attempted for fear of getting erroneous results. ACKNOWLEDGEMENTS .I am thankful to my colleague Mr. K. Narayana Rao for the assistance rendered both in the field and in the laboratory. REFERENCES ARORA, H. L. l95I. A contribution to the biology of the silverbelly, Leiogrtarhus splen dens (Cuv.). Sec. II, Proc. Indo-Pacific Fish. C0unc., 1-6. BALAN, V. 1967. Biology of the silverbelly, Leiognathus bindus (Val.) of the Calicut Coast. Indian 1.“ Fish, IOA: I18-134 (I963). CLARK, F. N. 1934. Maturity of the California sardine (Sardina caerulea), determined by ova diameter measurements. Fish. Bull., Calif. Div. Fish Game, 42 :49 pp. 68 MURTY CMFRI. 1978. Annual Report I978. Central Marine Fisheries Research l'nstitutc._ Cochin. 151 pp. CMFRI. 1980. Trends in total Marine Fish production in lndia-1979. Mar. Fish. Infor. Sen-'. T and Ser., N0. 22: I-19. James, P.~S. B. R. AND M. BADRUDEEN. 1975. Biology and fishery of Leiognat/ms bre virosrris (valeneiennes) from the Palk Bay and the Gulf of 'Mannar. Indian. J. Mar. Sc:'., 4: 50-59. JAMES, P. S. B. R. mo VIJAYAKUMAR M. BARAGI. 1980. Ovary as an indicator of fre quency of spawning in fishes. Proc. Indian natn. Sci. Acad. B 46: 476-489. KUTHALINGAM, M. D. K. 1958. The food and feedng habits of some young silverbellies. 1. Mad. Univ., 28: 13-22. Snaoscoa. G. W. AND W. G. COCI-LRAN. I967. S:ati.m'cu! Methods. Sixth Edition. Oxford and TBH Publishing Company Delhi. 593 pp. icomarambgizy'—~ - — IHLIT‘; __ -_ i. _ ___ MURTY, V. SRIRAMACHANDRA. 1986. Studies on the growth and population dynamics of the silverbelly Le;9gnathu§ bindus (Valenciennes) from Kakinada. gpdégg J; £§gh., 33 (3): 277-284. ltcoitraxemionifl Reprinted from Indian J. Fish., Vol. 33, No. (3), 1986; pp. 377--334 STUDIES ON THE GROWTH AND POPULATION DYNAMICS OF SILVERBELLY LEIOGNA THUS BINDUS (VALENCIENNES) IN THE TRAWLING GROUNDS OFF KAKINADA V. SRIRAMACHANDRA Murry Kakinada Research Centre of CMFR Institute, Kakinada 533002. Ansrnacr Leiognathus bindus attains average lengths of 72, 110 and 132 mm at the completion of first, second and third years, respectively. The parameters of von Bertalanffy growth equation are estimated as: [fiat = 153-4 mm, K = 0-53 PB‘-' year and t», -s-—- ~0.024 year. Instantaneous rates of mortality are estimated as Z = 5.2, M = 1.5 and F = 3.7. The yield per recruit analysis shows that the yield of L. bindus can be increased by increasing the cod-end mesh size of trawl nets. Irrrnonocrron Among the silverhellies landed by private trawlers at Kakinada, L. bindus is the most abundant species forming about 41% by weight. Aspects of biology of this species were studied earlier (Murty 1983). The present paper gives the results of investigations on age and growth, mortality rates and stock assessment of this species on the basis of data collected from private trawlers during 1979-81. MATERIAL AND METHODS Based on samples collected at weekly intervals, data on species composition of silverbellies and lengths of L. bindus were obtained on each observation day. These were raised to the day’s catch, and were further raised to get monthly estimates of cath of different species and length composition in the catch. From these data, annual estimates of species composition and length composition of catch were obtained. Growth and age were estimated from the modal progression in the mon thly le-ngth-frequency distribution of catch. Parameters of growth in length were estimated using the von Bertalanfiy growth equation, which is of the form: L. 1.. ( t-.=I<<~.>. where Lo: asymptotic length of fish, L1 length at age ‘t’. K growth coeflicient and to = arbitrary origin of growth curve. 278 MURTY Instantaneous rate of total mortality (Z) was estimated using the equa tion of Beverton and Holt (1956): .-q — z K(La*l_)_.-‘(l-leg) where It; is the length at first capture andT is the average length of fishes includ ing and above le . Estimate of instantaneous rate of natural mortality (M) was obtained using the equation of Pauly (1980): Log M = -0.<)t.1r»a~ 0.279 log 0.6543 log K + 0.4634 log T where La is in cm, K per year and T in °C. Value of temperature W115 taken as 27.2°C from Ganapati and Murthy (I954) and La Fond .( 1958). The value of M was also estimated taking the life-span of the species into account. The yield in weight per recruit (YWIR) was calculated from the equa tion of B-everton and Holt_ (1957): l 3S _ 391 S3 Y“/r’R F@”M"°‘ “’ “H 2 * *'21Ti'<.“ where S == {K 0°’ [° ). re = age at first capture, 2. r age at recruitment and Wm. K and to are parameters of von Bertalanffy growth equation. Gaowrrr mo Ace A total of 7452 specimens ranging from 17 to 129 mm were measured during February 1979-December ‘l98l. The data (Fig. 1) did not show p1'O~ gression of modes over a period of several successive months to facilitate deter mination of growth. Nevertheless. a few modes (Fig. 1) whose progression can be traced for periods ranging from 2 to 5 months are present. A mode a-t 32 mm in December 79 can be traced to 37 mm in January 80, giving a monthly growth of 5 mm (Fig. 1). Three modes at 37 mm in February 79, May 79 and July 80 can be traced respectively to 47 mm in A-pril 79, 52 mm in Au-gust 79 and 47 mm in September 80, showing an average growth of 5 mm per month. Further, the modes at 47 mm in September 79, February 80, October 80 and February 81 have shifted respectively to 52 mm in October 79, 52 mm in March 80, 57 mm in December 80 and 57 mm in April 81 again all the modes showing an average monthly growth of 5 mm. The mode at 52 mm in Novcm~ ber 19 has shifted to 72 mm in March so and another mode at 57 mm in August 80 has shifted to 67 mm in October 80, showing, once more, a monthly growth of 5 mm. It is therefore clear that the monthly growth rate is about 5 POPULATION DYNAMICS or SILVERBELLY 27*) lfl I25 _ _ O\O - | I ll it-2'’ Q-I " 7 _Ian aq §H3"T I‘I , ‘N 7’ 7" 1 . _li;§ _3;, ‘ r7', 57 4+. l.'1 |, » 1| 1 li IllI£5 ' I » =li.S i'>, ‘H7 H2' ll rii7 /l 77' | i ,,7Ii F' -O7, 17 !7 @.- ‘2 .- N*¢Q . ‘ IL7'1 ' 4|‘ ‘. ‘. \ ;‘4 r‘ l |7_ ‘ ' - I',>/ ‘L:‘ -‘ ‘__i L 7 , ,I a T’I 5‘= W ‘i L‘~ ‘_~_‘ . .I ll\ l1i I '\ L ~i ._ l " 7 A I 4; LL.1 J. J. 4 ' 5 1979J: ~:-—_:=~-:-~~¢M 5 1980: _: i_- .~J : ~:~-+'~.- M -r>_ ~¢* S use:*v"~;—-+1 J er er"M I - T" '-"'?*’1—'~'i 5 rs‘ r FIG. 1. Length range and modal lengths in L. bindus and their progression in different months during I979-’8l (vertical lines show the length range, the points indicate the modal lengths and numerals indicate sample size). mm in fish ranging from 32 to 72 mm length. The mode at 7 7 mm in Octo ber 79 is traceable to 92 mm in February 80 showing a growth of 15 mm in 4 months, with a monthly average of 3.75 mm. Similarly, the mode at 82 mm in September 79 has progressed to 97 mm in January 80 again showing a monthly growth of. 3.75 mm. Two modes at 82 mm in May and Dcccm-ber 80 have shifted to 92 mm in September 80 and May 81, respectively, giving an average monthly growth of 2.5 and 2 mm. The mode at 87 mm in August 79 has shifted to 102 mm in December 79 in four months, giving a monthly growth of 3.75 mm. Thus; the modal progression between 77 and 102 mm length has given three different monthly growth rates: 3.75 mm in 3 cases, 2.5 mm in one case and 2.0 mm in one case. Hence the average of these values was taken as the monthly growth between 77 mm and 102 mm length. Since a monthly growth of 5 mm between 32 and 72 mm length and 3.1 mm between 77 and 102 mm length were observed, fish with the smallest modal length at 32 mm (from which growth could be traced) can be reasonably taken as 4 months old with an average monthly growth of 8 mm. The Ford--Walford plot (Ford 1933, Walford 1946) of It r-1 against I1 on the basis of lengths attained at intervals of 3 months (Fig. 2) shows that TOTA L LENGTH in —a 43 uixi he 9- r ~— 1 46 __ 4 . :%.27 _ om _ _' 94 \ - A~_ .:~ ——K er M-‘~ - --¢—*2BS =-439 ‘S 1 Ii si. 44- ; — 165 .\ ..- fi\ --4_' . ~—...... _--414 -9 434 TIT1‘~—--—X—-———1 39 t——a --e—- 242 |__. 4: T1207 6 as-4355 — j;\ \i=---_a=s99 Hwoz 4-... _ 5 '14 _\ O6 l—;_ _ _._ 460 x 5 9 adé A‘--__ ~ -as 02 h__ YQO72 I M1 40‘ 280 MURTY ‘5°L.l,_ _ I .F‘HM}! 1__ . .1,l! . 2.60] 5.0.?‘ml qr 1 1,< 1 w 1 1I -Q ' 41/ '_ 1‘ '—"— " '—"v"an :“—'r' -'.'_—;11la— "~"—:; —,——" Oi./m-I . . ./ .--. . Wm.l -, 0 0-15 0-rs as :-rs to ,0 m AGE YEARS |*mm ‘ FIG.bindus. 2. Ford-Walford plot cally_ in L. FIG. 3. Estimation of to graphi the points are well represented by the straight line. The L0: was estimated at 158.4 mm and K per year at 0.58. The value of to was estimated (Fig. 3) as -0.024 year. The calculated lengths of L. bindus at Kakinada are 72, 110 and 132 mm at the completion of first, second and third years of life respectively (Fig. 4). Since the maximum length recorded in the present study is 129 mm, the maximum age works out to 2.9 years. ...l 11l ,/Z/' -I '| 40-! / j/ ° I 2AGE 3 YEARS 4 s s 1 FIG. 4. won Bertalanffy growth curve of L. bindus. Moantrry Russ The monthly length-frequency distribution (Fig. 1) shows that the smallest modal length in any year is at 32 mm. However, the annual length com position of the catch during the period shows dominant mode at 57 mm. Hence this length was taken as length at first capture (Le). The estimated values of Z in different years (Table 1) varied from 4.4 to 6.0 with an average of 5.2. TOTAL L£Q§TH 9 Ol._ cg, ll POPULATION nrmmrcs or SILVERBELLY 281 j TABLE 1. Estimated values of length at first capture (lo) .mean length (1) and total mortality rate (Z) during different years in L. bindus. Particulars I979 1980 1981 |c(IIlIl1) 57 57 S7 21 6.0281(mm) 65.9 4.3622 68.9 5.2422 67.1 The value of M was estimated as 1.5 on the basis of the equation of Pauly (1980). If it is assumed that there is no exploitation and that 99% of this species by numbers die by the time they attain the maximum age of 2.9 years, the M value can be calculated as 1.6 (Ln 100 + 2.9), which is almost the same as the one obtained by Pauly’s formula. The M value is taken as 1.5 and the average F during the period works ou-t to 3.7. YIELD PER Rncnurr The value of Wa was estimated at 54.7 g on the basis of length-weight relationship and L <.<. Taking 57 mm as lc. the value of Ic was estimated as 0.75 year. The smallest fish in the catch measured 17 mm. Hence this length was taken as length at recruitment (Lr) whose age (tr) was estimated as 0.18 year. The yield per recruit as a function of fishing mortality rate was calculated taking -four values of lc ranging from 0.59 to 1.13. (Fig. 5) representing lc val-ues ranging from 47 to 77 mm. It is observed that with to at 0.59 the yield increases to a maximum at F 2.0 and then declines with further increases to a maximum at F =-< 2.0 and then declines with further increase in F. With tc at 0.75 (the present value) and 0.93 the value of yield per recruit is maximum at F === 3.0 and 4.5 respectively and show decline with further increase in F. With tr; at 1.13, the yield per recruit increases with increased F and does not show any fall. It is also observed that yield per recruit is greater for higher values of Ic (Fig. 5). The yield curves show that under the current value of F (3.7) and tc (0.75) the yield per recruit already showed a decline and further increase in F will result in further decline of yield. The yield per recruit as a function of u; shows that maximum yield can be obtained at t¢ -—i- 1.1 (Fig. 6) with F at 3.7 (present value) indicating that yield can be maximised by increasing the age at first capture (i.e., by increase of codend mesh size) without further increasing the effort. 282 MURTY Tl\{ I-I3 |°3'L.L e O-93 Z l o-59 \ J -7’.-Q‘I|‘I -I‘ _-' I ll ‘IHI E t I.' V I Ié Ir Iti QO'| 5:ti. ‘ / I1i '' T it . .~—-1+I 4—-'i.. —t-~-—__i i ‘_i_ _,_ IAGE 5 AT 9 FIPST CAF'TU§’€ FIG. 5. Yield per recruit (YWIR) ingof L. mortalitybmdus in relation rate to (TheF1sh- FIG_vertical 6_ Yield . . per. Remit of L_ line indicates the present F)_ bmdus 111 relation to age at.first ageNumerals at indicatefirst capture. the values of cates°aPtl1T¢- the (T116 present V6I‘l1¢81 tc).11116 111(11 DISCUSSION It is well known that estimation of growth and age of tropical fishes is ditficult for a variety of reasons. Since in the present study there is no clear-cut progression of modes in the length-frequency distribution in each successive month in a year (Fig. 1), the modal progression during shorter intervals was taken in-to account, assuming that the modes considered belong to the same brood, and the parameters of growth obtained in the study seem to be realistic because the estimated value of Lot at. 158.4 mm is close to the maximum recorded length of the species: at Madras the maximum length recorded is I55‘ mm (CMFRI, 1977) though the maximum length recorded during the study period at Kakinada is only 129 mm. The estimated values of K and M obtained also show that the MIK value is just about the upper limit of the range known for fishes (Beverton and Holt 1959). Pauly and David (1981), however, esti mated the values of Le: and K in L. bindus on the basis of data from Calicut (of Balan, 1967) as 12.2 cm and 1.3 per year, respectively. An attempt to estimate M on the basis of regression of Z on eifort did not prove successful probably because, the fishery being a multispecies one. Y If. LU PER RECRU T-GRAMS Q U‘! F.-"....l“_-_j‘-¢___;__J_—_—L~—4 uT- GRAM5 Q—-Y€LO Q viPER RF CW O 7 Q J;L | |___‘_1___ 4 , it‘, H) I;-J 7}) PU POPULATION ovuamcs or SILVERBELLY 283 efiective -effort for the species under consideration could not be obtained. Hence the value obtained by using the formula of Pauly (1980) was taken. The regression coefficient in the length-weight relationship of L. bindus from Kakinada (2.96l82; Murty 1983) was tested against -the theoretical value of 3 by t-test and it was found that the ob-served value was not significantly difiere-nt from 3. Hence the results of yield-per-recruit study, using Beverton Holt equation, (which takes growth to be isometric) can be taken as reliable even to arrive at etimates of absolute yield. The yield curves (Fig. 5) show that the value of F, where the fall in the yield -per recruit occurs, is greater if te is greater, indicating that there is a possibility of growth overfishing under lower values of re and that higher yield can be obtained by increasing te. When te his 1.13, hte yield curve does not show a fall with increased F. It was shown earlier (Murty, 1983) that L. bindus attains first maturity at 80 mm (1.19 year). Thus, it appears that increasing te up to age at first maturity will not only result in increased yield out also give scope for increasing the effort. This is possible because increasing lc up to age at first maturity will not hamper the reproduction by removing prospective spawners, thus averting recruitment overfishing also. In L. bindus at Kakinada. hence, increasing the cod-end mesh size of trawl nets results in higher yields without adversely afiec-ting the stock. Acxnownnncnmenrs I am thankful to Dr. E. G. Silas, Director, CMFR Institute, for encou ragement arrd to Dr. B. Krishnamoorthi, Head of Demersal Fisheries Division for going through the manuscript. I am also thankful to Dr. K. Alagaraja, for llJS valuable advice in analysis of data and for going through t-hC111Ztl‘.ltSCI'lPl'. REFERENCES BALAN. V. 1967. Biology of the silverbelly, Leiognathus bindus (Val.) of the Calieut coast. Indian J. F:'sh., 10: 118-I34. (1964). BEvnRroN_. R. J. H. AND S. J. HOLT. 1956. A review of the methods for estimating rates in Exploited fish populations, special reference to sources of bias in catch sampling. Rnpp. P-V. Remr. Cons. Perm int. Explor. Men, 140(1): 67-83. BEVERTON, R. I. I-I. mo S. I. Hon. 1957. On the dynamics of exploited fish popula tions. Fishery Invest. London, Ser. 2, 19: 533 pp. BEVERTON, R. J. H. AND S. I. Hon‘. 195.9. A review of lifespans and mortality rates of fish in nature and their relation to growth and other physiological characteristics. In: Ciba Foundation Colloquia on ageing. G. E. W. Wolsenholme and M. O’Connor (E-'.ds.}. The life-span of animals, 5: 142-I77. CMFR]. 1977. Annual Report I977. Central Marine Fisheries Research Institute Co chin. 148 pp. 284 MURTY Form, E. 1933. An account of the herring investigations conducted at Plymouth during the years 1924-1933. J. mar. biol. Ass. U.K., 19: 305-384. Gmunn, P. N. mo V. S. R. Mvnrnv. 1954. Salinity and temperature variations of the "surface waters off Visakhapatnam coast. Andhm. Univ. Mem. (_)ceanogr., I: 125-142. LAFQND, E. C. 1958. Seasonal Cycle of sea surface temperatures and salinities along the east coast of India. Andhra Univ. Mem. Oceanogr., II: 12-21.. Munrv, V. SRIRAMACHANDRA. 1983. Observations on some aspects of biology of the silverbelly, Leiognathus bindus (Valenciennes) from Kakinada. Indian I. Fi.rh., 30: 61-58. PAULY, D. 1980. On the interrelationships between natural’mortality, growth parameters and mean environmental temperature in I75 fish stocks. J. Cons. int. Explors Mcr'., 39: 175-192. PAULY, D. AND N. DAVID. 1981. ELEFAN I, a BASIC program for the objective extrac tion of growth prarameters from length frequency data. Meeresforsch, 28: 295-211. WALFORD, L. A. 1946. A new -graphic method of describing the growth of animals. Biol. Bull. Woodshole, 90: 141-147. F______“ _: if ICONTRIBUTION 1 2 I MURTY, V. SRIRAMACHANDRA. 1988. Population characteris tics of the ailverbelly goiggnatglguq binding (Valenci ennos) along west Bengal coast. Q. g_n_a_;:_. biol. Q32. India 28 (1&2): 41-4'7 (1986). zattttstmt1 ztlulnncxfi " -- -T14” i-T12] CU J. mar. bio]. Ass. India, I986, 28 (l & 2) : 41 - 47 POPULATION CHARACTERISTICS OF THE SILVERBELLY LEIOGNA THUS BINDUS (VALENCIENNES) ALONG WEST BENGAL COAST V. SRIRAMACHANDRA MURTY* Central Marine Fisheries Research Institute, Cochin-682 O31 ABSTRACT Leiognalhus bindus occurs 6-15 m above sea bottom during night time in areas of depths ranging from 21 to 35 m. There is good correlation between depth of occurrence and mean length of this species. The length-weight relationship in the sea off West Bengal can be described by the equation log W=-5.382l7+ 3.28637 log L. The selection length for the 22 mm cod end mesh size is 42 mm. It appears that L. bindus in the sea off West Bengal belongs to a virgin stock and the estimated value of Z at 1.02 can be taken as M for the species. The yield per recruit analysis shows that higher yield can be obtained at a cod end mesh size of 42 mm with a maximum F of 3.2. INTRODUCTION end mesh size of 22 mm, in the sea off West Bengal during 2]. 2. 1985 - 25. 2. 1985. One IN FEBRUARY 1985, the Research Vessel R. V. hour hauls were taken at each station at a Skipjack of the Central Marine Fisheries trawling speed of 3.5 kn in a total of 16 stat Research Institute conducted a survey in the ions (Fig. 1). At each station, the depth (echo region between 20°-21° 03’N and 87° I5’ - 88° depth and year depth) was recorded along 55’E along the coast of West Bengal using a with all relevant particulars. Fishing was con midwater trawl. Leiognathus bindus (family ducted both during day and night. The catch Leiognathidae) was one of the most domi at each station was separated into constituent nant species in the catches. Since there is no species and then all relevant data were recorded. information on this species from along West In L. bindus all the specimens caught were Bengal Coast, an account of biology and measured: in cases where the catches were population dynamics of this species is given larger, a sample of fishes was measured and in this paper. then weighted to the catch. Some specimens were preserved in formalin and brought to The author is thankful to Mr. C. Mukundan, the laboratory for further studies. The length Head of Demersal Fisheries Division, CMFRI data were grouped into 5 mm- class intervals. for going through the manuscript and for For length-weight relationship the preserved offering useful suggestions. The author is also specimens were measured to the nearest mm thankful to his colleagues Mr. G. Sudhakara and 0.5 g and the relationship was calculated rao, Mr. B. Narayana Rao and Mr. M. Pra using the formula; log W=log a+b log L (Le sadarao and the crew of R. V. Skipjack for Cren, 1951). Maturation stages were fixed their cooperation during the cruise. following Murty (1984). The total mortality rate was estimated following Beverton and MATERIAL AND Msrnoos Holt (1956) method; for this purpose the data R. V. Skipjack operated a mid water trawl on length composition of catch at all stations 141.5 m long (including the leg) with a cod were pooled. Natural mortality rate (M) was estimated assuming that 99% of the fish by mi numbers would die if there is no exploitation, * Present address :Kakinada Research Centre of CMFRI, Kakinada - 533 002, India. by the time they attain maximum age (t max) 2 V. SRIRAMACHANDRA MURTY and by taking tmax as corresponding to Lmax from l2 to 23 m (6-I5 m above sea bottom in the catch (Sekharan, 1975) or to L QC - 0.50 having the depth range 21-35 m). Though fishing was conducted both during day and cm (Alagaraja, 1984) or to 95°/O of Loc Pauly, night, L. bindus was caught only during night 1983). Length at first capture (LC) was esti time or during early morning time before mated following Jones (1976): LC == SF X MS dawn (Table l). Only small quantities of ano where SF is the selection factor and MS the ther silverbelly (Secutor ruconius) were caught. cod-end mesh size. SF was estimated using A plot of mean length (of all the fishes cau the depth ratio (standard length/maximum ght at each station) of L. bindus against the body depth) of the species and the nomogram gear depth (Fig. 2) shows that there is a signi given by Pauly (1983). ficant correlation between the two (n=6; 7 i raj. 1 _-__—— ‘ R~V-SKIPJACK ' \. s\w \i " (CRUISE ~o- SJ I6/84 0 Xii i /I" ‘I . }‘/l :0 l / l 5 g ,-//’/ i 0.’-T;, i li I /I Il . __-4 .a- *2‘ ‘\____.\ _r ~ ‘_ ‘ Ir-. , '/ 1?/ ’//1/ ° ‘ I _ . T‘-_ _‘v" .- ’ 2' l (‘QQl Q/lo‘ I‘I i‘____ P’ ___‘ I .. / PU /4‘ 0 ,0‘ -' Dd __ .'a _ L, --so’ 1'’‘ Q-Q" 9i \/ O i"; I7OI "lI i lo4''7' i '-' ." f iiI‘ iC_i 1l ',4-~--r_:‘: DISTRIBUTION AND BIOLOGY F’-0.79) suggesting that larger fishes live in relatively deeper waters. The relation can be Di'stributi0n.' A total of 16 hauls was taken at described by the regression: 16 stations (Fig. l). Leiognathus bindus was ML = -— 27.0428 + 5.8778 D caught only in six stations and a total of 18.6 kg forming 13.5% of total catch in all 16 \ stations was obtained (Table 1). Fishing was Where ML is mean length in mm and D is conducted in areas having bottom depths gear depth in m. ranging from 21. to 150 m and the depth of the gear ranging from 12 to 68 m. L. bindus Length composition of catch: A total of I908 occurred in the catches at gear depths ranging specimens was caught and 234 specimens \. \\\ -F“is \‘I ll “.1 “'0 '5 wag: ll Y R-'€5' é-L /-' 5 l I H“ l\ \ ‘ 1,-1-;.-r ‘I \ * | \—+ I \\ g POPULATION DYNAMICS OF SILVERBELLY 3 were measured. The total length at different relationship was calculated separately for males stations varied from 20 10 135 mm (Pia 3) and females and the regressions are: with modal lengths at 47 and 102 mm. Sex ratio and Maturity: A total of l63 speci- males I log W : T’ 469562 T 294611 log mens ranging from 87 mm to l18 mm was L? Y2 '"= 0-30 TABLE 1. Details of fishing stations and catches St. No. Depth (m) of Time of fishing Total catch Silverbelly Catch os bottom gear (Hrs) (kg) catch L. binduf (ks) (kg) 1 21 12 0130-0230 25.86 1.00 0.10 5 150 60 1815-1915 1.00 ll 25 18 0510-0610 13.19 2.00 1.35 12 53 32 0930-1030 1.25 13 98 45 1325-1425 -0.05 — 15 94 50 1850-1950 0.66 — 16 58 36 2200-2300 0.65 - 17 35 20 0035-0135 2.28 2.10 2.10 18 26 20 0510-0610 27.39 0.13 0.13 19 35 25 0800-0900 3.78 20 53 35 1145-1245 0.10 21 89 68 1540-1640 22 44 32 1840-1940 34.10 0.20 23 33 23 2200-2300 17.33 15.00 15.00 24 27 21 0110-0210 8.20 0.28 0.08 25 34 29 0425-0525 2.70 ~1 Total: 138.54 20.71 18.76 . . _ a ~—- -1- i ' _;-¥;--- - —~_.~.. - - --- Note: The numbers of the stations where only hydrographic data were collected are not listed here. examined; of these 86 were females and the Females : log W = -— 5.70966 + 3.44844 log rest males. Among females 87.2% were in L; r2 = 0.83 stage IV and 12.8% in stage V. Analysis of covariance (Table 2) does not Length - weight relationship .' Data of the 163 reject the identicality of regression lines at specimens mentioned above were used. The 5°/O level of significance The data of males 4 V. SRIRAMACHANDRA MURTY and females were therefore pooled and regre ssion for the species was fitted: Estimation ofL(_: The depth ratio was cal log W= -~5.38217+3.28637 log L; r2-"=0.82 culated as 1.85 and using this value, the SF value was read as 1.9 from the nomogram of The t-test (Pauly, 1984) was applied to test Pauly (1983). Taking the cod end 1116811 Size whether the regression coefficient is signifi of the gear at 22 mm, the Le vfllufi WKS 081 TABLE 2. Analysis of Covariance to test I the significance of di)‘]’erence he! ween regression lines oj sexes in the /ength-weight relationship of L. bind us Source of variation Df DeviationSS from MS Regression Due to regression within sexes 159 0.187204 0.001177 Due to difference between regression coefficients 1 0.004361 0.00-1361 Residual due to regression pooled within 160 0.191565 0.001197 Difference between adjusted means 1 0.000006 0.000006 Total 161 0.191571 ' Comparison of slopes F=3.7l, df=l,159; NS Comparison of elevations F=0.005, df-=l,l60; NS. TABLE 3. Estimated values 0/' M obtained by different met/tods along with the values of Lmax and fmw. in L. bindus _ _Method _ - _ of -Lmax —-——_i (mm) tmax (year) __. M,,?__ M,=‘K Sekharan (1975) 135 3.27 1.41 2.43 Pauly (1983) 150.48 5.14 0.99 I. 55 Alagaraja (1984) 153.4 5.93 0.78 1.34 Pauly (1980) 1.50 2.59 eamly different from 3_ At dye: n_2’ the Q culated as 42 mm. The Le in the present study value shows that the regression coefficient is was taken as 40 mm being the lower limit of not significantly different from 3 at 1% level. the length class 40-44 mm. POPULATION DYNAMICS OF SILVERBELLY 5 Estimation of total mortality rate (Z): Murty ship. The smallest length in the catch at 20 (1986) estimated the von Bertalanffy growth mm was taken as Lr and its age (tr) is 0.2 year. parameters of this species as L:"_>c=l58.4 mm, Taking the value of M at 1.02 and taking diff K-"~'=0.58 per year and to = — 0.024 year from erent values of LC corresponding to different off Kakinada along the coast of Andhra Pra desh. Taking these values for the stock along West Bengal Coast and taking LC as4O mm (L value was calculated taking fishes above 40 mm TL), the value of Z was estimated as I6-1T '_l 102 rg 0-62 l .' ~4 .|1| iIf- > 9 at('\I |\ Q LENGTH Qnoupslwwv Fig. 3. Length frequency distribution of L. blndus F . Q (Data pooled from all stations). cod end mesh sizes, the yield per recruit (Yw/R), was calculated. The Yw/R as a function of F (Fig. 4) shows that Yw/R is higher if tc is tr‘ i—’ —r-r 1+ -e"; higher and reaches maximum at greater values 5 IO IS 2O 25 of F when to is greater. It is also clear that DEPTH lm l “ if to is 1.19 (cod - end mesh size 42 mm), maxi Fig. 2. Relationship between mean length of L. binds against fishing depth. mum Yw/R is obtained at F-=3.2. DISCUSSION Estimation of natural mortality rate (M): The values of M obtained by different methods Balan (1967) stated that in L. bindus, “very are shown in Table 3 along with the value good catches are reported to be procured dur obtained by Murty (1986) following Pauly’s ing foggy nights and also during the dark (I990) equation. In the present study M value phase of the moon when the shoals reveal was taken as 1.02 which is also the Z value. their presence by luminescence in the surface and sub-surface waters”. Venkatraman and Estimation of yield per recruit: The growth Badrudeen (1975) showed that silverbellies parameter estimates were taken from Murty “stay at the bottom during day time and (T986). The W0-c value was calculated taking a good portion of these migrates from there the L@<= value and the length- weight relation and rises to surface and sub-surface waters MEAN LENGTH (mm) an i3 ._ —.{¢Q ‘ .0 PERC ENTAGE ——l6 . 6 V. SRIRAMACHANDRA MURTY at night”. The present observations (Table 1) general are underexploited in West Bengal are in conformity with those of the above and L. bindus in the region can be treated as authors. There is justification, therefore, belonging to a virgin stock. This latter aspect in using the present data from midwater trawl is particularly clear from the estimate of in catches for a study of population dynamics of stantaneous rate of total mortality : off Ka L. bindus. kinada, the author (Murty, 1986) estimated the Z value of this species as 5.2 during 1979-‘8l Along the West Bengal Coast which has a whereas in the present study (in 1985), it is length of 600 km, an average catch of 13,634 estimated as 1.02 only. This latter value is I 3.3.‘. Q _ II“B —' - ‘—I-1Ol4O)= _|~l9l42l 7%; \ 1-1.‘.i-ii*4-4 Ix ‘ B ‘ - ; O-9ll35I \—rU‘! -| l -. 1 0 .74 l 301 I " l 2-O-i . -59l25l Q.5?t22l ;lH ‘#1. + 0-24 L1 .1 v —'-_ % "I _ ‘fiji - --Y’T'_'i -Ti : +' fii‘ " 77' - 03murg 24 OF Fl$HlNG 4'5 MORTALITY Fig. 4. Yield per recruit of L. bindus as a function of fishing mortality rate. Numerals indicate the values of age at first capture m years; those in parentheses are the corresponding values of cod end mesh size in millimetres. tonnes during 1976-‘8l (CMFRI, 1982), much less than the value of M estimated by of all fish forming 1.0% in the total marine Sekharan’s (1975) and Pauly’s (1980) methods fish catch of India, are landed annually. The and is only slightly more than the M values annual average catch of siverbellies (during obtained by Pauly’s (1983) and Alagaraja’s(l984) the above period) in this state was estimated methods. It is thus clear that there is virtu at 110 tonnes (CMFRI, 1982) which forms ally no fishing mortality for this species off 0.2% of all India silverbelly catch and 0.8% the West Bengal Coast. Since there is presently in total landings in West Bengal State. It is no way of obtaining an objective estimate of thus clear that marine fisheries resources in M particularly for the exploited stocks of ELO DEF? DECFJL) T POPULATION DYNAMICS OF SILVERBELLY 7 tropical fishes (Cushing, 1981; Alagaraja, with several other demersal species in the re 1984), the present estimate of M=l.02 for gion. The yield per recruit analysis (Fig. 4) of L. bindus can well be taken as the M value L. bindus, may therefore appear as having aca for those stocks of this species which are well demic value only. While it may be so at present, exploited. the results of the analysis provide an idea of the best strategy for rational exploitation of The stock of L. bindus along West Bengal the species and will be useful in future when Coast, like any other species in tropical mul similar information on all other demersal tispecies fisheries, can only be exploited along species in the region, becomes available. Rrrsarwcss ALAGARAJA, K. 1984. Simple methods for estimation MURTY, V. SRIRAMACHANDRA I984. Observations of parameters for assessing exploited fish stocks. Indian on some aspects of biology of silverbelly Leiognathus J. Fis/t., 3| (2)1 I77-208. bindus (Valenciennes} from Kakinada. Indian J. Fish., 30(1): 61-68 (1983). BALAN, V. I967. Biology of the silverbelly Leiog narhus bindus (Val.) of the Calicut Coast. Ibid., I0 A: ————— 1986. Studies on the growth and population 118-134 (1963). dynamics of the silverbelly Leiognarhus bindns (Valenci ennes) in the trawling grounds off Kakinada. Ibid, BEVERTON, R. J. H. AND S. J. H011 1956. A revicw 33 (3): of methods for estimating mortality rates in exploited populations with special reference to sources of bias in catch sampling. Rap. p. v. Reun. Cons. perm. int. Explor. PAULY, D. 1980. On the interrelationships between Meiz, I40 (1): 67-83. natural mortality, growth parameters and mean environ mental temperature in 175 fish stocks. J. Cons. int -—- AND i 1957. On the dynamics of Explor. Mer., 39: 175-192. exploited fish populations. Fishery lnv€Sl‘., London Set‘. (2), 19: 1-533. -—i 1983. Some simple methods for the assess CMFRI 1982. Trends in marine fish production ment of tropical fish stocks. F/40 Fish. Tech. pap. (234): in India- 1981. Mai'. Fis/1. Infor. Serv. T& E. 52 pp. Ser., 41: I-33. -?-- I984. Fish population dynamics in tropical. CUSHING, D. I-1. 1981. Fisheries biology: A study in waters : a manual for use with programmable calculators. population dynamics. The University of Wisconsin ICLARM Studies and Reviews, 8: 325 pp. Press, Second Edition, 295 pp. SEKHARAN, K. V. 1975. Estimates of the stocks of JONES, R. 1976. Mesh regulation in the demersal oil sardine and mackerel in the present fishing off the fisheries of South China Sea area. South China sea West Coast of India. Indian J. Fish., 21 (1): 177-182 fisheries development programme, Manila, S C S [76] WP/ 35: 75 pp. (1974). LE CREN, E. D. 1951. Length-weight relationship VENKATRAMAN, G. AND M. Baorauossw 1975. On and seasonal cycle in gonad weight and condition of the diurnal variation in the catches of silverbellies in the perch (Perc'a_/luviarilis). J. anim. £c0!.,20: 201-219. Palk Bay. 1bid., 21 (1):254-265 (1974). I'M‘ 7:"? if :_"*_:* ‘ iCONTRIBU'I‘ION 13] MURTY; V. SRIRAMACHANDRA. 1991. Biology and population dynamics of the silverbelly geggggg ingidlagpg (Bloch) from Kakinada. £4 _r§§_£. _§_§._2!._. §sms. Iondgg, 32 (1&2): 10-24 (1990). {j --"-‘r _».—:. +__—-% O-;O CONTRIBUTIODT"H l__i,t , ,__-.. O 1%, BIOLOGY AND POPULATION DYNAMICS OF THE SILVERBELLY SECUTOR INSIDIATOR (BLOCH) FROM KAKINADA J mar. biol. Ass. India, 1990, 32 (l & 2) : 10-24 BIOLOGY AND POPULATION DYNAMICS OF THE SILVERBELLY SECUTOR INSIDIATOR (BLOCH) FROM KAKINADA V. SRIRAMACHANDRA Munry* Central Marine Fisheries Research Institute, Cochin-682 031 Aesrtucr The biology and population dynamics of Secutor insidiator from the trawling grounds oil Kakinadu were studied. The estimated length at first maturity is 90 mm and the spawning season is protracted with a peak during January-March period. The von Bertalanffy parameters of growth in length are estimated as Loc'=' 123 mm, K=1.2 per year and to-=0.0l year. The estimated lengths on the com pletion of first and second years are 86 and 112 mm respectively. The length-weight relationship can be described by the equation ; log W(g)= -5_73713 —l-3.43654 log L (mm). The instantaneous rate of total mortality during the period is estimated as 6.] and the values of natural mortality rate, by different methods, are estimated as ranging from 1.8 to 2.6. Length and age at first capture are 80 mm and 0.87 year respectively. Under the present value of tr, yield increases with increased F without reaching a maximum ;highest yield, however, can be obtained at fc ranging from 0.5 to 0.7 with the present Z and different value of M considered. Imnoouiniou species from the trawling grounds ofi‘ Kaldnada. SILVBRBELLIES or slipmc uths (Family : Leiognathidae) are exploited in considerable The author is grateful to Dr. E. G. Silas, former Director and Dr. P. S. B. R. James, quantities and form one of the major demersal fishery reasources of India. Though some present Director of CMFRI for encourage ment and to Mr. C. Muktmdan for suggesting information on the fisheries and biology of improvements in the manuscript. Silverbellies from India is available (Arora, 1951 ; Balan, 1967; James, 1973 ; James and Badrudeen, 1975; 1982; Venkataraman and MATERIAL AND Mernoos Badrudeen, 1974; Venkataraman et aI., 1982 ; The study is based on data collected during Annam and Dharmaraja, 1982 ; Murty, 1983), 1979-83 from the catches of the commercial there is no information on the biology of trawlers operating off Kakinada. Data on Secutor insidiator from the Indian Coast, catch and effort were collected for 18-20 days excepting a. brief account on spawning from in a month. Samples for studies on the species Tuticorin (Pillai, 1972). Since this is one of composition and biology were collected at the most dominant species in the trawl catches weekly intervals. The data on species com at Kakinada, a detailed study of its biology position of siverbellies and length of S. was taken up in 1979 and the results are pre insidiator collected on each observation day sented in this paper. An attempt is also made were weighted to get the day’s and then the to estimate the mortality rates and yield of this monthly estimates. L" Present address: Kakinada Research Centre of Three types of boats are operated in the CMFRI, Kaklrlada-533 002, India. area under study (OMFRI, 1981). As the BIOLOGY AND. POPULATION. D_YNAMI.CS or SILVERBELLY 11 .Pamfret.-.Royya> category qof 1 boats is most Bertalanffy eurvebc fitted ‘to, the cube root dominant in the fleet (CMFRI, 1981), this was of weight at each age and this fictitious length considered as the standard. unit and effort schedule used in computations [of yield] by standardisation was made following Gulland the method of Beverton and Holt ’. Hence, (1969), by considering all the demersal group in the present study, the parameters of growth landed as one group since the trawl fishery is a in weight were also estimated : the values of multispecies one. lengths at half yearly intervals, obtained by the integrated method were converted into For biological studies the specimens in fresh weights at ages with the help of the length condition were examined. Maturation stages weight relationship and the cube roots of these were fixed following Murty (1983). Only values were taken for fitting the Von Bertalanfly females were considered for estimating length equation. at first maturity and spawning. Fishes in stages IV-VI of maturation were taken as Weight of each fish was talcen to an accuracy mature for estimating length at first miturity of 0.5 _g. The length-weight relationship was and fishes of and above length at first maturity calculated with the help of the formula : log only were considered to determine spawning W ==1og a-i—b Log L, where W=weight season. of fish in grams, L-=total length in mm, a==a constant and b=e xponcnt (Le Cren, 1951). To examine whether the monthly sex ratio is l : 1 or not, the chi-square test was applied. Instantaneous rate of total mortality (Z) A test of variance for homogeneity (Snedecor was estimated by length-converted catch curve and Cochran, 1967) was used to find whether method of Pauly (1982), cumulative catch the sex ratio over a period of one year is curve method of Jones (1981) and Jones and uniform. van Zalinge (1981), Ssentongo and Larkin (1973) method and Beverton and Holt (1956) The length data were grouped into 5 mm method. class intervals and the mid points in these groups were considered to study growth. The estimation of natural mortality rate (M) Parameters of growth in length were estimated was attempte d by the relation : Z ==M+qf where by the ‘integrated method ’ of Pauly (I980 a) q is the catchability coefficient and f =-fishing and using the well-lcnown von Bertalanlfy effort, but the plot of Z against effort showed equation for growth : that the points are not well-represented by a Lt:-Loc(l--—e"K(t—r,,) straight line. The value of M, therefore, was estimated assuming that 99% of the fish by Estimates of Loc and K were obtained using numbers would die, if there was no exploi the Ford-Walford plot (Ford, 1933; Walford, tation, by the time they attained tmax and by 1946) as adapted by Manzer and Taylor (1947). taking tmax as corresponding to Lmax in the catch (Sekharan, 1976), or to Loc-0.5 cm Since Beverton-Holt yield equation assumes (Alagaraja, 1984) or to 95% of Lcc (Pauly, growth in weight with length to be isometric, 1983). It was also estimated with the help computation of yield following this method of the empirical relationship (Puly, 1980 b): results in erroneous estimates of absolute yield in species in which growth in weight with log M =-—0.0066-0.279 log Loc-{-0.6543 log length does not follow cube law. Hence, K4,-0.4634 log T where Loc is in cm, K per "Peanut and Gales, (1964, as§»ci'te'tl._e_t;by Clark year and T is mean water‘ lj_:I11PO_1'&11_t1I‘t_3"_' in °C.i 1978) have recommended that ‘a von Forthe purpose of this equation the value of 2' \ 12 V. SRIRAMACHANDRA MURTY was taken as 27.2°C from Ganapati and Murthy length group at 90 mm was taken as the length (1954) and La Fond (1958). Length at first at first maturity at Kakinada. capture (Lc) was estimated following Navaluna Spawning : Fishes in stages Ill -V of matura (1982). tion occurred in almost all months (Fig. 1). Exploitation rate (U) was estimated by the The percentage of gravid and ripe (St. V-1-VI) equation of Sekharan (1976) and the total adults in different months (Fig. 2) shows that annual stock (Yl U) and average standing crop the spawning season of S. insidiator is pro (Y/F) were estimated by taking the average tracted running almost throughout the year, annual catch of the species (Y) during 1979-'83. witha peak during January-March period. The value of Y/F thus obtained was taken its Stage VI the average biomass |(B) during the exploited 3 phase of the species in the trawling grounds. .- _, I"_T’1_7;I_ n;rl_se:<-__~__.h.t;;, The yield in weight per recruit (3) was esti 6 Stage V mated from the equation of Beverton and Holt (1957). Since growth in weight with length in S. insidiator is not isometric, yield per StageIV recruit was also estimated following the method recommended by Paulik and Gales (1964). The biomass per recruit (B/R) was estimated ' Stageili from the formula : B/R=( YW/R)/F and recruit ment in numbers (R) was estimated by the relation R=B/ (B/R). Since the estimation of biomass was made under the present level of Siagell fishing mortality rate (considering difiierent values of M) and age at first capture, recruit st‘?P l l l ment was also estimated taking t‘-tese values 2.1 A .11 0 J Alll O J T Alb 0 into account. The values of recruitment thus I980 l9Bl tea: obtained were asstuned to be constant. F IG. 1. Monthly perc_enta_ge frequency distribution of ovaries of S. mszdtator II‘! each stage of matura The expected yield at different levels of tion dtufmg 1980-82. fishing mortality was estimated by the relation : yield in weight -=Recruitment (Nos) X yield sol 4 I in weight per recruit (g). d _i._ MATURATION, Srawmuo AND Sax RATIO 1 Length at first maturity: The data of the 1 three-year period (1980-’82) were pooled for 8(D¥ the purpose. Fishes of 72 mm and above = a—-I e for t‘ '-'1“ I ; F7 1 ml-_— showed mature gonads and the percentage of F AI980 J A O 981 1982 = mature fish in each length group showed increase with increased length. It was observed Flo. 2. Percentage coin osition of grrwitl and ripe that at 92 mm length, about 50°/O of the fish females (St. V-l~€'T) of S. insidiator in the total number of. adult females examined in each were mature. Hence the lower limit of this month during 1980-82. PERCENTAGE N PU PERCENTAGE FREQUENC Y Q Q2 9Q 0+ ....{ _>-J L-a > (D O *1 )> '-+bi O-t BIOLOGY AND POPULATION DYNAMICS OF SILVERBELLY 13 Sexy ratio : 1374 specimens (606 males, that the Xi‘ values are significant at 5% in 768 females) ranging from 72 to 112 mm were 1980 and 1981, but in 1982 it is not significant. examined. Females outnumbered males in It may be noted that data were available only majority of the months (Table 1) while the for 9 months in 1982. It was felt that the non reverse was true in January, June and October uniform nature of sex ratio in 1980 and 1981 1930; April, September and October 1981 could be due to greater predominance of and January, September and November 1982. females in one or two months as mentioned In the annual total, females outnumbered above. When the test of variance for homo. males in all years. geneity was applied after eliminating the data TABLE 1. Monthly sex ratio in S. insidiator 1980 1981 1982 jgi-Q-_.__.i.._.,-_.-\.-,-.._... _ .-.___._-- __-___._,._,____~i___‘_,_i_i;3 _-Q H 7-—— '— '——+—___6‘ __ -- ——-—Q A __-— ———»——-é<3‘ ~ -~- N 37- _*, ,_9 i.___i. _ _ _:______FebruaryJanuaryMarch .24 .7* 28 24 28* 24 10 24 43 12 30 55 -~12 7 —1410 AprilMay 27 7 4413 5*23 24*20 16— 16— JulyJune 8 10 17 5 18 12 21 17 28* — 49* — SeptemberOctoberAugust 13 34 3213 20 419 117 10 6 13 77 71020 6 DecemberNovember . .. .7 46 16 46 17* 44 45* 44 2031 1743 Pooled . . 243 291 222 292 14-1 185 ”' Sex ratio significantly different from 1: 1 at 5 %. At 5% probability level, the ratios are not of those months (February 1980, May and significantly different from I : 1 in all months December 1981) where the sex ratio was signi except February 1980, May and December198l ficantly diflerent from 1 : 1, the chi-square and July 1982 (Table 1). The test of variance value did not show significant difference. for homogeneity of sex ratio (Table 2) reveals Thu dam on sex ratio in diflhrem length TABLE 2. Test of variance for homogeneity of sex groups (Table 3) showed‘ predommancc of my,-0 5,, s_ insidiawr males upto 87 mm group and of females from at 3 7 7 s 1 3» _u __ _ i_ and above 92 mm. The mean lengths of fishes Year Df 1' in the sexes over the period did not show i 1981"*71980 “ ~ :7 . —_'"'_"""T 11. . 11 20.13* 27.83“'_'_' T" J Illafkfid dl1f6I'8TlC8$ 1982 -- 8 623 Esrmmon or Gaowrn Panamerens The1930-1982 monthly Pooled _, modal32 5543* lengths during 1979-s3 - Significant at 5°/y. are plotted in Fig. 3. While drawing the 14 V. SRIRAMACHANDRA MURTY. T/mu: ,3. Sex ratio in dijfererzr length groups of growth curves, the points. that were likely to S. insidiat0r"‘ fall in a curve were joined first and then the curve was extended further both upwards and Length N <5‘ 9 groups(mm) downwards. The curves thus drawn are parallel to each other. The lengths attained at intervals 72 4 50.0 50.0 of six months were read ofi these growth curves 77 19 57.9 42.1 for purpose of estimating the growth para 82 45 66.7 33.3 87 173 58.4 41.6 meters: the smallest m0dal length in a curve 92 347 46.1 53.9 was taken as the initial length (Lt) and from 97 255 36.5 63.5 there, the curve was marlmd at an interval of 102 150 35.3 64.7 six months (irrespective of occurrence of a 107 47 27.6 72.4 25.0 75.0 modal point at that point) and the length at 112 8 that point was taken as length attained after Pooled 1048 44.3 55.6 six months (L,-{-1) and so on for estimation liiean length 7 of Loc and K (Fig. 4). The smallest modal (nmfl - 915 910 length in the growth curves was 47 mm in July 1982 (Curve K, Fig. 3) whose age was read * Data of 1980 and 1981 only were considered off as 6 months from the origin of the curve. OS ,_ . --V ~--‘*-_- ‘ Q OT <7A ’°6 C '9 1 ._tttnii I OIO I OaCO O 4DO_, O CO 4, _= Q . " < E_% 75-»‘1 .‘ .'I' _'' ''. ____7;-. . I- . -- .~. . O ~_'_. w J I l I 5 / 0 5°‘- ‘ I /I1/ 1’/ /1 / // // I/ 1// 1/7/ / / /I 7< I .'/ / / ’ ' / / I / / ' I - \. I I I ; / / / / / / I! / X ' ‘° | I5 . I ' 7 I / I 1 / ' / / ‘ -4. , I I I I 1 / I// / / I ‘I! I / ' 2)atr! /’ I II 1 f/ I I,’ I/ ’ /I 1’I I II ' ll 1/I . II 1I II 1 I, I’I ,'I I’I ItI I’I /1 I ' i I I I :1 i / i 1, I \ . ._i-TJ@ta_t_i_el,FJ--OF-J0'FJOF~**~'=- T -1? Jéig F:-*‘v——L:" ._t;a. _L._.1.--q 2-,—:y 1'37‘? iogg I98! I982 I983 FIG» 3- Monthly modal lengths and growth curves drawn throngh them in S. insidiamr (I ntegratcd method Of Pauly 1930 3). The von Bertalanffy growth curve IS also shown, Tbta ength J.--I -£ \_. -L 4 Q 11 1... O BIOLOGY AND POPULATION DYNAMICS OF SILVERBBLLY 15 3.-07,754 ; this value was used in yield studies i30J_‘______‘ fol_l_o_wing_ 'Pa'u'li_lC and Gales (1964) and Clark I (1978). e-»W 1' E; .: LENGTH-WEIGHT Rararrousmr 270 i Data from 253 males ranging from 57 to 109 mm and from 2 to 19 g and 264 females ranging from 62 to 114 nun and from 3 to ‘ 1 22g were used for this study. The relation -14 ship for fishes in the sexes Separately are : — _n Males: Log W: --s.62499+3.37s29 LogL (r=0.96) lU--i———~T—~r ~—1—- ‘il'_T;‘1"—e " —~g r-~"*t ~ -—r"-1-»: Females: Log W= --5.s6469+3.s0201 log L 10 L1 130 (r=0.89) Fro. 4. Ford-Walford plot of growth in length obtained The values of slope and elevation of males by integrated method in S. insidiaror. and females when tested by analysis of covariance (Table 5) did not show significant Taking this length, the length, at successive difference at 5 % level. The data of both sexes half Years were estimated using the Ford were, hence, pooled and the relationship for Walforcl relation, for purpose of estimating to. the species from Kakinada was calculated as : The estimated values of parameters are shown in Table 4. log W= -—5.737l3 + 3.43654 log L (r=0.93). TABLE 4. Parameters of growth and mean lengths (mm) at ages in S. insidiator The value of the regression coelficient was tested against the theorcticaliyalue of 3 by Growth, Growth the t-test and it was found thatfit differed sign Particulars in length in weight ficantly. Hence growth in weight with length in S. insidiaror is not isometric. Loc (mm)IWa: (g) . I23 3.07764* t,K (year)(per year) --0.01 . 1.20 -0.071.11 Length at 1 year . 86 — Monrsmry Russ Length at 2 years . 112 -— Length at 3 years . . 120 - Total mortality rate : A plot of log e (N/At) against ‘ t ’ for different years is shown in ------,-"H ,------' *”Woci Fig.- 5. Only thosepoints which represented the straight descending part of the catch curve were considered for estimation of Z. Similarly Since the maximum length recorded during in the cumulative catch curve method (Fig. 6), the study period was 117mm, the maximumage those points which represented a straight line of the species in the fishing ground works out were used. The departure from linearity at to 2.5 years. either end in the above graphs (Fig. 5 and 6) Estimation of parameters of growth in weight : is likely to be due to non-representativeness of The estimated values of parameters are given smaller individuals in the catches, resulting in Table 4. _'_I‘_h_e cuberoot value. o_f_. Wot is from incomplete recruitment of fish. in these 4 l 16 V. SRIRAMACHANDRA MURTY Tsauz 5. Analysis of Covariance to test the significance of zlifli-rence between regression lines of sexes in the length-weight relationship of S. insidiator Source of variation Df Sum of squaresDeviation Mean from regression squares — ,,_, _ _’- .’ __-_ 377 *7 _x::'~ _‘ - i '77 - * —~*~* _- ,,,' _-.1-.. —~ ,_ _~:_——~ --_ - .-.~ Due to regression within sexes 2.024169 0.003946 Due to difference between regression coefficients 1 0.003972 0.003972 Residual due to regression pooled within 2.028141 0.003946 Difference between adjustmentcd means 0.000801 0.000801 Total: 2.028942 Cotnoarison of slopes : =l-.0066, df 1,5l3 : not significant. Comparison204 of elevations : F=0.2029,»- .df 1,514, ;was not significant. 1'3. ¢ -4 I0 —_""“;1*—"‘ - 0 W ‘*'“‘ ‘‘‘‘‘‘‘ ’1'E—_iI, ’ W; i ‘F .—.:.—r*"".—-.—r ‘.t_f..—.*;;‘_—.‘pDI*T?_‘ ‘L _*'__ 18-r . 9.0 I 982 5. ~.; 0' 0 .. Q3, .. or *‘ - ~ — ~?~I.f._*r:.f£:' .-‘;.-_f_T O I981 0 Used ‘I 0 NO! Ulid O I _: _ Loge (NI At) cl:l__LT4_-__—} 6 L BIOLOGY AND POPULATION DYNAMICS OF SILVERBELLY 17 1, ' Not used teaL: OUsed _ is-J 1983 1 11“ \ CI 17* 1982 13-A- O QI 1981 oi ‘OI! — 9+ Ti ""‘“T ““—__“—T ’ A — — .’ T; Q" 1980 11-‘=1 1 7 1? t3i§ 1979 9t j——r—-r——-r—-1~—%i-e—|1-8 2-7 i|"i r;‘f—“f36 er‘ ~ 11 “T'—t—‘—'=='l”7 4'5 4' '11-‘ Log 2 (1,; ltl Fro. 6. Estimation of Z by cumulative catch curve method in S. insidiator. . lengths and of the larger individuals due to the Natural mortality rate : The estimates variations in growth rates (Jones, I981) or obtained by different methods are shown in due to the possible over-estimation of age of Table 7. It may be noted that except the value these individuals (Pauly, 1983). The estimated by Sekharan’s method, all the values are more values of Z by different methods (Table 6) or less the same. show that the values obtained by Pau1y’s method for each year are the highest and those SFZLECTION PATTERN obtained by Beverton-Holt method are the lowest. The average (Z=6.1) of all these The selection pattem (Fig. 7) shows that the values for all years was taken as the total mesh sizes used during different years are not mortality rate during the period (Table 6). much difierent ; the 50% selection length L0ge Cumu a ve freq u ency C Z2 35_ In-_—§ -4-. 18 V. SR1 RAMACHANDRA MURTY TABLE 6. Estimated values of Z in S. insidiator by daffllerent methods in dlfierenr years Pauly’s Cumulative Ssentongo- Beverton- Average Year method catchcurve methodLarkin method Holt method ' _ _ _ - _ ~ __;';—_ —-i___ _ . -_—-—~~——----'_.-‘.4---i.—-i-a-_-.__—.-in 1979 . . 8.0329 7.0856 6.6093 6.0274 6.9388 1980 6.1908 5.1765 4.5160 3.9425 4.9565 1981 9.1357 8.0029 5.7397 5.1606 7.0097 1982 7.1845 6.4493 5.4458 4.8678 5.9869 1983 . . 6.2143 5.8505 5.5254 4.9471 5.6343 > —~:_ _ Q . ___ _.-Q Average . . 7.3516 6.5130 5.5672 4.9891 6.1052 TABLE 7. Estimation of M Following diflerent methods and estimation 0fF, U, Yl U, Y/F} Yw I R, Bl R and R in S. insidiator ( Z= 6.1 and annual average catch : 331 t) Method of 77840 H7137 U 0:'IUM'r'0/F YWI R BIR Recruitment estimation of M (t) (t) (2) (2) (NOS) ~ ——— —_— -av- _ ' ~_~_; Sekharan, 1976 . . 1.8 0.70 4-73 0.19671 0.045746 1682704499 Alagaraja, 1984 .. 2.3 0.62 534 0.124975 0.032889 2648453890 Pauly, 1983 . . 2.4 0.61 543 0.113915 0.030788 2905673370 Pauly. 1980 b . . 2.6 0.57 581 0.094432 0.026981 3505161135 -v 8 I983 7 ranges from 77 to 87 mm in different years and -__ their average works out to 84 mm. Hence the ' ~._.___,_,___*-.-~¢-_ -_,_.,.,_ _ ‘| lower limit of this length class (80-84 mm) 20-=7 H was talcen as length at first capture (L,) whose _J____. estimated age (t,) is 0.86 year. 505? I982 1 * “ “ _ “I-hn&Inn@s. ' “ ““" "~1113, 207 A 5 Csrcmas or Smvsnnsntlss 1. The estimated catches of silverbellies and > I l S. insidiator during the period 1979-83 Iii-o—%i_qi hie?‘_ Ix» a-1-_ ‘ 601%l I981 . _' (Table 8) show continuous increase in successive -r years and an annual average of 904 tonnes of silverbellies was landed at Kakinada, with $.60] _I980 * * *____|:J 331 tomes of S. insidiator, contributing to -\ about 37% of silverbelly landings. it 404,] .L _—— — LZ.__iT Q it ;£'_a_.__JI - .I Exrtomrrtou Rm: mo Sfrocx SIZE 801- 139279" ’-‘ 5 '2 Iii . Tq1Ci.I1g___ the;_Z._ value as 6.17 and d_ifi'eren_t 201“ valu'e_STo_f M, the exploitation rate '__(U)"n%as "" —T" t~e~ . 7 estimated as ranging from 0.57;“ tc 0.70 27 .47 67 a7 (Table 7). The corresponding values of total -Length groups mm annual stock (Y/_U) and average standing crop F10. 7. -Selection pattern in S. irisidiayor. ( Y/F) are alsofshown in TflblB.7@ Re aned Z'\J U|\O~J\I\o00O0\l BIOLOGY AND POPULATION DYNAMICS OF SILVERBELLY 19 Teams: 8 ‘ Estimated afar: (Trawltng hours) and carcb_(r0nne_s)_ of Sllverirellier in difierenr years -.__-a__.<._:.__-._.;._- -~»»._.. . ._t W-.»~-... ~u_-_ ~~fifb.tal_ 4. ~.-.._ ~ i'—— -. 1:_. 4; Year Effort Silverbell y % of S. insidiator __ oeteh? j __ i_|_1s1lverb_elly catch ____ I % 19791980 396864322655 569535 34.329.5 l1981 982 384-436459599 605 41.7 1 98 3 328461 1843969 33.439.3 ——— — — —— ___ 12- 7. :_; .1‘ :_ - ..._-._.@~4~_,.~,,¢k_,_Z_*__ leverage . 378403 904. . 36.6 ESTIMATION or YIELD PER RECRUIT 80 mm was taken as length at first capture, whose estimated age (tc) is 0.87 year. Beverton and Holt method: The value of Woe corresponding to Loc was calculated as The yield in weight per recruit taking all 28 g on the basis of the length-weight relation possiblevalues of M as given in Table 7 and L3 ship; the value of tr was estimated as 0.2 values of t,, at 0.69, 0.87 and 1.09 correspond taking 27 mm (the smallest length in the catch) ing to L6 values of 70, 80 anid 90 mm respec as the length at recruitment._ "“- As stated II‘ earlier, tively (Fig. 8 a-c) against F, show that yield I-9 ® I ® \-8 -'*r "jgif 2-i. I-7 -1- __ ' }Jy_ __ |-0&1 —--*"""'T59 9* 0'2-1. W ..--4 ._ M -4___U‘ ..I.i = I-09 . -.-1 4.._.k_§.-_~L_r 1 t__p,._512. %i___y_i___;,_®Ye I‘2 IF _I-Dial-1 Z’/9,’/if L '.3 I 2.’are . '.'1; =1/ / ~>.-59 -u \ / Zt - 8*' C404 _.. ?.. _ _, 26 _ . -.. 5-2.. on 0-7 . I? FI5HINf~-4-~--\. MORTAI.-nv RATE - AGEI ATI FIRST I csmune1 1 . F19} 3 fl-¢- Yield Der recruit as a‘ function of fishing mortality rate in S. inridxbtor under different values of to and M (Numerals refer to different values of M) and .d. Yield per recruit as a f unetion of age at first capture in S, :'ns_id:‘atvr with Zat 6,1 and d_ifi'crent values of M (Numerals refer to M values). Y ELD PEP RECRUT S ‘F3 ‘P _% @ » NI Q“-0 Z, 6» Y 1'! 5 20 V. SRIRAMACIIANDRA MURTY per recruit increafics with increased F without ESTIMATION OF RECRUITMENT AND YIELD reaching a maximum; the curves also show that yield per recruit imreases by decreasing Recruitment and yield were estimated taking the age at first capture. YW/R values obtained by Paulik and Gales (I 964) method. The yield per recruit as a function of age at first capture (Fig. 8 cl) with the present value At the present values of ta and Z and taking of Z at 6.1 and different values of M shows dilferent values of M the estimates of yield that maximumyield per recruit can be obtained per recruit, biomass per recruit and recruit at r¢=0.5 if M is 2.6; at 0.6 if M is 2.3 or 2.4 inent were obtained (Table 7). The expected and at 0.7 if Mis 1.8. The observations, thus, yield (Fig. 10) at difierent levels of fishing suggest that the cod end mesh size has to be mortality with the present cod end mesh size reduced because the present estimated value of ta:-0.87. 1-6 M.‘ Paulik and Gales method: The curves of yield per recruit against F (Fig. 9) taking the present value of ta at 0.76, corresponding to / \ J / 0~20z.-‘, .\. ***"T€""'_"' // 71rm "'1'.4? : “Vl x . ‘ 1...:Bl 3 .//.-' ,I '1I 0\ §- /I ‘I 1- O . _ ma J li- ' 1.3~ ‘*2-sf 6::I I‘» 4"\ I or _\ > , -JT\.\ \.\» r\ .. ‘\'\_ '\. ____ ! _ '__,__T_____] _t_____,‘ .._.,.1-..,.1 i_’______T_ __ l . ._ ‘_.._|._ __Y _] ..-... l \--4 \'\.. \-s. F'|Sl-llr;-S uoamutv RATE '- ll ..'\,.%“\ ‘N0. g..Q'.-:;:;j~__.- bchdbw &"'\ ’¢8.€"% . . ‘ 0 %-§, *' 09 '* Flo. IO. Estimated yield of S. insidiator as a func ,' ---;- __L' ...;__t ' -_._ ._ tion of fishing mortality rate (Numerals 0'0l20" 2" 4-I. 5.; 1 refer to M values). FISHING MORTALITY RAT? ‘ Fro. 9. Yield per recruit and Biomass per recruit as shows that the yield increases with increased functions of fishing mortality in S. insidiuror F without reaching maximum, suggesting, following Paulik and Gales method. (Numerals refer to M. values.) that the yield can be increased by increasing the effort. Though it is possible to increase the yield by increasing the effort, the increased the cube root of weight of fishes of the present yield will not be rcmtmerative because. for LC value of 80 mm, show trends comparable cXampIe, when M=2.6, a yield of 115% of to thoseobtained by assuming isometric growth the present can be obtained by expending an (Fig. 8 b) though the absolute values of yield effort equivalent to 200% of the present ule.) per recruit are different. only 15% increase in catch with 100% increase Yw/R -1- I B/R ___:. ‘P ¥~ e /Q8 l '4'" Q /' / '2 P L.) _> L‘ __.2....: _ .: -.:. _.I. _1__4 -_-li4._.1__ 4(D ¢.>slh“H"l._ "“ 4. f\l 09 w R) BIOLOGY AND POPULATION DYNAMICS OF SILVERBBLLY 21 in effort (Fig. 11). On the other hand, if the According to Murty (1983), L. bindus spawns effort is 97 % of the present (i.e. if decreased almost throughout the year in the sea oil by 3%) the yield will be 99% of the present Kakinada. Thus, the Indian silverbellics (Le. a decline of 1% only in the catch). For spawn round the year with one or two economic reasons, therefore, the effort should peaks. not be increased. Though the predominance of females in certain months and in the larger length groups DISCUSSION may suggest a faster growth rate in females The study on spawning shows that S. (Qasim, 1966), the growth rate in both the sexes insidiator spawns throughout the year with a may be taken as the same because : the depar possible peak during January-March. Pillai ture in the sex ratio from 1 :1 is restricted (I972) examined the ova-diameter frequency only to one or two months in difierent years (Table l) and both sexes are represented in all length-groups (Table 3). It appears, .S therefore, that the estimated length at first .m I-Q -Jf maturity for females (90 mm) can be talcen $7.5-i /H for the species as a whole. On the basis of the growth parameters, the age at first maturity for the species becomes 1.09 years. 1 'I I flu! The predominanm of females above the length at first maturity suggests a possibility of greater natural mortality rate in males after attaining first maturity. Supporting evidence, however, is not available to corroborate this o,'|.| view. esé.-ii I0 '**'"'s-’Ef"'"'""'é'5""—*_'?o We The estimated values of parameters of TH I-5\ ’"/¢ of present growth in length of S. insidiator in the present FIG. ll. Yield of S. insidiator as percent of present study appear to be realistic when compared against F which is also as per cent of present (Numerals refer to M values). to those of other silverbelly species (Table 9) from different localities, except L. equulus which is the largest known silverbelly species distribution from ovaries of mature adults (maximum recorded length from India 242 mm, of this species from Tuticorin during April James, 1973) and L. jonesi. It appears that June 1970 and stated that the species spawns Venkataraman er ul. (1982) underestimated more than once in a year and that the spawning the growth rate of L. jonesi because the values season is protracted. According to James and of M and K at 2.28 and 0.528 respectively Badrudeen (1975), Lciognatlms brevirosms lead to an M _/K value of"4.3 which is very much spawns throughout the year in the Palk Bay beyond the range (1-2.5) lmovm in fishes and Gulf of Mannar near Mandapam with (Beverton and Holt, 1959) ; similarly in the peaks during May—June and October case of L. bindus from Calicut the value of Loc November. It was tentatively concluded obtained (122 mm, Pauly and David, 1981), that L. dusszmiieri in the sea o ti‘ Mandapam appears to be an underestimate since the maxi spawns during April-May and November mum known length of this species from Indie December (James and Badrudeen, 1982) .is 155 mm (CMFRI, 1977) andalso since it is Yeld cs °/-0 pres-an Ln '5’ C) mg_+L.._+ 22 .. v. SRIRAMACHANDRA MURTY‘ ; ._ lcnown that the lish ‘ will not grow ’ b_cyondsL_oc also be .Vcr1’y;h¢igh, wh_i__ch_;t0.o wo uld__._havc contri (Gulland, I983). buted toja greater Z. An examination of values of Z estimated Since the trawl fishery is a multispecies one, by different methods reveals that the value apportioning of fishing effort with reference obtained by Pauly’s method is the highest to a particular species is not possible (Pauly, followed by Ctunulative catch curve, 1983) and apparently this resulted in the lack Ssentongo -Larkin and Beverton-Holt methods of good correlation between effort and Z. (Table 6). According to Pauly (1983) the The M values obtained by difierent methods equation of Ssentongo and Larkin ‘Produces are close to each other except the one obtained estimates of Z which are higher than those by Sekharan’s method (Table 7); the M/K obtained using equation’ of Beverton and value in all the four cases is within the known Holt, and Per Sparre (in Iitt. to Dr. Pauly, range in fishes. In this connection it is worth 1983) suggests that Ssentongo-Larkin equation while to quote Cushing (1981) : ‘ . . . .a precise TABLE : 9 Parametres of von Bertalanfi y growth formula of dzferent species ofsilverbellies Loc K Species Locality Source mm per year to year S. insidiator Kakinada Present work 123.0 1.20 ——0.0l L. bindus Calicut Pauly &David, 1981 122.0 1.30 L. jonesi Mandapam Venkataraman er aI., 1982 161.2 0.53 0.111 L. splendens Philippines Pauly, 1983 143.0 1.04 iw L. equulus Madagascar Pauly, 1983 212.0 1.75 -——_ is ‘ biassed upward’. There is, thus, an indi separation of fishing and natural mortality cation that the Beverton-I-Iolt equation is not remains inaccessible, and yet is one of the a biassed one. There is no indication in the central problems of fisheries research.’ literature whether the other two methods (Pauly’s and Jones and van Zalinge’s) are The yield per recruit analysis at the three not biassed and presently it is not possible to values of t, against F (Fig. 8 a-c and 10) and explain the disparity between the Z values the yield per recruit against t, (Fig. 8 d) show obtained; hence it was preferred to consider that maximum yield can be obtained by the average value. increasing F greatly, but with a maximum to of 0.7 only, thus indicating that t, has to be Though the value of Z at 6.1, considered in reduced from the present 0.87 (thus reduc the present work, appears to be very high, it tion in mesh size) and that F can be increased could be a reasonable estimate because, the to get. higher yield. Decreasing the mesh bulls of silverbellies (including S. insidiator) size results in increased production of smaller occur in shallow waters (Pauly, 1977) where fishes. Since the adult size of the fish under intensive trawling takes place for prawns, study is itself a small one, the increase in yield thus resulting in high (fishing mortality. so-obtained will not be of consequence to the Fur,t_.l;1er,, since the maximum length and life industry. Further, the present, age at first ere Observed to ‘bee smell. rmortalinra due capers is close to the age at_fi..I.st maturity to predation and other natural causes could andsit is not desirable to have the age first BIOLOGY AND POPULATION DYNAMKSS OF SILVERBELLY '23 capture less tlisn the age" at first "mitt'tirit'y', as regula;t'ion.'-of effort" "incl'tiding"'mesh regulation otherwise the- fishery takes away prospective has to take into account other species taken Spawners and increased effort in such a situa by the fishery, as otherwise any change in the tion can result in the eollapfle of the fishery due number of units or mesh size is likely to result to recruitment overfishing (Ursin, 1984)- at in the loss of a particular resource for the fishery Certain higher effort level. Since at higher or in overexploitation of another resource. values of tc also, the yield did not show a fall Still, such a study as the present one on the with increase in F, it is desirable to have the yield of any one component species is not an current t, retained, if not increased a little, exercise in futility, for it must be stressed, in to avoid possible fall in the stock size and to addition to enabling an understanding of the get increased yield of S. insidiator by increasing state of a palticular single species resource the effort. The analysis has also shown that in a multispecies fishery, such studies when though theoretically it is possible to increase conducted an all or most of the dominant yield by increasing effort increased effort will species, Will help in arriving at more meaning not be remunerative (Fig. ll). ful decisions for the management of a multi Since the trawl fishery is a multispecics one, species fishery. Rerensuces ALAGARAJA, K. 1984. Simple methods for estima CMFRI. 1977. Aimu_ai report. Central Marine tion of parameters for assessing exploited fish stocks. Fisheries Research Institute, Cochin. 148 pp. Indian J. Fish., 31 : 177-195. -—-—-—-~— 1981. Commercial trawl fisheries off ANNAM, V. P. AND S. K. DHARMARAJA 1982. Kakinada during 1969-1978. Mar. Fish. Infor. Ser. Trends in the catch of silverbellies by mechanised boats T. & E. Ser., 31 : 1-6. in Tamil Nadu during. 1971-75. Indian J. Fish., 28: 86-95 (1981). CUSHING, D. H. 1981. Fisheries Biology : A study in population Dynamics. Second Edition. The Uni Anoitgi, H. L. 1951. A contribution to the biology versity of Wisconsin Press, 295 pp. of the silverbelly Leiognathus splendens (Cuv.). Proc. lndo-Pacif. Fish. Coun. 3rd Meeting, Madras, Sec. (11 : Font), E. 1933. An account of herring investi 75-80. gations conducted at Plymouth during the years 1924 BALAN, V. 1967. Biology of the silverbelly 1933. J. Mar. Biol. Ass. U.K., 19: 305-384. Leiognarhus bindus (Val.) of the Calicut Coast. Indian GANAPATHI, P. N. AND V. S. R. Muamy 1954. J. Fish, 10 : 118-134 (1963). Salinity and temperature variations of the surface BBVERTON, R. J. H. AND S. J. Hou" 1956. A review waters oil" Visakhapatnam Coast. And/ira Univ. Mem. of methods for estimating mortality rates in exploited Ocermogn, 1 : 125-142. fish populations, with special reference to sources of GULLAND, J. A. 1969. Manual o_f Methods for bias in catch sampling. Rap. p-v. Reim. Cons. Perm. fish stock assessment. Part l. Fish Population int. Explor. Mer., 140(1) : 67-83. analysis. FAO Man. Fish. Soil, 4: 154 pp. '—--~—-—- also --—---7 1957. On the Dynamics of Exploited Fish Populations. Fisliery Invest, London, -——--- 1983. Fish stock assessment : A manual 19 : (2) 533 pp. of basic methods. FAOI Wiley Series on food and Agriculture, 1 : 223 pp. --————- AND —-—-—-—— 1959. A review of life spans and mortality rates of fish in nature and their Jams, P. S. B. R. 1973. The fishery potential of relation to growth and other physiological characteris tics. Ciba Foundation Colloquia on ageing. In: silverbellies.seas around India, Proc. Spl. Symp. Pub. Living. Central Resources Marine Fis o{ cries the G. E. W. Wolsenholmy and M. O. Connor (Ed) The life Research Institute, Cochin. pp. 493-444. span ofanimais, 5 : 14-2-177. -~-~-—-—-»- AND M. Bmnunnen 1975. Biology and CLARK, W. G. 1978. Dynamic pool models. In: fishery of Lelogriarhiis brevirosrrts (Val) from Palk Bay and Gulf of Mannar. Indian J. Mar. S'ci., 4: 701Models : 17- gor0. Fish stock assessment. FAO Fish. Ciro. 50-S9. 24 V. SRIRAMACHANDRAI MURTY ~7-——-—- AND --——*--— 1982. Biology and fishery _ -——-- 1982._ Studying single-species dynamics of silverbelly Leiogziatlms ldussumieri (Valenciennes) from in a tropical inultispecies-context. In: D. Pauly and Gulf of Mannttr. Inditm J. Fis/1., 28: 154-182 (1981). G. I. Murphy (Ed) Theory and management oft:-apical fisheries. ICLARM conference Proc. 9, 360 pp. Jonas, R. 1981. The use of length composition data in fish stock assessment (with notes on VPA and ELARM,ustralia. Manila; Philippines and CSIRO, Cronulla, Cohort analysis). FAO.Fis/i. Circ., 734: 60 pp. —-—-——~ 1983. _ Some simple methods for the ——-—-- AND. P. N. VAN ZALn~aoe. _ 1981. _Esti assessment of tropical fish stocks. FAO Fish. Tech. mation o_f mortality rate and population size of shrimps Pap., 234 : 52 pp. in Kuwait waters. Kuwait Bull. Mar. Sci., 2 : 273-288. —-—-——— AND N. DAVID 1981. ELEF-AN I, a LA I-'0ND, E. C. 1958. Seasonal cycle of sea surface BASIC program for the objective extraction of growth temperature and salinity along the east coast of India. Andhra Univ. Mem. Oceanogn, 2: 12-21. ggrametezrs:205- ll. from length frequency data. Meeres_/bi'selt., LE CREN, E. D. 1951. Length-weight relationship Pn.L_Ai, P. _K., lVIAHADE_VAN 1972. Fecundity and and seasonal cycle in gonad weight and condition of spawning habits of some silverbellies. Indian J. Fish. 19 : 196-199. ghié..l . perch (Perca fiuviarilis). J. Anim. Eco!., 20: 201 QAS1M,_S. Z. 1966. _Sex ratio in Fish populations *MAi~tzeR, J. 1. AND F. H. C. TAYLOR 1947. The as a function of sexual difference in growth rate. Curr. rate of growth in lemon sole in the Strait of Georgia. Sci., 35 : 140-142. Frog. Rep. Fish Res. Board Pac. Coast Sm., 72 : 24-27. Rtcictati, W._ E._ 1975. _Computation and inter MURTY, V. SRIRAMACI-IAi\lDRA . 1983. Observations pretation of biological statistics of fish populations. on some aspects of biology of thesilvcrbelly Leiognatlius, Bull. Fish. Res. Ba’. Canada, 191 : 382 pp. gindtg0 1 1- (Q/alencienncs) 8. from Kakmada. Indian J. Fish. SEKHARAN, K. V. 19_76. Estimates of stocks of oil sardine and mackerel 111 the fishing grounds oil‘ the NAVALUNA, N. A. 1982. Morphoinetrics, biology and population dynamics of the Croakcr fish Otolithes zvgs7t4)coast1 . of India. Indian J. Fis/1., 21: 177-182 ruber. In: Pauly D. and A. N. Mines (Ed.) Small scale fisheries of San Miguel Bay, Philippines : biology SNEDECOR, G. W. mo W. G. COCHRAN 1967. Statistical Methods. Sixth Edition, Oxford and IBH gndl: pp. zgock assessment. ICLA RM T echnical Reports, Publishing Co., New Delhi, 593 pp. "‘PAULIK, G. J. AND L. E. GALBS 1964. Allometric . SSENTONGO, G. W. _AND_ P. A. LARKIN 1973. Some growth and Beverton-Holt yield equation. Trans. simple methods of estimating mortality rates of exploited Amer. Fish. Soc., 93: 369-381. fish6 8 populations. J. I-'isI:. Res. Bd. Canada, 30: 695 PAULY, D. 1977. The Leiognathidae (Teleostei): their species, stocks and fisheries in Indonesia. with VENKATARAMAN, _G. AND M. BADRUDIZEN 1974. notes on the biology of Leiognarhus splendens (Cuvier). On the diurnal variation in the catches of silvcrbellies Marine Research in Indonesia, 19 : 73-93. in Palk Bay. Indian J. Fish., 21 : 254-265. ----—--- 1980a. A selection of simple methods 2?: "iii. —£e______-— ' /\N.D R. . THIAGARAJAN 1982. for the assessment of tropical fish stocks. FAO Fish. Population dynamics of S1lVCI'bClly Leiognathus jonesi Circ., 729 : 54 pp. in Palk Bay. Ibid., 28: 65-86 (1981). —-———-—— 1980b. On the interrelationships bet~ Unsm. E. 1984. Th_c tropical, the temperate and ween natural mortality, growth parameters and mean environmental temperature in 175 fish stocks. J. cons. the4:4 A?'%Ci.lC 0. seas as media for fish production. Dana, int. Explor. Men, 39 : 175-192. W’/t1.i=0tu>, L. A. 1946._ A new graphic method of * Not referred to in original. ggsciiiffnlgdgie growth of animals. Biol. Bull. Woodshole, C O CROAKERS Lcomamulq MURTY, V. SRIRAMACHANDRA. 1981. Observations on some aspects of biology of the black croaker, Afrobuqpq nibe (Jordan and Thompson) from Kakinada. Indian g. F1sh.. 27 (1&2): es-75 (1980) 1 Lcouwnxauufx du 14 Reprinted from Indian J. F:'sh., Vol. 27, -Nos. 1 & 2, 1980, pp: 66-75 OBSERVATIONS ON SOME ASPECTS OF BIOLOGY OF THE BLACK CROAKER ATROBUCCA NIBE (JORDAN AND THOMPSON) FROM KAKINADA V. SRIRAMACHANDRA MURTY Central Marine Fisheries Research Institufe Centre, Kwkinada sme mi eogs) £2 OBSERVATIONS ON SOME ASPECTS OF BIOLOGY OF THE BLACK CROAKER ATROBUCCA NIBE (JORDAN AND THOMPSON) FROM KAKINADA V. SRIRAMACHANDRA MURTY Central Marine Fisheries Research Institute Centre, Kadcinada Aasrnacr Observations on some as-pee-ts of biology of Atrobucca ru'-be are made from Kaki-nad-a. The -length-twefght relationship is described -by the equation log W = -5.524308 + 3.21347-6 log ~L. The fluctuations in relative condition factor appear to be associ-a-ted with fluct-uati-ons in gonad cycle. Individuals release ova in two batches during the spawning season -which extends from Febu-ary to July in the area. ‘Elie length at firs-t m-atu-ri-t-y is estimated at 1-45 mm. The sex r-at-io indicates predominance of males in most months and length groups. INTRODUCTION The fishes of the family Scia-enidae -fonn fisheries. of considerable ma gnitude along Indian coasts; off Kakinada (16.15’-17.10’ N Lat. and 82.22’ 35’ E long), an ~estimated 603.1 tonnes of these fishes were lan-ded by the trawlers during April l968—Dece-mber 1970 (Muthu et al 1975). The catches of these fishes have been increasing with -increased intensity of trawl fishing and during 1976 alone, an estmated 873.1 tonnes of these fishes were landed (CMIFRI, 1976) from this area. The fishery is a multispecies one and Atrobucca nibe sup-ports a rioh fishery at'Kakinada. Though there is considerable in~fo1"-mation on the biology of sciaenid fishes from different localities along the Indian coasts (Rao 1967, Annigeri 1967, Rao K. V. S. 1968, K-utty 1968, Devadoss 1972), there is practically no in formation on the biology of A. nibe from any where i-n the world -except for the work of Matsui and Takai (1951) from Japanese waters. The present paper gives information on some aspects of biology of this species from the trawler catch-es landed at Kakinada during the years 1975-1977. MATERIAL AND Mernons The -samples were -obtain-ed from the -trawler landings at weekly intervals. In the laboratory, the constituent species were separated and data taken on each species. ‘For '-biological studies, data on le.ngth, -weight, sex, stages of ma turation and relative fullness of the stomachs were taken. Always the data from BIOLOGY or A. NIBE 67 fresh specimens on-ly were taken.‘ The length-weight relati-on-ship was calculated by the method of least squares using -the formula W = a Ln or log W = log a + n log L where W = weight in grams, L = leng-th in mm, a = a constant and n = exiponent._ A The relative condition factor (Kn) was ca-lculated using the formula Kn = W/W (Le Cren 1951), where W = observe-d in-dividual weight and W = weight calculated from the length-weight relati-onship for each length. The colour and genera-l acppe-arance of the gonads were noted in fresh condi tion and ova diameter measurements were taken -from formalin-preserved ovaries. In taking the diameter me-a-surements the procedure of Clark (1934) was followed. From each ovary about 400 ova were measured at a magnifica tion where 1 md equals 0.014 m-m. Sp-awning sea-son is determined on the basis of the data on females -only. As A. m'be occurs in the catches seasonally, the biological data of corres ponding months in difieren-t years were pooled for purpose of the present study. LENGTH-WEIGHT RELATIONSHIP The data of 125 females ranging from 122 to 235 mrn length and from 14 to 136 -g weight and 164 males ranging from 94 to 218 mm length and from 6 to 10-9 g weight, were used to calcula-te the length-weight re-lationship. The equations for both the sexes are: Males: log W = -5.571216 '1' 3.234755 log L Females: log W = -5.461329 + 3.185315 Log L The reg-ression oo-efficien-t of males and females were com-pa-red by ana lysis of covariance following Snedecor and Cochran (1967). The results (Table 1) show that there is no significant difference both in the slopes and in -the eleva tions -between sexes. Hence -the data of sexes were pooled and a common re lationship calculated (fig. 1) -which can be expressed by the equation: Log W = -5.524308 '4' 3.213476 log L. RELATIVE couomon moron The values of relative condition factor calculated separately for each fish were added up and the mean for each month an-d for each length group obtained. It is seen that Kn va-lues in May, June and September are higher than the weighted average; whereas in other months the values are lower (fig. 2). It is also evident that the Kn value is minimum in March and maximum in September. As stated else-where in this paper (vide infra), the spawning season -for A. nibe is February-July. The generally low values du-ring Jan-uary-April may perhaps be due to the peak activity of ripening of gonads a-nd consequent spawning stress. _68 MURTY TABLE. 1. Comparison 0)‘ Regression lines of the length-weight relationship of A. ni=be. I ______4. df 2x2 Zxy Eyz Reg Deviation from regression coefiicient df s.s. M.S. Wiiihin Females 124 0.294305 0.93745 3.20119 3.185315 123 0.215110 0.0017488 Males 163 0.478141 0.54667 5.38772 3.234755 162 0.384623 0.0023742 285 0.599773300021043 Pooled (wi-thin) 287 0.772446 2.4841238.58892 3.215918 286 0.600178 0.0020985 diflerence between slopes 1 0.000445 0.000445 Between 1 0.068986 0.21979 0.70027 Total 288 0.841432 2.70392 9.28919 287 0.600195 between adjusted means 1 0.000017 0.000017 Compnrisonof slopesjzfi F ;4.7208764; df ;l285,9 1; Fuat = 254; not sig1;i ficant Comparison of elevations: F = 123441176; df = 286, 1; F at 5% = not signi ficant 5 I 0 '0I .'Q Q “'5 Q 9 -~9I1 NQ I!Q — ~. o e 1. 1 :4 G 1 n FIG. 1. Length-weigh-t relationship in A. nibe L60 w ¢u'r r r 0r¥~—i-it r0 P0 + 2.004; 'uJ*§ L m4oT BIOLOGY or A. NIBE 69 The Kn values in diflferenst lengths (fig. 3) show steep decline till 120 129 mm and thereafter show incr~e"ase- till 140-149 mm. A. nibe attains sexual maturity -for -the first time when the fish is 145 -mm and the peak Kn value at this length may be associated with maturity. The Kn values show -decline after 140-149 mm and reach another peak at 200-209 -mm group. Extending the previous suggestion, it is possible that individuals of A. nibe attain maturity for the second time when they attain a length of 200-209 mm. A similar conclusion was drawn in t-he case of Nemz'pIeru.s japonicus -by Krishnamo-orthi (1.971). M'A'r‘t;aA'rio.\' mo SP.-XV-/'Nla\'-G The study is based on 357 specimens (224 males anti einaies) ranging from 994 to 235 -mm in length. ;.:-'\....= / \ Yat iz \ ./r \\.4 I-O4\, " “I ¥uppm O-92 _ _I ‘T—i I all ll T'*I"“I" 0'1 "l_““ JAN Fee man APR MAY _JUN Jul. we 569 ocr NOV FIG. 2, Rel.ti\-e co-dE".ion factor in d:ifFeren-t months in A. nibe. Stage of maturation: The following stages of maturation are -recognised in fe males of A. nibe: Stage I (immature): Ovary -thin, occupying less than half -the slen-gth of body cavity; ova minute, irregular-ly-sh-aped, trans-parent, without yolk and with clearly visible nucleus. Ova range from 0.02 to 0.13 mm in diameter. Stage II (maturing virgins): Ovary thin, occupying about half the length of body cavity, whitish; yolk deposition initiated in most ova whioh are t-ranslucen-t. Ova diameter ranges from 0.02 to 0.26 mm. Stage HI (ma-turi-ng): Ovary yellow occupying about 1% of the length of body cavity; ova visible to naked eye; majority of ova translucent, but opaque ova also are present. Maximum dia-met-er at 0.60 mm. Stage IV (-ripening): Ovary pale yellow occupying almost the entire length of body cavity; ovarian wa-ll thin, ova distinctly visible to naked eye; majority of ova are opaque with the maximum dia-mete-r at 0.73 mm. VRLUES '0Q‘ Q3 '___L.._L._L._l-._ _1_.l_._l__L___l. ~\\‘$_‘-‘ /I \. \ \ \\ I’ I I I’ I / . /' ’ UG HT D) U.) Fh 70 MURTY Stage V (ripe): Ovary distended, occupying the entir-e length of body cavity; ova translucent with a distinct oil. globule. Maximum. ova dia-meter upto 1.03 mm. The diameter of -the oil globule ranges from 0.19 to 0.26 mm. Stage Va (Partially spawned): Same as stage V but the ovary does not occupy entire length o=f body cavity. Ripe, translucent ova with oil giobu-le are present but majority are opaque. Stage V! (spent): Not encountered in the samples. 1.200-#7] J-‘ io|‘°4 4 t.l ZOT -H l.OIO<-i 4-i I-040-Ti l - |.ooo ' i O.QOO‘T *1 r 0.920%’ ‘L " ‘-—zt——--192I I -125 *f+~' —+—_5 vi-1- t9* -T"-"11 '¢_f— - 1"‘ ' LCNGTH snoop: Q-cu) FIG-. 3. Relative condi-tion f-actor in d5iif'3FC'-nit length goups in A. nibe Males are recognised as immature, maturing and mature only, on the basis of macroscopic examination of fresh testes. Lengfh at first mraturify: For the purp-ose of determining -the minimum length at first maturity, maturing, ripening and ripe (stag-c l-ll-V) females a-nd mature males were taken in-to account. The pe-rcentag-e of t-hese mature fish in relation to immature fish in different lengths are presented -in figure 4. It may be seen that untill a lean-tgh of 200 mm, the percentage of mature individuals show pro gressive increase and that in specimens above this length, all are mature. On the basis of these observations, it may be concluded that A. nibe ma-ture first at the length of 145 m-m (50% mature). RELAT V I. COMO TON FITCH 70-79: 50. $94 70» ‘NE 2 Q2 2 IO. I II BIOLOGY OF A. NIBE 7| ,| | oo..i' -Li it -L, 40-I .1 atno F M1 no WW Jo g‘ iF LENGTH (mg FI-G. 4. Frequency distribution of mature "ind=ividua-ls in different length g-roups of A. nibe. Spawm'rrg: The ova diameter frequency distribution in ovaries of stages II, III, IV and V of maturation are presented in firure 5. It may be noted that there is only one mo-dc at 5 md in the diameter frequency distribution in ovary of stage II of maturation. In stage II"-I, a new mode appeared at 32 md. In stage IV, the-re are two modes in addition to the one at ll md: one a-t 32 md and the other at 41 "md in the darneter frequency dist-rilbutian of mature ova. Obviously, certain fast growing ova have got separated from the batch of ova that -formed a single mode at 32 md in stage III, by t-he time -the ovary passed on to stage IV. In stage V, -the ripe translucent ova got separated from other ova and formed a mode at 59 md. T-his mode must have -resulted by the further I‘ _ 50-I I 4:* stnfll.-11 IT,“ __, _ g stun-H ---""1.STAB U-I e oz {<-I SYAGI-InF-—‘vfl a -i-2 2 .*;r~.r*._= . . _l-_ :— 9 ' = £ Q '°ov». oumerenqvm) FIG. 5. Ova diameter frequency d-ist-ribmion in ovaries of d-iffeent stages of maturation in A. nibe. PERCENTAGE meousucv B 3 ' 6 9 PUICENTAGE ~1 O 0.4. ll.I7 64.0‘ 72 MURTY growth of ova that formed a mode at 41 md in the dameterfrequcney (_llSl.!'lb'U.i'iO£1 of ovary in -stage IV. Their-e is another mode at 29 md -in th-e diameter f1"tIqLlf:i'I-I_'i‘_;' distribution of -stage V ovary. In the partially spawned stag-e Va ovary, the ripe translucent ova form a minor mo-de at 59 md while the majority of the ova are opaque forming a -mode at 32 md. T-he fac-t -that: 1) there are -two closer modes in the dian _ '1'eqtten-:5.‘ distribution of mature ova in ovary of stage IV, 2) there are two modes one eaoh in th-e mature and ripe ova in the ovary in stage V and pa1'~ti:1!l_y spawed stage occurs with a major mode at 32 md and a minor mode ' S9 md indicate a possibility that each adult female of A. nibe spawns twice uring a sing!-e but extend-ed spawning season. The evidence is not strong enough to believe that there may be two distinct spawning seasons in a year because the ba-tch of ova that are tlestin-ed to -be released in the second batch are already 541 JAN .!U=‘4i£I | I4 ‘ ‘ I 40]201I'‘lU .i _.1‘I,-\ __' i' ' up |1: _\ ‘>3 ll PAAKJ.-* £05;=_-- < I 3 1-5! b SFFY _ _; fisptztt ll >l ll‘--——— i ""%"""' to av. .... 50]‘ lg]lI M33’ I NOV. -0-or4 ‘:ll‘ -it' ...... :.._ 2-‘ ‘i ... , ’ I MflunmionV | Hsnags F]-G. 6. Frequency distribution of different stages of maturatfon in diiTe:'o:‘.1 months in females of A. nfbe PEQCENTAGE FQEQUENCY I0 m “ ‘L J.§ .i_Y_t_ 1,_l*O 1:3 ET_t:1 Pt'RCEN fkgi - has o~ as C) O 6 F § Q if. l I‘.__L_T__!___l_-__.J_.__L__l___L_..t J_.._;_'§'..___t. .__ __...":.—'"._._..'.:_':'J _TIJ¥Lf::::::::] -pp-1__”" cw §..-- -_-.-._"T:::.".:1 —u%_—. E .111 E H_"1 (...... Q iii M \ EI .. __.=__<___-_,_i—.-_ n-I (U I"_'.\ FD1 '-P _J Q‘ C-J r-r BIOLOGY or A. mire 71 matu-re and opaque and h-ave= reached a modal diameter of 32 m-d i-n stage Va (fig. 5) and judging from t-h-e sequence of maturation process, it may not take more time for these ova to become ripe and be irea-leased. Similar conclu sions were drawn in the case of Pseudosciaena diaicrmthus (Rao, KVS. 1968) and Johnius dussuimieri (Devadoss, 1972). In other sciaenid species studied: Otolithus argenteus (Ann-igeri 1967) , Pseudo-sciaena aneus and P. bleekeri (Rao, T. A. 1967) and Otolithus ruber (Devadoss 1972) the ripe ova are stated to be released in on-ly one spawning act. The frequency distribution of mat-u-ration stag-es in females -in difierernt months are presented in figure 6. It may be seen that felale-s with ripe ovaries (stag-es V nda Va) occur in the catch-es -during February and March fbu-t fishes with ripening ovaries (stage IV) occur in several months from January to July.dF~urt-her,peno . the -ripening females dominate others during Fe=br-ua»ry-June The occurrence of -running ri-pc -females during February-March and the occurrence of ripening females in large numbers during F-ebru.ary-June period indicate that A. nibep spawns during February-July period in th sea off Kakinada. it may be stated in this co-nn-e-etion. that according to Matsui and Takai (1951; as cited by Trewavas I977), this species “pro~baeb"ly” spawns “during the period April»]une” in shallow waters between China and Japan. The spawning sea sons of other sciaenid species from India are deter-mined as June-August in I’. c!z'(rc'cm!/ms ofi’ Bombay (Rao, K. V. S. 1968), -October-January in O. eugen F6145 in the sea oi? Manga-lore (Annigeri 1967), Fe-br'..1ary»May in P. bfeeker.-’ anti .ianuary—Ap1"il in ./. c./.zrm‘!a oil We-ltair (Rae, T. A. 1967) and JU.-1}’-QCi0i)Ci' in O. rnber and .iune-September in J. dz.:ss::-12z;’er.>.' of Bombay (Devadcss l.972). T.’-\B|-E 2. Sex i't'u‘:'<> in clifierem months in A. nibe. Pi {on-H'"z.s' N K 1. 0 1‘ ff ‘Jr Pt’.-"tL'€i"iIGg(3 of I-’ei"c'c':-:.‘cz_s;r% of c.\':;r-iz."m'r:’ m.<¢1es' fen z::.’c»'.s" J am: 46ary 3 l. _ Fe-b"uary Adarch 43 A-p ril 37 M a y 26 42.3 June 38 81.6 J Lily 25 24.0 Aua-ug’. st No data -ii September 68 57.4 42.6 October No data November 43 95.3 4.7 Dee-ember No data Pooled 357' 63.7 7 37.3 \]'-""-11:5-I-‘~\] \.i §3‘.°°.*'.4*‘.*°‘9° *1 @-§\l'\Q{\)l\) .,’.'>. UJLII l‘Q.~J LIIU1 l\J rwulm. 3:/.2‘Q\. 74 MURTY TABLE 3. Sex ratio in difieremt length groups of A. nibe _-0-Q-’ ; i ;7_ 1 *1 ' :. ’ _. "f ~ W; ;_._ ; : 7 _ ‘i ‘f 7 _ 7.. _ _. 7 7 i _~ Lenglh groups (mm) Nexamined 0. of fish Percentage males 09‘ Percentagefemalesof _ _ . _ W .7 é 7 7 _ 7 i _._-_7 -_-7 -_>- —_— __ — _ 7 — ;_—— ;7 _— _ ——._ 140-149 24 83.3 16.7 150-159 52 75.0 16.7 160-169 75 64.0 36.0 180-189 48 58.3 41.7 170-179 71 59.2 40.8 190-199 28 42.9 57.1 200-209 19 42.1 57.9 210-219 11 54.5 45.5 220-229 7 28.6 71.4 Sex RAT10 The sex -ratio in different mon-ths and -in difieren-t length groups are pre sien-ted in Tables 2 and 3 -res-pectiv-ely. I-t may be seen tha-t males outnumber females in- all months except March and June (Table 2). Similarly, males do minate -femiales in all length group upto 189 mm. The preponderance of males in t-he catches in different -months and in different length groups upto 189 mm and the -genera-l preponderance of fema-lest from and above 190 mm is note worthy and -may -indicate differential growth rate of sexes as shown by Q21-sim (1966) in s-ome freshwater fishes of India. RE.FERENCES ANNIGERI, G. G. 1967. Ma-turation of 1:-he in-traov-arian eggs and the spawning periodi cities in a few fishes of Men-galore. Indian J. Fish., 1'-0: 23-32 (1963). CLARK, F. ~N. 1934. Maturity of the C-all-fornia sardine (Sardine caerulea), Calif. Div. Fish Go.‘-me, 42: 49 pp. CMIFRI. I976. Annual Report for 1976. Ce-n-tral Mari-ne Fis-he.=ri-es -Research In-s-titute, Cochin, 123 pp. DEVADOSS, .P. 1972. Miaturity and spawning in Otolirhus ruber (Schn.) and Joimius dussumieri (C. & V.). Indian .7. Fi.s"h., 1-6: 117-128 (1969). KRIS!-INAMOORTHI, B. 1971. Biology of the -th-read-fin Bream, Nemipreus ;'aponicu.v (Bloch) Indian J. F:'sh., 18,: I-21. KU'I"l"Y, M. N. 1968. A -note on the biology of t-he ‘kot-h’ Otolithoides brurmeus (Day). J. mar. biol. Ass. India, 9: 1'97-198. L12 c1u=.N, -E. D. 1-95-1. The length-weight -relat-ionshi-p and seasonal cycle in gonad weight and condi-t-ion in the perch (perca fiuvia-tilis). J. Anim. Ecol., 20: 201-219. BIOLOGY OF A. NIBE 75 MATSUI, J. AND T. TAKAI. 1951. -Ecological stud-ics on the black croakcr, Nibca nibe (Jordan & T-hornpso-n). Contr. Shimonoseki C0-H. F1'.sh., 1951: 65-89. MUTHU, M. 5., K. A. NARASIMHAM, G. S. RAO, Y. _-\. SASTRY AND P. RAMALING.-XM. 1975. The commercial trawl fisheries off Kaki-nada du-ri=n=g 1967-70. Indian J. Fi.s'h., 22: 171-186. QASIM, S. Z. 1966. Sex 1"-atio in fish populations as a -function of sexual diffcrcnc-e in growth ra-te. Curr. Sc£., 35: 140-142. RAO, K. V. S. 1968. Some as-pacts of b-io-logy of ‘Ghol’ P.s'eud0.s"ciaena diacanfhus (Lace pade). Indian J. F:'sh., 10: 413-459 (1963). RAO, T. A. 1967. M-atu-rity and spawning habit; of some sci-_.enids in offshore waters at V-isakhapatnum. Indian J. Fisl:., 11: 121-126 (1-964). Sueoacon, G. W. AND W. G. Coomuu. 1.-967. .S‘tatistica"f Metlzods. Sixth Edition, Oxford and IB-I-I publishing Co., New D~:I-hi, 593 pp. TREVVAVAS, E. 1977. The sc-i-an-n-id fishes (c-roake-rs 0-rdrums) of the Indo-w-est-Pacific. T ram‘. Z001. Soc. Land. 33: 253-541 F _ Loowmxsvrxou 15] MURTYO V. SRIRAMACHANDRA. 1984. Observations on some aspects of biology of the croakers Johnius (gognigogg) Qusgpmiggi (Cuvier) and Johnius (Johnius) carutta Bioch from Kakinada. Q. mar. biol. Ass. India, 21 (1&2): 77-B5 (1979). E-T;ICONTRIBUTION -_ ,;__,___.._ _,_._:__ 15] ._ J. mar. bio]. Ass. India, 1979, 21 (1 & 2) : 77-85 OBSERVATIONS ON SOME ASPECTS OF BIOLOGY OF THE CROAKERS JOHNIUS (JOHNIEOPS) DUSSUMIERI (CUVIER) AND JOHNIUS (JOHNIUS) CARUTTA BLOCH FROM KAKINADA V. SRIRAMACHANDRAMURTY* Central Marine Fisheries Research Institute, Cochin - 682 018 ABSTRACT Observations on some aspects of biology of Johnius dussumieri and J. carutta are made from trawler cat ches of Kakinada. It is shown that J. dussumieri spawns during March~August period. This species attains first maturity at a total length of 110 mm. There is a predominance of females in larger length groups. The length-weight relationship of J. dussumieri follows the equation log w = -4.84511 + 2.96347 log L. The flu ctuations in relative condition factor seem to be related to gonad cycle. Individuals of J. carutta attain first maturity at a total length of 155 mm. This species is a fractional spawner releasing the ripe ova in two spawning acts during the single spawning season which appears to extend from January to June. In this species also, as in J. dussumieri, there is a predominance of females in larger lengths. The length-weight relationship in J. carutta is calculated to be log W = —5.43389+ 3.23343 log L. INTRODUCTION I am thankful to Mr. K. V. Narayana Rao. Head of Fishery Biology Division and Mr, AMONG the demersal catches landed by the T. Tholasilingam of my Institute for going small trawlers at Kakinada, sciaenids rank through the manuscript and offering sugges second in abundance being next to prawns and tions for its improvement. I am also thankful among the fish catch these fishes rank first to Mr. T. Jacob for the advice in statistical (Muthu et al., 1977). In regard to the species treatment. abundance, Johnius dussumieri and J. carutta are among the important species in the sciaenid MATERIAL AND Meruoos catches ofi' Kakinada. Considerable informa tion is available on the biology of sciaenid fishes The material for the present study was obta from different regions on the Indian Coasts but ined at weekly intervals from the private traw there is no information on the biology of Johnius ler landings at the Kakinada Fishing Harbour. dussumieri“ and excepting the work of Rao On each observation day, random samples of (1967) on the spawning, there is no information all species of sciaenids were collected from 4-5 on the biology of J. carutta from India. An boats for studies on species composition and attempt is, therefore, made to present the details different aspects of biology. The pooled sam of some aspects of biology of these two species ples were brought to the laboratory and from Kakinada on the basis of the data collected data on length, weight, sex and stages of from the small trawlers during January 1975 maturation were taken on fresh specimens December I977. p of important species and gonads were preserved --_-.i_-¢i—i—~ in 4% formalin for detailed studies. Since the “ Present address: Kakinada Research Centre of sciaenid fishery is a multispecies one (about CMFRI, Kakinada - 533 002. 17 species at Kakinada), the samples collected """ The species referred to as Johnius dussumieri by (each about 2-3 kg) consist of different species. Sawant (1963) and Devadoss (1973) is referrable to either Johnius elongatus or Johnieops macrorhynus Mohan Another feature of sciaenid fishery at Kakinada (Mohan, 1975). is that none of -the species occurs throughout 78 V. SRIRAMACHAND RAMURTY the year in the catches (CMFRI, 1976). Conse groups in relation to immature fish are pre quently, relatively few numbers of each spe sented in Fig. 1. Specimens of 100 mm and cies could be examined each month and hence above only showed mature gonads. It may the data of corresponding months of the three year period were pooled for purpose of the present study. -. ./ The colour and general appearance of the gonads were noted in fresh condition and ova diameter measurements were taken from pre served ovaries. In taking the diameter mea surements the procedure of Clark (1934) was followed. In each ovary about 300 ova were 1?‘, --i 4r-_. <1 ‘ -—|—>~ Ii measured at a magnification where each micro 3° '00 :20 MO I50 meter division is equal to 0.014 mm. For TOTAL LENGTH mo Fig. l. Percentage frequency distribution of mature classification of maturation stages, the procedure individuals in diiferent length groups of followed earlier for Atrobucca nibe (Murty, J. dussumieri. 1981) was employed. The spawning season is determined on the basis of data of females be seen from the figure that there is a progressive only. increase of mature fish along with increase in length. All individuals above I50 mm are The length-weight relationship was calculated mature. The data show that 50% of fish are by the method of least squares using the for mature (Fig. 1) at a length of about 110 mm. mula W=a L" or logW= log a + n log L, where W= weight in grams, L= length in mm, The ova diameter frequency distribution in a =a constant and n= exponent. The relative ovaries in stages III, IV and V of maturation condition factor (Kn) was calculated using the is presented in Fig. 2. It is seen that there formula Kn=-_W/(Q, (Le Cren, 1951), where are two modes (a, b) in the diameter frequency W=observed individual weight and ‘Q. =weight distribution in all three stages. In stage III, calculated from the length — weight relation the mode (b) at 13-15 md group consists of early ship for each length. maturing translucent ova, whereas the other mode (a) at 25-27 md group consists of opaque BIOLOGY or JOHNIUS (JOHNIEOPS) ova. In stage IV these modes have shifted to DUSS UMIERI 22-24 md and 43-45 md groups respectively. While some of the ova in mode ‘b’ are translu Maturation and Spawning cent, all the ova in mode ‘a’ are opaque and are separate from the capsules. In stage V The study is based on 326 specimens (I76 (Ripe), these modes have further shifted to 28 females and 150 males) ranging from 81 to 30 md and 49-51 md groups. While the ova 168 mm total length. in the mode b are all opaque, those in the mode a are translucent with vacuolated yolk and For determining the minimum length at first with a distinct oil globule ranging in diameter maturity, maturing, ripening and ripe (stages from 8 to ll md. III-V) females and mature males were taken into account. The percentage frequency dis The process of maturation and ripening indi tribution of these individuals in dilferent length cated that the ova at mode ‘a’ in stage III FERCENTAQE MATURE‘ ‘Li I L34 4-.-l—?_._ BIOLOGY OF CROAKERS 79 attained a growth of 24 md by the time the ratio in different lengths is given in Table 3'; ovary reached ripe stage (V) and that the ova males dominated females upto a length of in mode ‘b’ in S121gC III attained a growth or I19 mm whereas in all larger lengths females l5 md, by the time the ovary became ripe. The dominated._ ova diameter frequency distribution in different stages of maturation indicates that the ova Length-weight relationship may be released in two spawning acts. The data of 144 females ranging from 81 to 168 mm total length and from 6 to 59 g weight ’sun -nr C and 132 males ranging from 85 to 168 mm TL .,¢ B and from 7 to 61 g weight were used to calculate 10"] the length-weight relationship. The relation I ships for males and females were calculated ,_J separately and equations are: ‘r-'"' —’——~-~—-- — I-'—-~ I Males: Log W = —4.67244 -|- 2.88164 Stage H - a log L; (r = 0.96) 5 Females: Log W = —5.06076 -|- 3.06496 =-*j log L; (r = 0.95) .'II \ significant difference both in the slopes and in 5 —-1‘ the elevations (Table 4), the data of sexes were *—7%l"'“$ pooled and a common relationship calculated L_w..,..I _ O 0 which can be expressed by the equation: Q~ - |2 On dander Q4 log W = -4.84511 + 2.96347 log L; (r = 0.95) Fig. 2. Ova diameter frequency distribution in ovaries of different stages of maturation in J. dussumieri. Relative condition factor Table l shows the percentage frequency dis tribution of maturation stages in females in The values of relative condition factor (Kn) different months. It may be seen that ripe calculated separately for each fish were added females (st. V) loccurred during March-June up and the mean for each month calculated. period with greater abundance in May. Females It is seen from Fig. 3 that the Kn value is mini in prespawning stage (st. IV) occurred during mum in June and maximum in September. lt February-July period with peak in June. March is also noted that the Kn values during March August is, therefore, considered to be the July period are low. As in the case of Atro~ spawning season of Jj dussumieri at Kakinada. bucca nibe (Murty, 1981), in this species also, The details of sex ratio in different months are majority of fish (84%) had either evorted or presented in Table 2. It may be seen that empty stomachs and hence the possibility of females dominated males during February food intake influencing Kn values could not July (except April) and November. The sex be ascertained. Person qt oquafliy G ._i__-_.6 a L_ 3454 .37 2 _ \ 3 ls I7-30 l 43~08 i GO -.9 I8 -I7 80 V. SRIRAMACHANDRAMURTY TABLE 1. Percentage frequency distribution ofdifl’ererzt maturation stages in females of J. dussumieri in diflerem‘ months Stages of maturation Months N I - II III IV V January 13 i 1--Q __-.. February 17 i 11.7 —--— March 38 w—< 23.7 April 26 * 30.8 May 45 i 26.7 June 10 .___. 60.0 J ul y 6 i 50.0 33.3 A August 15 26.7 60.0 .___ September 3 ~— 100.0 in October -- No data November 5 100.0 — —- December 14 35.7 64.3 i TABLB 2. Percentage sex ratio in drferenz months in J. dussumieri and J. carutta (P:150) J. dussumieri J. carutta Months N Male : Female N Male : Female n January 29 25.2 O 82 : 50.0 I February 29 20.7 0 45 : 48.9 I March 32 37.5 U 62 : 58.1 u April 57 54.4 Q No data c May 88 48.9 Q 2 50.0 : 50.0 Q June 14 28.6 I No data I July 6 33.3 U 10 90.0 : 10.0 August 31 58.1 : 94 56.4 : 43.6 September 5 40.0 : 22 36.4 : 63.6 October No data 24 45.8 : 54.2 November 6 : 83.3 13 23.1 : 76.9 December 29 : 48.3 51 33.3 : 66.7 TABLE 3. Percentage sex ratio in dtflerent length groups in J. dussumieri and J. carutta Length groups J. dussumieri J. carurta (mm) i Ni W H Male :gFerr|*ale J N 7* Male : Femalei 80- 89 3 : 33.3 2 50.0 : 50.0 90- 99 4 : 25.0 2 100.0 : -.-_ 100-109 35 : 37.1 8 100.0 : —--_ 110-119 64 : 43.7 24 58 a3 Oc 41.7 120-129 89 : 60.7 57 561. : 43.9 130-139 78 56.4 62 56.5 : 43.5 140-149 31 67.7 65 41.5 : $8.5 150-159 11 54.5 74 43.2 : 56.8 160-169 ll 72.7 48 375. : 62.5 aim ') . 170-179 i 41 51 QLI Q 48.8 180-189 iq i 33 33.3 : 66.7 190-199 imp in I l 9 .1 : 90.9 1...; 0 qh-_ 200-209 i l 100.0 I 210-219 jg in-0 3 - : 100.0 Nhwhw Llqa--0 .‘4$"!‘-’$*’§° u-o\-18;?‘!°$". ~m wmwmw wwou ~1-I 83 U1-l?~O\-I ob33rMPP$\I-F‘-‘O'\\IlU-Ix 0 i l\-31*)PP P8\O@ --\-ww-Ix~.1oo ?’9\$=:'*9‘P°!°w-IQ-5'-'~l-Pb \OI-O#38 53P~@\1\O@ BIOLOGY OF CROAKERS 81 For purpose of comparison of Kn values of Females of stages III-V of maturation and different lengths, data of April and May only mature males were considered for the purpose were considered because it is desirable for such of determining size at first maturity. The I'll I 1I-I ~‘"§.§‘~ |-08-1 t 0.0‘ ‘-I. -1 ---.1 —| *fi |‘- ti" AT H u" —-‘| F --W JANMAR MAY JU\.GP 8 V i Fig. 3. Relative condition factor of J. dussumieri in different months. comparison that data are collected during a reasonably short period (Lagler, 1952), so that the possibility of different factors (eg. matura tion, fat deposition etc.) affecting Kn values in . \ different months or seasons can be eliminated. l > The months April and May are selected because most of the length groups are represented in W‘ I these two months. ' l Kn value is maximum in 80 mm group (Fig. 4). After that length there is a fall in the \ Kn value and it reached a peak at 110 mm 1 ta... -1 group. As shown earlier, J. dussumieri matures m 90If ~ no =1 |3Q ~ 1 ;5°I 1 i first at a length of 110 mm. Again the Kn TOTAL LENGTH M, values showed a fall and increased gradually Fig. 4. Relative condition factor of J. dussumieri in till 140 mm. It is possible that majority of the different length groups. individuals mature for the second time when they are I40 mm. percentage frequency distribution of these fishes in relation to immature fish in different BIOLOGY or JOHNIUS (JOHNIUS) CARUTTA length groups are presented in Fig. 5. There is a gradual increase of mature specimens till Maturation and spawning 190 mm and, above this length all are mature. Since 50% of the individuals were mature at The study is based on 403 specimens (I90 155 mm, this length is taken as the minimum males and 213 females) ranging from 84 to length at first maturity. The ova diameter 215 mm TL. frequency distribution in ovaries of stages III, an VALUES i_ L,§ L Kg VALI-E5 1-A-.t....J 1 82 V. SRIRAMACHANDRAMURTY IV and Va of maturation are presented in Fig. 6. While the first mode consists of immature trans There are two modes one at 15-16 md and lucent ova, the second mode consists mostly of opaque ova. In stage IV, in addition to the immature and early maturing ova, there are ‘W two modes at 27-28 md and 33434 md groups in the mature ova. The latter mode (at 33-34 md) may be the result of faster growth of a group of ova forming a mode at 25-26 md a . group in stage III. Fishes with fully ripe, stage V 0 ovaries were not encountered in the samples. In stage Va (partially spawned) there is only one mode at 29-30 md groups in the diameter frequency distribution of mature ova. Though someof the larger ova were translucent (ripe O anni ova) with an oil globule, majority of them were -opaque. In this connection, it may be '0-r stated that stage Va ovary does not occupy the entire length of body cavity indicating that N tn D on some ova were already released. romp LENGTH mm The fact that there are two modes in the dia Fig. 5. Percentage frequency distribution of mature meter frequency distribution of mature ova in fishes in different length groups of J. carutta. stage IV ovary and that there is only one mode in mature group of ova in the ovary of stage Va, the other at 25-26 md group in the diameter indicate -that J. carutta is a fractional spawner frequency distribution of ovary in stage III. releasing ripe ova in two batches during the single spawning season. The absence of a 20-1‘ second mode in the frequency distribution of I $156!. m mature ova in stage Va ovary, unlike in that \ O], of stage IV and the‘presence of a few ripe ova in stage Va ovary, support this conclusion. Rao (1967) observed a similar situation in mature Q» ' STAGE IV ovaries and stated that only one batch" of -J. mature ova was likely to be released in the ‘ensuing spawning season.’ His data clearly / show that mature individuals occur. during November-March period which indicated a single spawning season and the second batch “$1 V; of ova in mature ovaries may not remain till next spawning seasonsince they were already |~a.-1. |'. ; _,., mature. '9an ‘.‘ I_. — The frequency distribution of maturation OVA .‘ stages in females is presented in Table 5. It is seen that mature individuals (stage IV) occurred Fig. 6. Ova diameter frequency distribution in ovaries of different stages of maturation in J. caruna. from January to May and partially spawned IIRCINTMI Pflqugudy - 3 vv ‘ 3 1': PERCENTAGE.Yau '-" MATUREIn*3 7' ’—t g as.35 zoJO"-' 1‘ as as ' BIOLOGY OF CROAKERS 83 individuals during January. During July The details of se ratio in different months December period only immature and maturing are presented in Table 2. It is observed that individuals occurred. It thus appears that the sexes are distributed more or less in 1:1 J. carutta spawns ofi'Kakinada during January ratio during J anuary—May period; incidentally, June period. "According to Rao (1967) this this happens to be the spawning season for species spawns off Visakhapatnam during Janu this species. During July—August there is a ary-April period. predominance of males and during September~ TABLE 4. Analysis of Covariance to test the significance of difierences/between regression lines of sexes in the length-weight relationship of J. dussumieri Sources of variation 8 H 8 8 Deviation from—1'egression It __ *8 _, h_ _ L 7 df sum of squares *_Mean squares due to regression within sexes 272 0.68029 0.00250 difierence between regression coefficients l 0.00621 0.00621 residuals due to regression-pooled within 273 0.68650 0.00252 difference between adjusted means 1 0.00090 0.00090 Total 274 0.68740 C0mpariso—n of slopes 8:88 “IF "= 2.484, df 1,272 NS Comparison ofl elevation F = 0.357, df 1,273 NS TABLE 5. Percentage frequency distribution of dijferent maturation stages in females of J. carutta in diferent months Months__.P:152 )N __ Stages __ of_ maturation______, ___*Wp p I_p pi II_ p W __III p IV__A A Va January 40 5.0 77.5 5.0 February 23 — 13.0 March 36 — April No data May 1 — — -— 100.0 June No data __.-. Iii July 1 100.0 i — August 41 53.7 46.3 —~ — mi September l4 — 100.0 -is _ October 13 61.5 — —._ I-11 November I0 i Q.) December 34 76.5 11.8 -1 xi TABLE 6. Analysis of covariance to test the significance of diflerences/between regression lines of sexes in the length-weight relationship of J. carutta (P:153) Sources of variation Deviation from regression df sump of squares _p _ p; Mean squares Due to regression within sexes 350 0.34203 0.00098 difference between regression coefficients 1 0.00013 0.0001 3 residuals due to regression-pooled within 351 0.34216 0.00097 difference between adjusted means 1 0.00061 0.00061 Total 352 0.34277 Comparison of slopes F = 0.133 df 1,350 NS Comparison of elevation F = 0.629 df 1,3751 NS **_ 4 _ i--@g.; 1-'.°9° OOOM M PQ oo~.| QOQ9:5?‘ D-Ii-I §°$*’."1 UIOVI 84 V. SRIRAMACHANDRAMU RTY December period, there is a predominance of Males: log W =- —5.4l602 -|- 3.22584 log L; females. The sex ratio in different length (r = 0.99) groups is given in Table 3. It is seen that upto a length of 1394 mm there is predominance of Females: log W = -5.46190-|~ 3.24570 log L; males and after this length females dominated. (I = 0.99) Tl / // i'0 ---_-_/ I// 1? 1'00 i i 'i;‘“I—'eJAN "eum F "T? um T" Tl JUL T T1; itSEP FM F ifN0" -“ii? 1'9 Fig. 7. Relative condition factor of J. carutta in different months. Length-weight relationship The regression coefiieients of sexes were compared by Analysis of Covariance. The The data of 163 males ranging from 86 to results (Table 6) show that there is no significant 200 mm length and 5 to 94 g weight and 191 difference both in slopes and elevations. Hence, females ranging from 84 to 216 mm length and data of sexes were pooled and a common rela 6 to 133 g weight were used to calculate the tionship was calculated : l0gW = -5.43389 + 3.23343 log L.; (r = 0.99) Relative condition factor The values of Kn during different months are presented in Fig. 7. It is seen that the values ill / during January~March and May were low. It O-04'-. I has been shown earlier that the spawning season ’i* QQ~ I-—*1e—-F-its IIO F ‘ HOF— r—*4r—*T— I70 i— 200 ‘P T ‘T ‘I for this species is J anuary-June and the low Kn tout uzueru M, values during this period (no data for April Fig. 8. Relative condition factor of J. carutta in dilferent and June) may be associated with spawning. length groups. It was observed that there was building up of fat in the body cavity during July-October length-weight relationship. The equations were period and the high Kn values during these obtained separately for sexes and they are: months may be associated with this. .0sq, wu.ur.s O : ahl L l .LnL,K4 \ \ \ T‘ \ \. O ._r -in,l.—:t—;tat -J ;l \. \\\ BIOLOGY OF CROAKERS 35 For reasons cited elsewhere in this paper, the La CREN, E. D. 1951. The le th- ' t 1 ' _ Kn values in different length groups during shiphand seasonal cycle _in_g_onad vrslrsighiviilgill efaiigiggn November and December 1976 were taken to 121}; e perch (Percafluv:atrl1s).J. Arum. EcoI., 20: 201 compare the values of different lengths (Fig. 8) LAL MOHAN, R. S. 1975. Two new species of Sciaenid fishes Johnius elongatus and Johnieops macro because most of the length groups occurred rhynus from India. Matsya, 1: 19-25. during these two months. Though the fluctua MURTY, V. SRIRAMACHANDRA 1980. Observations tions in Kn values in difierent lengths do not on the biology of the black croaker Atrobucca nibe clearly show any relationship with spawning, (Jordan and Thompson) from Kakinada. Indian J. it may be noted that high Kn values occurred Fish, 27: 66-75. in l5O—l59, 170-179 and 210-_2l9 mm length Mtrrrru, M. S., K. A. NARASIMHAM, G. SUD!-IAKARA R/to, Y. APPANNA SASTRY AND P. RAMALINGAM 1977. groups. On the commercial trawl fisheries off Kakinada during 1967-70. Jbid., 22: 171-186. REFERENCES RAO, T. APPA 1967. Maturity and spawning habits of some sciaenids in offshore waters at Visakhapatnam. CLARK, F. N. 1934. Maturity of the California Ibid.. ll: 121-126. sardine (Sardirra caerulea). Cahfornia Div. Fish. Game, 42: 1-49. "SAwA1~:'r, V. V. 1963. A study on a sciaenid Johnius dussumieri (C & V). Ph. D. Thesis, University of CMFRI. 1976. Annual Report for 1976. Central Bombay. Marine Fisheries Research Institute, Cochin. 123 pp. SNBDECOR, G. W. AND W. G. Cocmum 1967. Sta Devmoss, P. 1969. Maturity and spawning in tistical methods. Oxford and IBH publishing C0., New Otolithus ruber (Schn.) and Johnius dussumieri (C & V). Delhi. Sixth Edition, 593 pp. Indian J. Fish., 16: 117-128. LAGLER, K. F. 1952. Freshwater Fishery Biology. W. M. C. Brown Company, IOWA, 421 pp. "'Not referred to in original. NT RIB UTI ON 1 GJ MURTY, V. SRIRAMACHANDRA. 1986. Growth and yield per recruit of gwohinins (Jq1';niu_§) c_a_£utt§ Bloch in the trawling grounds off Kakinada. Indian _q_. _1f_‘__:|;_§1_}., 33 (2): 163-170. _...6._ O I ——+—_1lI-1‘ . 31 ‘T’-‘re T lconrateurton 16} Reprinted from Indian J. Fish., Vol. 33, No. (2). I986: pp. ">3-170 GROWTH AND YIELD PER RECRUIT OF JOHNIUS (JOHNIUS) CARUTTA BLOCH IN THE TRAWLING GROUNDS OFF KAKINADA V. SRIRAMACHANDRA Monty Central Marine Fisheries Research Institute Centre, Kakinada. Ansrtmcr The growth of J. carutta can be described by the von Bertalanily growth formula, with parameter values: L“, = 333.3 mm; K = 0-44 P61’ Year; and H —0.0002 year. The Instantaneous rates of mortality are estimated at Z = 5.07, M = 1.0 and F = 4.07. The Yield per recruit analysis shows that the yield can be increased by increasing the cod-end mesh size of the trawl nets. INTRODUCTION Among the sciaenids landed by commercial trawlers at Kakinada, Johnius Uohnius) carutta Bloch is one of the most dominant species. In an earlier paper, Murty (1984) has considered some aspects of biology of this species. The present paper deals with the estimation of growth_ parameters, mortality and Yield per recruit on the basis of data collected from commercial trawlers during 1980-83. Among the past attempts to estimate ago and growth of sciaenids from India, those which have estimated the parameters of growth are confined to two species, namely Pseudosciaena diacanthus (K. S. Rao 1971, K. V. S. Rao 1961, 197121, 1971b) and Otolithoides brurmeus (Kutty 1961, Iayaprakash 1978) from the west coast of India. There is practically no information on age and growth of J. carutta from anywhere along the Indian coast. Further, except for the work of Rao, K. V. S. (l97lb) on mortality and Yield per recruit of P. dicanthus from Bombay, there is no information on the population dy.-ramics of any sciaenid species of India. MATERIAI. AND METHODS Data on catch and effort from the commercial trawlers were obtained for 18-20 days in a month and samples for biological studies were collected at weekly intervals. Data on length-frequency distribution collected on all the obser vation days in a month were weighted to get the monthly length-frequency distri bution in the catch. The length-data were grouped into I0 mm-class intervals and the mid point in each group was taken to study growth. Growth in length was estimated I64 MURTY using the integrated method of Pauly (1980a) drawing growth curves passing through several modes in the monthly length-frequency distribution. The von Bertalanify equation fo-r growth in length: L, L... l 1 C--140-1.)-— 5 l where L., is asymptotic length, K is growth coefficient and 1° is origin of growth curve, was used to estimate parameters of growth. Estimates oi‘ Len and K were made using the relation: Lt+l = Ls, ( l—e_K ) -{— e“iK Lt and to was estimated using the relation: L11) Lt —log e ( -eff.“ -. t-—» ) -Kt, -P Kt I-/so Instantaneous rate of total mortality (Z) was estimated by the length-converted catch-curve method of Pauly (1982) using the relation: loge (N,/A1.) =—- a+ bt, where At is the time taken to grow from the lower limit to the upper limit of each length class, N >-= numbers caught in each length group, a =--- y-axis intercept, b =e= Z with sign changed and t age of midpoint of each length group. The natural mortality rate (M) was estimated using the relation Z = M r+ qf, where q is eatchability coefficient and f the fishing effort, and also using the equation of Pauly (198Ob): Log M —(l.OO66e— 0.279 log I-0:0 + 0.6543 log K + 0.4634 log T, where L... is in cm, K per year and T in °C. The value of T was taken as 27.2°C from Ganapati and Murthy (1954) and La Fond (1958). The yield in weight per recruit (YWIR) was estimated from the equa t_ion of Beverton and Holt (1957): YW/R=Fe-K(--M(te W» —lr) z Z-~;»K ( lcL _ _ (315 z+21<-10) g +. 35’ Z+3K _ (S? . where S = e , to = age at first capture and tr =age at recrui tment to the fishing ground. onowrn AND YIELD PER RECRUIT 165 ESTIMATION OF GROWTH PARAMETERS ln total, 8540 specimens ranging from 75 to 225 mm were measured during 1980-83. The monthly length-frequency distribution in J. carutta (Fig. 1) showed that modal lengths in difierent months varied from 95 to 215 mm. While drawing the growth curves, the modal lengths which were likely to fall in a cu-rve were joined first and then the line was extended both upwards and downwards to complete the curve. Six growth curves (A-F; Fig. 1) were identi 10 vs 7* |"\ QV 2- Q 275"\Q_QMQINRN T 2 _ I“ mmI _ if II n » iJm 1: MI J S1 N J M|96|( M _IA M ’J 5 n~ J M M- J FIG. I. Monthly length-frequency distribution of J. carnrta showing the 8F0“'*|1 "flwd by growth curves. The von Bertalanfiy growth curve is shown by thick line (Nu merals indicate the number of specimens measured in each month). fied in the data of the 4-year period and they were of the same shape. For studying the growth, the smallest modal length in a curve was taken as the starting point (shown by small dots in Fig. 1) and from there the curve was marked at intervals of six months and the lengths attained at half-yearly inter vals were taken. Care was however taken to include in the analysis the portion of growth curves only when there was a mode between two half-year intervals or beyond. The values thus taken (Table 1) were used to esti-mate the para meters of von Bertalanfiy growth equation. A p10-1 Of Lt-:-I flgflinSI Lt as read off -the different growth curves showed that the observed points were wall-represented by the straight line (r2 0.97). From the value of the slope (=- e"K) of the regression, the value of K was estimated as 0.22 per half year and then as 0.44 per year. The esti mated value of Lcn was 333.3 mm. The value of to was estimated as —0.0002 year. The estimated lengths of J. carutta at the completion of I, II, III and IV years were 119, 195, 244 and 276 mm, respectively (Fig. 1). Since the maximum length observed in the catch was 255 mm, the maximum age in the fishery worked out to 3.3 years. ' '1' *'Z‘I.f'1'.lI.“a 8 "'":s1—J\3" vl ~4__ __._._'*~'*-1 1>_._.___-_-J;--£:i':.i—_...._.-_e7_...___::g:i-“' ' W _ _. _.-____3 ____A c .. _ "L A... T= - ______‘-.__. _ “L-_.... _- _ ""'_ .°_ _ ,_. .__L,\ :=|='-_,D ;_r}_ ___._.-__.__..:,__ I".' ‘I: 1-‘ .\{ 15° 2 _. "“"32' __ L; ‘§._..__ 5 __‘._\=..., 9° __ _ -\\___.-_... ' I -_...... ' '.1 ""'.'._. '_ __ 3e____ '74 _..-.‘ F‘ ______‘3_5____ ~. ._.Z&.._ -_ _..-..-—-—-\?—— j" — "-..:.;.~,.-.——- ii}- as-4 e-.-'.l‘_;“7i .‘ '.».- "\ ,_?_____;3 ,_.._ _. .,..._.___.-.-;1'.'..____ L - ‘*\"*"'.‘<< ~}l;.f";'§‘-- 4 -.. -.. -._.. -J_1-pi|"‘ ":~—ii‘i __ ' ‘V. ]T—" "_'___' "'1-.:§'.'r'~."; §_ I_'1__! " 47 .,$.\_- - .__.,..___ 93 ... ' ___l -.3gT.___£\l_r_;-T-‘ — —' -at-?_°*~_"?t-:' - . . ___._:.-If E 1 ff‘ -__\."~ —..__._Z2 4‘ U._ ____4 B 4\\ _.__§__;_l__ -..T2“ ?_.;;j_ T VIA “ ‘I I m; °‘. ...JQAI mi’ U, ' _ . .47.- r* .. ___‘ __ - T. . z L4‘? I — —-Li 1 ____ _z_ ._T_.-*5 .4.Gv—-YOYAL -1 LEN g N IOUFS i 166 M unrv TABLE l. Details of lengths (mm) read 0]] diflerent growth. curves in figure 1 at intervals of 6 months. Initial Length at Length at Length at Curve length six months 12 months 18 months _._.___....- i_-.~_i----i--i--i--- --—i--~iv-vi- --i--~~i—-I» 7 I T— 7 — ' ~ “ 7' T ' * - " '“" " 142135 I83181 215 215 -— — 100125 I50 165 188 193 —— 12195 140 .157 175 -- 201 — ______'___ _ _——_ ~ ___—__ ;— —— _ __._ _ _ '——- _ _ 7~ _ —~-_ . ———~'._ . __ ' ’ —_~___ _ _ Esrnmrron OF Monnrnv RATES Total mortality rate (Z): The points that represented the straight, descending part of the length-converted catch curve (Fig. 2) were taken into account for estimating total mortality rates. The estimated values of Z during different years and the average worked out are as Foilowst 1980 5.0589Z 19821981 4.42475.6504 Average1.983 5.1651 5 .0748 Estimation 0)‘ natural mortality rate (M): A plot of Z against efi'ort (Fig. 3) showed that there was good correlation (r“— 0.320) between effort and Z with the estimated value of M at 2.05 and q at 0.000059533. But the above value of M gave MIK value of 4.66, a value much beyond the range (1.0-2.5) known in fishes (Beverton and Holt 1.959). This value, thus appearing to be an over estimate, was considered to be unrealistic and, therefore, the value of M esti mated by the formula of Pauly, being 1.0 with MIK at 2.3, was taken. Fishing mortality rate: The present fishing mortality rate, derived from the values of Z and M estimated above. was 4.07. ESTIMATION 01* Ynzu) PER Rectum" Using the length-weight relationship (Murty 1984) of the species and the Len value obtained, the value of W... was estimated to be 529 g. The "!'lt'1'1U"3W> onowru AND YIELD PER RECRUIT 167 81;I, ,rm ¢Nol . ' OUs:€ usvr . .'21'> ___ ———~—. . I —' .. __... mi?»° *~i~ W Tr 1 0I O .._,._. é. A. ___. ,.._-_2- 51; _.__ 2 W .. ' 1"ll ..‘ O LuG 1' 8]Iiitn" * ‘ F .-F . °r-2' a:9 6":; : 4 . 1' 0 4‘OI 'v" 1 w ~ v— - v'———v7— v. 'r—+7-I ~ v I v 1- v v' Y 24as 1-2Ago 1-0. Your:2-4 1--s1| *5“ail i I’ ‘555 '. '1'""5 7' ' -1' FIG. 2. Estimation of ‘Z’ by length-converted catch curve FIG. 3. Plot of Z against effort method in J. carutta. to estimate M in I. carutta. smallest fish observed in the catch was 70 mm and therefore the age, estimated of it, i.e., 0.536 year, was taken as the age at recruitment( Ir ). The annual length-frequency distribution of catch during the 4~year period showed the smallest mode at 135 mm and, hence, 130 mm (lower limit of 135 mm-group) was taken as the length at first capture. The lc was calculated as 1.123 years. The Yield per recruit with M at 1.0 and the five values of to ranging from 1.014 to 1.486, respectively representing lc values a-t 120, 130, 140, 150 and 1. 60 mm (Fig. 4A), showed that the Yield per recruit increased with increased lc. It was also observed that. with is at 1.014, the Yield per recruit reached its maximum (20.6 g) when F was 1.6, and then on slowly decreased with further increase in F. With to at 1.123 (present value), the Yield per recruit reached its maximum (21.5 g) when F was 2.0. With the Ie values at 1.238 and 1.359, maximum Yield per recruit (22.3 and 23..1 g, respectively) was at F = 2.4 and 3.0, respectively. With te at 1.486, the yield increased with increasing F and reached maximum (23.7 g) when F was 4 and decreased slowly with further increase in F. Thus, the Yield per recruit not only increased with greater values of tc, but also reached its maximum at higher values of F if Ic was higher. The estimated values of present F and lc were 4.07 and 1.123, respectively; and the Yield per recruit had already shown a decline. The Yield per recruit with M at 1.0 and F at 4.07, as a function of age at first capture (Fig. 4B), showed that it increased, reaching maximum (24.1 g) at t¢ 1.7, amt! declined with further increase in to. O9 Q N/A tr -st OTA MQR A N! 1 68 MURTY ?4 _, w_ __r. 4 4,1-__-4 pg‘; .. . ® 1 re4% _ _+ V- ‘LI-230_ H59 — 7- — _ -1 J: I-Qfl our ~; 1: \ ..1‘TI1 -- .14 X ‘l ir Q .id A‘ at‘ \ ‘ 1?- fif~".:Lf*1 ‘fry T -7-—‘T*f'? 1|J ‘L ‘ U2 R llfioa' AGE¢>‘Tfi u %+"fi AT3-2 ; 'r -i~"'-ifrmsr 3-: T" euvrwi .:K:",4.*. 4-2 ~ - ¢4.' $4 ;'-q' %;_i‘H FISHING MORTALITY RATE FIG. 4. A. Yield per recruit as a function of fishing mortality in J. carmta. The nume merals indicate the tc values and the vertical line the present F. B. Yield per recruit as a function of age at first capture in J. carutta. The vertical line shows lhfi present tc. (The small vertical lines on the curves in A and B indicate maximum YWIR values). ___I_ 1-486 . an - 1 V ‘. .ll W ‘\ \ 60? ‘ Qf. ‘~~I 1\ 3 '1 ; 1 MlQ T. ~44: I * M‘ I _ — — ~ " v1* -|l _w_ - -— - 1 * I "\ ~04 l -J‘-—-Q-——v—-I—""7_-f—-v—'1—-Pv—"v—'*'-"f*'T_‘“I_‘"|'—'_' _‘ .0 5° F90 1 v. OF n30F'QE$ENT 1 FIG. 5. Yield per recruit (as percent of present value), as A. function of fishing mortality (also as percent of present value),for two values of age at first capture. B. fumitlon at first capture (also as peI'CCIlt of present value). It was observed (Fig. SA) that if the fishing mortality rate was about 49% of the present value (of 4.07) and 1'0 was 1.123, the Yield per recruit was 104.3% of the present value, and if the F was about 98% of the present value and tc 1.486, the Yield per recruit was about same as the present value (see also fig. 4A). It was also observed (Fig. SB) that if the tc was 151% of Y ELO Pt}: HECFPU I " GQAMS e*_\-AL _e ..~— as -_ OF PRE SENT -. 5 Y E 0 Pia ntcnu r- anus G) 2 E s 3’, MoreFIESEHT 0* Q24 an 6: $9 Q I3‘ g 1 5 . "3 GROWTH AND YIELD PER RECRUIT I69 the present value (1.123) and F was at 4.07 (also the present value), the Yield per recruit was 117% of -the present value (Fig. SB). It was thus cle-ar that higher Yield per recruit could be obtained by one of the following: i: decreasing the fishing mortality to 49% of the present value (by de creasing the fishing effort) without changing the cod-end mesh size ii: increasing the age at first capture to 150% of the present value (by in creasing the cod-end mesh size) without changing the fishing effort iii: increasing both effort and cod-end mesh size. DISCUSSION The study of growth in Johnius carutta is rendered diflicult by the entry into the fishery of several broods over an extended period, and estimation of growth by following the modal progression in successive months is likely to lead to erroneous results, because there is no evidence to show that the modes interconnected really belong to the same brood. According to Pauly (1980a), however, the integrated method makes it quite hard to trace “wrong” growth curves, and the parameters obtained from such curves will describe the growth of at least the exploited part of a population well enough for most purposes. Estimation of M of a particular species in a multi-species fishery by regression of Z on effort is not likely to lead to reliable results because of lack of knowledge on the effective effort for the species under consideration. It is perhaps for this reason that, though the correlation is good ( Fig. 3), the M value obtained by the regression method is very much higher, particularly when viewed against the estimated growth parameters. The value obtained using the equation given by Pauly (l980b) appears to be a reasonable one for reasons mentioned above. The yield per recruit analysis shows that under the current values of F (4.07) and tc (1.123) the yield has already shown decline, and that maximum yield can be obtained by reducing the effort to about 49% of the present. It also shows that greater YW|R is obtained at higher F for greater tc, which indicates that the yield can be maximised by increasing the cod-end mesh size without further increasing the effort (Figs 4 and 5). In an earlier study (Murty 1984) the author had shown that the length at 50% maturity of this species was 155 mm and whose age was 1.422 years. In the present study the tc is at 1.123 years (lc 130 m). Thus the need is apparent to increase the cod-end mesh size to get tc value above 1.4 years, so that the fi-sh will get at least one chance to spawn before being caught in large numbers and it will help avert the possibility of recruitment overfishing at higher levels of F. 170 MURTY Acxnowtnocnmnnr The author is thankful to Dr. E. G. Silas, Director, for his encourage ment and to Mr. C. Mukundan, for the critical reading of the manuscript. Thanks are also due to Mr. P. Ramalingam, for the assistance in the field and in the laboratory. REFERENCES Br-zvnnrou, R. J. H. AND S. I. 1-Ion". 1957. On the dynamics of exploited fish popula tions. Fishery Invest. London. Ser. 2, 19: 533 pp. Bnvtznron, R. I. 1-I. AND S. J. I-101.1". 1959. Av review of the lifcspans and mortality rates of fish in nature and their relation to growth and other physiological characteristics. Ciba foundation Colloquia on ageing. G. E. W. Wolsenholmy and M.O.’ Connor (Eds.). The life-span of animals, 51 142-177. GANAPAT1, P. N. sun V. S. R. Munmv. I954. Sailinity and temperature variations of the surface waters off Visalthapatnam coast. Audhra Univ. Mam. Oceanogra. 1: 125-142. Javavnamsn, A. A. 1978 Age and growth of juveniles of ‘Koth' Otolithoides brunneus (Day) in Bombay waters. Indian I. Fish., 23: 86-96 (1976). KUTTY, M. N. 1961. Scales and otoliths of ‘Koth’ Otolithoides brunneus (Day) as age indicators. Indian I. Fish., 8: 145-151. LA FOND, E. C. 1958. Seasonal cycle of sea surface temperature and salinity along the east coast of India. Andhra Univ. Mam. Ocean0gr., II: 12-21. MURTY, V. SRIRAMACHANDRA. 1984. Observations on some aspects of biology of the Croakers Johnius (Johnieops) dussnmieri (Cuvier) and Iohnins (Johnius) camrta Bloch from Kakinada. I. mar. bioi. Ass. India 2l(l & 2): 77-85 (1979). PAULY, D. 1980a. A selection of simple methods for the assessment of tropical fish stocks. FAO Fish. Circ. 729: 54 pp. PAULY, D. 1980b. On the interrelationships between natural mortality, growth parameters and mean environmental temperature in 175 fish stocks. J. cons. int. Expior. Mer. 39: 175-I92. PAULY, D. 1982. Studying single-species dynamics in a tropical rnultispecies context. pp. 33-70, In: Pauly, D and _G. I. Murphy (Eds.) Theory and Management of tropical fisheries, ICLARM Conference proc. 9, 360 pp., ICLARM, Manila, Philipines and CSIRO. Cronulla. Australia. RAO, K. S. 1971. Studies on the scales of Pseudosciaena diacanthus (Lacepetle) for esti mating growth parameters. Indian .1. Fish., I5: 127-144 (1968). RAO, K. V. S. 1961. Studies on age determination of (Gh0l’ Psendosciaena diacanrhus (Lacepede) by means of scales and Otoliths. Indian J. Fish., 8: 121-125. RAO, K. V. S. 1971a. Age and growth of Ghol Pseudosciaena diacanthus (Lacepede) in Bombay and Saurashtra waters. Indian J. Fish., 13: 251-292 (1966). Rao, K. V. S. 1971b. Estimates of mortality and yield per recruit of Ghel Pseua'0s triuena riiacanrlms (Lacepedel. Indian J. Fish, 15: 88-98 (1968). !LC0N'I‘RIl§'U'I‘I0N1 vj MURTY, V. SRIRAMACHANERA AND P. RAMALINGAM. 1988 Observations on some aspects of biology of Jogging (yohnieggg) vogleri (Bleeker) and §gQn§h;§ maopophppaigpg (Bleeker) in the Kakinada region._0 J mar0 o biol 0 ______p Ass India 28 (1&2): 57-62 (1986). ——~——_—T ’;—_'_*.7 It -‘—* " i‘— CONTRIBUTI ON 1 7} J. mar. biol. Ass. India, 1986, 28 (l & 2) : 57 - 62 OBSERVATIONS ON SOME ASPECTS OF BIOLOGY OF JOHNIUS (JOHNIEOPS) VOGLERI (BLEEKER) AND PENNAHIA MA CROPH THA LM US (BLEEKER) IN THE KAKINADA REGION V. SRIRAMACHANDRA MURTY* AND P. RAMALINGAM Central Marine Fisheries Research Institute, Cochin 682 031 ABSTRACT The length-weight relationship in J. vogleri and P. macrophrhalmus can be described by the equations log W=-5.08923+3.07931 log L and log W=-4.637354.-2.89703 log L respectively. The length at first ma turity in J. vogleri is estimated as 190 mm and in P. macrophrhalmus as 147 mm. These two species appear to spawn atleast twice in a year during protracted spawning periods: November-June in J. vogleri and October - June in P. macrophrhalmus. INTRODUCTION owing the procedure of Clark (1934); in each ovary a minimum of 300 ova were measured AMONG the demersal fishes landed by the pri at a magnification where 1 mm=59 divisions vate trawlers at Kakinada, the sciaenids of occular micrometer. The gonads were constitute the most dominant group. Though classified into seven stages of maturation. 18 species contribute to the fishery, only a Length-weight relationship was calculated few are dominant. The present paper gives following Le Cren (1951) using the formula an account of length-weight relationship and log W = log a+b log L. spawning in Johnius vogleri and Pennnahia macrophthalmus on the basis of data collected LENGTH - WEIGHT RELATIONSHIP from the landings of private trawlers during 1975-1979. Though considerable information is available on the biology of sciaenid from In J. vogleri, the study is based on 132 males India, in the case of J. vogleri the only account ranging from 94 to 234 mm length and from available is from Bombay (Muthiah, 1983) and 10 to 138 g weight and 144 females ranging P. macrophthalmus from Visakhapatnam (Rao, from 99 to 238 mm length and from 11 to 1967, 1983). 145 g weight. The relationship was calculated separately for sexes and equations are: MATERIAL AND METHODS Males: log W=-5.0l103+3.04169 log L; I'2=0.99 Samples were collected at weekly intervals from the landings of private trawlers. Data Females: log W = -5.13942 + 3.10374 log L; on length, weight, sex and stage of maturation r2=0.99. were taken from fresh specimens and ova dia meters were taken from formalin-preserved In P. macrophthalmus, a total of 90 males ovaries. Ova diameters were measured foll ranging from 98 to 222 mm length and from 15 to 148 g weight and 100 females ranging * Present address : Kakinada Research Centre of from 91 to 219 mm length and from 12 to CMFRI, Kakinada-533 002. 140 g weight was used for the calcul-ation of 2 V. SRIRAMACHANDRA MURTY AND P. RAMALINGAM the relationship. The equations for sexes J. voglm." log W=-5.08923-i-3.07931 separately are: log -L; .r2=0.99. Males: log W-=-4.56.‘/'671~2.86347 log L: P. macrpphthalmus: log W==-4.63_735 + 2.89703 r2 =0.94. log L; r2=-0.96. Females: log W= -4.70991 +2.93l936 log L; The t-test (Pauly, 1984) was applied to see r2=O.98. whether the values of regression coefficient (b) in the above equations‘ were significantly The differences between the regression lines different from 3; it was observed that the b of males and females of these two species were values are not significantly different from 3; l '-an ISO’ -l» ‘_ ' g)?0-OOOOOGMIEM ‘ _ lb w=o-00002205 3'89???‘ u 110+ I ~:' @00 ' II 9 \ -+ml 0 -l~ .._¢-'gt I '0 . _. III 0 . . Q'\ 0 .I . .~-' _ J; .;, ‘O . ini- ,.." 10;»T 0 O ¢--\_.1_90 }__}<—iI30 r:T+_170 1 1:-1 r 1_;t¢i1-—1_:a210 ; 910 _ t__—l - _}_- _i,=1- ~‘-;(Tl;-1.-—|_2_4'.o—+m-:4_| TOTAL L ENCTH (mm! Fig. 1. Length-weight relationship in: a. P. mar-rophrhalnms and b. J. vogleri. tested by analysis of covariance following hence growth in weight with length in these Snedecor and Cochran (I969). It was found two species can be taken as isometric. (Table ll) that the differences are not signifi cant at 5°/0' level.- The data of males and LENGTH AT Fmsr MATURITY females were, therefore, pooled and relation For determining the length at first matu ships for the two species obtained (Fig, 1). =rity, only females were considered and fishes The equations for the species are: ' in stages IV-V1 of maturation were taken as WE OHT an o.,_. BIQLOGYOF J. (J.) VOGLERI AND MACROIPHTHALMUS 3 TABLE 1. Analysis of Covariance to test significance of differences between regression fines of sexes in the length weight relationships of J. vogleri and P. macrophthalmus J. vogleri P. macrophthalmus Source of "variation df Deviation from "regression df -Deviation from regression ' .SS .MS SS M ""' -‘ 1 V "‘—v—-i" -' 77- ~—v. I _ '~ ‘Due to regression within sexes 272 0.308146 0.001133 186 0.419714 0.002257 Differencecoeflicients between regression l 0.002205 0.002205 1 0.001514 0.001514 Residuals due to regression pooled within 0.310351 0.901137 187 0.421228 0.002253 Difference between adjusted means l 0.00359] 0.003591 I 0.002483 0.002483 Total 0.313942 188 0.42371 1 Comparison ofslopes F=l.95, df=l,272; NS., F=-0.67, df=l,186; NS Comparison of elevations F=3.l6, df=1,273 NS., F=1.l0, df=1,l87; NS 100] ® ..c_ ® .o "1 | __l‘ 2011 -l I "-I30 -—|c I60 -~—|—-—l 190 i no1 1‘1 170 if.' . 1<2 Z30 I _-f “I_ ,_... Total length (mm) Fig. 2. Percentage of _ mature females in the total numbers of females examined in each length group in : a. J. vogleri and b. P. macrophrhalmus. mature (Fishes with fully spent ovaries - stage In J. vogleri, the smallest mature female VII - were not _encountered in the samples). was observed in 120-129 mm group. The The tota_l lengths were grouped into 10 mm percentage of mature females in each length class intervals. group (Fig. 12 a) shows that 50% of fishes‘ were Percentage 05 I-+_l;~ OI 1 J::l- 1 4 V. SRIRAMACHANDRA MURTY\ AND P. RAMALINGAM mature at 190 mm; hence this length was taken lucent maturing ova and the other group as length at first maturity. (mode b) consists of mature, opaque ova. In stage VI the above two groups are present In (P. macrophthalmus (Fig 2 b), the per with more or less same modal diameters; centage of mature fish in each length’ group there is another group consisting of ripe ova indicates that 50% are mature at 147 mm; with distinct oil globules. The above obser hence this length can be taken as length at vations indicate that each adult female spawns first maturity. at least twice during the course of one year. no--&~_—_—_ a ll ST-V ST. V I b C ST- V 5,. ‘ W FVI foil i sf. V1‘? tar“ V a ff 15 if if K if if E I srfvr ii 52+* -‘ ~¥ i T1, if-$46 ?T{- 25'-2?‘I _ ‘<-~ *efi‘*~ as-as‘T *- —_ i -—~q _visit: ;~ — _*' i OVA DIAMETER (GM) Fig. 3. Ova diameter frequency distribution in mature and ripe ovaries‘of J. vogleri (diameter ranges of : maturing translucent ova MT; mature opaque ova MO; ripe translucent ova RT). SPAWNING In P. macrophthalmus, fishes with ripe ovaries were not available 'in the samples, The ova diameter frequency distribution in therefore only those with stage V ovaries were gravid (St. V) and ripe (St. VI) ovaries of J. considered. The ova diameter frequency dis voglerr‘ (Fig. 3) shows that two groups of ova tribution (ova measuring upto 4 md were not (in"_g addition to immature ova measuring upto considered in this species also) in. stage V 4i_n<1 whichwere not considered in the present ovaries (Fig. 4) in this spwies shows a‘ situaé study)y are present in stage V ovaries. One tion similar to that -7 in I. vog'Ieri indicatiifng group (mode a) consists of yolked, trans similar spawning habits. ' ' "H PERCEN TAGE “iotaea <'éL§# 2? D’ y ml Y ._l_ - - + %| iv l -4-L +r-—i -4 l s BIOLOGY OF J. (1.) VOGLERI AND P. MACROPHTHALMUS 5 For purpose of determining spawning sea of regression coefficient (b=3.286l males; son only females of and above length at first 3.2808 females) of males and females from maturity were considered and data of corres Bombay appear to be different from those ponding months of different years pooled of sexes of this species, from Kakinada. The In J. vogleri fishes in stage IV of maturation value of ‘b’ for P. macrophthalmus from Visa occurred in almost all the months and the khapatnam (Rao, 1983), however, is close to proportion of gravid and ripe adults in each the one obtained from Kakinada. The above shows that spawning takes place from Novem authors did not test whether the growth is ber to June with maximum spawning activity isometric in these species; however the fact during May-June. In P. macrophthalmus, that the values of b are not significantly fishes with stage V ovaries (fishes with ripe different from 3 in the two species from ovaries were not encountered in samples) Kakinada shows that Beverton~Holt (I957) occurred during September, November, De yield equation can be used in yield studies without any modification. ,- -- -.-_nM r -1:-_z1=#" ‘i Q-O‘ In J. vogleri, Muthiah (1983) estimated the length at first maturity as 159 mm whereas the same estimated from Kakinada is larger (190 mm). In the ova diameter frequency dis tribution in ripe ovaries of J. vogleri from Bombay, Muthiah (1983) observed a situation comparable to that observed from Ka-kinada (Fig. 3), but stated that “the spawning in this species seem to be restricted to a short period Ly,:_*y.-_"':;-‘__t -' Z7 *1 F: T ' _——‘{ F'"_ ii‘ Ii, 5.5 i7-\B 2990 N with an indication of second spawning, the ova om-1£TER IMF duration in between being short”. He, however, Fig. 4. Ova diameter frequency distribution in 5)mature ovaries of P. macrophthalmus (Abbreviations as in Fig. 3). s60f - ® cember and February-May (Fig 5) indicating that spawning takes place during October-June. It is thus clear that spawning season in these , - ii two species is more or less the same and that . FT ® it is protracted. The study of ova diameter frequency distribution (Fig. 4 & 5) lends 20¢ U "V support to this conclusion. J M M J s N Fig. 5. Monthly percentage of gravid and ripe females in the total number of adult females examined DISCUSSION I each month: x. J. vogleri and y. P. macro phrhalmus. Muthiah (I983) calculated the length-weight relationship separately for males and females of J. vogleri from Bombay, but did not calculate observed mature (st. IV) fish throughout the the relationship for the species as a whole year, but stated that J. vogleri spawns twice nor did he state that the regression coeffici a year during June-July and October-Novem ents are significantly different. The values ber. The ova diameter frequency distribution PERCENTAGE (U Gm ‘4':_1__ 4_i P . g-q;-i» op-nfl-&w~—'-F‘ Q4 0 PERC E N TA +_°Q’) 9»- N) 6 V. SRIRAMACHANDRA MURTY AND P. RAMALINGAM (Fig. 3) in J. vogleri from Kakinada shows reaches ripe stage and this process continues that the maturing translucent ova and mature (James and Baragi, 1980). The ova diameter opaque ova" have more or less the same modal frequency distribution in P. macrophthalmus also suggests a similar conclusion. Rao (1967) values in stage V and VI ovaries. This indi however stated that Pseudosciaena aneus cates that by the time the mature opaque ova (= Pennahia macrophrhalmus) spawns only in stage V reach ripe stage the maturing trans once a year during December - March. The lucent ova in the same ovary become mature present observations show that both J. vogieri and opaque. This further suggests that after and P. macrophrhalmus have more or less the the ovary reaches stage VI and spawns the same spawning period and that the periods batch of ripe ova, it reverts to stage V and again are protracted. REFERENCES BEVERTON, R. J. H. AND S. J. Hon 1957. On the MUTHIAH, C. 1983. Study on the biology of Jaimi dynamics of exploited fish populations. Fish. Invest. eops vogleri (Bleeker) of Bombay waters. Indian J. Fr'sh.. Ser.lI, 19: 1-533. 29: 118-I13 (1982). CLARK, F. N. 1934. Maturity of the California sar PAULY, D. 1984. Fish Population dynamics in tro dine (Sardina caerulea), determined by ova diameter pical waters : a manual for use with programmable measurements. Calif. Div. Fish. Game Fish. BuII., 42: calculators. _lCLARM studies and Reviews, 8: 325 pp. 1-49. RAO, T. APPA 1967. Maturity and spawning habits of some sciaenids in offshore waters at Visakhapatnam. JAMES, P. S. B. R. AND V. M. BARAGI 1980. Ovary as Indian J. Fz'sh., I1: 121-126 (1964). an indicator of frequency of spawning in fishes. Proc. Indian natn. Sci, Acad., B 46 (4): 479-489. --—— I983. Length-weight relationship in Pemzahia macrophthalmus (Bloch). 1b:'d., 29: 263-266 (1982). LE CREN, E. D. 1951. The length-weight relation ship and seasonal cycle in gonad weight and condition SNEDECOR, G. W. mo W. G. COCI-IRAN I967. Stati sricaf Methods. Oxward and IBH publishing Co. New 201-in tlge I9. perch (Perca fluviatiiis) J. anim. Ec0I., 20: Delhi, Sixth edition, 593 pp. D . CARANGIDS—-—SC.AD QONTRIBUWL_ iii" ia_ 18] MURTY, V. SRIRAMACHANDRA. 1991. Observations on some ;, aspects of biology and population dynamics of the scad paoapaagqg ;u§seiii(Ruppe11) (carangidae) in the trawling grounds off Kakinada. Q»‘QQ£. biol. 535. India, 33 (1&2): 396-408. x CONTRIBUTION 18 I OBSERVATIONS ON SOME ASPECTS OF BIOLOGY AND POPULATION DYNAMICS OF THE SCAD DECAPTERUS RUSSELLI (RUPPELL) (CARANGIDAE) IN THE TRAWLING GROUNDS OFF KAKINADA* J. mar. bio}. Ass. India, I991, 33 (1 & 2) : 396-408 OBSERVATIONS ON SOME ASPECTS OF BIOLOGY AND POPULATION DYNAMICS OF THE SCAD DECAPTERUS RUSSELL! (RUPPELL) (CARANGIDAE) IN THE TRAWLING GROUNDS OFF KAKINADA* V. SRIRAMACHANDRA MURTY1 Central Marine Fisheries Research Institute, Cochin 682 031 Aasraacr Decapterus russelii (RuDPcl1)“ is abu ndant in relatively deeper waters and forms 80-90 °/0 of carangid catches by trawlers. The von Bertalanffy growth parameters are estimated as Lee = 232.3 mm, K = 1.08 per year and to = --0.08 year. The length-weight relationship can be described by the equation log W (g) == -S.93433+3.40764 log L (mm). The length and age at first maturity are estimated as 150 mm and 0.88 ycar respectively. This species spawns off Kakinada during December-August. The different mortality rates are estimated as Z = 6.65, M -= 1.90 and F = 4.75 and the length and age at first capture as 158 mm and 0.98 year r espectively. The yield per recruit analysis shows that : with te above 0.6 the Yw l R increases with increased F without reaching maximum. The highest Ywl R, however, is obtained with tc at 0.6 only. INTRODUCTION landed. Excepting the work of Srecnivasan THE FISHES of the family carangidae are an (1982. 1983. 1984) from Vizhinjam. there is no important group of exploited pelagic resources information on the biology of D. russeili from of India; an estimated average annual carangid India. The present paper deals with some catch of 38.685 tonnes was landed during 1981 aspects of biology and population dynamics of D. russelii on the basis of data obtained from and 1982 (CMFRI. 1982 ; 1983) forming 2.8?/0 of the total marine landings of the country. commercial shrimp trawlcrs at Kakinada during Though this family is represented by about 50 July 1979-June 1983. species in Indian seas. only a few contribute The author is grateful to Dr. P.S.B.R. James. to the fisheries at different places and -D. russelli Director. CMFR Institute for encouragement. is the most dominant carangid landed by He is thankful to Mr. M. Srinath for his sug trawlers at Kakinada: an estimated annual gestions on statistical analysis and to Mr. average of 1229 t were landed during July P. Ramalingam for assisting in the field as 1979-June 1983 forming 83% of all carangids well as in the laboratory. " Presented at the ‘ Symposium on Tropical _ Marine MATERIAL AND Msrnops Living Resources ’ held by _the Marine Biological Data on effort and catch were collected for /association1 88. of India at Cochin from January 12-16, about 18 days each month and samples for 1 Present address : Kakinada Research Centre of biological study were obtained at weekly CMFRI, Kakinada 533 004, India. intervals. The data obtained on each i Smitl-|.Vaniz (1984) considered Decapterus dayi Wakiya as a junior synonym of D. russeIIi(Ruppe1l). observation day were weighted to get the BIOLOGY AND POPULATION DYNAMICS OF SCAD 397 estimates for that day and the pooled estimated following the length-converted catch days’ estimates were weighted to get monthly curve method of Pauly (1982). The natural estimated effort. catch and length composition mortality rate (M) was estimated assuming of catch. The length data were grouped that 99 % of fish by numbers would die if there into 5 mm class intervals and the mid was no exploitation by the time they attained points of these groups were considered tmax and by taking tm, as corresponding for estimation of growth. The parameters to L max in the catch (Sekharan. 1975). or to of von Bertalanffy growth equation were esti Loc - 0.50 cm (Alagaraja, 1984) or to 95% of mated using the monthly length frequency Loc (Pauly, 1983). The value of M was also data obtained during March 1979-February obtained using the equation of Pauly (1980 b). 1983 and following the integrated method of taking the average water temperature as 27.2°C Pauly (1980 a). The length-weight relation following Ganapati and Murthy (1954) and ship was calculated following Le Crcn (1951) LaFond (1958). The length at first capture using the formula log W = log a -1- b log was estimated following Pauly (1984 a) and TABLE 1. Estimated annual eflbrt and catches (I) of all carangids and Decapterus russelli by private trawlers at Kakinada (Values in parantheses show % increase or decrease over each previous year) Effort All carangid Catch of 7, of D. russelli Years -T. - - catch D. russelli in all carangid Units Tr. Hrs. catch 1 979-80 47, 948 3,41,997 442 350 79,2 .1 980-81 40,294 3,29,1v9 1,003 900 89.7 (-16.0) (-3.7) (+1269) (+1s'/.1) 1981-82 50,462 4,4s,794 1,652 1,360 82.3 (+-25.2) (+3s.4) (+647) (+s1.1) 1982-83 48, 550 3,19,864 2,323 2,305 81.7 (--3.8) (-28.2) (4-70.9) (+69.5) 77 — ~—~ - ~ ——— _ __ 4 L, where W=weight in grams. L=total length the yield in weight per recruit by following in mm. ‘ a ’ a constant and ‘ b ’ the exponent, Beverton and Holt (1957) method. The specimens were examined in fresh condi tion; each fish was measured and weighed Carer-res /mo Errour to an accuracy of 1 mm and 0.5 g respectively. The estimated annual catches of carangids The stages of maturation were fixed following by trawlers at Kakinada varied from 442 t Kagwade (1971) and Sreenivasan (1981). Ova in 1979-80 to 2.823 t in 1982-83 (Table I); diameter measurements were taken from ovaries though there were fluctuations in the effort fixed in 4% formalin following the procedure in difilxrent years, the catches showed con of Clark (1934). From each ovary about 300 siderable increase in succeeding years. The ova were measured using an ocular micrometer seasonal variations in the catches of carangids at a magnification where each micrometer showed (Fi g. l) that peak periods of abundance divisi 11 (md) was eq al to 0.017 mm. The varied during difierent years: there were instantaneous rate of total mortality (Z) was major peaks during February 1932, 1983; 398 V. SRIRAMACHANDRA MURTY April 1980 or May 1981. A minor peak in of six months starting from the smallest modal abundance was observed during September length in each curve were read off these curves : 1979 and 1980. Decapterus russelli was the in each curve. only the portion between the most dominant species in the catches and formed smallest and largest modal lengths was taken ; about 80-90% of carangid catches during sometimes to enable reading the growth for different years (Table 1). though it contributed 6 month period the portion of the curve slightly to the fishery significantly only during certain beyond the largest modal length was also 601‘‘ 1982- 83 iiii ___f *;_14fl pi-1 1981-82 III 1l X \[_ __ _ . __ _ _ 4°} 19eo—s1 Q;i -ii -40% zol.'.'_.- i979-80M .20‘O-'-i ‘L-"FJ ‘ ‘*|A |‘>~ S “F O ”— Nre it 11O I-~ J if F* |'——~1~~ M A 4-—~< M J4 MONTHS Fig. 1. Estimated monthly percentage of carangids in the total catch of each year. months particularly during January-April taken. The values thus taken from all the (Fig. 2). curves were used to estimate the parameters of von Bertalanffy equation. Gnowm PARAMETERS A total of 8.984 specimens of the length A plot of L,+1 against L, (similar to that range 52-217 mm were measured. The monthly of Manzer and Taylor, 1947) shows that the modal lengths and growth curves drawn observed points are well represented (Fig. 4) by through majority of them are shown in Fig. 3 ; the straight line (r'=0.89). From this relation. it may be seen that the curves are more or less the values of Loc and K were estimated parallel. The lengths attained at intervals as 232.3 mm and 1.08 per year respectively. PERC E N TAGE J-> in do 4J_‘;_|:_~—L-:rI-u-IO O O +£—_i-half %l——_{_ BIOLOGY AND POPULATION DYNAMICS OF SCAD 399 From the origin of the curveD (Fig. 3). the Females : log W -=8) --5.97804 + 3.42534 age of the smallest modal length at 67 mm log L (r2 = 0.92) was read as three months and taking this into Males : log W = —5.88927 + 3.38898 account. the lengths at successive half years log L (r2 = 0.86) were estimated using the constants of the above regression for estimating to (Fi g. 5) ; the value The analysis of covariance (Snedecor and was estimated as —0.08 year. Cochran. 1967) showed that the diiferences between regression coefficients and Y-intercepts of sexes were not significant at 5% level. 3°‘? ‘A l"; Hence the data of sexes were pooled and the 51982-as . li l relationship for the species was calculated as : l l- 7 il log W= —5.934-33 -l- 3.40764 log L (r2=0.90) 20*-_l-_L__'__J '_.-|-.-glai ti. ._ The value of regression coeificient was tested 8° 1981-82 against the theoretical value of 3 by the t-test ; .\ y, 1 it was significantly different from 3. .i I } MATURATION mo Smwnmo fl. - %vm, ~ all_ _,____.l—— e -—~ Length and age at first maturity: Only _ 51980-8: T l q females were considered and individuals in stages III-VII of maturation were taken as mature. Fishes of I35 mm and above showed mature ovaries. On the basis of the percentage 20?_ _ _ w ‘__ _ ]_:_;*_V__:: ___?::l._:?3_?:,l ‘_ w" of mature fishes in each length group. length sol I979-80 -; _ 3 at first maturity could be taken as 150 mm (Fig. 6) whose age could be calculated as i”ll "r -l1 tl 0.83 year. an-lli a Y I’ ” Spawning habits Three specimens each of JASONDJFMAMJ stages IV and V and one each of stages VI and MONTHS VII were examined for ova diameter frequency ‘Fig. 2; Monthly percentage composition of D. russelli distribution. Three types of ova were recognised in the carangid catches of each month. in ovaries in stages IV and V. the first one representing immature ova with the diameter The estimated lengths at the completion of extending upto 4 md and the second one l. ll and III years are 160. 208 and 224 mm representing maturing ova with the diameters respectively (Fig. 3). The maximum recorded ranging from 5 to 18 md. The former were length at Kakinada was 217 mm (age 2.4 years). transparent and irregularly-shaped with the nucleus clearly visible and the latter were more LENGTH-WEIGIIT Rntxrronsmri or less spherical. yolked. translucent and the Data of 267 females ranging from 132 to nucleus was not clearly visible. For the present 201 mm in total length and from I9 to 87 g study, ova upto 6 md were not considered as weight and 325 males ranging from 120 to they were of no consequence in interpreting 205 mm and 15 to 89 g were considered. The the periodicity of spawning. The third group equations obtained for each sex were ; Fig. 7) represented the mature ova with the PER ceurnezO N | -_| 3 <2 1.1j_~_—J 400 V. SRIRAMACHANDRA MURTY diameters ranging from 19 to 32 md; these suggests that D. russelli in the sea oh‘ ova were spherical and opaque. In stage VI. Kakinada spawns during December-June the in addition to the above. there was another period sometimes extending upto August. group (Fig. 7) which represented the ripe translucent ova with a distinct oil globule; these ova were spherical and ranged from 33 MORTALITY Runs to 48 md and the diameter of the oil globule Total mortality rate : During 1982-83 the ranged from 9 to ll md. data were not available for several months. The ova diameter frequency distribution in hence the data of this year were not used. ovaries of difl'erent stages of maturation (Fig. 7) Through the length-converted catch curves showed that the mode at 11-12 md in stage IV (Fig. 8), the values of Z were estimated to remained stationery in stage V. but in stage VI range from 4.78 to 3.75 with the average at it had shifted to 17-18 md; the ova in this 6.65. zoo 8 I E¢ _ __,*._..~»0' F _e-——.—_~4:_‘_ 5. ‘.'... . I/Q .I 00__‘ Q0 O, . I Q ‘,‘O O0t /gnuosnitsavauasnosernasnfgaguas . ‘.4983an Fig. 13. Growth curves in D. russelli to estimate- growth. The VBG curve. is also shown. group were mature opaque and maturing. Natural and fishing mortality rates : The The mode at 23-24 md in stage IV had shifted values of M estimated by following different to 27-28 md in stage V and then to 39-40 approaches are shown in Table 3. In the md in stage VI. In stage VII. in addition to present study. however. the M value obtained the modes in maturing ova. there were two by Sekharan’s (1975) method at 1.90 was con minor modes one each in mature opaque sidered. Since the average total mortality ova and ripe translucent ova. The situation during the period was estimated as 6.65. the therefore. indicates that the species probably present F value became 4.75. spawns twice in a season in the sea off Kakinada. ESTIMATION or Lenora AT Fmsr Cnrruna Since the gear operated was the same with Spawning season: Only females of and the same cod end mesh size in all the three above the length at first maturity were con years. the data of these three years were pooled sidered. The frequency distribution of females and a length converted catch curve was obtained in different stages of maturation (Table 2) to estimate the number of fish in the first length rornuteneru§ "5 O . O O BIOLOGY AND POPULATION DYNAMICS OF SCAD 401 class that was fully selected (i.e.) the estimated 2. With t, above 0.66. the Yw /R increased number of fish corresponding to the first point with increased F without attaining a in the straight descending portion of the length maximum. convertcd catch curve. Taking this value. and the M value at 1.90. the length at first The Y, /R as a function of to with the capture (Le ) was estimated as 158 mm (Fig. 9); present F (Fig. ll) showed that maximum Y“, /R the te could therefore be calculated as 0.98 was obtained with tc at only 0.6. whereas the year. present t,, was 0.98. YIELD Pan RECRUIT It is thus clear that highest yield of D. russelli. The smallest length in the catch (52 mm) with the present F or by increasing the same. was taken as the length at recruitment (L, ) can be obtained only if the tc is 0.6. It is also and its age at 0.15 year as t, . The value of clear. however. that yield can still be increased TABLE 2. Gonaddl condition of adldt flsmales of D. russelli in diflierenr months (data of all years pooled) Months Females(No) examined II'7, of maturation IlI+IVstages V-i-VI V11 July 1_. August 22 86.4 4.5 4.5 4.5 September 6 100.0 October 13 100.0 November -_q Dwember 41 80. S 14.6 4.9 -— FebruaryJanuary 157 I98 44.6 1 .0 40.932.5 54.520.3 2.53.5 AprilMarch 946 $5.5 15.2 69.645.5 13.0—- -— 2.2 JuneMay -——19 63.1 --my36.9 ——- inn -1 — Woc was calculated as 134.4 g taking the value from the present level. without decreasing of Lee and the length-weight relationship. tc . but by increasing the effort. though the yield will be less than when tc is 0.6. The yield in weight per recruit (Y, /R). at M=-1.9 and five values of t., corresponding to DISCUSSION L¢ values of 108. 118. 128. I48 and 158 mm (Fig. 10) against F showed that. within the The trawling experiments in the sea ofl‘ range of F values considered : Kakinada in the depth range 5-100 m by Narayanappa er al. (1968). Satyanarayana 1. With tc ranging from 0.50 to 0.66. the er al. (1972) and Satyanarayana and Naraya Y. /R was greater if tc was greater and nappa (1972) have shown that De capterus spp. attained maximum at greater values of are abundant beyond 50 in depth. According F if ts was greater ; there was however to Muthu et al. (I977). the abundance of these no maximum if tc was 0.66. fishes during February-April off Kakinada 403 V, $RIRAMACHANDRA MURTY may be due to possible upwelling in the-region. of spawning in three batches. in a year. the On the basis of data of I0 year period (1969-’79) observations of Rao et al. (1977) show that the it was shown (CMFRI. 1981) that .Decapterus scad spawns over an ‘extended period with spp. are abundant in the catches during two or three peaks in an year ’. ' January-March at Kakinada. The greater re TABLE 3. Estimated values of M obtained by dzfiisrem‘ turns of D. russelli during January-April. as methods along with the values of Lmax and observed in the present study. may be because {max in D. russelli at Kakinada the boats conduct fishing in the relatively deeper waters during this period. M6thOd adopted Lmax (max M ?@& hp-iii (mm) (years) Sekharan (1915) In the catch: 211‘ 2.4 1.9 Alagaraja (1984) Loc -5 mm: 227.3 3.5 1.3 Pauly (1983) 95% Loci 220.7 2.7 1.7 I70 O Pauly (1980 b) —- —— 2.0 i Z §' -Ii ' 0 5 \ F4 8 -J LI IO :0 so 90 130 170 zto Lt tmrnl Fig.4. Plot of Lt+1 against Lt in D. russelli a intervals of 6 months. 2 It is known (Qasim. 1973) that spawning in majority of Indian marine fishes is prolonged i lasting 7-9 months in a year and the present observation on D. russelli are in agreement with this. The conclusion on spawning period I 2 3 4 as December-August is in conformity with the .AGE YEARS observations of Rao et al. (1977) along the Indian west coast : they observed scads with Fig. S. Estimation of to in D. russeili. ripe and running ovaries during October August. The ova diameter frequency distri .-From Vizhjnjam along the southwest coast. bution in mature and ripe ovaries (Fig. 7) Sreenivasan (1983) estilnated the growth para indicates that spawning takes place in two meters of D. dayi (=D. russelli) as Lo¢=260 batches during a season. The growth curves mm fork length (288 mm TL*). K=0.74 per (Fig. 3) show that 2-3 broods are recruited year and to =—-0.13 year whereas the same to the fishery in different years indicating that |_- __ _ _'_ ._ _ ova are also released in 2-3 spawnings a year. '8 Sreenivasan (I983) considered fork length only; the total length was calculated 7-from TL-FL relation Though the data on hand do not give evidence ship given by him. mm) iiii t -u -toes °° BIOLOGY AND POPULATION DYNAMICS OF SCAD 40$ from Kakinada were estimated as 232.3 mm ing that the (,6 values producing the normal TL. 1.08 per year and -0.08 year respectively. distribution have indeed resulted from reliable The length range and maximum length at growth estimates). In the case of D. dayi Vizhinjam (20-219 mm FL or 21-243 mm TL (=.D. russelli) from Vizhinjam. the ¢ value and 271 mm FL or 300 mm TL) are greater can be calculated as 1.6 (taking different para than those at Kakinada (52-217 mm TL and meter values from Sreenivasan 1982. 1983) 217 mm TL); these differences appear to be and the one from Kakinada as 1.5 which are responsible for the differences in the estimated close to each other. values of growth parameters though such It is well-known that estimation of natural |00-1, mortality rate in exploited fish populations is l difficult (Cushing. 1981 ; Alagaraja. 1984). In the absence of knowledge of effective effort 1% ““‘l ' ° pertaining to a particular species in a multi s_¢O U species fishery. it is not possible to estimate \ i 0 IO1 M with the help of the regression of Z against 0-4 effort. It is also clear (Fig. 8) that Z showed zoli an increasing trend over different years though such a trend is not present in the effort (Table 1) free :—~ -— I ¢‘—‘—‘t—-i~ —‘=r- 1 1 ———T| ————| ---1- -1 which is due to the fact that the effort is not I35 :55 ns :95 Total length (mm) elfective effort for the species. In the present Fig. 6. Percentage of matured individuals of study. the M value was estimated following D. russelli in each length group, different approaches (Table 3). In the Sekharan’s (1975) method, the value of tmax in a virgin differences in growth parameter estimates can stock is required (Sekharan. 1975; however. also occur (for various reasons) in different considered tmgx in the catch) and this value stocks of the same species and during different is not available for the stock of D. russelli at periods in the same stock. Further. the non Kakinada. Though Alagaraja (1984) sug availability of data in some months (Fig. 2. 3) gested that maximum length in a population and the narrow length range in the catch in (to calculate llmax value in a ‘ virgin stock. most months (probably because of size specific and to estimate M) could be taken as Loc shoaling behaviour) which resulted in the data —-0.50 cm. the reasons for doing so were having over 90% of the modal values between not mentioned; it is also not known whether 100 and 200 mm (Fig. 3) only. could also this can be done uniformly for all species having possibly have lead to the differences in the widely varying Lo: values. Pauly (1983) sug growth parameter values. gested that Lm, could be taken as 95% of Lo: following Taylor (1962). It is, therefore. According to Munro and Pauly (1983) the clear that all these approaches are subjective. frequency distribution of the values of qb Recently Alagaraja er al. (1986) estimated M (¢=log K+0.67 log Woo) of a particular in shrimps ‘ Assuming that when X% of Lac species from different areas produces normal is reached by fish X% of mortality takes place. distribution and that the growth parameter one gets M/K=1 for all X’. Though these estimates pertaining to a species of a particular authors have not stated. it is also necessary area have to be checked, if the qb value from to assume t°=0. as otherwise M/K is not that region does not fit into the already known always equal to 1. This approach however. range of normal distribution (obviously assum presupposes M/K=I (which means M-=K) MO u 8 °/ om I1 1: ___|_ O O Q 404 V. SRIRAMACHANDRA MURTY whereas the M/K in fishes is known to range by Pauly’s (1983) method (Table 3). The from I to 2.5 (Beverton and Holt. 1959). value obtained by Alagaraja’s method is. The equation of Pauly (1980 b) does not require however much smaller than those obtained by assumptions or adjustments as above. but other methods. according to Pauly (1984 b). the value obtained by this equation ‘ may be biassed upward in the case of strongly schooling fishes ’ and The value of LC at 158 mm as obtained by therefore this approach cannot be followed in following Pauly’s (1984) method was used in D. russelli which is known to form schools. the present study. Taking the depth ratio Under the circumstances it is not possible to (standard length/maximum body depth) of this n---—-—- M1“ as ~ M0 »_>~»_.—.f- _-. —T s RT ----- I st. IV £21-1-tee: 'n.. I62 M ST \.-' 7*l“l9Bi TL- I795‘!!! l[_ ___'_‘j’_ ____7_ __ i_ __ ._ __. . 2?'l" IQBI L 152mm stvu |so~s-me TL lflmm I ' FM‘;cl *?*~-1-a Fen 15- 1- *i_'T 16 l'——*'_F-—'t_T‘I'!_F' as-24 at-:2‘ as-40 limit?’ wk" ‘*t‘—"?l—-‘F 41-ea-\ f"" OVA DIAMETER (ind) F58. 7. Ova diameter frequency distribution in ovaries of different stages of maturation. MT. MO and RT indicate the diameter range of maturing translucent ova, mature opaque ova and ripe translucent ova respectively. state which of the methods considered here species from Kakinada (as 4.2) and using the gives the most satisfactory estimate of M for nomogram given by Pauly (1983). the selection the species under consideration. The M value factor of D. russelli can be read as 2.5. Using obtained by Sekharan’s method (Table 3) the cod end mesh size of the gear under use was taken into account in this study. because (average 15.6 mm). the LC value can be cal the maximum length in the catch was con culated as 39 mm which is less than even the sidered as 1-mi. without any adjustment; length of the smallest fish caught (52 mm). the value obtained this way is only slightly The Lé obtained by the Pauly’s (1984) method less than that obtained by Pauly’s (1980 b) is therefore much greater than the theoretically equation and slightly more than that obtained possible value, It may be mentioned in this PE RCE NTAGE FR EQU ENCY Z5 on 5 u Z5 on ~_ F if-. L m__1_ 4 U’. n_‘.'i-:1.-. _|_‘L-_—~L -4 IQ 1 I 1 ill S O _ .l qfli it-:1 '--C‘T l'\) BIOLOGY AND POPULATION DYNAMICS OF SCAD 405 connection. that fishing being prawn-biassed. in the Le values shown above. It may be the elfort is not uniformly distributed in the argued that since Decapterus spp. are pelagic. fishing grounds and this can result in the non catches by bottom trawl are not representative representativeness in the catches. of the lengths of the population. It may not hold good, in the populations of finfishes i.e. fishes of because the resources surveys conducted by l98l- 82 l 1 Q' > o l Z*8-75 ;. 1980-8i '0-Q Jl ‘Q‘-_ IlIt ~ . Z= 6~41 \Z fleaI .\-/ O l 1 ll? 1979-80 Z = 4'; T3 l r . . O 1;: -—l‘ 1—~+-—-i“—F+*~*r'=~+ *r-1~.+——1T~‘-e:r~ s =1!-v**—1-Hive? D I I 1'0 2-O t YEA RS Fi8- 3- Length-converted catch curves in D. rm-selli during different years. certain smaller lengths are not available in Rao et al. (1977) clearly show that the scads areas where fishing activity is concentrated, as are distributed in dense vertically extended Otherwise one would expect smaller fishes schools at or near the bottom during day and (smaller than the smallest fish caught) to be ascend to surface layers at night ; according to retained in the gear in large numbers since the Lowe-McConnel (1977) also, the neritic pelagic cod end mesh size -is very small. This could fishes like the scad, have the habit of forming probably be the reason for the wide difference demersal shoals congrcgating near bottom L. n ll3* ab _Q_.L “IL--l__~;l: 4—-l-<1.-..J ij _J :l- _ Ti‘:-‘~1Ti:|;— ‘ f * +1 —_-.-it— 0 O 0 0 . Q O . O . r C 406 V. SRIRAMACI-IANDRA MURTY depressions by day and moving up to feed at The non availability of smaller fishes in the night. It may noted that the trawlers at presently fished areas could probably be due Kakinada conduct fishing during day time. to the fact that Decapterus spp. are more abundant beyond 50 m depth (Vide supra) or. . as already observed by Rao et al. (1977). the current system is such that young scad probably cannot enter the fishing grounds to be captured. The data of different years also show that fishes of the length range 52-89 mm were caught Q-0 only during 1979-80 and not in other years. --_!:DIi-ii-“Zak Since it is known (Fig. 10) that te determines the shape of the yield curve, there is need to -:-:°*i 1 determine Lc of D. msselli by experimental fishing using commercial gear in areas where it occurs in abundance for any realistic advice on optimum mesh size. The yield per recruit analysis shows that ¥--r—1>:r-'|—- ‘ *"1—— :—‘—T—*-—i-"-~ Ll -0,...»-I-‘" -_- -an-\ """"' g_ _ W ‘ ' -an_ ~ eIi 0 8-Sri ,7“ QII0 1 I -soi Il E;‘UT >- A.: if ._._ g_ _ _ _ _ -7 ~.; ~_ ._ -~ %- _ .— 1 "-1 O.‘ l—F | tfi—1—3f2 | —t—1— fi 1*; 1 P I %fi T.‘ Fishing mortality mic Fig. 10. Yield in weight per recruit as a function of fishing mortality rate in D. rmelhl The numerals pertain to ages at first capture and the vertical line the present F. NQProbclb v65 of cupO ure QQ -.O _4i1:i t___L44A -4-_ 1 -i-1: L._ '—;1——l:¥~4;;l- — -v—+ per rec fl} Q ?‘I U i_'r——li| L; t—-be “*2 Mkji L "t 0 I \l\ I. ‘x\*\ % \. e-Q11 1ole 1- ;~ -4g _- -474: -— J44 Q I 4! \!I 96 99? 3: $832 BIOLOGY mo POPULATION_DYN_AM_ICS or scan 401 valueof Li: in the present study. this regulation are at I02 and 107 mm. If the average of should not be implemented. The data of these two values at 105 mm is taken as the _difl'erent years show that the smallest modal present Le the present té works out to 0.48 lengths (excluding the fishes of the length year which is almost the_ same as one of the range 52-89 mm caught only during 1979-80) te values (=0.50) considered (Fig. 10).. In this case the Yw/R reaches the maximum at F=4.4 and then declines slowly with increased 5 F. thus indicating that the effort has to be 1-s-i decreased (present F =4.75). The Yw/R as a an.\ I‘ function of tE (Fig. ll) shows that maximum nI\ 1‘ Yw/R is obtained at te=0.6. If the present te is indeed 0.5 (as mentioned above) there is scope toincrease the cod end mesh size to get increased and sustained yield. ‘Further. '(l) 1-‘ since the length at first maturity and’ Lc are at 150 mm and 158 mm respectively. reduction in mesh size will afi'ect the recruitment adversely and should not be recommended; (2) since * 3+ the Yw/R does not attain maximum with in 4. creased F at higher levels of te (Fig. I0). there -S1 : *1 is no harm to the stock evenif the mesh size I II is increased. Finally it may be pointed out that i F%F‘_—‘l"l'-i*’—’¥|’0'2 I-2 |2~2 I i._-_l i—=|"‘t'~~~r-=i—; whichever may be the optimum mesh size for A9! at lira! capture D . russelli. any regulation of mesh size or efl'ort has to take into consideration the (possible Fig, ll. Yield in weight per recruit as a function of age at first capture. The vertical line indi efl‘ect of such regulation on other species since cates the present age at first capture. the trawl fishery is a multispecies one. Raven: NCBS Al-AOARAJA, K. 1984. Simple methods for esti CMFRI 1981. Commercial trawl fisheries oil‘ mation of parameters for assessing exploited fish stocks. Kakinada during I969-1978. Mal’. Fish. Infor. Sen". Indian J. Ff:h., 31 (2). T& ESer., 31 : 1-6. —-—--—, M. J. Gnoigor, K. NARAYANAKURUP mp ——i- 1982. Trends in marine Fish production C. Susmm 1986. Yield-per recruit analyses on in India—-1981. Ib:'d., 4 : l-33. Parapenaeopsis srylifera and Metapenaeus dobsoni from Kerala State, India. J. App], Ichthyol., 2 : 1-11. --—-—— 1983. Trends in marine Fish production in Il1dl3,—-1982-'83. Ibid., 52 2 1-21. BEVE_R'l‘ON, R. J. H. AND S. J. HOLT 1957. On the dynamics of exploited fish populations. Fishery Invest, London, (2)19 : 533 pp. CUSHING, D. H. 1981. Ff-fheries biology .' study in P0PuIarion ¢_iynam:'cs. The University of Wisconsin Press, 2nd Edition, 295 pp. AND —-—--—-- 1959. A review of lifespans and mortality rates of fish in nature and their relation to growth and other physiological characteristics. GANAPATI. P. N. mp V. S. R. M0111"? 1954. Salinity Ciba Foundation Colloquia on ageing. In: G, E,W. and temperature variations of the surface waters oil‘ Wolsenbolmy and M. O'Connor (Bd,) The lifespan of animals, S 3 142-177. Yisglgaflaztnam Coast. Andhra Univ. Mem. Oceanogra, Clank, F. N. 1934. Maturity of the California KAGWADE, V, N. 1971. Maturation and spawning Sardine (Sdrdina caerulea). California Div. Fish., of the horse mackerel Caranx kalla (Cuv & val). Indian Gmle, 42:1-49. J, Fish, 15 : 207-220 (1968). 3 Y'e d per reicru I (0 + ¢__?_ ;—l:.—.l_ i 438 V. -MUR'I'¥ "L/tFo_im, E. C. 1958. Seasonal cycle of sea surface ' 1984 ~b. -Fl$h..DOfi-llfltioli dynamics . in tcmpcratlmc and Salinity along the east coastof India. tropical-waters : a manual for use with programmable Amflira Univ,‘ Mem. Oceanogn, 2: 12-21, calculators, ICLARM S!llJ§8"0Ild Reviews, ' 8 : 325 -pp; B. 0. 1951. Length-weight’ relationship Qasm, S. Z. 1973. An appraisal of the studies _oi_i and seasonal cycle in gonad weight and condition of Induration and spawning in marineiteleosts Indian waters. Indian J. FI.lll., 20 (1) : 1-6&18l. tzlg perch (Perm fluviatillr). J. Anlm. EcoI., 20 : 201 Rm, K. V. N., M. KUMARAN no J. Sanctum Lown-McCommi.i., R. I-I. 1917, Ecology of-fishes SUBRAMANIAN 1977. Resources of horse mackerel ofl’ {tithe tropical wafers. The Institute of Biology/’s Studies 1_n Biology. Edward Amold; London, '76: '1-64. 9fl‘l€8)§OliltillzVeSl : - . coast of India. Seafood Export 1.. !"MA7~m. J._I. mn,F. H. C. TAYIDR 1947. The Sarvmanaraun, A. V._ V. mo G. NARAYANAPPA rate of growth in lemon sole in the strait of Georgia. 1972. A review of experimental trawling from small and medium sized mechanised vessels off Kakinada. Rep. Fish. Res. Board Pac. Coast. Sm, 72: Fish. Technol., 9 : 97-103. Mtnmo. J. L. AND'D- PAUHLY 1983. A simple method _-~-=, -~ 7 AND D. A, N. RAJU 1972. On forFt'shby;e, comlllliw Uovrth 1 (1) of fishes I 5-6. and invertebrates.' " the comparative experiments with a four-beam and 9:two-beamgtrawls 169-17 . on the east coast. Fish. TecImol., . Mutant, M. S., K. A. Nsmsnmnii. G. SUD!-IAKARA 111.9, Y. AND P. Rmnmom 1977. Siixnnnax, K, V. 197$. Estimates of the stocks of Ofi'th'e "commercial trawl fisheries olf Kakinada during oilsai-dine and mackerel in the present fishing grounds 1967-70. Ir,I4i¢l3.J. Fish.» 22: 171-186. (1975). off the went coast of India. Indian J. Fish., 21 (1): ‘NAlAYANkPPA,- G., D. A. 1*}. Run mo A. V. V. 177-182 (1%) is 8.irvA,_t~tutAi_r)oi1\ Certain observations on the Sr-n'rl-I-VANB, W. F. 1984.‘ Carangidae. In : W, otter trawl operations carried out in the mshore and Fischer and G. Bianchi (Ed.) FAO species icientifioarion deep waters ofi‘ Ktikinadii. Proc. Illddi-PG¢”l‘C.FI'JIl. sheets(Fishing for area fishery 51), {MPO-$83. . Westem Indian Ocean PAULY, D. 1980--a. A selection of simple methods Srtimiioon, G. W. AND W. G. Cociriytit 1967. Stan £0r"the;assei~$ment_- of tropical fish. stocks. FAO Fish. stical Methods. _ Qxford and IBH publ1shin8 C0.. New Delhi, Sixth edition. 593 PP Q. Qn the interrelationships between Snaaurvasm, P. V. 1981. Observations ‘on the natural mortality, growth parameters and mean environ mental temperature in 175 fish stocks. J. Cons. int. atfishery Vizhiniam. and biology Indian. of M?mIa._ipisJ. 1312., 25: cordyla122-I40 (Linnaeus) (1978). Explor. Meta, 39 : 175-192. —-----— 1982. Length-weight relationship in ———- l982._ Studying single species dynamics Decapterus day!’ Wakiya. Ibid., 28: 283-286 (1981). in a tropical multispecles context. In : D. Pauly and G. I. Murphy (Ed.) Theory and management of tropical ----- 1933. Age and growth of the scad fisheries. ICLARM conference pnoc., 9 : 360 pp. Dwqpterus dayi Waklya. Ibid., Z92 144-150 (I982). ICLARM, Manila : Philippines and CSIRO, Croimlla : Australia, 33—70. ' ' 1934. Feeding biolofy qf. an ma 1983. Some simple methods for the Decapterm‘ dayi Waltiya. J. mar. bio . Ass. India, 21: assessment of tropical fish stocks. ‘FAG Fish. Tech. 97-102 (1979). ' ' 1109.. 234152 PP. 7 ‘Tartan. C. C. 1962. Growth equation with metabolic parameters. J. cons. int. Explor. Men, 27: 1984 a. 'Lei}Q.h-converted catch. curves : it powerful tool for t'ishet1es.resca1'ch in the tropics 270-286. ' Part II. Firhbyte, 2(1) : 17-19, " i_ Not referred-to iI1*,°li8il1l_l] PART III MIXED FISHERIES ASSESSMENT _ " .. r“ J._—*-3 LCONTRIBUT ION 19 ' MURTYI V. SRIRAMACHANDRA. 1987. Multispecies stock asse ssment with particular reference to major demersal £0fish species mar. in thebio]-0 trawling A350grounds off India’ Kakinada. J. mar.ssaria-; biol. Ass. India, 1985, 27 (1 8:2) : 39-48 ‘ E _ “ii" i——‘ ION _ 19 i MULTISPECIES STOCK ASSESSMENT WITH PARTICULAR REFERENCE TO MAJOR DEMERSAL FISH SPECIES IN THE TRAWLING GROUNDS OFF KAKINADA V. SRIRAMACHANDRA MuRTY* Central Marine Fisheries Research Institute, Cochin-682 031 Ausrrmc 1' On the basis of data of four dominant demersal finfish species landed by trawlers at Kakinada, the method of multispecies stock assessment using the Beverton and Holt model is described and the problems involved are discussed. It is shown that with the present gear in use, the efi'ort has to be reduced by about 6% to get MSY or with the present effort unchanged, the cod end mesh size has to be increased by 28 % to get MSY. The latter option is considered to be the best because the present lengths at first capture are less than the lengths at first maturity, a situation that, if allowed to continue, can lead to recruitment overfishing. Iuraooucrros years. Though this model appears to be good for stock assessment of tropical multispeeies T-ma TROPICAL marine fisheries, particularly fisheries, it has the significant draw back that it those exploiting demersal resources, take several ‘is ostensibly empirical with no theoretical basis.’ species belonging to different genera and (Larkin, 1982) and, ‘real fish stocks do not fit the families having different maximum lengths, simple models ’; besides, the curve of catch as a growth Cl13I‘2l.Cl€"lSlLiCS, mortality rates, etc. function of effort usually does not have such a For various reasons-— bcth biological and non sharply defined maximum as the parabola biological--the estimation of important para corresponding to the simplest assumption nor meters of individual species in these areas is does the maximum always occur ‘ tidily at half still diflticult, though methods to obtain reaso~ the unexploited population’ (Gulland, 1983). nably accurate estimates have recently been Further, ‘ what we gain in simplicity with the developed (Pauly, 1980 a, 1980 b, I980 c, 1982, surplus production models has the cost of a 1933; Pauly and David 1981; Jones, 1981; Jones and van Zalinge, 1981; Srinath and number of assumptions on the dynamics of fish stocks, which may be (and nearly always Alagaraja, 1982 ;Alagaraja, 1984). The available methods for stock assessment of exploited fish are) impossible to justify ’ (Sparre, 1985). On the other hand, the analytic model, which populations fallunder two main categories : the takes into account the growth, mortality, etc. surplus production (Schaefer, 1954) and the of a particular species stock, has a major analytic (Beverton and Holt, 1957) models. advantage of the ‘ existence of an established In the former, all the species together are body of theory and methods for dealing with treated as one species and the data required single species ’ (Larkin, 1982). However, since are only effort and catch for over a number of several species are exploited by several gears * Present address: Kakinada Research Centre of in the tropical seas like those of India, single CMFRI, Kakinada-533 002, India. species assessments do not generate meaningful 40 V. SRIRAMACHANDRA MURTY management options. So far as the author is collected at weekly intervals. The data of aware, there has not been any attempt to assess each observation day were given weightages multispecies stocks using analytic models excep to ultimately obtain monthly estimates. ting Munro (1983) who considered the problem in general terms and Mennes (1985) who Estimation of parameters : Parameters of attempted stock assessment of s parid species off growth in length were estimated earlier (Murty, western Sahara region using his (Mennes, 1983) MSS) using the data of 1980383 and the integ computer programmes. From India, there has rated method of Pauly (1980 a) in N. japonicus, been practically no attempt in this regard. J. carutta and S. insidiaror whereas in L. bindus they were estimated using the data of 1979-’8l Among the demersal fin fishes landed by and following the modal progression method. private trawlers at Kakinada, sciaenid, leiog For estimating all other parameters and yield, nathid and nemipterid fishes are most dominant the data of 1980-’83 only were used. and Johnius camtta, Leiognathus bindus, Secutor insidiator and Nemipterus japonicus The coefiicient of total mortality (Z) was estimated following the length-converted catch are most dominant in these three groups. The curve method of Pauly (1982); the average present paper describes the method of assessing of the four-year period was taken as the present multispecies stocks, taking into account the value. The coeflieient of natural mortality above four species. Studies on the biology, (M) was calculated using Pauly’s formula mortality rates and yield per recruit of these (I980 b) taking the average water temperature four species were made earlier (Murty, 1983 a, as 27.2° C and K per year. b, 1984 a, b, MSS). The length at first capture (Ls) was estimated The author is thankful to Dr. P. S. B. R. following Pauly (1984) and the smallest length James, Director, CMFRI for the encouragement in the catch was taken as length at recruitment and to Mr. C. Mukundan, Head of Demersal (Lr). Fisheries Division, CMFRI for the useful criticism. Thanks are due to Mr. P. Rama Yield-per-recruit 1 The yield in Weight per lingam for the assistance in the collection and recruit (Yw/R) was calculated using the well analysis of data. known Beverton and Holt (1957) yield equation. In each species the value of Wm was calculated with the help of Length-weight relationship and MATERIAL AND Mernoos the estimated value of Lot. Catch and effort : Data were collected from Multispecies assessment : The values of the the landings of private trawlers operating off catchability coefficient (q=F/E) were calculated Kakinada (Lat. 16°35’-17°25’ N ; Long. 82°20 ' following Ricker (1975) and Pauly (I980 e), 83°l0' E). Boats of three different sizes taking into account the present value of fishing operate in the region (CMFRI, 1981). Since mortality rate (F) of each species and the present the Pomfret-R-oyya category is the most domi average annual effort (E). The resultant values nant one, the effort (units as well as trawling were used to derive values of F : taking a set hours) put in by this category was taken as of values of effort, values of F for each species standard elfort and all the demersal groups corresponding to the same effort were calcula landed were together considered as one group ted (F=Eq). The F values thus obtained were for standardising the effort. The data on effort used to calculate Yw/R in each species; this and catch were collected for about 18 days each enables plotting of yield per recruit against month and samples for biological study were effort instead of against F. ASSESSMENT OF DEMERSAL FISHES OFF KAKINADA 41 For each species, the selection factors (SF) values of all species corresponding to a parti of the gear under operation were calculated cular effort level or cod end mesh size were as SF.=present Ls/present cod end mesh size pooled to get a yield curve common to all (Jones, 1976). The cod end meshes (stretched) species as a. function of effort or mesh size. were found to vary from 15 to 20 mm with the average at 15.6 mm, ‘hence this was taken as The values of effort or mesh size against which maximum yield is obtained were considered the present cod end mesh size. A set of values of cod end mesh sizes (MS) were taken as those giving maximum sustainable yield (MSY). L, values for each species corresponding to these mesh sizes were calculated as LC:-SF X MS. These LC values were converted into tc OBSERVATIONS AND Rusurrs and the to values thus obtained were used to calculate Yw,’R, thus providing to plot Yw_l’R Catches: The demersal component in the against mesh size instead of against to. catch during the period under study (1980-83) formed about 66% of the total trawl catch. ln each species, the present values of F and Sciaenids, silverbellies and threadfinbreams Ywj R were taken and the present biomass per together contributed about 2670 tonnes (annual recruit (B/R) was calculated as Yw/R+F. average, Table 1) forming about 18.5% of TABLE 1. Particulars of catches (tonnes) of different groups and species and the effort during different years by private rrawlers at Kakinada. v "— ” 7 ’ “T -' * " "Z - - —' - — *_- _* %+— izimiv ‘ ‘ . i_ ._r;':_:*+m 1980 1981 1982 1983 Average 1-._%__; .._._. fez _ ; _ ..______~_- , __:_- _ _ .. .r _ _ _, Total trawl catch 9,911 9,275 16,554 21,857 I4, 399 Catch of clemersal groups 7,155 6,928 9, 854 14,053 9,498 Catch of sciaenids, silver bellies and threadfin breams 2,348 1,641 2,712 3,977 2,670 N. japonicus 261 201 632 365 365 J. carufla 410 132 60 167 192 L. bindas 269 246 428 612 389 S. insidlamr 168 252 323 725 367 Standard efl‘0rt No. of units 48,144 42,954 62,000 50,450 50,887 Trawling hours . . 3,22,655 3,84,436 4, 59,599 3,2s,461 3,’/3,788 _;_;:*_;_ii _ 7 _—<~ _ ' am a ———'— The average biomass (B) of each species in the total trawl catch and 28.1 % of total demersal fishing ground was calculated as Y/F where Y catch. An estimated annual average of 1,313 is the annual average catch of a particular tonnes of the four species under consideration species and F the present value of that species. were landed, together forming about 50% Prom these values, the recruitment (R) was of the above three groups. Except S. insidia calculated as B-e~B/“R and the resultant value tor, the catches of which showed an increasing was taken as constant. In each species, the trend in successive years irrespective of fluc Yw/R values at , different levels of effort or tuations in effort (Table 1), there is no clear mesh size were multiplied by the R value of that trend in the landings of the other three species to enable to obtain yield. The yield species. 42 V. SRIRAMACHANDRA MURTY Parameters of yield equation : The estima effort should be 128°/, of the present and the ted values of diiferent parameters are shown in yield will only be 100.6% of the, present (Fig. 2). Table 2. It is observed that in all four species, Further, this increase in yield is obviously only the lengths at first capture are smaller than due to increase in yield of S. insidiaror-a those at first maturity. smaller species (Table 2) whereas there is Estimation of yield : The yield in weight bound to be a decline if the effort is increased as a function of effort (Fig. 1) shows that MSY in the yield of the other three species (Fig. 1), is obtained at different effort levels in different two of which attain greater lengths (Table 2). EFFOR "S3O T'“_1' 3130 1 fii7l":'1'_*?"[ T X _ ' 7'IOOO '_l ”_l?'1‘“—i; H8_3H)RS F" ;'~.—_j_‘?-—l:;—-_--i. . * _ -r ff-.1‘ _~ ? I} I ‘ ‘ — if‘;-' ' l——-— '7 7.". _;__~— _V __ i All species S Z 4 ; HOO]l A e+l we _ t I1 t -I I -4: ...F | 1 04Ii \ .______if __ ;___V_’ ____ '1»; _‘_ "HT __ -_F“, ' - ___ '7 ~ __,.,_-¢~;? ‘ - ,7“, -0- ___ v- "-_"-"_. __ ___ 1t _|_.b‘;[1dgiS—_'“' .-v '- ‘ti i V i " -‘- 7 ._.:~*;_ _ , in ' -I . . r - ~~—- P _ _:41 /.-nIV’-""' 1.‘. 5.21 onrcus i '1”.L / _. .___/' 1 .1»(1 ’“ r" ~ %— __q l.f --1* _ P. _J_-cartifta 551,§:=l _.t..s1__|g _t:_t+1, L ..t__L ,L._.4._. H4;-L...... L__1, 4;; 1 ._ L ___t,_,|_- L: t L'_T7L 4 44EFFORT 84 X POOO UNITS FIG. 1. Yield as affunction of fishing effort with the present gear. The smaller vertical lines on each curve indicate the MSY and the bigger vertical line the present efibrt. species with the present gear in use ; in S. insi If S. insididtor is ignored, the MSY of the other diator, however, there is no maximum in the three species together can be obtained at an yield. In L. bindus and J. carutta, the present effort level slightly less than (88°/O of the effort is greater than the one that gives MSY present) the present one (Fig 1 and 2). Since whereas in N. japonicus it is slightly less. The decrease in efl'ort does not result in any harm pooled yield curve of all species, however, to the resource of S. insidiator, decreasing the shows (Fig, 1) that there is scope to increase same slightly will ensure sustained returns of efi'ort to get MSY, but to get the same, the these commercially valuable species. ' Y E._D -TONNE S tn <.n O .—J~ In"-‘IQ ASSESSMENT OF DEMERSAL FISHES OFF KAKINADA 43 The yield as a function of cod end mesh It was also observed (Murty, MSS) in the size (Fig. 3) with the present rates of mortality eases of N. japonicus, J. -carutta and L. bindus (Table 3) operating, shows that for all species that the effort giving maximum yield is greater except S. insidiazor, the present mesh size is if the age at first capture is increased. For the mach less than that which gives MSY. In all management of the resources of these species the four species together, the MSY is obtained at (ignoring S. insidiator for reasons“ explained a mesh size slightly less than the present one, z‘.e. above) thus, the following options are available. Q;‘. __ 1». ~ =<-'__.;*|-:n ,l. pt. H.’ MAI,‘ l %~_,I 'SPQCEOS ' l '_—_ —e — wa4 asX ,/' /. i *¢lud . "~ m9 S |n,idia';;'r_O ./0/ . U1U ' 5 ' E3>- ,4‘ t_. 1 .L| .1 .1,so F*1. 1 F f"] Etfort {hours} as % of present Fro. 2. Yield as percentage of present against. effort-also as percentage of present. The smaller vertical lines indicate maximum values and the horizontal and vertical lines the present values. at about 96 ‘X, of the p1'CS61'|t mesh size (Fig. 4)- (i) to decrease the present effort by about 6% and to retain the present cod end mesh this situation, again, is brought about by size; S. insidiazor. If this species is ignored, the (ii) to increase the cod end mesh size about mesh size can be increased“ to about 135% 20 mm and to retain the present effort, or of the present,to get over 11.0% of the present (iii)_ to increase both cod end mesh size and etfort. yield2 of the other three species (Fig; 4). 4 ._. . ~°/0 of present 44?U1 -4 .4 _1 lg J at O E‘ R t .\.\ I 44 V. SRIRAMACHANDRA MURTY Of these, the second one appears to be better because of lack of knowledge of effective effort because, while giving sustained yields, this in respect of a particular species and, because measure will also ensure adequate recruitment. it is also known that{'any attempt to relate multispecies effort to Z of a particular species DISCUSSION may, not only result in unrealistic estimates Among the available methodS of estimating but in certain cases negative values also natural mortality rate of exploited populations (Ricker, 1975; Pauly, 1982). Though the U 1-: 1 l I 1 IOS0'1 -qr l I . f%__\~‘ % > IH 1|s é ‘ | sotf. +<>° ‘vQ&\‘ r 0% J Lvbhdus 1 l ..---°"""'"'_"..‘__.“‘° . W. \°‘ ‘ N-japcnicus l 2» .'~°"‘b I '/ J-carutta , .,w’./0',’ | i A' * J’; l S0 ./ l ' e-it i ——i‘* I;-111-;l"“§—“l“*‘l‘_‘1‘ |- -1 |-L1-——$T 1 — r 1-1—— ~—F* "I_““‘ COD END ME5'>H SIZE mm 2‘ F10. 3. Yield as a function of cod end mesh size with the present effort unchanged. The smaller vertical lines indicate MSY and bigger vertical line the present cod end mesh size. the one in which the changes in total mortality equation. of Pauly @1980 b) helps in estimating are related to changes in fishing effort using a reasonably reliable value of M, the value the equation Z=-M-{-qf (Beverton and Holt, of the other constant in the above equation —— 1957) gives an accurate estimate in addition to the q ——has to be estimated through some giving an estimate of catchability coefficient. other method. Pauly (I980 c) states that the This was not possible in the present work method of obtaining this as a ratio of fishing YE L2 - TONNE S +- +5.3 €0,%‘ ‘I 45¢ Q’. .100, ASSESSMENT OF DEMERSAL FISHBS OFF KAKINADA 45 mortality rate of a particular species and effort (b) estimate of M and hence of F for each (even a multispecies one), ‘can now be used species can be obtained without taking the as a routine method, since it is easier to estimate multispecies effort into account and M than to estimate q’. Although it may (c) values of q of different species can be appear that the q value thus obtained cannot derived using the same efl'c-rt value. be regarded as realistic for the same reason as pointed out above, it is believed that in It must be accepted, however, that this is multispecies assessments, this approach, which all that can be done under the prevailing situa T ’,,..o""""'+""*I_\ ,/1_//'| I /_/ ' ~ spa0'9Q/' r 4”8 .4s°“.4,_//Q, __ll/'e° ./.o<°+,/ Q...-4 ;/ ./ i. '1 5 1 il 5? YT8 —i F T1.8 ‘ l""_i ‘ii I F f "1:90 I 1 -i* I --til‘? l132 *|*——I I -|--*1——{.“; Cod gnd mesh size as 0/O of present FIG. 4. Yield as percentage of present against cod and mesh size — also as percent of present. The horizontal and vertical lines indicate the present values. takes into account the catchabilitics of all tion and there is need to develop methods species, can be followed with reasonable justifi to obtain more reliable estimates of M and q cation because : in tropical multispecies fisheries. (a) ‘ each unit of fishing gear will generate The reliability of the estimated values of a certain amount of mortality in each species Yw/R and recruitment in the present work in the fishery (defined as the ‘ catchability ’ q) tvide supra) can be {questioned on two (Munro, 1983). Counts: Yed rt5./I of present (D (D 1-fl -5?“ J—._:l—_~ e '45 46 V. SRTRAMACHANDRA MURTY The Ywl R was estimated following Beverton |¢8$s ever if recognised to be. in error the Holt yield equation which assumes growth in methods do provide useful first estimates and weight with length to be isometric, whereas the insights into what is taking place ’. Further, situation in three of the four species considered, since the species considered here, like majority is not so (in L. bindus, however, the ‘ b ’ value of tropical marine fishes, are short-lived and in length-weight relationship is not significantly the fishable life-spans are still shorter (Table 2), dilferent from 3) and therefore the estimated it is believed that there is justification (Pauly, values of Yw/R and hence R cannot be taken 1982) in making estimates as above. 21$ 63.8011 . According to Jones (1976), the selection In answer to this, it may be stated that factors for fish tend to range from about 2 while the value of Woc taken is exact (vide to 6 and once the selection factor is determined supra), only for a part of the computation of for a given species and a particular cod end Yw R, the exponent value of length-weight mesh size, it can be used to calculate LC for relationship (b) was, perforce, taken as 3. a given mesh size or vice versa. From the Even the method of Jones (1957) which is Gulf of Thailand, the selection factor was supposed to take into account the exact value estimated as 3.2 for both N. japonicus and of ‘b’ and hence give accurate values of J. carutta (Isarankura, 1966 ; Jones, 1976) with Yw/R, does not do so because in the available the help of a trawl net having a cod end mesh tables of incomplete Beta function such as size of 40 mm. In the present work, since those of Wilimovsky and Wicklund (1963), selection experiments were not conducted, the the differences between successive entries are L, values were estimated following Pauly large and linear interpolation is not accurate (1984) and from these values (Table 2) (Clark, 1978) and hence, it is not possible to and the cod end mesh size at Kakinada, the use the exact value of b. Therefore, it appears selection factors of the above two species were that the use of Beverton-Holt yield equation, calculated as 7.7 and 8.3 respectively (3.7 in under the assumption of isometric growth, is L. bindus and 5.1 in S. fnsidiator) which are not the only alternative (however disagreeable it only beyond the range given by Jones (1976) may be) if one cannot calculate yield using a but are also much greater than the values for computer. Further since the important objec these species estimated from Gulf of Thailand. tive of tne present study is to examine whether lf the selection factor of 3.2 is taken for any regulatory measure in respect of effort or N. japonicus and J. carutta, the LC values are mesh size is necessary, it is believed that the estimable at 50 mm from Kak nada whereas method followed gives the desired results. the data show that the lengths at recruitment It may be mentioned in this connection, that (L,) of these two species were 50 and 70 mm Clark (1978) has clearly shown that both the respectively and an L, of 50 mm (50% reten methods of calculating Yw R (original as well tion length) cannot be regarded as realistic. as the modified versions of Beverton-Holt Since the S.F. values of these two species from model) will produce the same regulatory Kakinada are not comparable to those obtai recommendation. ned from Gulf of Thailand, the validity‘ of the One of the prerequisites in estimation of estimated values of LC in the present work may Yw/R by Beverton-Holt method and R by the become questionable in view of the smaller equation B+B/R is the requirement of steady cod end mesh size, though all possible care state condition which is difficult to verify and was taken to obtain adequate data and the most which is ‘ patently false ’ (Murphy, 1982). recent and acceptable method was followed to However, Murphy (1932) states that ‘ Neverthe estimate Le. It may be stated that the present ASSESSMENT OF DEMERSAL FISHES OFF KAKINADA 47 situation has arisen probably because of prawn are smaller than the lengths at first maturity biassed trawling which is restricted to areas (Table 2); which means that the fish are preven ‘supposed ’ to be rich in prawns and where ted from spawning at least once before they smaller individuals of N. japonicus and are caught in large numbers. In S. insidiator, J. carutra are probably notavailable to be the present cod end mesh size is much greater retained in the gear. than the one that gives maximum yield (Fig. 3). In the light of what has been stated above, The combined curve of yield of the four increased mesh size may not efiect the stock of TABLE 2. Estimated values of different parameters in the four species. (All lengths in mm, weight in g, ages in years, K~per year and mortality rates on annual basis) Parameters N. japonicus J. carurta L. bindus S. insidiator ‘ "t_—' :-—~n._>Ti_--_?—_--- '_ 1.4 . . 339.0 333.3 158.4 1'23 1') aw‘ . . 389.7 529.0 54.7 28.0 K . 0.52 0.44 0.58 1 .20 . . -—-0.16 -0.0002 --0.024 -0.01 2.7 5.1 4.4 7.2 1.1 1.0 1 .5 2.6 . 1.6 4.1 2.9 4.6 LsLr . . 50120 70 17 27 Lm . . 125 130155 8057 9080 Lulu . . 305 255 142 117 Ir 0.15 0.54 0.17 0.20 l.c 0.68 1.12 0.75 0.87 llm 0.72 1.42 1.19 l .09 limb: 4.26 3.29 3.89 2.51 (immrl-c) . . 3.58 2.17 3.14 1.64 * Calculated from length-weight relationship and L4. species against effort (Fig. 1) indicates that this species adversely though it may result in the clfort can be increased substantially to get decrease in yield. Since the largest size of this maximum yield without any fear of adversely species is itself small, decrease in mesh size affecting the stocks, though in respect of may result in increased yield brought about three species (N. japonicus, J. carmm and by the yield of still smaller fish which are not L. bindus) together (Fig. 1), the effort can only cf considerable value to the industry. In be slightly less than the present one to enable regard to the other three species, the present getting sustainable yield. This contradicting mesh size will not only result in decreased situation has come about because the yield yield but is likely to result in recruitment over of S. insidiator increases with increased effort fishing of these three species; the latter is without reaching a maximum (Pig. 1). The true in the case of S. insidiator also. There is estimated values of L; in all the four species therefore, need to increase the present mesh '-ngw-"’ 48 V. SRIRAMACHANDRA MURTY size to 20 mm (Fig. 3) to get sustained yield actions do occur, it is not clear whether they though it may result in some loss of S. insidiator exert such an influence on the stocks that for the fishery. In this connection, one can ignoring them would lead to erroneous results argue that increase in numerical strength of this (Larkin, 1982). species in the sea brought about by increase in mesh size can result in greater competition Though the present study did not take all for food particularly in earlier stages (since the species in the fishery into account, it is most tropical fishes spawn almost round the believed that the results of the same can be year) and thus can cause depletion of the taken to indicate how the other demersal preferred species in the long run (Gulland, species in the region might respond to exploi 1982). It is also possible that the increased tation because, since the four species consi numbers of S. insidiator thus available in the dered have widely difiering maximum lengths sea (at least some) may be consumed by preda (Table 2) which are comparable to a majority tors inhabiting the same area. It may, how of the other demersal species in the region, it is ever, be stated that management of multispecies perhaps reasonable to assume (at least until resources requires a knowledge of possible information on all species becomes available) interactions between species and attempts that the growth and mortality rates of the other at understanding them are wanting in India. species in the fishing ground are also com Though it is recognised that interspecies inter parable to those of the species considered. Rzreneucns ALAGARAJA, K. 1984. Simple methods for estima JoN_as, R. 1957. A much simplified version of the tion of parameters for assessing exploited fish stocks. fish yleld equation. Contribution to the Joint Scientific Indian J. Ft‘sh., 31 (2) : 208. 2hgeegng : pp. of ICNAF/ICES and FA 0, Document No.; BEVERTON, R. J. H. AND S. J. Hon" 1956. A review of methods for estimating mortality rates in exploited -——~—— 1976. Mesh regulation in the Demersal fish populations, with special reference to sources of Fisheries of South China Sea Area. South China Sea bias in catch sampling. Rap. p. v. Reun. Cons. perm. Fisheries Development Programme, Manila. SCS/76/ int. Explor. Meta, 140 (1) :67-83. WP/35 : 75 pp. —---——- 1981. The use of length composition data —---- mo --—-—— 1957. On the dynamics of in fish stock assessment (with notes on VPA and Cohort exploited fish populations. Fishery Invest, London Ser. (2), 19 :1-533. * analysis). FAO Fish. Ci'rc., 734 : 60 pp. CLARK, W. G. 1978. Dynamic pool models. In: ---- AND P. N. VAN ZAUNGE 1981. Estima. Models for fish stock assessment. FAO Fish. Ci:-c., tion of mortality rate and population size of shrimps 701 : 17-30 . in Kuwait waters. Kuwait Bull. Mar. Sct'., 2 :273-288. CMFRI 1981. Commercial trawl fisheries ofi‘ LARKIN, P. A. 1982. Directions for future research Kakinada during 1969-1978. Mar. Fish. Infor. Serv. in tropical multispecies fisheries. In: D. Pauly and T. & E‘. Sen, (31) : I-6. G. I. Murphy (Ed.) Theory and mrlnagemettt of gopiggl fisheries. I CLA RM Conference Proceedings, GULLAND, J. A. 1982. The management of tropical : 3 pp. mutispecies fisheries. pp. 287-298. In: D. Pauly and *MBNN£s, F. 198$. Descriptions, examples, tests, G. I. Murphy (Ed.) Theory and managetnent of tropical printouts, plots and listings of programs which process fisheries. ICLARM conference proceedings, 9 : 360 pp. the data of bottom trawl surveys of south-Morocco; ---—— 1983. Fish stock assessment: A Manual 231 pp (Mimeo). of basic methods. FAO! Wiley series on food and. '—----— 1985. Multispecies assessment of fish agriculture, 1 :223 pp. stocks of-1‘ the Western Sahara region with emphasis on the family sparidae. Fishbyte, 3 (3) : 5-10. *ISARANKURA, A. P. 1966., Size selection of some commercially important species of Gulf of Thailand Muuao, J. L. 1983. Aeost-efi’ective data acquisi ersal fish by otter trawl cod end;1_nesh_size-of-4 cm._ tion _systegn for assessment and management of tropical Mar. Fish. Lab.) Bangkok. multispectes, multl-gear fisheries. "Ibtd., 1 (1') : -7-lI_. ASSESSMENT OF DEMERSAL FISHES OFF KAKINADA 49 MURPHY, G. I. 1982. Recruitment of tropical ~——--- 1980 c. A new methodology for rapidly fishes pp: 141-148. In: D. Pauly and G. I. Murphy acquiring basic information on tropical fish stocks: (Ed.) Theory and management of tropical fisheries Growth, mortality and stock recruitment relationships. ICLARM Conference proceedings, 9:360 pp. In: S. Saila and P. Roedel (Ed.) Stock assessment for tropical small scale fislterles. Proc. Intern. Workshop Munrr, V. SRIRAMACHANDRA 1983 a. Observations Sept. 19-21 (I979). Univ. Rhode Island, Intern. iii some aspects of biology of silverbelly L-ei‘ogna1hus Center Mar. Res. Development. 198 pp. bindns (Valencienncs) from Kakinada. Indian J. Fisli., 30(1) : 61-68. —-—---~ 1982. Studying single species dynamics -—---— 1983 b. Estimates of mortality, popula in a tropical multispecies context. In: D. Pauly and tion size and yield per recruit of Nemiprems japonicus G. I. Murphy (Ed.) Theory and management of tropical (Bloch) in the trawling grounds ofi' Kakinada. Ib:'d., fisheries. ICLARM conference proceedings, 9 : 360 pp. 30 (2) : 255-260. -~—-—-—- 1983. Some simple methods for the —--—-—- 1984 a. Obscrvatioiis on the l"isl1eri_es of assessment ol’ tropical fish stocks. F.--IO Fisli. Tech. thread finbrcams (Nemipteridae) and on the biology Pap., 234 : 52 pp. of Nemiprerus japonicus (Bloch) from Kakinada. Ibid., 31 (1) : l-18. ---—-~ 1984. Length-converted catch curves: -----— 1984 b. Observations on some aspects A powerful tool for fisheries research in the tropics of biology of the croakers Jolmius (iolmieops) dnssumieri (Part II). Fishbyte, 2 :(1) : 17-19. (Cuvier) and Johnius (Johnius) carutra Bloch from Kaitl nada. J. mar. biol. Ass. India, 21 (l & 2) : 77-85 (1979). ----— AND N. DAVID I981. ELEI-‘AN, l, a basic programme for the objective extraction of growth para ----— (in press). Growth and yield per recruit of Jolmius (Johnius) carutta Bloch in the trawling grounds meters28 1205- grom 11. length frequency data. Meeresforsch, off Kakinada. Indian J. Fr‘sli., 33 (2). RICKER, W. E. 197$. Computation and interpreta ------(MS). Studies on the growth and popula tion of biological statistics of fish populations. Bull. tion dynamics of the silverbelly Leiognathus binclus Fish. Res. Bd. Canada, 191 : 382 pp. (Valenciennes) in the trawling grounds ofl" Kakinada. _SCI-IAEPER, M. B. 1954. Some aspects of the dyna ---—---— (MS). A study of the biology and popula mics of populations important of the management of tion dynamics of the silverbelly Secutor lI1Sl(ll(1(0I' marine fisheries. Bull. I-ATTC., 1 (12) :25-56. (Bloch) from Kakinada. SPARRE, P. 1985. Introduction to tropical fish ------(MS). Further studies on the growth and stock assessment. Denmark Fluids-in-trust. Fl : GCPI yield per recruit of Nemipterus japonicus (Bloch) from INT/392,lDEN Manual, 1 :333 pp. the trawling grounds ofl‘ Kakinada. PAULY, D. 1980 a. A selection of simple methods Snirtnrn, M. mu K. ALAGARAJA 1982. A method for assessment of tropical fish stocks. I-‘A0 Fish. of estimation of mortality rates from length samples. Circ., 729 : 54 pp. Indian J. Fisln, 28 : 183-188 (1981). ---— 1980 b. On the interrelationships between *WILIMOVSKY, N. J. AND E. C. WICKLUND 1963. natural mortality, gro wth parameters and mean environ Tables of the incomplete Beta functlon for the calculation mental temperature in 175 fish stocks. J. cons. int. ofFish population yield. University of British Columbia Explor. Men, 39 : (2) : 175-192. Vancouver, B.C., 291 pp. _* Not referred to in original. icowraxsurzon___ 20,_ _ __.1i MURTY, V. SRIRAMACHANDRA. 1989. Mixed fisheries assess ment with reference to five important demersal fish species landed by shrimp trawlers at Kakinada.p 69-86; ig: Venema, S. C. and N. P. van Zalinge (eds) Contri IQ“-1°1I!$=»S9e trsuzésael if 1512 5 *"-Q¢1<"_ss§@ Bsmsnetligzelendia Papers prepared by the participants at the FAO/DANIDA/ ICAR National Follow-up'Training Course on Fish Stock Assessment. FAO Rome, 157 pp. lCOl~i'I;RIBU"I‘IONw20I DENMARK FUNDS—IN~TRUST GCP/INT/392/DEN/1 CONTRIBUTIONS TO TROPICAL FISH STOCK ASSESSMENT IN INDIA § . Papers prepared by the participants at the FAQ/DANIDA/ICAR National Follow-up Training Course on Fish Stock Assessment Cochin, India 2 — 28 November 1987 edited by ProjectS.C. Venema Manager N.P. -- Consultantvan Zalinge Rome,FAD Italy - Rome,EAO Italy FOOD.AND.AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Rome, 1989 A . _ ___ L’ ' ia The designations employed and the presentation oi material in this It publication do not imply th_e expression oi any opinion whatsoever on the pan of the Food and Agriculture Organization of the United i Nations concerning the legal status oi any country, territory, city or areaor orboundaries. oi its authorities, or concerning ' the delimitation oi its frontiers ‘J '4" ‘ W — ~ fa-;:r‘_~_ - ' _ _ All rights reserved, No part oi this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechani cal, photocopying or otherwise, without the prior permission ol the copyright owner. Applications for such permission, with a statement of the purpose and extent of the reproduction, should be addressed to the Director, Publications Division, Food and Agriculture Organization oi the United Nations, Via delle Terme di Caracal|a,0O100 Rome, Italy. © FAO 1909 _ 69 _ MIXED FISHERIES ASSESSMENT WITH REFERENCE TO FIVE IMPORTANT DEMERSAL FISH SPECIES LBNDED BY SHRIMP TRAWLERS AT KAKINADA by V. Sriramachandra Murty Kakinada Research Centre of CMFRI Kakinada — 533002 India F--- --I TilI ABSTRACT I -as I I Data collected on five species in the by—catch of shrimg itrawlers at Kakinada (Andra Pradesh) during 1984-86 are used yfor a length based cohort analysis and Thompson and Bell‘ ‘assessments. An assessment of this mixed fishery is alsq carried out. The methods used are described in detail an iassessvproblems mixed involved trawl fisheriesin estimating are discussed.the important Growth parameters parame ta iters and mortality estimates for l‘~1em_ipgt.e_ru,s japonicus, Ij_.M :E§§QE£l2Q'Kakinada.insidiator were Q9§Pi9$ taken ?a§Qt§§' from publishedfiworfi Pei°9"§tDU§ biDQU$ on*resources and 3eCut°%y of Ll.-xi-r-I l-ii__e.;ee_..e_--_eee_:_i:eeI_~_;L\ 1 INTRODUCTION In the trawl catches at Kakinada, some fishes of the families Nemipteri dae, Sciaenidae and Leiognathidae are very important. They constituted over 20% of the total average annual trawl catch of 19,525 tonnes during 1984-86. Various aspects of the biology of the dominant species in these groups Nemipterus japonicus, §. nmsoprion, Qohnius carutta, Qeiognathus bindus and Secutor insidiator, were studied earlier. The mortality rates and yield per*ra¢£uit‘¢r four of the above species were estimated on the basis of data collected up to 1983 (Murty 1982: 1983; 1983a: 1984; 1984 a; 1986; 1986 a). However, studies pertaining to mixed fisheries assessments which help in regulating the fishing effort and mesh size of the nets effectively, are lacking. An attempt is made in this paper to assess the resources of the above five species together on the basis of data collec ted during 1984-1986. For the mixed fisheries assessment to be meaningful, it is necessary to take into account the majority of the species, particu larly the more valuable species like shrimps. As the present study does not take into account the shrimps, it should be considered as a beginning for a more detailed study. 1-1 Psssrinfiiov at the_fi$hsr2 Small shrimp trawlers started operating off Kakinada in 1964. The industry has expanded substantially, particularly due to the lucrative export value of shrimps. During 1984-86, an average of about 120 boats was in opera tion. The length of the trawlers ranges from 9 to ll m. The trawl gear is made of synthetic monofilament twine of 0.5-1.0 mm diameter, and it has a codend mesh size of about 1.6 cm. Fishing is conducted at depths ranging from 5 to 80 m but mainly in the 5-50 m depth range. Several species con tribute to the fishery and data are regularly collected for 40 species or species groups. Shrimps, sciaenids, silverbellies, nemipterids, ribbon fish, scads, drift fish and lizard fish are the more abundant groups (Muthu gt gl., 1977 and CMFRI, 1981). From year to year there are varia N_@N B.¢¢ ©_© @_@@ @_¢M | QDOHU way MO :OpflU wcp CH w m_Hm.N _O.¢ m_o m_N H.mNob@_mCUPMUHQPOP ®m©H0>0 N©NNON@@H®@mWWW OQB ®@ Bfifi ®@© @m¢ ©¢ wmfi N©@ OPQ @OH @H@ K Ofim NWOH @NH m®@ @©BH©O@HFB©H@NBH©OVHNB¢HWHDH¢mNH@©B@@©wvmO©OH@Nm@Hm¢¢NNHm¢®fi@F©BHNm¢©mm wmm“w>< NWmw©m CQQH ©m¢O@m WQOH FQWOHW QQOH HOPMHU Op COHHQ WDOHC |HmCH_m MDUcHn.Q |pDHMU.G |Om®E_z |OQ0h_z W®HO®Qw xn WQ£UpMU WQMMHQQ |_H@>H_H_m MUHC mofihwp |®MHOm |QHE@z Qjohm “Q m@£OPmU SUPMUHGPOBWHQU»PMo%wmMHUHSQHF HQMOHUEOU Us“ Mwfiflfixfix PM omtqwmfl mflflkfiu MUHUUGW USN MQSOHG HUHSUHQHQQ NEON HO WU£UpQO On“ “GM Apv £OpfiU HMvOp _AmN5O£ mCwH3fiHuV PHONMU UUPMEHPWM Am£PmcmH Adm mfipocmfl Hfim mQPmcwH Ham WSPOCQH HHO Ucowwn 0 _mM new E0 NH OPQ5 fiHMW@‘Um0%‘WmWm_WmHopflfluflwcfl WSUCHDQppDHMUCOHHQOWQE WDUHCOm0fl m_zW‘J‘hUUHHQWmfluwamN mdflmfi tions in the abundance of the different groups, within the year, though, the maximum catch is obtained from December to March in most years. The boats land the entire catch without discarding, because also the trash fish has some value as poultry feed, manure etc. Some prices of fish at the landing centre are presented in Table 1. The estimated total annual effort and the catch of the different groups considered in this paper are shown in Table 2. 1.2 Qotes on biology Estimated values of the von Bertalanffy growth parameters, length and age atunder first maturity,study are natural given mortality in Table (M) 3.and ma L X of the five species Information on the biology of Q. japonicus from different centres in India other than Kakinada is available in the works of Krishnamoorthi (1973, 1976), Dan (1980), Vivekanandan and James (1986), Vinci and Nair (1975) and Vinci (1983). It has been shown that this species is a fractional spawner. The spawning period off Kakinada is from August to April (Murty, 1984). Further north (Andhra Pradesh—Orissa) this species spawns during September—November and further south, off Madras during June—March. For Q. mesoprion, the spawning period was determined as December~April. Also this species is a fractional spawner (Murty, 1982). For Johnius carutta, the information on biology is restricted to the accounts of Rao (1967) and Murty (1984 a, 1986). This species is also a fractional spawner with a spawning period from January to June. For peiggnathus bindus the available data show that the spawning season is during December-February off the southwest coast (Balan, 1967) whereas the study of material at Kakinada shows that this is a fractional spawner and that it spawns almost through out the year (Murty, 1983). For gecutor insidiator Pillai (1972) showed that this is a fractional spawner with a protracted spawning period. Murty (MS) showed that this species spawns almost throughout the year. 1.3 Data base During 1984-1986 data were collected on the landings of the small commer cial trawlers operating off Kakinada (16°35'-17°25’ N, 82°20‘-83°10‘ E). Data on effort and the landings by family groups were collected on about 18 days in a month and samples for biological studies were obtained on 6-8 days ixxaa month. Excepting silverbellies, length data were collected at the landing place for all species. The data on effort, catch, species composition and length composition collected on each observation day were weighted following Alagaraja (1984) to get monthly estimates. The monthly estimates were pooled to get annual estimates. Parameters of growth estimated earlier using the integrated method of Pauly (1983) in Q. japonicus, Q. carutta and §. insidiator and following the modal progression method in E. bindus and §. mesoprion (Murty, 1982; 1986, 1986 a, 1987, MS) were used in the present study. The natural morta~ lity range was estimated using Pauly's (1980) formula; for this purpose the average water temperature was taken as 27.2° C from the works of Gana— pati and Murthy (1954) and La Fond (1958). 2 METHODS Yield and biomass estimates were made using a micro computer with the help of the LFSA package, Sparre (1987). An assessment of the mixed fishery was made based on length frequencies, using the length-converted Thompson and Bell analysis developed by Sparre (1985). For easy reference the theory and method are described below. COHPMDUQ LPZOHQ NPHQQEOO Q3” £mDOH£p WHOPQEMHMQ np3OHm UOPMEHPMQ Amwmfiv Oflm UCM Omm A* UO£P®E©0pmummPCH COHMWOHUOHQ HOUOZUO£P0Z©wPmMmmUCH COflmm0umOHQ HMUOZUOCPUEUUPQHUQPCH ©O£POEUUPMHOQPCH COHWWQHOOHQ HUGO:A* mwflufipm ®H®OwCOHWMOHOOMQ HMUOZHWWQHQ CHV “PHD: wfimcflimx §_HH H'H A§@mHV madam PDUHHQU | o_H Am©@®H@mmfiv %P“:z mfimcflimx N_¢H N_H ©@@H_m¢mmHv %PMsz m_@N €_H ANQQHV MPH:: mfimcfiimx m.HN B_O A©®@HVmmemfi Ucm CmUCmCmXm>H> mmhnmz H_Om §m_O Abmoflv MPHQE mUmCHXm¥ m_Om Nb_O QQGA_mmmmHv %PH3: mU@CHXmM m_®N m_O fiwwafiv EQCPQQ Cam 'm£XmmH> hm§oH_mbmHV mwmfluo H£PHOOEmG£wHHM lmunncm O_mm v_H m_®H O_@B_®O_@@.mfio_NH@_vfi[email protected]©_N H0.0|@_H ¢NO.ol N_Hm_%@@_OO_H O ¢V_O §_H ©N.O| m@_O ¢@N@_N B@NN_O ¢OO_H %_H ®fi.O| N@_O ®fi¢%'% fimF%.O| qH@§_O @@¢H_O W¢N©_O §mO@_O @fiOfl_%' H¢fim_O @_NfiN_N%®.@Hm_m@@.HNm_O®@.m@¢_H@O_@Nm_O@HOPQHUHWCH HOp3O@mmflgflfinWmzpmmmqwwg MPPDHMU mDHC£On COHHmOmmE _m __ ‘m3UHGOm©fi WmkM“mmEwZ WHUPQEUHUQ cp3OHm MO COHpflEHpm® “O UOQPUZ 0UHDOm COHm®m AEOV fimhflwwv xme E EQ P QAhmww AHm®%V Akflmx hwav HUQV Z KAEOVsqWQHUQQW MMvGH cw SUHQUWUH GO UUWMQ W@fiUUmm U>fiu HO“ A Wnpmflwfi EdEHxME “Cm Rap _EqV ipfihflpma pmhfiu M000 wcfl m£ymGUH _AzV UQQH %pfiHQpHOE Hfihapfifl _AWp _¥ _8qv whflpwefihfim £p3OHm WUSHMD umyfiaflpmm M UHQMB 2-1 Theory of lsn9Fhib8Bsd_Tb°@2§09 and E¢ll,m°¢sl The Thompson and Bell model (1934) is an age—structured model for predic tion of catch and stock size for a given fishing pattern (the array of fishing mortalities by age group). The model used here (Sparre, 1985) is the 1ength—structured parallel of the Thompson and Bell model. The starting point is Jones‘ length-converted cohort analysis: X(L1,L2) = ((L ~ Ll)/(L - L2))M/2K N(Ll) = (u(E2) x(L1,L§) + C(Ll,L2) X(L1,L2) F/Z = C(L1,L2)/(N(Ll) - N(L2)) F = M (F/Z)/(1 - F/Z) wherethe (lower LN is limit, the asymptotic upper limit) length. of the K lengththe curvature class considered, parameter and N is(L1,L2) stock number, C is number caught, F is fishing mortality, M is natural mortality and Z is total mortality, (for further details see Jones (1984) or Sparre (1985). The forward projection. of the length. based cohort analysis is named "length converted Thompson and Bell" analysis (Sparre, 1985) It takes the fishing mortalities by length group and the recruitment (number in small est length group) as inputs and calculates the number caught and the stock numbers. To turn Eqs. 1 to 3 into "forward projection", Eq. (3) is rewritten: C(Ll,L2) = (F/Z) * (N(Ll) — N(L2)) (4) which inserted into Eq. (2) gives: N(Ll) = (N(L2) X(L1,L2) + (F/Z) (N(Ll) — N(L2))) X(Ll,L2) Solving this equation with respect to N(L2) gives: N(L2) = N(L1)*(l/X(Ll,L2) - F/Z) / (X(Ll,L2) — F/Z) (5) Eqs. (4) and (5) form the "forward version" of length converted cohort analysis. In its simplest form, the length converted Thompson and Bell analysis uses the F—array estimated in cohort analysis as the reference F—array and assesses the effect of raising (reducing) all F's by a certain factor. In the general case where all F-values are raised (or reduced) by the factor XX the general step becomes: N(li+l) = N(li) * (1/X(Li,Li+1)-E(Li,Li+l))/(X(Li,Li+l)—E(Li,Li+l)) where E(Li,Li+l) = XX * F(Li,Li+l)/Z(Li,Li+l) Z(Li,Li+l) = XX * F(Li,Li+l) + M C(Li,Li+l) = XX * F(Li,Li+1) * (N(Li)-N(Li+1))/Z(Li,Li+l) The yield (catch in weight) in length group i is: YIELD(Li,Li+1) = C(Li,Li+l) * W(Li,Li+l) where W(Li,Li+1) is the mean weight of fish of lengths between Li and Li+1. It may be calculated from: ' W(Li,Li+1) = a * (Li“b + Li+1“b)/2 I'\f'\/-\ OJNH \-I\-/£1 where a and b are the parameters in the length—weight relationship. The value of the yield is given by: VALUE(Li,Li+l) = YIELD(Li,Li+1) * PRICE(Li,Li+1) where PRICE(Li,Li+1) is the kg price of fish between lengths Li and Li+l. The mean number of survivors in length group i is: NMEAN(Li,Li+l) = (N(Li) - N(Li+1))/Z(Li,Li+l) and the corresponding mean biomass is BIOM(Li,Li+l) = NMEAN(Li,Li+l) * W(Li,Li+l) The prediction made by the length converted Thompson and Bell analysis is a prediction of the average long term catches, assuming recruitment to remain constant. 2.2 hssessment_of mixed fisheries based on_length frequencies In the present case the kg prices differ between species and between size categories within some species. Therefore it is not correct to treat each species separately and subsequently sum the results in terms of yield. value.Before a summation ' makes sense the yields must be converted into units of Moreover, even if yields are converted into values it is still not pos sible to sum the results of single species assessments. It will usually be so that the effort level which for one species gives the maximum sus tainable economic yield (MSE), will not be at that level for the omher species. The approach suggested below combines all species in 1fim2 estimation of MSE. The computational procedure of the assessment of a mixed fishery based on length frequency data works as follows: a) Perform ea single species length converted cohort analysis (nu each species separately. This gives estimates of the current fishing pat tern for each species. b) Perform separate length converted Thompson and Bell yield analysis on each species. Use the same F-factor for the fishing patterns of each species. Sum the values of the yields of all the species. c) Use the sum of values to determine the optimum effort level. The assumption behind this approach is that when the fishing mortality on one species is increased, that on the other species will automatically be increased also by the same relative amount. The above suggested c0mputa~ tional procedure involves a large number of calculations and is greatly facilitated by the use of a computer. The LFSA—package (Sparre, 1987) with the program "MIXFISH" was used. _ 75 _ 3 RESULTS 3.1 §ength based cohort analysis The raised annual length frequencies of 13m; three years (1984-86) were pooled and the annual average frequencies were obtained as inputs for cohort analysis. The other input parameters are given in Table 4. The data of 1980-83 were earlier analysed for estimation of mortalities (Murty, 1986, 1986 a, 1987, MS) and F/Z values were found to range from 0.6 to 0.8. The terminal F/Z values for length. cohort analysis were= guessed (Table 4) on the basis of these values. The results of the cohort analysis on the five species are shown in Figures 1 to 5. For §. japonicus (Fig. 1), F shows an increase to a maximum of 1.95 at 22.5 cm which is followed by a decline. The average F for fully recruited fishes (L>= 13.5) was 1.1. For Q. mesqprion (Fig. 2) F increased to 3.68 at 11.5 cm, then decreased cruitedto 1.1 at 14.5 cmlengths and then increased (L>= again. 11.5) The average was F for 2.7. fully re~' For Q. carutta (Fig. 3) F increased with increasing length to 17.5 cm and from there onwards was relatively stable. The average F for fully recrui ted fish (L>= 16.5) was 3.6. \ v For Q. bindus (Fig. 4) F increased to a maximum of 4.5 at 8 cm and then showed a decline, after which they were more or less constant at around 3.5. The average F for fully recruited fish (L>= 6.75) was 3.4. For §. insidiator (Fig. 5) F in different length groups showed an increase fnmn a minimum of CL]."n3 a maximum of 3.9, with increasing length. The average F for fully recruited fish (L>= 9.25) was 3.6. Table 4 Input parameters for the length converted cohort analyses given in Figs. 1-5 *) Parameters N.japonicus__i ---Q; % §.mespprion_ mp;--3- in 1n. J.carutta I-Qpu-ir L.bindus wk‘ xix-Q1--nquii S. insidator .3 L” (cm)(30) (18.5)33.9 21.9 (24.5) 33.3 (13.0) 15.84 (11.0) 12.3 K.perM per year year(0.71) 0.52 1.1 (1.20) 0.83 1.7 (0.85) 0.44 1.0 (1.00)0.58 1.5 (1.20 (1.79)2.6 Terminal (1.4)F/Z 0.50(2.27) 0.68 (1.68) 0.78 (2.22) 0.68 (3.41) 0.6 q in w = qLb 0.0287 0.0158 0.0053 0.0153 0.0050 (9, Cm) b in w = qLb 2.702 2.877 3.233 2.952 3.437 *) Values for Lw, K and M were taken from Table 3, while those in brackets are7. the parameters used for an alternative' assessment presented in Fig. 20+ E 4|“,'I. ,. ..‘.'. . . . T‘ '<'.'."Nemigferus ..'.'.‘ jagonicus j[.;.:.§ .‘.:.:. I ' \ "0'! I ._ .4 :&:5r5:iY"'.‘.'.‘r1.. ¢'.'.‘¢‘...‘. I!:2:?:l Catch numbers ‘\|-..|,-,1‘‘._._..\.... '..1..q ||_-.. .‘ .j.:.ji. J T 13-» @2525; P2525; Population numbers 1.5 " :7:1:‘ \ I517‘i 1:-5-:; $1511 Effifi .._? ' _ f ' V-\ ':-:-:~ #5252?--255%? -I-I-I‘ £515?F" o=%=%=I 255;? iigiei 52525;PM M“ ‘my £292: 15252;? LTo .. 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'-'-'q. - .~.. .< ‘-.4I -:-:-:|:-:-: "-'-"' ‘ o:-'-:|"-:-:-: '- -. - :-:-'.-: :-I-:~, . . I-i-:- =:1;-:1 -:-:-: ' I-1+ ' :-:-: 1E-:-:I- , :-:-:< 1 ¢ -»F-'-‘;,‘.‘.‘| ‘ .~.-. ‘>'-'-'0'-‘—" 1'0.‘ '.'..-.-.4 .'\'. . - | '-'-‘-'.‘-‘ ,'.-.1, .'.'-'.'.‘.‘ ,‘-'.'' " .'.' .‘-‘ .‘ -_-_-_ .Q 5-_-,-I - ~r‘-'-‘ I' y ._-_-_-I I _-_-_-;- 0 \» ‘_-,-,‘ - vi .... .-.-. .'..1 '.-.2 \.. ~-. ,.-_-, '.., ... _.;.j. '.'.'.\ 1:-_._. ... ‘..-_1 .j.;._| _--.‘ _ _ _ -Fff‘ '-‘v ._._ -.- | .'.'. ‘ .-- '.' \ ...".‘.‘4 _-_._ -.\ _|‘-_-... _-_-‘- ‘:-:-:1 ._. ..4 >_¢_|.4;:::,-,-,', I-'-_<| ~_-_-'1, __-_I._._. '.‘-' .. .‘;.' \;._.- -<->- \'.'.'\ -\ -' ._.;.; \,. I.' '.'.‘... ,-.-. . .. -- .;.;.<\,. ‘_ ..‘,1 _-;-;- "." - ""--- ’ '_-j-" “... .'.‘. \ [:.f.;....5.1.; . ....:.j.:. .'.' ..j._-.‘ . '_'.' .‘ V1.11 -,-,1| ||;.:,: _ ____,-_' ,.-.'.' I ,,-_-4 ....\ \_-_-,-_- __ , ___, .:.§. '_ -I-I-:~,. . , V-_-_-I-‘-‘-_ ,’" V .-;-I_:_:_| >1-:':- ,-1-I-1 :-:-:-:\ -:-:-.‘ >_-‘.._ ~:-:-:- :-:-: -:-: ;.;1; :-:': ._._--:-:- -:-:- -'.:.. 0 0 o_,._4.5 - r.-'176.5 1 __20.5 H-_~.. Y 22.5 . _ Length - - - Q growswe .. (cl) Ion 1 F“?-or-"— o.ss 1 t"""F""t" 112 F r’1.93 1 +—***r—~——fij\"*r-@' Ar (rwrl nuarv: rag} Fig. 1 Length1986. cohort Mean analysis of F Bgmiptegus = 1.1 japonigps%M at Kakinada, 1984 § t Nemiprerus Qrggggfion -0-‘KI I III.‘4 :1+' . -'...‘ - Catch numbers 4. 0~j~ U Pop ulafion numbers 4_I ¢s0- 4 .|d—— Fish. morfilify -1-A ‘_._.l ;:;:§' :_,_." .;.;‘!§:§:§: |.;.;.;>_._. ;.:.:< 3"-- .-.<~_-_~'-_< ._-_- ._-.1 ._-_< i ” / 3.0 -—~ V5555.:.y..1 E5553 .'.:.j‘-4 .-.3 |-._._‘ - 1 - -.j._| - . -| _ ' ‘ ma.‘Q-1.11||'u'.‘|.;.;<¢ . I-.'. >'4‘: '1-I".>'.'.: - . ‘._._10 1 "" ...... {-1.11_.:.:‘ I‘ .'.' '.'.'. .:.;.: I»_- I, -II)-4| . . .|-_-_ . . 1‘ -'1'-''.‘.‘-‘ -'|' '.'»' >'.'.‘ I‘-'|' I. v. .| -\'\-1< 1. ‘I--‘-. .n .‘I'll!- .u . -1- I '.'."1 '0'!‘ P‘I'I. Q.I_I E‘' 1:111 I.. ‘ .‘ >‘.’.‘ - ;I:Ij:. '.-.'. Ff‘:[':':‘ ‘.'.' §._ ,._ _ .._ . .> . I-I- I ~I-I- -I-F . ‘I-1-1 .'.- I 1;.;.' I I I I ._.'._I I v p U - v.-. .-1-I'.'-". . >°-‘o .I-1+ .. '-'.'¢ _. -'-'-‘I rm >'.'.“ | ‘ _.‘._ _._,_..4.1 -..1 ...- ->_._.‘ .-.u,- ¢ . .1>. .-.2] r. k._»_.‘| - - ....v.‘._.| 1 ._-_<| -.. - ..4 .. . ‘,|._¢| ’¢'.'<, p ._._.| .'._. ' .;.j< ‘.:.:.|‘ ‘.'.‘| >.'.w ‘I .'." :.j.j.j ‘,'.'. ‘ ‘-'-_.l‘_...‘| ’ ' il‘ .i y_.l _ _._._.I -'‘.3. h-'9'. 4-\~ -'-H '>'.°~'1.2;..'.\ >'.'. ‘,'.'.]\ 7-'-‘.‘ ... :.: ‘ | I 1». ,,'.°,;.;. .:.'.:‘],-.-1: ,§.:.; .'.'.' ;.;.j.‘, |1,-.' -,j. ‘ j.:.f. .. ._._. >_-_.| _._. .\ _ > _._._. w-- , 52%;‘ I552% n '-a - . I 0 1‘: $5525»I I I4 0 1 In 1 _4 _‘- - |._._._I 1 \ I u._._< I ' v -\~_-_~_ Q n a n """ pg:.:.l .'.§.' .“,‘. :21. '.‘.‘ " ' '-:.:.‘ 5.1.; 1.2.:1.1.2. . -" .3.‘ -_-_-I._._.| |o.o. ._._-I'._._ I A-.._. . . \..._<‘.....'-'4 ,_._.‘ ..\ -'-'.‘ -_. ....1--. ‘.'-'.... - -.... F>'|'-‘ --\-_-_-| |_._._ . '-'-‘o ,.-,_-.._.‘ |‘.. \'-'-'| ....._.“ ...‘...'-'4' -_-_ -' ' ' _ !?:;'< ;:;:-;'.'.'.|. '-:-:- ,-.;:;;-1 .'.'.‘ '-t;:-| 1:-:;:1 r.'.'., :;:;: - -;I;I; . 0 i 0* i=?1?= =*‘“ ;-.151 =52? *1? =iaI;5=% 52%; 55252 ~ __ 4.5 “"9", rm, 9.5 was 14.5 HURTY:~ Ago rig (years) %"‘F‘""‘ro—‘*—*+2 0.16 0./.2 Pfi 0. r 1 +76 1? s‘"“‘1 1.22 ‘“‘l"—I"“' Fig. 2 Length cohort analysis of Nemipfierus me§op§§og at Kakinada, 1985 1986. Mean F = 2.7 FISHING MORTALITY 4 L-.-‘_p43 STOCK NUMBER \n1 @ o FISHINGvs:- NOR No TAU1 N Ll TY _ } o__[ . # N STOCK NUMBER f x10‘ ) Q ;-4-_-4 F: _L 1:11:11; 8 -:§§:§:§: .. @»»£"" . - . .1’-'.*r \ vw—v—vv|.-.... _._._-_._.‘,,, 44 v'-'-rv.11 ‘.... .v . G. . .. .u. .~. .0. .Q‘\. . .. I ...-...... _._._...... -1 ~._'__-'~_~___-_.‘___nnI|l\--I ‘-H...... _LA_jJ‘lAlAA 4-. -‘ff.. . {. '1. . -‘. T '?:?:1:I: AA‘u v u ~ 0 0-;“' l.Q G ' m fi ..77_ # A Johnius ggruffa - Cafch|_._._| numbers -5 :.:.:.''.‘.'. , . ..|_-.._ 4_o__»F 4___|_-_._. . .5 . j;§§§; .. .. Population numbers "1'1'1 \.l‘I.| |I|\.I'I I . @5252 , —--\ --1- '1‘,§.:.: [.:.:.‘ :.;.: I-:-:- -:-:-q -:-: ; '1'!-1 I-I-I-,-IIII4 |'I.I.\ I~.'»I '1': 3J .1-:15 '1'“.:.:.:‘s. i.l.|. . . . '.'. | ._.'. 1'-'-‘1._-_ 1I -'.'..'.'.I I 1 I-I-I-I,I __'. .' 3_0_.+ 3-4. 5:5: I215 151215: . 9:‘: o:j 1‘1.-‘ 1.1. ‘1_-.1‘ 1.52.: - _.'.‘ ._ .1.; .-.;.-.P Ii .'.'.1 0 '.I 1 I-.-II 1 '1'.‘I I. - |1'.'1‘g'1_-_-. 1 41 . ' .' WI ‘.‘|‘ >_’.\ ,1 "_._._. 1-1\:v,~:1 1 1 |1 _._.‘'1 1|1 ||.§.;.; 1 J‘-'-' 4.'1 Ira.‘JF" ...... _~! 1- '1'.I _ j|. Iv!“_._'_. . .| . ,1 .| _‘;.-.-. ..:,:,~ ._ .\ , .‘ -.5 -_:i-:-:- ..| n:-'-' I:~ '13:: 5 1'1‘1 L l'-'--+|>‘.‘..\ + _ _ _.~ r, _ ,\ -51.1.;_.;._.;4 1 _-_< 1 >.j.;< 1 1 >_.'-_ "'I~.~ 4 , ,‘,',>.-.-.;. ‘... .‘ ',',',\5'-‘I’-' - ‘\'-'1- _~,1 1'.‘ >_-_- '.'.'. |>.:.:.; ’ "' \ 2-°—+~ -—- 2:25;22252. =-=J 5&5? .- 2155‘ 52%?» ======E5555 . ,1‘»'11 . .~.'. . . 1,-_<| .. . _-_ . 1_ 1 ‘ ,.‘ ‘ U1‘.,-‘P '-_1_1| ' I1 1 1 1 1 ...»)1 , 1. .~ -51,5 I. .' '. _< I-j-'1>_-_-‘ .'§'§‘ -“'1 ‘F1’? _. ‘I'M. . | . if.-.11.I »'1 '.'.' '-'1 ,-1': ' -.-.-.I:>' '.‘ -_-_.: ‘.'.' -1.’-‘ 1,___Z:.1 |.'. :_:_;;1‘ :.:.: >1-;.= ,'.:,: 1.3.,-_-_|_ _.;._| -A-‘ .;.;. I1.. .' q_ p‘1_1l >~11||,_.',\ I.| |-|'»'-' .:_:':| 111\l\, - 1‘, |‘.'.’._1_1 '.'.‘. ‘.'.'.1 '.',*|.1_o_|; “' '_-_1_<. "."' 1'1’. III-- 4 , I1|', » ',. - | .|._. . 5 ., ’.._.- - . .,_,.' , \ _',,,, ,~,I,4_'_'_ _.' : :_:,‘ ,:,:_:‘ :_:_:|\:1'1:5:.:.: 5,~,-_~ '5!-1321:1 ;~I5I- ‘5:12:17 r_~_-_:.;.;. 5:-1-: :-:13.'.' 1 -.-.- . _-_|‘-;-;-1» _._.., .,._._. 1.04 1* "'1 1 5_1_1‘ F2525 fl...‘ ,., 5 = , .-.-. =. -'-'1?5, |'-‘-'|! ! :-:-:-;'- . | "'3F .'.'.‘ I ',',',' . _-..- '- '1'.‘-‘J?v5. ~ ' V ->‘-°-‘-I . '5 '‘.'.' .. 1. 1 .1 ll5 1'-_| |, |‘1_-_\ FII; 1- -, ‘}§;§;.j4, . |'., .‘.'.I 0. - - 5»,',°,‘.\P - - ' ',' 1_-_‘ ‘I |.|._-_|i .1| . . .|_._-'4.‘ . , '_-_- 1 . 1 -_-.1 .___,‘ v.-_ _ _ _ ,1,, ,1 _ . 0-51- 1 ... .52; 1- 222:2,1 I 1 1 . :_~,-_ iii; _1ziiaiag - . -,-‘I 2:; , , -I-I-2 -I-I-: . ;.-;-Z- :I---.-I5 5 :-;-; 0 __h+ 0 _L_ §':'3 ' -.-:1 E3351 - , ‘EIEIEY % E5355‘ §:1:3 E u __ i + + +T“"i;'5 1a.s rLengm i i +7 km, +-—~5+-—II13.5 16.5 10.5 Age (years) 1.18 184 Fig. 3 LengthMean cohort analysisF = 3.6of Johniug M’ carutta at Kakinada, 1984-1986. L Le:'o@i!'Qq§ bindu; 4% - Ca fch numbers ! 600* Population numbers ,.'._1 * 5?-2225? ,@2:&; —F1$h- mwamy ;i§§;§&% *i%ii§?= -84-sssieag ' I-I-Z-\ II-I-1' | | i:-:-:1 |:-:-: 7-I-I-I F |.:jI;§;1 . |j1;I;l|. .‘I-I-I" '.'.'. >1-I-L I:-:-:\_.‘. a ..4 1 »:-:-11. .51‘ 11 ’.‘.‘.‘:-:-: ‘ 4 \\ ‘. -1 -';.'.'. -’1-'-'-''-'-' 1 - 1‘CC. '1' .'1.1 . "-‘.‘,',',‘| 1| ... I-.-I; 5:-:- ‘III!I-:1|._.;.;. '-:-:-:5111 IIII ;-1-:-‘ I11‘ -Iv,-‘I,-,-3‘;-1-j-_ »_-_-_| "-'."-_-_|. I _;.;~, >_._._, |.. ‘I1-I-1' |._._.1.1 |f.:.'-‘'31‘.--.‘ ‘-1.‘1‘1‘1 __ ,. .1'.'.'| ,-.'.f, n‘-'| »‘1‘.' ' ',-.-,|'-'>'1' ‘.'.'. \ ‘; .j.:.' ._._J *.:.:.‘ .'.'.. .f.:.:. f.:.:, .'.'.‘ , >_-_-,' ;,:.:.:|:I.-.-.< I V-.-.-1:-_-_-.. -_-_-...| .:-:».- ... » .....1 »:-:-:1 | -...... §.§.§..:.f.j| 1.1.; :.:.:1 4.1.: .:.:.;. >.;.;.' ,:.-_-. -.-I-I1 '1_1_ 1 ....» l5:; ,j.f.; .£52525; . .. :.;.j.. E3355? ._. \j.;-f.._ 555%; \._. .:.:.: »z:s:2»_‘ 5.1. '.' 51:55 , :.;.;_ _ ---"I-I-I‘ ... 1 I-P4 ,..I .'.'.‘- --1..1 '.' .'.'.‘I-.-1' c-- -‘.'.' ... \ -l- -_-_-.-'-‘.‘... 1_-.1‘ ..\.'.'. ‘...; '1 1 '1_1 ‘.'.‘|[._1-._| ... '-‘-‘||-.-_<. .-. -_-_-.1'.'1‘ ... 1'-'1 .,, , , 1 + .;.;.; .I-_.;. ,-_._< >.-.-I _. ;.;.;I _._._.j.. -;-;-1' ._-_-. ; 1 ;.;I:._ _ _;_:_I-I-1 -1-; _ '.*.'.._._. -_¢_ 5,-.'.''.-.1. ._.'- .1.-,: 3.‘-_<[.j._< -,-,: _.‘.‘1-.-.-. . 5.1.; _.:.j| ! ,-,-_._._, , .;.;.5; :1:I:-.§.§.} :-'-:.[.'.'I ' +11,_ j.:.;.| A if-I-. 1 vi‘? ' 1.1»;-, -:-:-; -IQ:-:- -f-j:-: :j.:.:> 1 1 7 . 11.1.. W 1 1 1 '1'1‘-‘ 11:11:: ‘1'1‘1 1‘-'1 '.'.'-I.-.-I _--1.1 .‘-'j-j-1-' '.', g 0 0 »- ___...d§is "0 Lcnqfh 1-1.1. .- (cm)-- - -- 6'5 5 Q as rm -1» ... _HURTY ' 5* ' :--*” 5“-+—flg.4 -~t-5—+' 0.75Age 0.48 RH. (yous) . +0,39 ' |~~~+ 131 F5 ' + 1 | I 1 | i | P’ Fig. 4 Length cohort anaiysis of Leiogna1;?§):x,§§; 13j:n_ FISHING nonuurr N W ‘U -4 rs S TOC K NU FISHING MORTALITY Q mam gr no‘) .1.; _... 1’ $——_—In 4.-.in- 5+.--.~kn L If .w—v r1-I-r1~r.1.111 -11 srocx NgHBER r 110‘ I I‘: 1-11:.-. 111111 1 111 I'I 1 1..1.. 11. ....-_-.._--vv.11 . .. 111.111.111...1.. 1.. _1 1.1: ‘ff 11 1 1 1 1 -L1'1_-1 F.‘-“ 1 1'1 1 1 . 1111‘) wwrr12525? 11.111 1'.'1‘1'11‘. 11111 111 1-11111111 A " 7'o“I—1 GT 11.-_1_1_ 1 . O 11.1. 1 '11 .111‘iv: 11.1....11 .....'.'.'.01 01.0... BI .. '] £3 .. l ‘ Securor insidiaror 44- 480 . C a fch numbers 44 ‘Pf. 4 y 4_.:4.| 4 =:=»| 4 4 4 Populifion numbers 3904* 55;;r4 40 I4 I 40I 44;;;;;; -—-—F!$h. morrahfy :4:4:4 >:4:4: -1_o_o_d D’: 4 . . .| 44 4 4 4 4 | 4'4‘_4 1 >_-_4_\ 3-4- 5555'? , .IE1- ,isisisi* -...|I I \ eiiiiiv O iiiiéiiD I I 325252Q ' . . \,-_-\ ~14-1 4 V . . . I -,.1. .1431. I-1-14 i""|I .-.< ‘4°4°44 -;-;~. 444I ;" 4' '4_1. . , , _‘ 4 4 44 -4. ...4 =:,:,_1 :4:4_444 ._4‘ 4 0 y-.4.-_ '1 4,:,:‘: 4 , 4, , Q°.'.'' I,I -'.l4 I.'4 I4 ,-I |-I |I u-I v4 1I‘: I 0 0 4 0.c. I‘ . 4 4 4'4°4‘4'4.4. '. 4'4'4‘ . 4'4'4'. p _._...... 4 ‘-404144‘ . - .1 -—4->- ~_'_<‘“Hi551 >|. EEE~ 4‘it 4 IIbra4 4 . 43.4‘rvq , (...-4.41‘ 4 '4a4 3.4.4..... wavi ... l':‘4‘\-+1,‘' _ ' y':‘:':\e' ~,-,~,', \ -:‘:':1, :4:-:4!1; 4 |'4':'~ Ff.:.:|| . 4 '4'4'<. ‘HQ4 4 -4-» n 4'.'.'. 4 KI .'4‘4‘ v v 4'.'.'4j 4 4'4'4‘4‘ 4 ' ' '>‘-’.' ' ' ' 4 4 4 4 4 » . . 4 4 4 4:4:44.-.-.;|'4'.n 4 4.4.4‘ P°°4 >.-.-. , >4_4:4:4:4444I ,._.;. 4|->44 v.44-4' _ '.I I4'~~5:11, 4_. 4 I ' ‘I ' ' ‘r 4 4_4_4' ' -3"4 ‘4 4 44 4 4I 4 44 > -4 4 4 2:: .... bra41.1.;4.4.4' \ '4'4',... >44‘-~». '4°4°4 phfl‘DD!"'44 "' IIII44 . .| 4 4 4 |44 .44|.~‘—l| 4444 4|_l_\_I 4|'.'. P >.4'4‘ ,'*'4 , , |'4'.' _4‘4'|' \ A I4 |'4'4 4 >4 0 _4...4.--4444 _ ‘444‘>'4 >44I.4» _ 4'>_-_ __ .',""¢ _, 4444 ','4' >;.-.;' ‘»4..444 \|4'4'4 |_‘.'.'.'- 4 _ 4 _ 7"-.\ 4 .;.'.' '.'.*.4 4'4‘. >_-,-,~ t4'4'4‘ ,-1-1-‘ ,_ R, $4‘ 4‘4' |>_.'._ || 4'4 -1 1 120\ 4 '"' 4 .-:-:4‘ 1D.-.4‘ »:-;-:-.-_-_-..51.} _4_o_q‘ '11.:-I-1 .°4'4'4‘»:-;-: I, 4, 4 4.4 1-I-I- ' ‘P.'.' ' '4 '4.4' ":1-1:'4 -'4'.‘4'4 '.'.'. 4'457.3‘. #1321:4 >.~.-0'-'-'4, ' . l| \4°4‘4'- .;=- 4 :3‘.'==4 | ,,q|\_ ‘ ‘4'.',':P_,i ==.I 4'4’, ===| I “'4'g» -== ‘. .4_4,4'. 2.: ;.j.;.'4'...‘ ....F,4 ,v_I_ . 4_-_ l--4 , ,>‘< .-.-.- -_->\ 4.4.4: §.;.'. |4_4.4‘... 4..,- I-II_- -4- 14:4:'.-. .. ~44 |.4- >---4 \I -44‘ -4m II 444 .-'4_4‘\h_-_4‘_4 _ ._ I... ‘ _"|I4.4:4 . 4, -_4_-‘ ._44_|, 4, ~_4_4| -_~_~_< | ‘.4 ~‘r40|: 4I_'_°_' _4_.'1 all F‘ 4' " ,',-,-I "' ‘I444 ' II4‘ 4‘ ..4_ . .;>-3‘ -“.1.~ W>'4'44- 4- 444. ,'Uv,%.mm4'4‘ |\_--.1.4 .‘.'.'. _ _,. *4:4. _-_-444 4m'uw ‘,°,','| 44....‘ .44 -44.4.4 »~ -4, %'.'.','_ -==.44‘.'l‘ i:_:_:| 44|422q';..| ,:_:_: 4444 _,‘4.|-=rr |,;_.' --4| |4_4_4_I..== '- ,, , .== 44||_4,I| _ _ r ;4=< 444'_ |_4_4_|‘ ,‘.'. -,,:\,,, 4_4_ .4...:44 »=. .'4‘ ,,4- I4 .. 1\.|1 ' _._,.--444-44 |_ >44.44,444 4441-.-44 -4 .444 ---144» |-'-'->444 4r441 444‘444 ‘444||',',' ~41 4.4q -44|41 --I 44| --4 44_4,,,|,.| .| .4 44.1---444 ,.___ ,,, -0- H 44444;,.| ‘|_,_I444444|,,| 041 444j|,,,‘_____ .|,,, III.4 .4 .44 44 _-_-444_,'__ 444__ _ 44 04444 -0 44.4444. _,_ ‘‘ _ 4.44. '4_4 P-4,. 4..\'--._‘4i-_ 4- 4.4|_4_4_44.. 44.|-44 ‘_ '54‘4 _4''- |.,' 4441,_._._|._ 44 __..','.'|' "'.4 T,,’4.4.4| ,"'P3,‘;_ ,,‘ , 4.4_4'. . _,4'4. _~_-,‘- '-_4-_'_|44 ‘I4'4 .44.43‘_,_4‘ , . 0 0 ,______3.0 |_4_4_4 6.0 _‘ ,_4_4I L -_.'._|M ,:_:,I ) 4'... 9.0 __ _. ‘I ¥"‘Q22 ‘1>‘_" ‘¥:I“‘ ¥**1=**l'--- .055 "r 4 r 1 4 455351-F=s»§3I!.~~.-+ 109 *1 | i‘ ‘”“‘F——~-‘1II* A ge (years) £LUl?.I..Y_-'__.'.'!.q;£_ Fig. 5 Length1986. cohort Mean analysis F = of 3.6 §ecutor *0? insidiator 0“ 0* at Kakinada, 1984— 3-2 Eensih b2§s§l_T!.>2§\_12$<>n and Bell...._an2lY$is by..-§Pesi<=s To assess the conflicts between management strategies for individual stocks usually inherent in a mixed fishery, predictions were made for each rized.stock separately. The conflicting‘ results of this exercise can be summa For §. j_ap9§_1icus, the maximum sustainable yield (MSY) of 2.54 t can be obtained by increasing the effort by 40% (Fig. 6). The maximum sustainable economic yield (MSE) can be obtained however, by increasing the effort by 20% only (Table 5 ). Furthermore, the 40% increase in effort will result in only 1% increase in yield which indicates that the catch per unit of effort will be reduced drastically. For Q. mesoprion (Table 6), the results indicate that the effort can be increased by 80% to get the MSY as well as the MSE (Fig. 6). Also in this case 80% effort increase will only result in a 1.8% increase in yield and will therefore not be remunerative. For Q. carutta (Table 7 ).the present effort is at optimum level (Fig. 6). For Q. bindus, the Thompson and Bell long term forecast (Table 8) shows that the present effort is 40% more than the one giving the MSY (Fig. 6) thus suggesting a need for a reduction in effort. For S. insidiator, on the other hand, the analysis (Table€9 ) shows that the effort can be increased by 140% to get the MSY but the increase in yield will only be 6%. Y HSHWKF HQFTAur x 10‘) SHWJFNq§BfiQ ( \4J 3 8 U_I_TTT_Y—rY_y:v:1iVfi‘4L‘ Yvw4.4 1' up4 44444 444-44 35] _ 79 _ 3-3 Mixed_€i$hs€ie$ assessment The assessment of individual species has indicated that the present effort is optimal for one species only, it can be increased considerably in the case of three species and should be reduced for one species. The mixed fisheries assessment (Table 15) shows, on the other hand, that the MSE of all the five species together can be obtained by increasing the effort by about 19%. This suggestion should only be considered in the light of simi lar studies on shrimps and other valuable species. It may be stated here that any gain or loss in yield should be considered together with a corresponding change in CPUE (which can be taken as rough ly proportional to the biomass as calculated by the Thompson and Bell ana lysis). Table 5 ThompsonKakinada and Bell long term forecast 7 of N. japonicus at XX Yield Mean biomass Value factor (t) (t) (000 Rs) O 725 0 Q 126 539 751 U 191 423 1132 O 225 346 1325 I 243 293 1420 251 255 1460 254 226 1470 MSE 254 MSY 204 1463 253 186 1447 250 171 1425 248 159 1400 244 149 1374 241 140 1348 238 132 1322 235 125 1296 232 119 1271 Table 6 Thompsonat Kakinada and Bell long term forecast — of N. mesoprion XX Yield Mean biomass Value factor (t) (t) (O00 Rs) I 0 707 O U 175 539 526 C 272 430 817 Q 327 356 982 I 359 803 1077 I 377 264 1131 O 386 234 1160 Q 391 212 1175 O 393 194 1181 I 393 MSY 179 1181 MSE 392 167 1178 390 158 1172 388 149 1165 386 142 1158 383 137 1150 380 131 1142 wronawroa>H+-»¢H+~c>O<3cJO wrohJMrou)H+~Hw~r*O O 231 O 56 148 168 78 107 234 86 85 260 89 71 268 90 62 270 89 56 268 88 52 265 87 49 262 86 46 259 85 44 256 84 42 253 83 41 250 82 39 247 81 38 245 81 37 243 Table 8 Thompson and Bell long term forecast of E blndus at Kakxnada Yield Mean biomass Value (t) (t) (O00 Rs) O 1854 O 587 1115 587 768 768 768 815 583 815 814 473 814 796 402 796 774 352 774 751 315 751 728 287 728 707 264 707 688 245 688 670 229 670 653 215 653 638 204 638 623 193 623 610 184 610 uJt\Jt\Jt\>t\>r\>r-I-*r-I-1|-'OOOOO (.0 ~.)f\J£\)f\ I\)l—'r—*$—'i-'P*OOOCDO O0O0\|bt\>OCDO'\|D~l\JOOJO\|bl\JCJ CDCDO'\1bb~)OCDO\nb~NCD@O'\|bt\)O _.81._ Table 9 Thompsonat Kakinada and Bell long term forecast of §. insidiatgr XX Yield Mean biomass Value —,-ell’factor f" _ — ,___ __'(t) (t) (O00 Rs) 0 631 0 197 519 197 304 448 304 366 398 366 404 361 404 429 331 429 445 307 445 456 287 456 463 270 463 468 255 468 470 242 470 471 231 471 472 MSY 220 472 MSE 471 211 471 470 202 470 469 194 469 Table 10 Thompsoncombined and Bell long at termKakinada forecast all species ' XX Yield Mean biomass Value factor (11) (11) (O00 Rs) O 4151 O 1143 2862 2231 1615 2179 3257 1821 1770 3750 1911 1503 3986 1945 1316 4089 1951 1178 4120 MSE 1942 1071 4113 1926 987 4083 1907 917 4042 1885 859 3993 1862 810 3942 1839 767 3890 1817 730 3838 1795 697 3786 1773 668 3736 4 DISCUSSION An assessment of the mixed trawl fishery off Kakinada based. on length frequencies has been attempted for the fish component of this fishery. Ideally shrimp, the most important component, should have been included. Data for this component, however, was not available to the author. The assessment presented here is thus not complete. The present paper should therefore be considered primarily as a presentation of a methodology for assessment oi‘ a mixed fishery rather than an actual assessment of the Kakinada demersal trawl fishery. (nhJNb0h>N+~h¢H+~h»O -» -+\., Ixx ‘\ u0 i ,__‘ y“~~_ J. caruffa ““Iu§_~__ 40'_ “"\\“ ———— -_._____ J.--3 carurf _____ M _..0 -200 0 ‘ + r + r + i U1‘ "f"”‘”lLTi_ Fi'—1'>'“‘“ 0 10F-Factor Z0 Jfi MURTY:f@A Fig. 6 Estimation of yield and biomass by length based Thompson and Bell method for different species and mixed fisheries assessment. (Small vertical lines on curves show the Fmsy and Fmse (value) levels, vertical line at X-Factor 1.0 shows the present effort level) amass NJ Y eld H’)/B Q "5 ./U" ?'\- II // 1/ ’: a‘ "f 1' Value 1000 Rs) _83_ ever,In the thepresent estimated analysis average no explicit stock estimate biomass of can the beCPUE used was as anmade. index How for CPUE. The above mentioned considerations apply in particular to many tro casespical have nofish pmaximum. es, ors whicheci the. f yield ' ' curves are flat-topped or in some Theform present the basis analysis for ais len composed th di of a number elements all of which could taining_ . g to y the scussion, mixed fisheries however, will be considered only those in detail. aspects per In particular the estimation of growth parameters and its implications for the cohort analysis presented here could be discussed in the light of the following aspects: a) In addition to catch statistics, assessment of exploited fishery re sources requires information on various aspects of biology and beha viour of the populations, in particular their distribution in space and time, spawning periods and recruitment. mo-0-gA -----biomass W-em A @5000 06' ~ ;\ ------vafue *°\-~/ 1 I200~J; \\\ .-/--/ \*__ f aw\ A \ " + 760y\\\ -- IDd”-*‘ \/\ I L‘ .. 680.‘_3\* \ / \%-' .-/ v--3400 ~ I =; -0\ ~ -»,¢\=*° i ! tlo \»\\ : /.'\\ \ \ Xd\\\\\\\ \\5or'\°“ N» ’//’ mtl -- -‘i520-I {\ \ I\\‘ \\ \\\3*“A‘ \\I‘‘ \\*1 f é 4-noI \l ’\ \ \\ \ *’Z"""<>»es l “ ‘p ' \ \ /‘/O\ Op . gggl,=I. \ ‘: ~.v §s_\ '-=P<>""¢"$ \\ - I' __\\\ \ _ "L zoo-11 . I\\ \~L-"33,:-,,,,I - \\“LndUS *-l_ gl 120j'li'\~\_\H1 “~~~ glpcargffqw g_~ F 40-L, \ A --~______£_t_a_£uHa“ ;1 r?°° IT Q _,_J}‘ | -Th ~"F--+- I + r-—~ P ‘L t"TUR,TT_-'__UQ_¢Zi_ 0 ' ‘-0 F-Factor 3-0 3-0 Fig. 7 Estimation of yield and biomass by length based Thompson and Bell method for different species and mixed fisheries assessment, using arbitrarily selected lower values of L“ with compatable K values. (Small vertical lines show Fmsy levels, and the vertical line at X-Factor 1.0 the present effort level) YeId H‘)/B omass O; Luat Q 0 Q -_L <7 * / ,*\ // / I .% /9 I I I I 1 Vaue 1000 Rs) _ 84 _ b) Informationsuccessful assessment. (M1 the selectivity cnf the gear nun! be essential for a The above mentioned features may have had an impact on the estimates of the growth parameters used in the pmesent study (Table 4), which might represent overestimates of Lm and underestimates of K. The fishing patterns estimated by cohort analysis (Tables 5-9 and Figures 1-5) show fishing mortalities increasing rapidly with the length of the fish. There is no straight forward explanation of this result. One expla nation is that the L ‘s are overestimated, as lower values of L would make the slopes of the F>curves less pronounced and make them resemble more the sigmoid selection ogive expected for trawls. An alternative ex p anation is that fishing mortality is mixed with the effect of migration outl of the fishing. grounds. . . To assess the impact of changed growth parameters on the mixed fisheries assessment an set of alternatiye growth parameters were worked out. The ly.Lm's These were parametersreduced arbitrarily are presented and the as K's the subsequently figures in brackets modified in according Table 4. Based on this alternative set of growth parameters, the entire assessment exercise was repeated and the result is summarized in Fig. 7. It is believed that Fig. 6 represents the best possible assessment of the mixed fishery. Fig. 7 is given here primarily to illustrate the evaluation of the sensitivity of the results relative to the growth parameters and the natural mortality. It is noticed that the reduction of Loo and the related increase of K and M produce higher estimates of the MSY and MSE. ACKNOWLEDGEMENTS I am thankful to Dr. P.S.B.R. James, Director, Central Marine Fisheries Research Institute, Cochin for nominating me for this follow-up programme and for his constant encouragement. I thank Mr. P. Ramalingam for the assistance in the field and in the laboratory. 5 REFERENCES Alagaraja, K., 1984. Simple methods for estimation of parameters for as sessing exploited fish stocks. Indian J.Fish., 31:17?-208 Balan, V., 1967. Biology of the silverbelly, Leiognathus b'ndus (Val.) of the Calicut coast. Indian J.Fish., 1O(1963):l18-34 Banse, K., 1959. On. upwelling and. bottom trawling1 off the south west coast of India. J.Mar.Biol.Assoc.India, 1:33-49 CMFRI (Central Marine Fisheries‘ Research Institute), 1981. Commercial trawl fisheries off Kakinada during 1969-78. Mar.Fish;Inf.Serv.TechL %@~#Ext“ Ser ‘ ‘, (3l)'l. 1 6 Dan, cusS.S., (Bloch).1980. Intraovarian Indian studies J.Fish., and fecundity 24(l977):48—55 in Nemipterus_japonij ' Ganapathi, P.N. and V.S.R. Murty, 1954. Salinity and temperature varia~ Oceanogr.,tions of the surface waters off1:l25—42 Visakhapatnam coast. AndhraSEE) Univ.Mem. James, P.S.B.R., 1973. The fishery potential of silver—bellies. In Procee dings of Symposium on the living resources of the seas around India. Cochin, Central Marine Fisheries Research Institute, pp. 439-44 Jones, R., 1976. Mesh regulation in the demersal fisheries of South China Sea area. Manila, South China Sea Fisheries Development and Coordina ting Programme, SCS/76/WP/34:35 p. M 35 i _ _i pip, yr 1984- Assessing the effects of changes in exploitation pat tern using length composition data (with notes on VPA and cohort analysis). {A0 Fish.Tech.PaR ., (256):ll8 p. Krishnamoorthi,nicus (Bloch). B., 1973. Indian Biology ofJ.FishL, the threadfin l8(l97l):l—2l bream Nemipterus . japoa y p g__ y, 1976. A note on the size difference between males and fe EalesO8—9 of Nemipterus iaponicus if (Bloch). I Indian I q.Fish.,9 21(l974): p__g__ _ 7, 1978. A note on the mortality rates and yield per recruit in Nemipterus japonicus (Bloch). Indian J.Eish., 23(l976):2S2-6 La Fond, E.C., 1958. Seasonal cycle of sea surface temperature and salini ty21 along the . east I coast * of India. I AndhraI“ Univ.Mem,Oceanogr., * *7 ' (2):l2— Murty, V.S., 1982. Observations on some aspects of biology of threadfin bream28(l98l):l99—207 Nemipterus mesoprion (Bleeker) from Kakinada. if 9’ Indian 7 J.Fish,, pg; p y y pf, 1983. Observations on some aspects of biology Of silverbelly Beiognathus61-as bindus (Valenciennes) from Kakinada.I Indian” J.Fish., 30: g y_ yé, 1983a. Estimates of mortality population size and yield per recruit of hemipterus japonicus (Bloch) in the trawling grounds off Kakinada. Indian J.Fish., 3O:255—6O Awmgg W Ty W] 1984. Observations on the fisheries of "threadfin. breams (Nemipteridae) and on the biology of Nyemipyterus j_aponicus (Bloch) from Kakinada. Indian J.FishL, 31:1-18 Murty, V.S., 1984a. Observations on some aspects of biology of the croa kers Johnius (Johnieops) dussumieri (Cuvier) and Qohnius (Johnius) carutta (Bloch) from Kakinada. J.Mar.Bi0l.Assoc.India, 2l(l979):77-85 _p 1986- Growth and yield per recruit of J0'hniu_s §..J9l3ni_gs)p carutta (Bloch) in the trawling grounds off Kakinada. Indian J.Fish., 33:l63—70 gm W y, 1986a. Studies on the growth and population dynamics of sil verbelhy Leiognathus bindus (Valenciennes) in time trawling grounds off Kakinada. Indian J.Fish., 332277-84 _g__ 1, 1987. Further studies on the growth and yield per recruit of Qemipterus ieponigus (Bloch) from the trawling grounds off Kakinada. Indian J.Fi§h., 34 _y;"y , (MS). A study of the biology and population dynamics of the silverbelly, Secutor insidiator (Bloch) from Kakinada. Submitted for publication in J.Mar.Biol.Assoc.India Muthu M.S. gt al., 1977. On the commercial trawl fisheries off Kakinada during 1967~70. Indian J.Fi§h:, 22(l975):l7l—86 Nair, K.V.S. and A.A. Jayaprakash, 1986. A note on the monsoon fishery for threadfin breams off Cochin. Indian_J.Fish., 33:lO6—l2 Narayanappa, G., D.A.N. Raju and A.V.V. Satyanarayana, 1968. Certain ob— servations on the otter trawl operations carried out in the inshore and deep waters off Kakinada. Proc.IPFC, l3(3):45O—5 _ 35 _ Pauly, D., 1977. The Leiognathidae (Teleostei): their species, stocks and fisheries in Indonesia with notes on biology of Leiognatps splendens (Cuvier). Mar.BeslIndones., (19):73—93 __mHM"M*w, 1980. On the ihterrelationships between natural mortality, growth.stocks. parameters q.§ons.§IBM, and. mean lenvironmental 39:175~92 temperature. in, 175 fish _mMgM_,,, 1983. A selection of simple methods for the assessment of tropical fish stocks. EAO Fish.Tech.§ap., (234):52 p. Issued also in French and Spanish Pauly, D. and N. David, 1981. ELEFAN I. A BASIC programme for the objec tive extractitwx of growth parameters from length frequency' data. Meeresforschung, 28:205—11 Pillai, P.K.M., 1972. Fecundity and spawning habits of some silverbellies. ln.d.i_a11,l.-,€i§_h;. 19: 196-99, Rao, D.M. and K.S. Rao, 1986. Studies on the age determination and growth of332426-39 Nemipterus japonicus (Bloch) off Visakhapatnam. ' I Indian J.Fish., Rao, T.A., 1967. Maturity and spawning habits of some sciaenids in off shore waters at Visakhapatnam. Indian J;§ishi, 11:12l—6 Satyanarayana, A.V.V. and G. Narayanappa, 1972. A review of experimental trawling from small and medium sized mechanised vessels off Kakinada. Fish.Technol.Soc.Eish.Technol.,Qochin, 9:97—103 Satyanarayana, A.V.V., G. Narayanappa and D.A.N. Raju, 1972. On the compa~ rative experiments with a four-seam and two—seam trawls on the east coast. FishlTechno1.Soc.Fish.Technol., Cochin, 9:169—79 Silas,Res E.G., 1969. . Inst.Exploratory Cochin, fishing by R.V. Varuna. 12: Bull.Cent.Mar.Fish. 1-86 Sparre, P., 1985. Introduction to tropical fish stock assessment. Rome, FAO, Denmark Funds—in-Trust, FI:GCP/INT/392/DEN, Manual 1:338 p. g___HJgyg_m_, 1987. Computer programs for fish stock assessment. Length~ based fish stock assessment (LFSA) for Apple II computers. FAOzflzfl Fish. Tech.Pap., (101) Suppl. 2:217 p. Thompson, w.F. and F.H. Bell, 1934. Biological statistics of the Pacific halibut fishery. 2. Effect of changes in intensity upon total yield and yield gun: unit of gear. Rep.Int.Fish.(Pac.fialibut)Comm., (8):49 p. Vinci, G.K., 1983. Threadfin bream (Nemipterus) resources along the Kerala coast29(1982):37—49 with notes on biology of Nemipterus iaponicus. Indianu 'J.Fish., Vinci, G.K. and A.K.K. Nair, 1975. Length—weight relationship in the threadfinJ.Fish., bream, 21(1974):299-302 Nemipterus japonicus " along the Kerala coast. Indian Vivekanandan, E. and D.B. James, 1986. Population dynamics of Nemipterus japonicus (Bloch) in the trawling grounds off Madras. Indian*§iFish., 33:l45—54 Zupanovic, S. and S.Q. Mohiudiin, 1976. A survey of the fishery resources inl5:469—537 the north eastern part of the Arabian Sea. J.Mar.Biol.Ass9c.India, " L¢ MURTY, V. SRIRAMACHANDRA, T. APPARAO, M. SRINATH, E. VIVEKANANDAN, K. v. SOMASEKHARAN NAIR, s“. K. CHAKRABORTY, S. G. RAJE AND P.U. ZACHARIA. 1994. stock assessment of threadfin breams (§1_grégf_@P;e%ru3 spp) of India. Indian Q. Fish., 39 (1&2): 9-41 (1992). - [courriraurrou Bil Indran Journal ofFr'sheriss 39 (l, 2) : 9 -41, 'March, lune l992 Stock assessment of threadfin breams (Nemipterus spp.) of India v SRIRAMACHANDRA MURTY‘, T APPARAOz, M sarnxm’, E VIVEKANANDAN‘, K v somasmtrtanm NAIR‘, SK crrarqutsoarv‘, s o RAJE7 AND P u zncrraamrr‘ C enrral Marine Fisheries Research Institute, Cochin, K erala 682 014 ABSTRACT ‘The annual average estimated landing of threadfin breams in India during 1980-83 was 22 247 tonnes which increased to 48 100 tonnes during I984-88-; a matrimurn of about6000Otonnes landed in 1986. Over 90% of threadfin bream catch in the country was obtained by commercial trawlers. Among the maritime states of India, Kerala contributed maximum 6-2%) to the nemiptcrid landings, followed by Maharashtra (13.6%), Tamil Nada and Pondicherry (I 1.2%), Kamataka and Goa (8.8%), Gujarat (7.8%), Andhra Pradesh (5.5%) and Oriska (1.1%). Though a total of six nemipterid species contributed to the fishery in different states, only two spedes vizNemiplerusjapom'cus and N. mesoprion contributed significantly; the former was most abundant in Tamil Nadu - Pondicherry, Kamataka - Goa, Maharashtra and Gujarat and the latter in Andhra and "Kerala Periods of peak abundance were January-March in Andhra Pradesh, Kamataka-Goa, and Gujarat whereas April-June in Maharashtra and July-September in Tamil Nadir ~ Pondicherry and Kerala. The parameters of growth and mortality were estimated. 'lhe results of stock assessment from each state show that though there is scope to increase the effort by 40%-100% to get MSY from the fishing grounds, the increase in yield will be marginal (1%-12%). There is need to increase the cod end mesh size of trawl net (or length at first capture Le) by l0—30% to get MSY. The maximum possible yield of N. japonicttr and N. mesoprion from the fishing grounds along east coast (Andhra Pradesh, Tamil Nadu and Pondicherry) is around 5 (D0 tonnes and along west coast between 43 000 tonnes and 46 000 tonnes. These are close to the yields in l984-88. The problems in stock assessment and different options for management of fisheries are discussed. The threadfin breams are one of the most dian seas which formed 7.7% of total dcmersal dominant components among the demersal fish and 3.0% of total marine fish landings of fisheries resources of India being exploited by India. Though six species occur in the catches, small commercial trawlers up to depths of only two species, Nernipterus japonicus about 5O—60 m all along Indian coast. An (Bloch) and N. mesoprion (Blocker) are most estimated 67 677 tonnes of these fishes were abundant and contribute to bulk of thread landed in 1989 (Anonymous I990) from In fin breams catches. Considerable work on the distribution, Present address: 1Senior Scientist, 3‘ ‘Scientist taxonomy, biology and fisheries of threadfin (Selection Grade). 2Principal Scientist (Retd), No. 8, S4-1, Chinna breams was done from different regions along Waltair Colony, Visakhapatnam 530 (T23. Indian coasts (Banse 1959; Narayanappa er al. ‘Senior Scientist, Madras Research Centre of 1968; Silas 1969; Kuthalingam 1971; CMFRI, l4l, Marshalls Road, Egmore, Madras 600 (D8. Satyanarayana er al. 1972; Krishrtamoorthi ‘Senior Scientist, 7Scientist (Senior Scale), Bombay 1973a, 1973b; Vinci and Nair 1975; Silas er Research Centre of CMFRI, 148, Army and Navy Building, 2nd Floor, M G Road, Bombay 400 O23. al. I976; Rajagopalan et al. 1977; Dan I980; ‘Scientist, Mangalote Research Centre of CMFRI, CMFRI I981; Indra 1981; Madanmohan and P B No. 244, Bolar, Mangalore 57$ 001. G0pakumar1981; Murty 1981 , 1982a, 1982b, MURTYETAL (Vol. J'. No. 1.2 10 March. June I992] STOCK ASSESSMENT OFTIIREADFIN BREAMS 1984; Rao 1981; Rao and Rao 1981, 1983, Species composition and Iengthfrequert 1986; Vinci I983; Acharya and Dwivedi cy distribution: At each of the seven above 1984; Madanrnohan and Velayudhan 1984; mentioned trawl landing centres, data were Muthiah and Pillai 1984; Nair and collected for 4-8 days every month. In some Jayaprakash 1986; Vivekanandan and James cases, data on species composition and length l986, 1987; Viveltanandan 1990; James er al. composition were collected at the landing I987; Reuben er ai. 1989; Rao 1989 and Nair place and in others the samples were brought and Rcghu 1990). Detailed studies on stock to the laboratory. Biological data were col assessment of threadfin breams were also lected from samples brought to the laboratory. made (Krishnamoorthi 1973a; Murty, 1983, Total length, measured from tip of snout to tip 1987a, 1987b, 1989; Vivekanandan and of lower caudal lobe, was considered for James 1986; Devaraj and Gulati 1988; John length frequency and other studies. The data 1989; Kasim er al. 1989), but they were on species composition and length composi restricted to analyses of data from particular tion collected on each observation day were trawl landing centres or of data from re frst weighted to the estimated total catch of search/exploratory vessel from particular the group (threadfin breams) and the species areas. These studies are, ~to a .large extent, respectively, obtained on that day and then not able to meet the requirements of agen such estimates in a month were pooled and cies engaged in management of fisheries. then raised to the estimated caich of the mouth Therefore, concerted efforts were made to following the procedure of Alagaraja (1984). examine the data collected on dominant The monthly estimates were pooled to get species of threadfin breams from over wider quarterly and annual estimates. The data ob areas off the Indian coast for stock assessment tained at the observation centre were suitably and the results are presented in this paper. weighted to get estimates for each state. As the data on production were available in the form MATERIALS AND METHODS of quarterly estimates, the monthly estimates Detailed data on species composition, from each centre pooled for each quarter (I length composition of catch, and biology of quarter: January-March, ll quarter: April dominanv species collected from the trawl June and so on for four quarters) were landing centres at Visakhapatnfm, Kakinada weighted to get qu:-frterwise and statewise es and Madras along east coast; and Cochin, timates. In the states where detailed data were Mangalore, Bombay and Veraval along west collected at single centres only, the centre's coast during 1984-88, were considered. The data were raised to the dataof states: thus the Fisheries Resources_Assessment Division of the Central Marine Fisheries Researchin data collected at Madras, Cochin, Mangalore, stitute collects effort and catch data in the Bombay and Veraval were raised respectively to the data on catches of Tamil Nadu country through a well-designed Stratified Multistage Random Sampling Scheme and Pondicherry, Kerala, Karnataka - Goa, Maha makes estimates of districtwise and gear rashtra and Gujarat. However, in the case of wise effort, and disuictwise, gearwise and Andhra Pradesh, detaileddata were available group/spccieswise production. These data from two centres : Visakhapatnam and were also taken for the present study. Kakinada. In this case, the data obtained at Two species (Ncmipterus japonicus and Visakhapatnam were raised to the catches ob N. mesoprion) were fselected for the tained in the northem districts of Srikakulam, study. I Vijayanagaram and Visakhapatnam together M URTY 15'!’/IL. lVol. 39, Nu l,2 and those obtained at Kakinada were raised to the catch during the five-year period was the total catch obtained in the remaining coas taken as length at recruitment (l.,). The length tal districts (East (iodavary, West Godavary, corresponding to the first value in the des Krishna, Guntur, Prakasam and Nellore) of cending limb of the length-converted catch the state. Stock assessment was done separate curve was taken as an estimate of the length at ly for these two sets and then pooled to get first capture (LC). I estimates for the state of Andhra Pradesh. Yield and biomass: The raised annual Biology: The results of detailed studies length frequencies of catch of each species on length‘-weight relationship, food and feed from each state were pooled for all the years ing habits, maturation, spawning, sex ratio (1984-88) and annual average values ob and fecundity carried out at different centres tained; these were used as input for the study. were taken from published work. Estimation of yield and biomass at different Estimation of von Bcrmlrmffy growth fishing effort levels was made, using length parameters: The length data were grouped eonverted Thompson and Bell ( l 934) analysis into 10 mm-class intervals. The parameters of (Sparre 1985, Murty 1989) with the help of the growth in length were estimated following the ELEFAN method (Pauly and David 1981, programme MlXFlSll of the LFSA package Gayanilo ct ai. 1988): the growth parameters of Sparre (I987). The estimates of yield and were estimated using the monthly length fre biomass were made separately using the two quency distribution of each year (from 1984 sets of growth parameters (as mentioned to 1988) separately from each of the seven above) and their average corresponding to centres. In the data of each year, different each effort level was taken. These values were starting lengths and ‘samples’ were used and considered for the purpose of present study. best fit values were taken. Thus, 1-3 estimates The assessment of N. japonicus and N. of growth parameters in each year from each mesoprion was done separately and then centre were obtained. Of all such estimates in together from each maritime state. all the years, the smallest and largest lengths For studying the effects of changes in the at infinity (Lu) values and their associated cod end mesh size, the following procedure growth eoeflicient (K) values were selected was adopted. from each centre for all further studies. The 1. For each -species, the present Le values estimates thus obtained were compared with were converted into present tc values those available in the literature from India and using VBG parameters (tn is taken as 0). outside. 2. The present ts values in the species were Mortality rates: The instantaneous total decreased and increased by same factor mortality rate (Z) was estimated using length (as 10%, 20% . . . 120% . . . 200% of converted catch curve method (Pauly 1982), present tc). using the pooled data of all the five years and 3. Using these t¢ values, the present F and the LFSA package of Sparre (1987). The in other required parameters, the Beverton stantaneous natural mortality rate (M) was Holt (1957) yield-per-recruit analysis estimated using the empirical formula of wasymade. This resulted in yield-mesh Pauly (I980) and then the fishing mortality curve for each species. rate (F) was obtained as Z-M. 4. Taking the value of yield-per-recruit Lengths at recruitment and first capture.‘ (Yw/R) at current F and lc and the value The midpoint of the smallest length group in of annual average yield of the species, the I 12 M:|rclt,.ltme W92] S'l‘()(.‘K ASSl".S'S.\"liiN'l'()l'“l“llRliAl_)l"lN lll{li1\.\-'13 recruitment in numbers R = Y/(Y/R) was November-February in depths extending up estimated. to ill.) Ill. Most of the boats returned the same 5. The Yw/R at each ((1 in cacti species as day alter fishing but some boats stayed in the obtained at 3 above was weighted by the sea and conducted fishing for 2—4 days and value of R (obtained as in 4 above) to then retumed. Shrimp trawl with cod end Obtain values of yield in weight at dif mesh size of I5-20 mm was operated by all ferent tc (i.e. percentages of present lo) the boats. In Tamil Nadu, the small vessels values. (9.8—l1 m OAL) operated shrimp trawl with 6. The values of yield at different ta values cod end mesh size ranging from 15 to 18 mm. (i.e. percentage of present t¢) for the two In this state, some boats conducted daytime species were pooled to get yield mesh fishing and some night fishing in different cttrve for the two species together. depths up to 50 m. In Kerala also, the trawlers The estimates were made separately operated shrimp trawl in the 5-50 m depth using the two sets of growth parameters. The zone; some returned to the base every day average values of yield corresponding to each while some returned after 3-4 days. In Kar tc level, for the two sets of estimates, were nataka, however, boats of varying lengths of taken for the present study. 6.7-15.0 m OAL operated in the depths ex Similar analyses were made separately tending up to 70 m; the smaller-‘sized boats for each maritime state. used shrimp trawl with cod end mesh size of 18-20 mm and conducted fishing during day RIESULTS time whereas the bigger ones conducted stay Fishr:i y fishing up to 4 days using shrimp trawl of Though the exploitation of threadfin 25-28 mm cod end mesh size during nights breams was confined to relatively shallower and with fish trawl of 30-40 mm cod end mesh areas, the results of exploratory and ex size during day time. In Maharashtra, boats of perimental fishing (trawling) showed that 13.5 in length operated shrimp trawl in depths these fishes were more abundant in depths extending up to 60m; these boats stayed in the .beyond 50 m (particularly in the 100-200 m sea for 2-3 days and after fishing for about 36 depth zone) (Silas 1969; Zupanovic and hours returned to the base. In Gujarat also, the Mohiuddin 1973; Silas er at. I976. James ct commercial trawlers (14 m OAL) used shrimp at’. 1987, Philip and Joseph 1988, John 1989, trawl with cod end mesh size of 15-20 mm; Sudarsan ct at. 1990, Vivekanandan 1990, trawling was conducted in 20-70 m depth Vijayakumaran and Philip 1991, Siva zone and most of the boats conducted fishing prakasam ct al. I991) and known to move into and rctumed the same day whereas a few relatively shallower areas of the depth range boats returned after 3-4 days of fishing. 35-40 m during certain seasons (Banse 1959, All-India catches: The landings of Nair and Jayaprakash 1986). It is for this threadfin breams increased considerably reason that threadfin bream catch in different during 1980-88, consistent with increased ef states of lndia was obtained mainly by fort. Thc average annual landing of threadfin trawlers only and not by other gears. breams during 1980-83 was 22 247 -tonnes In Andhra Pradesh, commercial trawlers whereas the same during 1984-88 was 48 104 of three different sizes (ranging from 10 to tonnes. Starting from about 22 600 tonnes in 11.4 m O A L) operated in the depth range 5 1980 the landings showed considerable in 50 in during greater partof the year and during crease (cxeept a minor decline in I981) over MIJRTY I;'l'AL_ [Vol 39,140. 1, 2 65* increased from 1980 till I983 but from W84 J. it fluctuated. Major trawling in this state took place of 1' Visakhapntnam and Kakinatla. The trawling effort in the state during I981-88 ranged from 98 200 to 124 000 boat-days (Fig. 2) with an 454-‘ p1\ annual average of 112 450. The nemiptcrid '5-“'1 landings varied from a minimum of l 100 i tonnes in 1988 to a maximum of 2 800,tonnes in 1983 with an annual average of about 2 000 tonnes. During the period, two peaks in the Q1 landings, one in 1983 and the other in 1987, were observed. The catch per unit effort in different years varied from about ll kg in W 1988 to 23 kg in 1983. There were two peaks 15-,-E in catch rates also, in 1983 and 1987, in con .L fonnity with those in catches. TAMIL NADU AND PONDICHERRY2 The 5'9‘ estimated annual landings of threadfin breams by all gears during 1980-88 ranged from 2 1930 1988 100 tonnes to 6 800 tonnes with the anhual Fig. l. Estimated annual landings of lhreadfin breams in India during 1980-88. average at 4 100 tonnes. There were two peaks, one in 1982 and the other in -1987. the years and reached a maximum of over Major trawling took place off Madras, 60 000 tonnes in 1986, the catches declined to Cuddalore, Nagapattanam, Mandaparn, about 50 600 tonnes in 1987 but in 1988 they Rameswaram, Tuticorin, Pondicherry and increased to over 53 000 tonnes (Fig. 1). Karaikal and the total trawling effort varied Statewise catch efiort and catch rates: from 412 000 to 558 000 boat-days (Fig. 2) Among the maritime states and union ter with the annual average at 487 500. At all the ritories, West Bengal did not contribute to D Elton I Catch - cPuE threadfin bream landings. Among the remain ing, Kerala contributed the maximum (52%) 311" 6_“‘ Karnateltaa"8 ' ll -30 Goa ‘ i- I . 1° of all India nemipterid catch, followed by ‘i ~’< III I1 Maharashtra (13.6%), Tamil Nadu - Pon ‘A ‘i ami QUI - ontc any 20 dicherry (11.2%), Kamataka - Goa (8.8%), Y3 ' Gujarat (7.8%), Andhra Pradesh (5.5%) and \-I Orissa(1.l%). The total landings in each state -r along with the catches and catch rates by trawl are dealt with here. ANDHRA PRADESH: During 1980-88 the 2_1 Q A 1901‘J cm toes Prndoeh 19 7 in estimated landings from all gears varied from 0 1 0 Fig. 2. Estimated effort, catch and catch rates of thread about 1 130 tonnes in 1988 to about 3 000 fin breaml by trawler: during 1981-88 in tonnes in 1983, with the annual average Andhra Pndesh; Tamil N adu and Pondicherry; during this period at 2 030 tonnes. The catch and Kamaulra and Goa. Ca ch {x 1000 onnes N Q ‘F OI U1 LII r ._l— —.1, Ellen: Osimns + 7. - 9,19-:. C-fill! GIJUIIIOS '9_+ ‘?i_° :13 _ b-L-.4 O 5‘Itl3fld9 March, June 1992] STOCK ASSFSSMENT OF THREADFIN BREAMS J U Eflort I Catch -— CPUE' ‘ catch from trawlers varied from about 600 to -—36 i Korala ~90 6 700 tonnes with an annual average of 3 400 tonnes during 1981-88. The catch per unit of effort varied from 2 to 22 kg in different years. 1 J The effort and catch showed more or less tl ‘son-0 similar trends but the catch rate in 1988 was ,0-. the highest though the effort and catch were an 91 '8‘ T4‘ l less than in some previous years. q KERALA: The yearly estimated threadfin 5'1| 101 4i i “ bream landings by all gears in this state 6 ranged from 6 400 tonnes to 38 000 tonnes 1<| with the annual average at.l9 000 tonnes. ii W981 1983 1M5 1987 Apart from the two major fishing har I-1;. 3. Estimated effort, catch and catch rates of thread bours at Cochin and Sakthikulangara, fin bream! by trawlers during I981-788 in mechanized boats operated all along the Kerala. coastline and the estimated annual trawling effort varied from 268 O00 to 863 000 boat trawl landing centres, threadfin breaths were days in different years during 1981-88 landed in considerable quantities but at Man (Fig. 3). The catch of nemipterids by trawlers dapam and Rameswaram the landings were varied from abut 4 900 tonnes in 1981 to negligible. The estimated annual landings of 37 500 tonnes in I986 with an average of threadfin breams by trawlers during 1981-88 18 3(1) tonnes. The catch per unit of effort varied from 1500 tonnes to 6400-tonnes varied from 14 to 93 kg. lt is clear that over (Fig. 2) with the annual average at-3' 600 the years. the catches and catch rates showed considerable increase._It could also be seen tonnes. The catch per unit of effort varied between 3 kg and 13 kg. Duringil98l-88 the that the effort variation among different years peaks in effort, catch and catch rate were more was not as significant as among landings of the threadfm breams by trawlers (Fig. 3). or less in the same periods (Fi g. 2). MAHARASHTRA! In this state, the es KARNATAKA AND Goa: An estimated timated annual tl'u*eadfin'bream landings by annual average of 3 200 tonnes of ncmipterids all gears varied from about 2 200 to 12 300 were landed with the yearly estimated catches by all gears varying from a minimumof 700 tonnes. Starting from 1980. the landings in tonnes to a maximum of 6 800 tonnes during creased with a peak in 1983; the landings I980-88. Starting from 1980. the landings showed decline in 1984 and 1985 and in increased slowly, but suddenly showed a creased further with highest landings in 1988. fivefold increase in 1983. The landings ‘flue annual trawling effort varied declined in 1984 and 85 and showed increase from 73 000 to 245 0()0 boat-days (Fig. 4) with in 1986 and the maximum catch of 6 800 an average of 174 000. The estimated thread tonnes was obtained in I987. fin bream landings during the same period There was considerable trawling along varied from 2 100 to 12 300 tonnes with an Karnataka-Goa coast and the trawling effort annual average of S 100 tonnes. The catch ranged from 179 000 boat-days to 397 000 rates fluctuated between 14 and'e54 kg. The boat-days in different years (Fig. 2) during trawling effort and catch showed more or less l98l—88, with an annual average of 271 000 same trend over the period as also the catch boat-days. The estimated thrcadf in bream rates. Eflort x Osurtts \J _ Catt:nn000tnnnes ‘PM M 9*. UI '14 O o thand3 MURTY ETAL. [V0]. 39, No 1,2 I U t mm I Catch —-CPUE~60 five species occurred in the catches; here also, t§u| tr"t| _' O the above two species formed the bulk of the 1‘°‘.% catches and the other three species formed .205. about 40% of nemipterid catch. ln Kcrala, N. ,*9-v‘ o japonicus. N. mcsoprion and N. mctopias oc curred in the catches but the first two species together formed about 99% of thread tin bream C ‘-— Maharashtra '50 Q catch. In Karnataka-Goa and Maharashtra " ll1 " 130' 2 T only -two species (N. japonicus and N. .__ ~10, ~10 _ £ " mesoprion) contributed to the fishery. In Gujarat, in addition to the above two species, 6i i N. delagoae also occurred in the catches but teat teas tens tan? in very small quantifies forming about 2.0% of tltrcadfin brcam catches. Fig. 4. Estimated effort, catch and catch rates oft.hread fin brcams by trawler: during 1981-88 in It is thus clear that only two species are Maharashtra and Gujarat. of any importance to the fishery. Of these, N. mesoprion is more dominant in Andhra GUJARAT! The annual trawling effort var Pratlesh and Kerala and N. japonicus in the ied from 82 000 to I49 000 boat-days (Fig. 4) remaining states. with an annual average of 101 000 boat-days. Seasonal variations: The data on es The nemipterid catch ranged from 1 200 to 5 timated catches in each month were pooled for 900 tonnes with an average of 31 000 tonnes. periods-of three successive months from 'l'hc catch per unit of effort ranged from l2 to January (4 quarters) and were then converted 67 kg. The period 1984-86 recorded good into percentages in each year. These values annual catches from trawls with highest in are shown in Fig. 5 for each state separately 1986. The catch rates by trawls showed in for the years from 1985 to 1988. Though there creasing trend up to 1986. were slight variations in the periods of peak Species composition: A total of six landings within each state, the first quarter species, Nemipterusjaponicus, N. mesopriort. appeared to be the peak period in Andhra N. tolu, N. dclagoae, N. luteus and N. Pradcsh, Karnataka and Goa, and Gujarat, mcropias, contributed to the fishery along In second quarter in Maharashtra and third tlian coast during the period. Of these, the first quarter in Tamil Nadu and Kerala. While there two species contributed to the fishery sig was trawling round the year along east coast, nificantly all along the coast whereas the there was no fishing along Karnataka and others occurred in the catches occasionally in Gujarat on the west coast, and only very poor small quantities. The last mentioned species fishing in Maharashtra during monsoon contributed to the fishery in small quantities (June—August) months. In Kerala, however, along southem Tamil Nadu and Kerala there was trawling during rnonsoon also and regions only. major portion of threadfin bream catch was In Andhra Pradesh five species (except obtained during this period. ing N. metopias) contributed to the fishery and N. japonicus and N. mesoprion together Biology formed over 90% of nemipterid catch. Along Considerable work on various aspects of Tamil Nadu and Pondicherry also the same biology of different species of threadfin Eton it 05 UPTS o. ,- to Ca ch ix ml;-.~es Z NJ ‘.5 _l' March, June I992} STOCK ASSESSMENT OFTHRIZADFIN DREAMS 40 Andhra Pradosh Quiarat -0 0, 0 40 & +~_4”_ %:_r| + 1; Tamil Nadu and Pondlcharry 40 0 Maharashtra '-,—*—*~ 40 _. + - r_-.4 - ra_L_.»_i Keraia 40 1;L.....L L - x.__.r \_.._1._|.. Karnaiaka and Goa 40 O O 40 40 B0 ,~ ; "2".-="v ‘<:—,-H>- ;__; .*_" ;__;i"T“! _ ’__ ‘234123 12a4i§341§3 4 1T 2 3 4 1987 1995 1955 1987Quarters/years 1969 1985 1986 was Fig. 5. Quancrly variation in catches of lhrcadfin hr-cams in different years in Andhra Pradcsh; Tamil Nadu and Pondichcrry; Kcrala; Kamalnka and Goa; Maharashtra; and Gujarat. I. January--March 2. /\pril—Junc 3. July-Scplcmbcr 4. October-l)cccmhcr. brcams was carried out on the basis of data Nemipzerusjaponicus collcctcd from particular ccntrcs along In- FOOD: According to Krishnamoorlhi dian coasts. The rcsults arc briefly given (1973b),lhcchicf ilcmsof food of this spccics bclow in mcrcasc of N. japonicus and from off Andhra-Orissa coasts arc Squifla, N. mesoprion. crabs, carried prawns, squids and fishes in the 17 Percentage n each year # CDO o MURTY ETAL. [V0]. 39, No 1,2 order of dominance; this species is a bottom starting from December. This means that the feeder. second batch of ova will be released during I.ENG'I'll /tr FIRST MATURITYZ From off March-May period. Since the first batch is Andhra-Orissa coast, Krishnamoorthi released during December-February, the (1973b) studied the data obtained by ex spawning period becomes continuous from ploratory fishing vessels and taking females in December to May. each fish releasing the ripe stages V and VI of maturation as mature, ova in two spawning acts. determined the length at first maturity of the Murty (1984) studied the gross structure species as 165 mm. Based on data from com of ova of different diameters and the ova mercial trawlers from off Kakinada, Murty diameter frequency distribution in several (1984) determined the length at first maturity ovaries of different stages of maturation and as 125 mm; for this purpose he considered the concluded that N. japonicus was a fractional data of spawning season only and took spawner releasing the ripe egs in two spawn females of stages III-VI as mature. From off ing acts during August-April in the sea off Madras, Vivekanandan and James (1986) es Kakinada. In the sea off Madras (Vivekanan timated the length at first maturity as 145 mm dart and James 1986), the spawning season on considerations similar to those of Murty was determined as June-March with peak (1984). ~ " during December-March. From off Cochin, sv/twnrrvo: The data of Ki-ishnamoorthi (l973b) showed that fishes in stage IV of the study by Vinci (1983) and the present data showed that spawning in N. japonicus takes maturation were, available from August to place during June-January with peak during March with peaks in September-October and J une-August (monsoon). From the findings of J anuary—February; stage V fish occtured from September to February and stage VI (Ripe) Kuthalingarn (1971) and the present data, it from September to November. According to appeared that off Mangalore the spawning the author, September-November is the period extended from November to May with "probable" period of spawning in the sea off peak during November-February. Off Bom north Andhra and Orissa coasts. bay, mature and spent fish occured almost Dan (1980) used a part of the material and throughout the year but their proportion was data of Krishnamoorthi (l973b); he examined highest during - monsoon months (June 38 ovaries of fish of lengih range 130-209 August). Off Veraval, spawning appeared to mm collected during November-February take place during October-April with peak (4 mouths) of 1965-(Ya. According to him "the during October-December. fish breeds over ta short and definite period FECUNDITYI Dan (1980) examined 38 from December to February. Since about three ovaries and estimated the fecundity as ranging months time is necessary for the second mode from 13 900 to 58 400 in fishes of 13$ to 205 [in the ova diameter frequency distribution] to mm in total length. The author knew that this become ready for spawning, it appears that the species spaw_n§l~ip two batches but did not fish may breed for a second time in J une—Jtily consider§t,his fact for estimating fecundity. period’ However, lookittgiat the data on ovg The estimates given, therefore, are to be taken diameters presented and the above con as ‘batch fecundity‘ estimates only. clusions, one would conclude that the second _ Murty (1984) estimated the total annual batch will be released after three months start fecundity (two batches together) as ranging ing from March since the firstbatch is released from 23 000 to I39 200 in fishes of the length March, June 1992] STOCK ASSFSSM IZNT OF Tl IREA DFIN BREAMS range 134-199 mm. Two relationships ob species contributed over 90% of threadfin taincd were: brcam catches. Growth parameters: The smallest and r=--11s.sm1t+1.119o<> L; gz - 0.69 1== -0.15615 + 1.113110 w; R -=o.as largest L... values and their associated K values pertaining to the two species are shown where F, fecundity; L, total length (mm); and in Tables I and 2. The corresponding length W, total weight of fish (g) frequency data (restructured) with the growth _ SEX RATIO: According to Krishnamoor curves are shown in figures 6-I3. The values thi (1976) and Murty (1984) males were of L... and K of N. jap'om'cus from all the predominant in almost all lengths and beyond 215 mm there were no females; the mean centres in both the sets (Table 1) varied from 305 to 351 mm and from 0.40 to 0.70/year length of males was always greater than that of females. respectively. While the maximum recorded length (Lmu) in India is 350 mm (Krish Ncmipterus mcsoprion namoorthi l973b), the Lmx values observed FOOD: According to Rao (1989) this at different centres (Table 1) are close to the species is camivorous subsisting mainly on estimated values of L... Further, the values of crustaceans and teleosts. Among the former, L... and K in each set from different centres small prawns, stomatopodsr and crabs were are closer. The growth parameters estimated dominant. by earlier workers (Table 3) from the Indo MATURATION AND SPAWNING: The Pacific region show wider range in both L... length at first maturity was estimated in (235-382 mm) and K (0.12-1.00/year). females as 100 mm (Murty 1982a). This __ In N. mesoprion, the values of L... and K species is also a fractional spawncr spawning from different centres vary from 222 to 297 in two batches during the season which off mm and from 0.405 to 0.84/year (Table 2) Kakinada extended from December to April respectively and the 1-mu observed at dif with peak in January (Murty 19823). ferent centres are close to L“ values con Though results of investigations from sidered. The values of lower L... from different other centres on spawning in N. mesoprion centres are more or less close to each other but were not published, the available data indi in higher L.., the range is slightly larger. cated that off Cochin spawning takes place Mortality rates: Taking the two sets of during June-September with peak in June. growth parameters (Tables 1 & 2), the total Along the Bombay coast mature and spent lish mortality rates were estimated using the occur almost throughout the year with peak length converted catch curve. The Z values during June-August. Off Veraval there was obtained by using each set of parameters from no trawling during J une-August, the propor different centres varied from 1.80 to 3.02 tion of mature and gravid fish in each month showed that spawning in this region takes (lower parameters) and 2.12 to 3.39 (higher place during October-March with peak parameters) in N. japonicus (Table 1) and during December-February. from 2.01 to 3.76 (lower parameters) and 2.25 to 5.37 (higher parameters) in N. mesoprion S tock assessment (Table 2) (Here and elsewhere in the text the For this study, only N. japonicus and N. estimates obtained by using smallest L... and mesoprion were considered as these two related K are referred to as having been ob l\1L'R'l'Y 15'!‘/11.. [v<>|. 39, No. 1, 2 Visakhapalnam 1986 7 ' — _ il l 1 i E _ r —. 18 wfi‘i' | 1] _' 1I .-1"1 I I : | I. I ‘I 60 O L. i|||I|||‘ I ? Visakhapatnam 1987 240 I} _-—_ F ‘ 18Of' I F Q . 120 T I 4~ I 1 J-Q 60¢ 1 pm OJ. if Kaklnada 1988 11 1&0 A‘ ' T * 120so° M8 I a Kaklnada 1988 240 ; ¢ 8 8 » 7 * 180, 12060 _ __’__, Jan Feb Mar Apr May Juno July Auo Sop om Nov 09¢ Fig. 6. Rcatructuvcd0 length frequency data (IELUFAN 1) and growth_ curves of Nemiptermjaponicus. Visakhnpab mam 1986 : L, = 305 mm, K=0.$2 pcr year, SS=9. Sl,=14$ mm; Visakhapalnam 1987 : L... = 335mm, K=0.40 per year, SS=2, SL=l15 mm; Kakinada 1988: L... = 315 mm, K=0.51 per year, SS=2, SL=120 mm; Kakinada 1988: L... = 351 mm, K=0.49 per year, SS=6, SL=I25 mm. ' Tota length n'm * 2: Qr—T—1—r"*-" <9 0 March, June 1992] S'l'O(‘.l-( ASSIZSSMIZNTOI-‘ 'l'l1RF.ADl"'1N BRIE/\MS Table l. Estimated values of growth parameters, mortality rates, ages at recruitment and first capture, and other parameters used in the assessment of Nemipterus japonicus from different centres Parameters Visakha- Kakinada Madras Cochin Mangalore Bombay Vcraval pautam 350 315 295 305 285 325 345 bower L. and 305 315 305 323 ‘ 323 320 320 related K (151 0.51 0.62 0.70 0.43 0.56 0.60 11.14 1. 12 1 .28 1.37 0.99 1.18 1.23 2.29 1.80 2. I 4 3.02 2.72 1.95 2.70 1.15 0.68 0.86 1.77 1.81 0.77 1.47 1.06 0.99 0.60 0.41 1.14 0.88 1.10 Ir 0.23 0.30 0.32 0.16 0.52 0.48 0.19 Terminal FIZ 0.548 0.5% 0.5% 0.624 0.683 0.5% 0.5% Higher 1.... and 1-. 335 351 350 350 350 345 related K Q49 0.49 0.58 0.68 0.50 0.55 0.94 1.06 1.18 1.30 1.07 1.14 2.12 2.16 2.92 3.39 2.16 3.05 1.18 1.10 1.74 2.19 1.09 1.91 1.22 0.89 0.58 0.38 0.88 1.10 t, 0.28 0.28 0.29 0.15 0.48 0.19 Terminal F/Z 0.676 0.5% 0.5% 0.770 0.5% 0.5% 10;. _4.244t -4.2441 -4.3665 4.4793 4.4793 -5.5272 —5.5272 1! 2.102 2.7m 2.9661 2.8487 218487 3.2839 3.2839 All lengths are in mm, weights in grams and ages in years; log a and b an: the constants of length-weight relationship. tained from "lower parameters" and similarly the present effort. In N. mcsoprion, maximum for largest L... and K from "higher para yield of 1 023 tonnes can be obtained at 140% meters"). The estimated value of M from dif of the present effort. In both the species ferent centres in N. japonicus ranged as together the highest yield of 1 636 tonnes each 0.99-1.37 with lower parameters and 0.94 be obtained at 140% of the present effort (Fig. 1.30 with higher parameters (Table 1). In N. 14.A). Thus the effort should be increased by mesoprion the range of M values was 1.02 40% to get MSY. The present yield of these 1.59 with lower parameters and 1.12-1.67 two species is 1 6% tonnes and a maximum with higher parameters (Table 2). increase of 2% in the yield cart be attained Length-based Thompson and Bell from the present fishing grounds through in analysis: The results pertaining to each creasing the effort by 40%. This means a maritime state are presented first followed by drastic reduction in catch per uniteffortas also those of cast coast and west coast and then all indicated by low biomass values at this effort India. level (Fig. 14.A). ANDIIRA PRADESIII In N. japonicus the TAMIL NADU - PONDICIIERRYI In this yield increases with increased effort and region, maximum yield of I 850 tonnes can be reaches a maximum of 617 tonnes at 160% of obtained at 140% of present effort in N. 5‘-:1NZ7< 8'*-nNZ7=1F§ MURTYETAL [Vol. 39, N0. 1,2 Madras 1988 I I '-_ 8 -DI. -f ‘ac?bI I :0 n 09~ -. . LaI I 60¢" 0 3.. —- Y __, J7 Madras 1985 240.;- P1* -L A1V—— A 7 if~ — é % _ 4 120180 I .IJE *1 Tll + 60O '“ ;' 1-’?il‘E i "1I “I*:i "-3 Cochin 1986 240 7 —-'l’— ; l ;"LL u% i 180 1 20 i 0 | J - _ 0 60 O ....‘:lE Cochin 1987 1. _ I — I 240 L1 I I _._-lY_ T“ ~ D - Y 1601: > \ I h 120 :i ' * I 1 L Ii" 1-‘v .1‘ 0, I so 0 L J A an’ Feb Mar Apr May June July Aug sap 0¢| Nov 09¢‘ l.-‘ig. 7. Rcslruclurcd lcngdr frequency datl (IZLIEFAN I) and growth curve: ol'Nema'pI¢ru.rjap0m'cu.s. Madtu I988: 1.. = 305 mm, K=0.62 pcr year, SS=6, Sl.=I20 mm; Madras 198$: L‘ = 350 mm, K=O.58 per year, SS=3, Sl.=l0S fn_m; Cochin 1986: L. = 32.3 mm, K=0.7O pcr year, SS=4, S&13S mm; Cochin 1987: L. = 350 mm, K=O.68 per ycar, SS=2, Sl,=125 mm. -Q m0 f’F—l;; March, June 1992] STOCK ASSESSMENT OFTllREJ\DI’1N BREAMS Table 2. Estimated values of growth parameters, mortality rates, ages at recruitment and first capture and other parameters used in the assessment of Ncmiprartu-n1¢sopr1'0n from different centres Parameters Visakha- Kakinada Madras Cochin Mangalore Bombay Veraval patnam 229 215 195 265 205 255 295 Lower L. and 240 225 223 244 222 246 255 related K 0.65 0.76 0.61, 0.62 0.74 0.77 0.405 1.41 1.59 1.38 1.36 1.57 1.56 1.02 3.76 2.91 2.01 2.04 2.28 2.21 2.09 2.35 1.32 0.63 0.68 0.71 0.65 1.01 1.13 0.62 1.11 1.30 0.99 0.92 1:16 t, 0.24 0.29 0.46 0.25 0.47 0.47 0.36 Tcmtinal l'-‘)2 0.5 0.5 0.5 0.5 0.5 0.5 0.5 lligher L. and 267 255 . 238 273 260 288 29'? related K (}_77_ 0.465 0.34 0.51 0.60 0.53 '0.6s 1.47 1.12 1.61 1.36 1.31 1.24 1.33 5.37 2.47 3.39 2.25 2.33 2.51 3.06 3.90 1.35 1.12 1.09 1.51 1.33 3.13 0.88 0.94 0.79 1.34 1.033 1.04 0.39 1| 0.19 0.42 0.31 0.21 0.43 0.52 0.19 Terminal FIZ 0.5 0.5 0.5 0.5 0.5 0.5 0.5 loga -4.650917-4.650917 -4.79260 -4.83784 --4.83784 -4.25225 -4.25225 _b 2.87707 2.87707 2.9692 2.9840 2.9840 2.89912 2.89912 All lengths are in mm, weights in grams and ages in years; log a and b are constants of length-weight relationships. japonicus. in N. mesoprion and in both the 36% increase in yield can be obtained through species together, the yield increases with increasing the effort by 100%. However, at increased cf fort up to 200% of present this effort level, the increase in yield of both (Fig. lS.A) and the yields are 1670 tonnes the species together will be only 12%. Though and 3470 tonnes respectively. The increase this means a decline in catch per unit effort, in yield of the two species will be only the yield of N. mesoprion can still be increased 7% with 100% increase in effort. Thus, the by suitably deploying the effort in the grounds increase in effort can result in decline of catch during monsoon. It may be noted that thread per unit effort from the present fishing fin brcams are principal group in the fishing grounds. grounds at depths of 30-40 m during monsoon KERALA: The MSY of N. japonicus cor period (Nair and Jayaprakash 1986, Murty er responds to 11 900 tonnes at 60% of the al. -1992). present cf fort. In N. mesoprion and in both the KARNATAKA-GOA! In this region the species together, the yield increases to 23 230 MSY of N. japonicus corresponds to 80% of tonnes and 31 12$ tonnes respectively at present effort whereas the yield increases with 200% of present‘. effort (Fig. l6.A). Thus there increased effort up to 200% of present effort is scope to increase yie1d_ofN. mesoprion and in N. mesoprion. In both the species together r~=1t~1Z> Mangalore 1988 240180 _— 'I I -_ -: I' “F _'l“M—I" i ‘"1'_‘ I‘ Bombay 1985 -.. 240‘I . _ L T " ' Z 01% _T we‘ 0 fie. T 3 i 240Bombay was - ' 18°I 5. 3'"' 120 i _ 3 :., 60 Jan Feb Mar Apr May June July Aug $99 Q¢1 Nov Dec Fig. 3. Reslmcmred length frequency dntn (F.LF.|7l\N 1) and growth curves of N¢'miprr'm.r jnp0m'cu.t'. Mangrllorc I988: L, = 32$ mm, K=0.43 per year, SS: 1, Sl:l05 mm; Bombay 198$: I... = 320 mm, K=().56 pt-.r your, SS=4, Sl.=1130 mm; Bombay 1988: L, = 350 mm, K=0.5O per year, SS=l, SI,=l I5 mm. MSY corresponds to‘ 140% of the present species also maximum yield corresponds to effort (Fig. l7.A). The increase in yield at this 200% of present effort (Fig. I8./\); the in effort level will only be about 1%, indicating crease in yield is, however, 9% only. a drastic decline in CPUE. GUJARATI In this region the MSY of N. MAIIAR/\Sll'I‘RA: In N. japonicus the japonicus corresponds to 160% of present ef MSY corresponds to 140% of present effort fort and in N. mcsoprion the yield increases up whereas in N. mesoprion the yield increases to 200% of present effort. In the two species up to 200% of present effort. In both the together the MSY corresponds to 180% of 25 Toalength rrm O) R; Q O_1fi_@ 2IaN_3dWfl_WRM_§>g§§38§g§E&§E_§E&i§§i§%£ 82so 3G35 aas$0 336¢g QQ25:‘ $A95 QQ1§ 3Q: 1$0 ___A23a_ 8Ami3 nQ520 5Q63$8E35 0“$63Q: 5Q3Q 3A8Q: TNCB1E _~83¢E 2glN2 353g QA2133"86$02 8as5 a$18~_ aqg§ aA9E QQ 35 38_ Q“Q2g QA233 ___Q2i 3$3_§ 3as§ 2fig§ :asE QA9KN Qpi$9S1an S:__N|vN: finpgl8' QQ__ 25 2e_R+VN8 3flagan 3¢d_+VFa Q86$§ QheE _NA21$2“:35 2AzlE5QSIV8N FQ638!;A23E 2G3§___Q32 2Qi8 258‘ NasP: 8as:9 g81E g38¢Q8:86¢so %E8° mmQiv2 %Q3O8 %Q3E 'A9§__Q:N8 __£18“ _:635 _%:63axEE N535 N635 flasE NQ3é NQBuQ3g NA______v=8 GQ55 _51as _338 N$3Q9 N$33 NEQ. NG3R;52:Q35 NQOTVg N86$8” _25¢5 _A8_¢§628_628_838§+V8_meA586 8_83_ 8STV8839638£08“3__€__k_3_“E 81% fig8_§&aE E}nagfig ‘ii fig 33%: 3%: 3 §§_m_g~z 355:2 _E8_____$2_ =88“ 1: AA 113 _?‘J All [N I N ‘OK? ‘I, \ In !__ _=_8\l_ Sm! Al‘ _ i :85 §E°__gn___E_°___3_3__B_§ 53£2Eaggg§§5§§§a§z_Z_§ila%zUA§v§> _‘ as M March, June 1992] STOCK /\SSl'ISSMl~INl“O1iTllRli/\l)I¥'lN liRIi/\MS Varaval 1984 2401ao II I I I _ I _ I is 120 _ so V ° " s r Mn» t “'?rfi‘-~ e Veraval 1987 2-to 0- I I I g 180‘I20 I 60 ° llJan Feb't Martracers‘ Apr May June July t Aug"ti" Sep Oct | Nov ‘W Dec Fig. 9. Rcstmctured length frequency data (F.LlZFAN 1) and growth curves of Nemipterqs japonicus. Veraval 1984: L. = 320 mm, K=0.60 per year, SS: 1, Sl.=l00 mm; Veraval 1987: 1,, = 345 mm, K=0.55 per year, SS=4, st.=200 mm. present effort (Fig. 19./\). The total yield of effort whereas in N. mcsoprion the same is at the two species (at 3 900 tonnes) at 180% of 200% (Table 4). In both the species together present effort gives only 5% increase - in --the yield is maximum at 20()% of the present yield, thus suggesting decline in catch per unit effort. At this effort level, however, there will effort. be 14% decline in the yield of N. japonicus 12/ts'r consr o1= mom: The results of though 32% increase in the yield of N. stock assessment off east coast (except Orissa mesoprion and thus about 10% increase in the and West Bengal) of N. japonicuys showed that yield of both the species together over the MSY is obtained at 140% of the present effort yield at the present effort level. (Table 4). In N. mesoprion the yield increases ASSESSMENT ON ALL-INDIA BASIS; In N. with increased effort up to 200%. In both the japonicus the M_SY corresponds to 80% of species together MSY is obtained at 180% of present effort whereas the yield increase eon present effort. At this effort level, increase in tinues til_l 200% of the present effort in the yield of N. japonicus will be 1%, in N. N. mesoprion and both the species together. mesoprion 9%. and in both the species By increasing the effort by 100% the yield of together 5%, over the present yield. N. japonicus decreases by 12.3% (Table 4). In WEST COAST OF INDI/\:' In N. japorticus N. mesoprion the yield increases by about the yield is maximum at 60% of the present 30% and, by 9% in both the species. Thus the Toalengh rrrn MURT Y ETAL. [Vol. 39. No. 1, 2 Visakhapatnam 1986 130+‘,Q,"" ___( I 0___ _ -____ - | 1}‘ _ + ' I. : . ' F’%I |-. .. 2| ear*’. _._. ..| |I1 | '. ' .- ' 0L,T .4 _?_f‘ . 54‘visakhapatnam ' d i\ i _ 1987_ j ___. 120601 VA i " -' 0 " F *F *1 "1" ' _ jfi _ Kaklnada 1987 wow ' ' = ' ' _ \ “"\I '.O % ' ’. 1207-60;’P‘ W U ' I : _ _ L 01 41 11-W **T*‘ F ?*i; * Kaklnada1988 vaO.»+ I (+‘ I ;’ é 120i ‘\ 60 0 - Jan Feb Mar A;PTv|Qy f .;u{1;rJI»|; ?'* iufl sap Oct Nov 09¢ Fig. IO. Rcsuuclu rcd length frequency data (ELEFAN 1) and growth curves ofN¢mipterus mesoprian. Viukhapab rlam 1988: I... = 240 mm, K.-=0.65 per year, SS=5, SI;-50 mm; Visakhapatnam 1987: L. = 267 mm, K=0.72 pcr year, SS=2, S1.= I 30 mm; Kakinada I987: I... n 225 mm, K=0.76 pct year, SS=5, SI.--110 mm; Knkinada 1988: L. = 255 mm, K-20.465 pct year, SS=2, SL=$0 mm. To a Iength mrn _i:i* 11% ii. P J March, June 1992] STOCK /\SSIi.'§SMPINTOF11lREADFlN BREAMS Madras 1988 T 1a0L -p— — Q 120T .._gI j_ I »-L| I ' iII -—— \\ 60'“ T 0 Madras 1985 T“ 1ao,L L w— ‘ 120 E wr L. 0% \-0 0 ._ _, ii __ i-— ~Cochin 1985 aw I 180 '“ II: 6U_ @ 04. 4%AA y ;Jfi IV. *1 1J i'“"1 4 COChin 1988 180i" __ —I |I | n _ " 120£ Q. I 60 ‘T fl— : our ' Jan Feb Mar Apr May June July Aug Sep Ocl Nov Dec "ig. I l. Rcslruclurcd length frequency data (ELEFAN l)and growth curve; of Nemiplerus mesoprion. Madras 1988 L. = 223 mm. ‘(=0-6! pct year, SS=4, SI.=I 10 mm; Madras 1985: 1. = 238 mm, K=0.84 per year, SS=I SI.=9S mm; Cochin 1985: I. = 244 mm, K=0.62 per year, SS=2, SI- = I25 mm; Cochin 1988 L, = 273 mm, K=O.5l per year, SS=7, SL=155 mm. Toaengthmm ORS T‘T— 1.5"! M URTY ET AL. [Vol 39 No. 1,2 Mangalora 1988 L I 180 120 4%L _ 60 .... _---"",-II"__-,—_ _.aI"* I‘ _..-i#""' J. 0 1* W T {| *‘ F * " Ff F" Mangalore 1988 1&0? P 1201» J I ~=<>P~ ni -i __--—-P"""'I °L jrw 1* * 1 ‘ * T T‘ Bombay 1986 180 120‘ l 60+ O \ L. . -Bombay 1986 '4 \ i 18U L». _-— 0—__.: ;I "' I|I 1_1 '-Il I" I| ' __Q fi I 1 I _ 1 a I 120 '#= I u» \ -‘} 1I I—II I'I I 60 T I II 0 L .-an Jqn Fab Mar Apr May Juno July Aug Sop Oct Nov Dec Fig. 12. Rcsuuctumd length frequency data (ELEFAN 1) and growth curve; of Nemiptcrus mesoprion. Mangalorc 1988: L. = 222 mm, K=O.74 per year, 88*-=7, SL=l60 mm; Mangalon: 1988: I... = 260 mm, Kr-0 60 per year. SS=l, SL=95 mm; Bombay 1986: L, = 246 mm, K-=0.T7 per year, SS=2. SL=l1O mm; Bombay 1986 L. = 288 mm, K=O.$8 per yéar, SS=1l, SL=7$ mm. Total length (mm Ft_iTf' ém March, June 1992] STOCK ASSESSMENT OFTIIREADFIN BREAMS Aif __ VeravalI H 1 965 1e0-#--é "' , ir . 1204' , .. 0 60M. 1 L "" serrate in i Veraval 1986 I»; 180 120 __.-Q-f 60 0Jan F91; Mar —— Apr May ‘dun? July ' A110 Sop Oct Nov/ 99¢ Fig. l3. Restructured length f requeney data (ELEFAN 1) in Nemipterus mesoprion. Veraval 198$: L. = 255 mm, K=O.405 per ycar, SS=l, SL=8$ mm; Vcraval I986: L, = 297 mm, K=O.6S per year, SS=l , SL=$S mm. present effort is beyond the one that together, maximum yield is obtained by in corresponds to MSY of N. japonicus along creasing the age at first capture by 20%. In west coast and both the coasts together. Kerala (Fig. l6.B), the yield is maximum at However, the present effort is less than that 200% of present tc f or N. japonicus and at only which gives MSY in N. japonicus along east 70% of the present tc for N. mesoprion. For coast; in N. mesoprion along both coasts; and both the species together, the yield is maxi in both the species together along both the mum at 90% of present tc thus indicating that coasts. ' A 10% decrease in cod end mesh size is neces Yield assessment with reference to cod sary. In Kamataka and Goa (Fig. l7.B) the end mesh size of trawl: In Andhra Pradesh MSY is obtained at 140% of present tc (Fig. l4.B) for both the species, the assess for N. japonicus whereas the same can ment shows that thcre is need to increase the be taken at 80% of the present tc for N. age at first capture by 10%. _In Tamil Nada mesoprion. The highest yield of the two Pondicherry (Fig. 15.8), for N. japonicus species together can be harvested at 130% there is need to increase the cod end mesh size of the present t¢. In Maharashtra the of trawl net by 80% to harvest the MSY presenttc of N. japonicus is 20% smaller whereas for N. mesoprion the same has to be than the one that gives MSY whereas the decreased by 20%; for both the species same is 20% larger in N. mesoprion. In the Totallenqh nm MURTYETAL. [Vol. 39, No. 1,2 Andhra Pradesh 13 " 45.0 1a» ll\ 8°"! Q) Species T *5 rl -540.0 ts. O ‘be ll . 1.35.0t 141-°e '‘go 14st -H L l 4. \\ .1 30.0 123 12+\ \ -“ i’ \ } Nomiptorus masopnbn 04-l IQ FY‘ »~ 101-\ \ ‘ — -». 4% i ll -t -1: as <\\ \ \B°(/I W 6‘ Jr /Q00/webs/Y 41 \\\\\\\\ 1 ,l RN w. -i 10.0 4 " i $i \ ““~“;~.- /779* : ?P"0~ .‘i 7 2 N /390/7/'¢-‘Z ~ ‘H 2 T‘ _ . _ _ _ ., _, l li *4 - _ L1 -.__L 0 .* __J _ t _:-J _ *,__l— I-_:'_J_.A.i ° 2h aio ‘$0 Tie 1oo1§o14oTiso1§o_éioo ° 25 40 é'o 6'6 1001501-1o1e01a0t2rio Ellort as % ol present lc as ‘Y. ot present Fig. l4. A. Yield and biomass of Nemipterusjaponicus and N. mesoprion at different effort levels (expressed as percentage of present effort) in Andhrn Pmlesh (email vertical lines on the curves indicate MSY and the long vertical line the current effort level and yield). B. Yield of N. japonicus and N. mesoprion at diffenerit t¢ levels (expressed as percentage of present t¢) (small vertical lines indicate MSY and the long vertical line the current t¢ and yield). two species together the yield is maximum at DISCUSSION the present level of tc (Fig. l8.B) indicating The present assessment is based on the that there is no need to change the present cod data collected from seven centres along Indian end mesh ‘size. In Gujarat (Fig. l9.B), the coasts. Only two species were considered be MSY corresponds to the present tc in both the cause these two species form over 90% of species. threadfin bream catches and the results of The analysis thus shows that except in assessment of these two species are believed Kerala, there is need to either increase the cod to reflect the situation in the threadf in breams end mesh size of trawl net by l0-30% or to as a whole. maintain the currently used mesh size. In lt is essential in a study of this kind, to Kerala, however, the analysis shows that there first ensure whether a species from all along is need to decrease the cod end mesh size by the coast line belongs to one unit stock or not. 10%; as the increase in yield is only 0.3% by There is, however, no information on this this regulation, the present cod end mesh size aspect except in N. japonicus from east coast has no adverse cf feet on the stocks. (Rae and Rao 1983) which is not conclusive. Y'eld x1 00 onnes Oi O T ,1... / // / 4 6-o o8t Bo Biomasstxtootonnesl Yeld it 00 OM65 Qi‘ O => ~> March, June I992] STOCK ASSIFSSMIENT OF Tl IREA DFIN BRF./\MS Tam1lNadu and Pondicherry . 36 Both species 1 08 36 0 ,1 l ® I, 32 ‘E+ 32; @ A _it 96 l: so”) so 5*.‘ 1 J I84 1:l 28 1 \ \ 72 24 . -. » 1 V _ ontc Jim -~. . QIU5rill) \ , Nflmip‘ ‘ZR Nomibfer $5 Us/:‘9P0fl/'cu_; g € Q-n F \ ion * -~16~ \-4 16 1- \ i N. m95°p' * \ \ ': ‘ - L I I1 4/ \ \ '1 36 12 -/ p ’b@&O1 . 12 F \ \ \9% -l 1 \°*>a,, 8i-i _ \\ \\\\ \ ~1\N Q% _+ 4 ~\k\* \ ;”’°‘°Pna~I12\“44 \ E -\ * _-k 4 O _i20 _L_ 40 .1 60 _ _ 80 i _ 10012014016011“)_i_ ._i_.._t._.__i.._4 0 0 200;_1_,_ 20 _L_,-~"J_-0 40 so an _-K,--l__l:=l._.~_1~1oo12o14o1eo1ao2oo ___t Ettort 85 % Of M9880! tc 35 °/, Qt present Fig. IS. A. Yield and biomass of Nemipterurjaponicus and N. mesoprion at different effort levels (expressed as percentage ofpresenl) in Tamil Nadu and Pondicheny. B. Yield ofN.japonicus and N. mesoprion at different ta levels (expressed as percentage of present ta) in Tamil Nadu and Pondicherry. As data were obtained from centres in dif to compare the results with those already ferent maritime states and as the management available. It was, however, found difficult to of the fishery is within the purview of the arrive to a set of true growth parameters be administration of different maritime states of cause, in each year's data from any centre, 2-3 India, the estimation_of growth parameters seemingly ‘best estimates’ of growth and resource assessment was done for stocks parameters were obtained. Therefore, the of each state separately. Yield estimates for smallest and largest values of L. and the country as a whole, however, were also their related K from among the sets of made. values from each centre were, perforce, The estimation of parameters of growth selected and stock assessment was done and mortality using the length-based methods separately using both the sets of parameters. is beset with problems and there is criticism The average yield values corresponding to against almost every available method which each effort level were taken. This was done uses length frequency data as input. It was under the belief that the true values fall decided to use the ELEFAN method for somewhere between the ranges considered extracting the growth parameters and then and the stock assessment thus made 33 Yield x 00 onnes ZR) bNJ Q('0 /in-i Ii T““ ‘T a’. I 1*’ // 4 L L _ _L h Cb Q O Biomass X100 onnes Yeld x100 onoes N O*- ?~ r Y;i MURTY Hf AL. |V"l- 39. N“ 1.2 Kerala 312 . 65 E Bot“ spec‘ 21m ~-\ 1012 \\ 200} \\ 920 ~ \\ -5 P3-l \\ sopdofi . metel“ \ til‘? 208" \ s -+“° - vss ts \ '1 182\\ -~ \\ \\ \ it -*1 L-.p. Q \ \ ‘\ '— 5: \ \\\\ \ \-I F ll W t w-4 \,:130|— \.__kX \”‘ 0 \~\ \“M 0VII *\ I % >' \\ es, L104 r—\ , | /V/Q00/7lbys ' i H. T'\ -W 276 \ . J ra‘t~/ s2i~ l \ I -1s4 '1 264T \\ ‘inA \ i \& g I {Q2 5we. -_I % _ ___‘ __ 0A/.]8p0n;CU$ _ -1-t 0 ._._L.__L20 L__.J;. 40 L__l-.-i_J__ccL__60 80 100_i__1.e-_i 120 140 _ cr_160 I p_.1e_.180 200 1 - 1 e :0 , Elton as % ot present Fig. 16A. Yield and biomass of Nemipterus japonicus and N. mesoprion at different effort levels (expressed as percentage of present effort) in Kerala. would hopefully lead to more meaningful con A comparison of the growth parameters clusions. This was also done to account for and mortality rates estimated (Tables l, 2) possible uncertainties associated with the pro with those available in the literature (Table 3) cedurcs of estimation of parameters and the showed that they were in close agreement with consequent uncertainties in the conclusions those obtained earlier from India and, barring arrived at on the basis of only one set of a few from‘ other areas in the Indo-Pacific parameters. region also. kl /5, l§/ 18.1 =1 A Lat l_J_ -_t_;J O7 U1tn an A O to b Bemass x 00 tonnes) Mnrch, June 1992] STOCK ASSl~ZSSMliN'l'OF 'l'llR1iADI"l1\' DREAMS Karaia 288 V‘ L. 264 * T 00”, S09 240 3 C‘/as 216 7' 192 J it I 168| J. /In . . nicus . U5 lapo Q-I -II Nermpie‘ '— &I 4.235 l‘ asu 1 ‘*?o .0°») F‘ 72* 6 I 48 | L I J 24 ‘, J Q _»_- -t__J_____1s_20 40 60 ls Le_r80 t_»__t_s,,_l100 120 j 1 - 140t__ga 1 160 »_at__ 180I 4,, tt_4.I-_,J 200 lg: as % ol present Fig. 16B. Yield of Nemiprarmjaponicus and N. muoprion at different t¢1CVQlI (expressed u percentage d’ present le) in Kenln. 'I‘he Thompson and "Bell long-term" smaller, thus making it difficult to formulate forecast of yield gave conflicting manage regulatory measures. Such conflicting options ment options for individual species (Fig 14 are not uncommon while dealing with assess~ 19). In one species the present effort was ment of single species stocks in a mixed greater than that giving MSY and in the other, fishery because the growth and natural mor 35 Y'0ld x 0OOH HQS -I -5 oto §Q MURTY 1-mu. rva. 39, No. 1,2 54 -+150 Karnataka54 and Goa O Bolh species1~16O 48 T ~4 p \ -i1|l40 42ll—__ $E lt t it "0 as_ M lx i/époniaus l ~°”’4°'@'m -- 120 A as e’ A—\ *1l ‘I l T '“ Q?' /\ Q-A [Q { \ 1 * _ 18‘I l \ \\ soji 1s_ . Ll \\ \K. I\ "\ N, mes0P"'°Q_ '* * 12 - I‘ \ -. k Eqfiispecios-— 40 ‘I2 - _ I 0'0 '\ : ”" m l%fl/cus~\ N ' _ .. sln \ 1%a ’\| “I‘\ ~ iii};-_t‘ ~ __-*“& .. - -" 6 I Q r t_.+__1_._. l_._ t__i__1_,._i_. O O. t__t .1. .L_.r _i_._t__t.__1 20 40 60 80 100120 140160180 200 20 40 sofao 1eo12o14e1se1ae‘aeo Elton as % of present t¢ as % of present Fig. 17. A. Yield and biomass of Nemipterurjaponicus and N. mesoprion at different effort levels (expreued or percentage of present effort) in Kamatalta and Goa. B. Yield of N.japonicu.r and N. mcsoprion at different ta levels (expressed as percentage of present t¢) in Knmatalta and Goa. tality rates are different in different species MSY of t.he required species together is likely and there is no knowledge of the effective to be viewed seriously in the" context of over effort for any one species in the fishery. The fishing of those species. It is believed that such simplest solution to such situations is mixed a fear need not be entertained in multispecies fisheries assessment which gives maximum or mixed fisheries because even if the yield of yield and lheicorresponding effort level for all one species crosses the MSY level because of the species together in the fishery, that is, the increased effort, the same gets stabilized at effort which gives maximum yield (or value) particular stabilized effort level according to of all the species in the mixed fishery together steady state assumption. As long as the yield has to be taken into account for resource of other species in the fishery is increased the management. It may so happen, however, that total yield will automatically increase and such an option results in reduction in yield of there is no biological wastage. The manage species whose economic value may be ment decisions. however, often depend upon greater. Such a reduction (some times drastic) the economic returns of -a fishery. Then the in yield of species (by exceeding Fmgy of these simplest option is to stabilize the effort which species) caused by increasing the effort to get gives MSY of economically important 36 Y'e d X O0‘ OOFIQS N Q b Q toa A»CD + 1— 4T iii +_;__;...-r f———l I-oi / I 1' I/ / > / / l__l Q O 8 O Biomass x100 onnes Y'eld (X 00 0nn8$ Nb *1 4%, ea,/ . "°~», March, June 1992] STOCK ASSESSMENT OF TIIREADI-‘IN BREAMS Maharashtra 72-® go!““"216 spec‘. as ; 72*,’ -4 192 ML.r se-\ was 59'?-6’ »-\ \Ti —t-. Q? 43*\\ \t _ 4e¢- ‘ an-u 'l t . F"1 \ Nemtpterus . /aponicus . 7 ,_'J Q-I -@\ \ ‘ , ": as0 5-4 \ ' 'l' ‘L' \ \\ ipterus \ t"°‘°pnO- n - av“ , 1 t m 24r is\ \ , t\ \ -"°90:1, 8 -?t —o—~\ \ I \ _\Dgq-08 \ \ K _. 4 tel 'l"’"°$evn'o i \-an 161- "r I ~:~-2. -ls | Br p '/qO°'7/¢‘Ug-.~._‘a ‘J a- it1 -¢— 0 L_t._ tqq _t._ L. 4 --~_ 4-4‘ Ql-tt J J_J- ‘--_t..__t_ t 4.-.1 2O 40 60 80 100120140160180200 _20 40 60 BO 100120 140160180 200 Ellort as % oi present Io as % ot present Fig. 18. A. Yield and biomass of Nemipterusjaponicus and N. mesoprion at different effort levels (expressed as percentage of present effort) in Maharashtra. B. Yield of N. japonicus and N. mnaprion at different lo level: (expressed as percentage of present t¢) in Maharashtra. species. This of course can result in biological catch per unit effort. It, therefore, appears that wastage because certain species may be un in the present fishing grounds, there is no derexploitcd. While there is presently no solu scope for increasing effort to increase the tion to this problem , a sound knowledge of the yield of threadfin breams. However, the biological interactions between species con threadfin breams are known to be more abun tributing to the mixed fishery is essential to dant in the relatively deeper areas of the sea understand the dynamics of the species better beyond the pnesent grounds and yield can be and to effectively formulate" regulatory substantially increased by deploying the addi measures. tional effort beyond 50 m depth. It has been The assessment of the two species of estimated that vast potential or these fishes threadfin breams (Figs I4-19), on the basis of exists beyond 50 m depth (125 000 tonnes of the present knowledge, indicated that maxi perches of which threadfin breams is a mum yield of the two species together can be dominant component, Anonymous l9_9l). taken through increasing the effort by 40% Moreover, off Kerala coast (Fig. SC), it is l00% in different states and in the country as known that peak landings are obtained during a whole. The increase in yield, however, will July-September mainly due to movement of only be 2%-12% and will not be proportional threadlin breams into shallower areas to to increased effort leading to reduction in avoid oxygen deficient waters in the Yeld x1000l'lFIGS L0 & Ci N O 5 ._ ___ / I 1 / j/ /I 8 F6o Biomass x 00 onnes Yard x (X) onnes ‘.2 ‘re’ ob 1 2 ‘E,a MURTYETAL [Vol 39.No. 1,2 Gujarat 120 45.0I r — 1 (D 0-4 40,0 L\ Both species -@112 40.0 L P_ \ T 35.0\ _f-T \ 98 35.0 ‘T . 8’ t \" » 4 .. isf , 30.0i\'J \ \ ‘ - ao.oi- Q? r‘ ‘ 1+ it ._ ii \ \ Nemlptqrus \ E laponlcus Ll um \ - 20.0 |-..\ \ \\ \i A Lit \_ \ \ \\\l ~_ mgsoprlon\ _.‘ , +42 15.0 _- t T) \ i \ \8o”'~9p _" 10.05»t \ \ ,\\90- 4, _ \“"osfi2a ‘ 10.oL ' t »-' \ 1% \ \ N‘Y/s mE {Q70/7,‘ x‘. -i + ‘I ~" ' ‘xi t q_\_.-\_____ 5.0%t . - - - Pwpnon-14 5.0 .. M ‘an O\ __.l_..._l-- -16-L.-.1 ~ -.»f.__L .i-T-4 _ 4,___L---i 0 gl_._L_._1.__L.._l if __t. ..t.__.1___1_.._.J 20 40 60 BO 100 120140160160 200 20 40 60 BO 1001201401BO1BO2OO Ellort as % ol present lg as % ot present Fig. 19. ‘A. Yield and biomass of Nemipterusjaponicus and N. mesoprion st different effort levels (expressed as percentage of present effort) in Gujarat. B. Yield of N. japonicus and N. mesoprion at different ta levels (expressed as percentage of present tc) in Gujarat. deepcrwaters (Banse 1959). Hence suitable ACKNOWLEDGEMENTS deployment of trawlers during the monsoon The authors thank Dr P S B R James. period is likely to result in substantial in Ex-Director, CMFRI, Kochi, for encourage crease in the landings of thrcadlin breams off ment; Mr K Narayana Kurup, Mr K Balan and Kerala. Mr T V Sathianandan, Scientists, CMFRI, The assessment of yield as a function of Cochin, for help in analysis of data at the cod end mesh size (Figs 14-19) showed that computer centre in the Institute. there is need to increase the same in all states REFERENCES except Kerala. It is known that smaller cod end mesh sizes in trawl fisheries can lead to Achsrys P and Dwivedi S N. I984. Condition factor and length- weight relationship ofNemipteru.rjap0nicu.s' recruitment overfishing and adversely affect (Bloch) off Bombay coast. Journal of Indian the exploited stocks in the long run and, there Fisheries Association 10 & ll : 37-44. fore, efforts to regulate the mesh size by sug Alagarsja K. 1984. Simple methods for estimation of parameters for assessing exploited fish stocks. In gesting at least 20% increase, will help dian Journal of Fisheries 31 : 177-95. improve the thireadfin brcam stocks in the Amomchairojkul S and Boonwanich T. 1982. 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Distribution pattern of thrcndfin Silas IE G. I969. lixplorntory fishing by R V Varuna. brcams along Tarnil Nadu and south Andhru coasts. Bulletin ofCcntral Marine Fisheries Research In Indian Journal ofI"islteric.s 37 : 269-80. Stilute 12 2 1-36. Vivcknnandan Ii and James D B. 1986. Population Silas Ii (I, illnntnarttja S K and Rcngnrajttn K. 1976. dynamics of Netniptarus joponicus (Bloch) in the lixploited nizrrine fishery resources oi India. A trawling grounds off Madras. Indian Journal of synoptic survey with comments on potential resour Fislrcries 33 : 145-S4. ces. Bulletin of Central Marine Fi.slierie.s Research Vivekanandan E and James D B. 1987. Length-weight Institute 27 1 25 pp. l rclationshipin four species of thrcadfin breams from Sivaprakasam T Ii, Parttsiirarnnrt P S, Premcltand, Raj Madras. Journal ofMarine Biological Association lrumar S A and Nagarajnn G. I991. Marine fishery resources of 1' the lower cast coast of India. Bulletin oflndia 26 ; 132-35. ofFishcry Survey oflnrtia 21 : 29. Zupanovic S and'Mohiuddin S Q. 1973. A survey of the Spane P. 198$. Introduction to Tropical Fish Stock As fishery resources in the no|1.h castcm part of the sessment. I7/\(). Rome. Denmark Funds -in-trust. Fl; Arabian sea. Journal of Marine Biological Associa Gc1>nN‘1‘/392/|):zN Manual 1.33s pp. tion oflndia 15(2) : 496-537. f:”"* 7‘? *— -"‘*”" EONTRIBUTION 221 MURTY, V. SRIRAMACHANDRA, M. SRINATH, P. LIVINGSTON, Y. APPANNA SASTRY AND S. SRINIVASARENGAN. 1994. Stock assessment of silverbellies of India with particular reference to Andhra Pradesh and Tamil Nadu. Indian Q. §_‘;t_§_1_1., 39 (1,2): 42-64 (1992) P "1 E!-ONTRIBUTION 22% lrtdrarr Journal offisheries 39 (1,2) : 42-64, March, lune 1992 Stock assessment of silverbellies of India with particular reference to Andhra Pradesh and Tamil Nadu v sammncrrnunnn MURTY', M sR1N/mt’, P trvmosron’, Y APPANNA s/tsmv‘ and s SRINIVASARENGANS Central Marine Fisheries Research Institute, C ochin. K erald 682 014 ABSTRACT Along Indian coasts, the silverbellies are exploited by trawl and artisans] gears but hull: of the landings are obtained by trawls which operate up to 50 m depth. During I979-83, the estimated annual average silverbelly landings were 69 (X30 tonnes, whereas during 1984-88 these were 62 0(D tonnes. Maximum silverbelly landings were obtained in Tamil Nadu whidt contributed 70.5% of total all-India silverbelly landings followed by Andhra Pradesh (9%), Kerala (8.4%), Kamatalta (6%) and other states (6.1%). Out of 20 species of silverbellies, known to occur in the seas around India, Leiognarhus bindrts and Secular insfdiaror were most dominant along Andhra Pradesh and northem Tamil N adu coasts, together contributing to 64% and 55% respectively of silverbelly landings. Along southern Tamil Nadu, L. jonast‘ and L. drsssunrisri were most dominant together forming about 60% of silverbelly catch in the region. The available infonnation on the biology of different species from several localities along Indian coast was reviewed. Parameters of growth and mortality of dominant species were estimated. Stock assessmmt was made separately for L. bindus and S. irrsidiator and then mixed fisheries assessment made for these two species combined from Andhra Pradesh and northem Tamil Nadu. From southem Tamil Nadu coast, stodt assessment was made forL.jonesr' and L. drtsswnieri separately and combined. Along Andhra Pradesh coast, the effort level was found greater than the" one yielding MSY in the existing fishing grounds. In northerh Tamil Nadu there was scope to increase the fishing effort to get MSY. In southem Tamil Nadu yield can be increased by about 1.5% through increasing the effort by 40%. The assessment of yield of L. bindrrs and S. insidiaror in relation to cod end mesh sire of trawl along Andhra Pradesh showed the need to reduce the cod end mesh size by about 40%. In northern Tamil Nadu also more or less similar situation existed. In southern Tamil Nada, the MSY corresponded to the existing cod end mesh size md, therefore, did not warrant any change in the latter. The fishes of the family Leiognathidae, considered as trash fish at certain places, the popularly called as silverbellies or ponyfishcs, quantities landed make them important both are among the important demersal fishes con from fishery and management point of view. tributing to_ the fisheries along lndo-west Silverbcllies are known to be more abundant Pacific region. Though these are small and are in shallower regions in the sea (James I973; Pauly 1977a, b; Pillai and Dorairaj 1985; Present address: ‘Senior Scientist, 2Scientist Sudarsan er at. 1988; Sivaprakasam er at. (Selection Grade). 3Scientist (Selection Grade), Karwar Research Centre 1991) up to about 40 m depth though they are of CMFRI, Post Box No. 5, Karwar, North Kanara, available in depths of 100-150 m also (Sudar Karnatalta. san ct al. 1988). These fishes are known to ‘Scientist (Selection Grade), Visalthapatnam Res undertake diumal vertical migrations staying earch Centre of ' CMFRI, Andhra University P O, Visalthapatnam 530 (D3. at the bottom during day time and moving up 5Scientist (s-2). Madras Research Centre of cmmr, to surface and subsurface waters during nights 68/1', 4th Floor, Greams Road, Madras 600 (D6. (Venkatraman and Badntdeen 1974, Murty Q-s-II March, June 1992] S'1'0(jK /\SSl§SMliN'l'OF SlLVliRlilil.l.ll-IS 1986b). A lot of work has been done on groupwise/specieswise landings made by the various aspects of these fishes as evidenced by Central Marine Fisheries Research Institute two bibliographies exclusively on these fishes for the years 1984-88 were used for the (Pauly and Pauly 198 1 , James ct al. 1992). ln present study. Further, the estimates of catch India an estimated 53 876 lonnes of silverbel for each maritime state pertaining to the lies landetl during 199() (Anonymous 1991) period 1979-88 were also used. which fortncd 5.7% of the total tlemersal lish Detailed data on effort and catch were and 2.5% of total marine fish landings. collected for 18 days in a month and on I Total 20 species of silverbellies are species composition, length composition and known from India and a lot of work on dis biology of dominant species for 4-8 days tribution, taxonomy, biology and fishery has every month from the trawl landing centres at been done (Arora 1952; Balan 1967; James, Visakhapatnam, Kakinada, Madras and Mart 1967, 1969, 1973, 1975, 1986; Pillai 1972; dapam. These data of 1984-88 formed the Venkatraman and Badrudeen 1974; JiJtnCS major input for this study. _ and Badrudeen 1975, 1981, 1986, 1991; Rani For stock assessment, .Ler'0gnarhu.r bin Singh and Talwar 1978a, 197811; Annam and dus and Secutor 1'nsidr'at0r from Andhra Dharmaraja 1981; Kurup and Samuel 1983; Pradesh and northem Tamil Nadu-Pon Marty 19s3, 1991; Jztyzlbltltm 1985, 1986, dicherry; and L. jonesi and Lrdussumien‘ from 1988a, 1988b; Jayabalan and Ramamoorthy southern Tamil Nadu were selected because 198521, 1985b, 1985c, 1986; Pillai and these species“ were most dominant in these Dorairaj 1985; Vivckanandan and Krish regions and determined the‘ success or namoorthy 1985; James ct (11. 1987; Reuben failure ofsilverbelly fishery in the respective ct al. 1989 and Srinath 1989). Population areas. dynamics of dominant species from particular Species composition and lcngthfrcquem localities have»-also been studied (Venkat cy d£srrt'buu'on.' At each of the above four ramanctal. 1981; Mttrt) I985, 1986a-, 198611, trawl landing centres, samples were collected 1991-and Karthikeyan ctrrl. 1989). Anattempt from different boats and brought to the is made here to -study the dynamics of the laboratory for taking data on species composi exploited silverbelly resources making use of tion, length composition -and biology. Total data obtained during 1984-88 on dominant .length was considered for length frequency species of the group from Andhra Pradcsh and and other studies. The data on species C0111 Tamil Nadu coasts. '1 ‘he results are presented position and length composition collected on in this paper. . each observation day were first weighted l\1/\'l'1-Iltl/\l'.S‘ /\l\'l) M|~1'1'1t()t)s respectively .to the estimated total catch of the group and species obtained on that day and Data obtained from trawl landings only such estimates in anmonth were pooled and were considered. Bulk of the silverbelly land then raised to the estimated catch of the month ings in India were obtained from Tamil Nada as per Alagaraja (1984). The monthly es Pondicherry and Andhra Pradesh and con timates were pooled to get quarterly and an siderable data were generated from this nual estimates. To obtain estimates‘ of total region. The stock assessment in the present catch (weight) of each species as well as catch studywas, therefore, restricted to this region. (numbers) at length also of each species, the The estimate-s of districtwise and gear data obtained at the observation centres were wise effort and districtwise, gcarwise and suitably weighted to get estimates for each I-tult I r I .T AL I Vul . J~ .r.;Y . I .2 11 . Ltj "II~QI !m.' hi" oI"... 11 . L. J""ui. C. L . ,/ILu",,,]t,i. U• .'itCUux u...;.J;"/fH . •\.1 March, June I992] STOCK ASSESSMENT OF SILVERBELLIES state. As the data on production from each E.'stimatiort of von Bertalanfiy growth district were available in the form of quarterly parameters: The parameters of growth in estimates. the monthly estimates from each length were estimated following the ELEFAN observation centre pooled for each quarter method (Pauly and David 1981, Gayanilo er (January-March: I quarter, April-June: II al. 1988); the estimates were made using the quarter, July-September: Ill quarter, Oc monthly length frequency distribution of tober-December: IV quarter) were weighted catch of the species, separately from each of to get quarterly estimates. For this purpose, the four centres. In the data of each year, the data obtained at Visakhapatnam were different starting lengths and ‘samples’ were raised to those obtained in the northern dis used and best fit values were taken. Thus, 2-4 tricts of Srikakulam, Vijayanagaram and sets of growth parameters in each year from Visakhapatnam together, and those from each centre were obtained for each species. Of Kakinada to the data obtained in the remaining all such estimates in all the five years, the coastal districts (East Godavary, West smallest and largest 1.-on values and their as Godavary, Krishna, Guntur, Prakasam and sociated K values were selected from each Ncllore) of Andhra Pradcsh (Fig. 1). The centrefor all further studies. The results ob former is referred as northem Andhra Pradcsh tained by using the largest Lo»: and its as and the latter as southem Andhra Pradcsh. In sociated K were referred to as having been Tamil Nadu—Pondicherry (Fig. 2), the data obtained by using ‘higher parameters’ and obtained at Madras were weighted to those of those obtained by using the smallest L... and Madras, Chengalpattu, South Arcot and Pon its associated K by ‘lower parameters‘. dicherry together and those obtained at Man Mortality rates: The estimates of in dapam (Mandapam, Pamban and Rames stantaneous total mortality rate (Z) were made waram) to the ones from the southern coastal using length-converted catch curve method districts of Than javur, Pudukkottai, Ramana (Pauly 1982) using the data of all the five years thapuram (presently Muthuramalingam and pooled and the LFSA package of Sparre Ramanathapuram), Tirunelveli (presently Chidambaranar and Kattabomman) and Kanyakumari. These two areas are referred to Q ltltoltopoto‘ ,1. .<.:2e.w as northem Tamil Nadu (A in Fig.2) and Bhimunipntnnm southern Tamil Nadu (B in Fig. 2) respective Vlaolthopol nom Uppodo ly. Stock assessment was done separately with Kcrltinddo these sets of data. For Andhra Pradcsh, the two ' v ts lore estimates were pooled to get estimates for the “ MunqinogutgiNizornpotnom W state because the species dealt with from the Vodorovu Kothopotnom two regions were the same. For Tamil Nadu - Tummolo pent o lsdkoptllll Pondicherry, however, the species dealt with 9 Krishnopotncm were not same from the two centres as the dominant species were different in the two regions. The estimates obtained, therefore, )'.¢\_.1 ‘‘~n'\,i/ ." were treated separately. Fig. 1. Map of coastal districts of Andhra Pradcsh. I, Biology: The results of detailed studies Sriltaltulam; 2, Vijayanagaram; 3, Visakhapat made on aspects of biology of particular nam; 4, East Godavary; S, West Godavary; 6. species were taken from published work. Krishna; 7, Guntur, 8, Praltasnm; 9, Nellore. MURTY 11'!‘/lL. |Vol. 3", No. I, 2 Tamil Nadu. south Tamil Nada) in each year '\..r/,3 * *“ *" were pooled for the five years (1984-88) and ‘Madras average annual values obtained; these were used as input for the study. Yield and biomass at different effort levels were estimated by the "., I length-converted Thompson and Bell (I934) 2 ii" Ctgdolora 5 iiiijiiq-Z‘, analysis (Sparre 1985, Murty I989) and the programme MIXFISH of LFSA package of Sparre (1987). In each‘ species, the yield and - vur i biomass at different effortlevels were first ‘Q tittuituonot 4' estimated separately using the statistics ob tained with the help of ‘lower’ and ‘higher’ Romano! Dl"°"‘ growth parameters. The average of the values corresponding to each ef f on level were 8ll <;~°8P ‘sh B t Tutlcorln then obtained and were considered in this ' o study. \\. 6 0’ The assessment of different species was Fig. 2. Map of coastal districts of Tamil Nadu and done~scparatcly and combined from each Pondichcrry. l, Chengalpallu and Madras; 2, region of Andhra Pradesh and Tamil Nad u. South Arcot; 3, Pondichcrry (U.T.); 4, Titan Yield and cod end mesh size: Trawl data javur; 5, Pudukkottai; 6, Muthurarnalingam; 7, Ramanathapuram; 8, Chidambaranar, 9, Kat alone were considered for this purpose. For tabomrnnn; ll], Kanynkumari. studying the effects "of changes in cod end mesh size on the yield, the following proce (1987). The natural mortality rate (M) was dure was adopted using the data of each region estimated using the empirical formula of in Andhra Pradesh and Tamil Nadu Paul y ( I 980) and then the fishing mortality (F) Pondichcrry: as Z-M. For each species from each centre a. For eachspecies the present ti; values estimates of mortality rates were made (corresponding to LC values as stated separately using both the sets of growth above) were taken. These values in each parameters. species were decreased and increased by Lengths at recruitment and first capture: the same factor ‘(as l()%, 20%, ...... 'l'hc mid point of the smallest length group in . 150% ...... 200% of present lc). the catch ‘during the five-year period was b. Using these resultant t¢ values, the taken as length at recruitment (14,). The present F and other required parameter lengths corresponding to the first values in the values, the Beverton-I loll (1957) yield descending limbs of the length-converted per-recruit (Yw/R) analysis was made. catch curves (with both the sets of growth c. Taking the value of yield-per-recruit parameters separately) were taken as lengths (Yw/R) at current F and ti; and the value at first capture (LC). of annual average yield of the species Yield and b:'0mas.r.' The data on catch during 1984-88, the recruitment in num (numbers) at length of each species at each bers (R = Y + Y/R) was estimated. centre weighted to total catch ofthe species of d. The Yw/R at each tc in each species as the region(n0rth Andbra, south Andhra, north obtained at ‘b’ above, was weighted by >b ;\1:|tL'|t, June 19‘).I| S'l‘()(TK /\SSl".‘\‘SI\1IiN'l' ()1: SILVI-IRlli~Il.I.l|iS tltc valtte of R obtained in ‘c’ above to were estimated as 49 000 tonnes and 54 00() obtain values of yield in weigltt at dif tonnes rcspeetivcl y (Attottytnous 1991). ferent tc values (i.e. percentage of presettt Catches in dtffcrcn! stares.‘ The silverbel lg). ly landings in different maritime states and e. In each species, tlte yield corresponding union territories during the decade l979—88 to different tc levels was first estimated showed that maximum landings were ob separately using the statistics obtained tained in Tamil Nadu (70.5%) followed by with ‘lower’ and ‘higher’ growth Andhra Pradesh (9%), Kerala (8.4%), Kar parameters and averages of yield cor nataka (6%) and others. The maximum es responding to each LC level were then timated landings_ in any year were about obtained and used for this study. 62 000 tonnes in Tamil Nadu in 1983, fol f. The values of yield at different I-4: levels lowed by ll 500 tonnes in Karnataka in 1986, for different species in each region were 9 900 tonnes in Andhra Pradeslt in 1981, and pooled to get the combined yield-mesh others (Table 1). Thus the southeast and south curves for the species considered. west coasts contribute to over 90% of silver The results pertaining to the two belly landings in India. regions in Andhra Pradesh were pooled Districtwise lartdings: In Andhra Pradesh and those pertaining to ‘northern Tamil (Fig. 4.A), maximum silverbelly production Nadu-Pondieherry and southern Tamil Nadu was obtained in Srikakularn district with an were treated separately for reasons stated nual average of 2 100 tonnes during 1986-88 earlier. forming 35% of total silverbelly landings in RESULTS Andhra Pradesh. This was followed by East Fishery G odavary (l 645 tonnes, 27.7%), Nellore (992 Along Indian coasts, the silvcrbellies are tonnes, 16.7%), Visakltapatnam (709 tonnes, exploited by trawl and a variety of ttrtisattal l I .9%), Prakasatn (234 tonttes, 3.9%), Guntttr gears suclt as shore seine, boat seine, gillnet, (170 tonnes, 2.9%), Vi jayattagaram (51 ton nes, 0.9%), Wcst Godavary (23 tonnes, 0.4%) etc. However, these fishes are caught in large quantities by trawls which are operated in 936* j shallower regions up to 50 m depth. All-India silverbcfly catch: The lattdings it in India during 1979-88 (Fig. 3) showed that ._ ' I J t I they ranged from about 53 000 tonnes (I985) s1e- , L to 92 000 tonnes (1983). During the first half !_> I I 1 5 _ , of 1979-88 period, the average annual land h- r t|l ings were estimated at 69 000 tonnes whereas '_ t 5 | during the second half of this period the same was 62 000 tonnes. Though the fluctuations in .-l | the annual landings were not very large (ex 1ss[ ‘ y cept 1983), with the annual average during l_ V 9 'v 0.‘ r r I’ r: I r 1979~88 at 69 000 tonnes, the landings 1979 1981 1983 1985 1987 showed a declining trend. In fact, in 1989 and Fig. 3. Estimated annual landings of silverbellies in 1990, the annual silverbelly landings in India - India during 1979-1988. Catch x 00 tonnes fi i— Ica MURTY HT AL. [Vol 39,No. l,2 Ii I-I and Krishna (20 tonnes, 0.3%) districts. ln 3 WI! Srikakulam and Vijayanagarnm there was no trawling and maximum silverbelly production @ OI-d N *0 an was obtained by boat seine followed by shore C“ 893 V 7* (‘I ii -'€‘4O\ v-0 l'~ '8 Q W seine and other nrtisnnal gears. In West Godavary the trawl landing was almostnil and I—0 shore seine landed the bulk of silverbelly T“ ('3 I8 .q_‘ v i § catch. In Prakasam district, uawls contributed to about 40% of silverbelly production and in all the remaining districts the contribution of Vi R58 O~ ii‘ t~~r I-1 i i $3Ii 0-4 N § trawl to the production of these fishes ranged from 61% to 93%. In Andhra Pradesh as a whole, the trawl accounted for 47% of silver (‘<8 O—1 *1‘ bclly landings and the remaining by other 8 ("3 § 8 Sf. mi Pi 1-: II-1 CH4 i O gears. In Tamil Nadu (including Pondicherry) Ffl Pi i pi j (Fig. 4.B), Ramanathapuram (presently i Muthurarnalingam and Ramanathapuram dis tricts, Fig. 2) contributed to bulk of silverbelly I-i pan I-1 landings with annual average of 17 323 tonnes during 1986-88 forming 45% of silverbclly landings in Tamil Nadu-Pondicherry. This V‘) was followed by Pudukkottai (10 650 tonnes, I“ 3 0\ 27.5%), Thanjavur (5 216 tonnes, 13.5%), Tirunelveli (presently Chidambaranar and Kattabomman districts, Fig.2) (5 211 tonnes, OI-I ? ? i 13.4%), South Arcot (36150 tonnes, 8.1%), Madras (2 913 tonnes, 7.5%), Chcngalpat tu (I 075 tonnes, 2.8%), and"Kanyakumari (352 tonnes, 0.9%) districts and Pondicherry (749 tonnes, 1.9%). In all the districts except Chengalpattu, there were considerable land ("1 1"! '5 ings by trawlers and the contribution of trawl § P" V1 lg:-I ‘:3 to total silverbelly production ranged from I 77% to 99.5%; in Kanyakumari district, how V V\ V1 o—4 82-’i bl 1" O\ 3 ever, the trawlers contributed to only 25% §E~='=‘ 5. I I 4 of silverbelly landlngs.' In northern Tamil Nadu, the trawl catch formed about 80% of l total silverbelly catch and in southem Tamil Nadu it was 96%. u-0 1'"! V3 @ ® @ Z Trawl fishery: In Andhra Pradesh, com § O O\ °\ QI > u-I on-1 éi on mercial trawlers of three different sizes rang 48 Tabel Estimated landings (tomes) of silvcrbellics in different maritime states and un on territories of [ndia during 979-88 West Andhra Tamil Pmdi Kerala Kama Mahara Gu arat Bengal Pradcsh N adu cherry taka shtra 1979 108 3 585 43 083 3597 156 881 54 054 1980 3 832 38237 681 4148 47 3 727 54 587 9856 50 942 2826 1 638 2 075 29 69 449 1982 1 133 5132 52 577 538 8730 247 Ol 69 72 668 8154 6216 1763 951 7 024 929 95 91 733' 1984 363 5035 399 2 924 39 3 355 669 I06 38 578 5348 374 0' I 359 3 419 25 s 357 381 52725 986 21 5392 44515 1 095 6029 541 445 57 7350 1987 428 8904 46 276 871 6027 234 5 66 750 469 3505 4-67$) 329 6522 265 664 63 757 Annual avenge 5874 4686 928 5472 3829 215 6549 March, June 1992] STOCK ASSESSMIZNT OF SlLVERllEl.I.II£S I 180 l 4 20-7Andhra@ Pradesh ._. -1“Tamil Nadu and Pondicherry 3 # 1 -96w Q-0 l _“_' l ‘-" 12 -A 4—Q‘'5 TG -|"1 "'I 12¢ a>>ssi'=§§‘%'X3900 iiiifiifiiga Fig. 4. Average diltrictwite landings of nilvcrbcllicl during“ I986-B8. A. In Andhn Pradelh (SKK: Sriknlrulam, VU: Vijayanagantn, VIS: Visakhapatnam, EGD: Bast Godlvary;-WGD: West Godavary, KRI: Krishna, GUN: Guntur, PRA: Pnksam, and NEL: Nellora district). B. In Tamil Nadu-Pondicherry [MAD: Madras, CHE: Chengalpattu, SAR: South Areot, PON: Pondicherry, TAN: Thanjavur, PUD: Pudukkotttti, RAM: Ramanathapuram (presently Muthuramalingam and Ramanathapurarn), TNL: Tinmelveli (presently Chidambarttnar and Kattabomman), and KKI: Kanyakumari districts]. ing from 10 to 11.4 m OAL operated in the mostly conducted during day time up to depth range 5-50 m during greater part of the depths of about 50 m. In the southem districts year and during November-February in particularly along Ramanathapuram coast depths extending up to 80 tn. Most of the boats both night and day fishing was carried out returned the same day But some conducted regularly up to depths of about 40 m. In this fishing continuously for 2-4 days . Shrimp region silverbelly was used for human con trawl with cod end mesh size of 15-20 mm sumption and a small quantity was reduced to was operated by all these boats. Silverbelly fish meal. was considered as a ‘trash’ fish and used most Seasonal variation in silverbelly land ly in poultry feed§ ings: The quarterly catch estimates (as per In Tamil Nad u-Pondicherry, the trawlers centage of each year) from the northem (9.8-1 1.0 m OAL) operated shrimp trawl with Andhta Pradesh, southern Andhra Pradesh, a cod end mesh size ranging from 15 to 25 northern Tamil Nadu and southern Tamil mm. In the northern districts, fishing was Nadu during 1985-88 are shown in Fig. 5. Cach x00 OHHES Cach x 00 onneS MURTY ET AL [V0]. 39, No. I, 2 and northern Tamil Nadu also, but in small 'ouantities. L. jonesi, however, is known from the southern Tamil Nada coast only. Andhra Biology Andhra Various aspects of biology of different species were studied from different localities Northern Tamil Nadu along Andhra Pradesh and Tamil Nadu and on Southern Tamil Nldu one species (Leiognathus bindus) from Kerala. 1985 1987 The results are briefly given below for each Fig. S. Seasonal (quarterly) variations in catcher of lil species. verbclljes. Leiognathus bindus: According to Balan (1967), this fish spawns of f Cal icut in relative There were year to year variations in periods l y deeper waters during December-February. of peak landings in the four regions. However, The length at first maturity was estimated as the second quarter was the peak period in 87 mm and fecundity as ranging from 4 950 northern Andhra Pradesh, first quarter in to 7 7.35 in fishes of the length range 98—l 14 soutltem Andhra Pradesh and third or fourth mm. Copepods were the most dominant food quarter in both the regions of Tamil Nadu. item followed by polychaetes, cladocerans, Species composition .' Out of 20 species of larval bivalves and larval crustanceans; silverbcllies known to occur in the Indian seas phytoplankton occurred -_in stomachs frequent (James and Badrudeen 1991) most of" them ly during monsoon period. occur in varying proportions in the Palk Bay From Kakinada, Murty.(l983) reported and Gulf of Mannar along southem Tamil that this species is a fractional spawner Nadu coast. Of f ,the coasts of Andhra Pradesh releasing the ova in at least two spawning and northern Tamil Nada, 9-12 species con acts during the course of one year, this tribute to the fishery. Along Andhra Pradesh species spawns almost throughout the year coast, Lct'0gnalltu.t' bindus was the most with a peak during December-February. The domittant species forming 40% of silverbelly length at first maturity was estimated to he Catch followed by Secutor insIdz'al0r'(24%); 80 mm. all other species together formed the rest According to James and Badrudeen (36%). Along northern Tamil Nadu coast also (1986) the spawning is continuous in batches these two species were most dominant over prolonged period along southeast coast together forming about 55% of silvcrbelly of India. catch; among these two, S. insidiator was This species exhibits sexual dimorphism. more abundant. These two species occurred The males have a black spot under the pectoral along southem Tamil Nadu coast also but in fin near its base which is absent in females negligible quantities. ln this area L.j0nesi was (J ayabalan and Ramamoorthi 1985a). the most dominant species forming 44% of Leiognathus dussumieri: According to silverbell y catch. The other important species James and Badrudeen (1981), this species was L. dussumieri which formed about 15% releases the ova inbatches during shorter of silverbelly catch followed by other periods and spawns in the Gulf of Mannar species. TL. dussumicri occurred along Andhra during April-May and November-December. March, I une 1992] STOCK ASSESSMENT OF SILVERBELLIES The length at first maturity was estimated at and between fecundity and fish weight as 78 mm in males and 83 mm in females. The tr»; F = o.a0$6 + 2.3833 log w. tnaxitnum length recorded was I6] nun. According to James and Btnlrndeen According to Pillai (I972), this species ( 1986), this species spawns in batches in quick spawns offTutic0rin during prolonged period. succession over a short period. The fecundity was ,estimated to range from Secular :'nsr'dt'a!or: Pillai (1972) estimated the 5 400 to 32 500 with an average of l4 300. fecundity from Gulf of Mannar as ranging Leiognathus brev£rosrrt's.' In the Palk Bay from about 7 250 to 15 700 with an average of and Gulf of Mannar this species spawns l0 620. throughout the year with peaks during May According to Jayabalan and Ramamoor June and October-November (James and thi (l985b), this species spawns during Badrudeen 1975). The lengths at first maturity March—April and J uly-November in the sea were estimated as 68 mm in males and 63 mm off Porto Novo. The length at first maturity in in females and fecundity 3 650~l6 240 in males was estimated as 79-82.5 mm and in fishes of the length 106-132 mm. The maxi females as 81-82.5 mm. The relation between mum recorded length was I42 mm. Diatoms, fecundity and total length was determined as: copepods, Lucifer, nematodes and poly Log F = -5.2419 + 4.5010; t. ' chaetes were important food items. Leiognatliusjonesk James (1986) gave a and between fecundity and total weight as: detailed account of the biology of this species Log = 2.3155 + 1.3806103 W. from Palk Bay and Gulf of Mannar. It was Murty (1991) reporting on the biology of concluded that spawning takes place S. insidiator from Kakinada stated that the throughout the year with individual fish spawning is throughout the year with a peak spawning at least twice in a year; the during January-March. There was predomi prolonged spawning period was also indicated nance of males up to 87 mm group and of by the occurrence of smaller fish of the length females above this length group. The maxi range 14-39 mm round the year. Length at mum length in the fishery was 117 mm and first maturity was determined at 70 mm in length at first maturity of females was es males and 75 mm in females. Feeundity was timated as 90 mm. estimated to range from about 700 to 39 800 Garza minuta: Pillai (I972) estimated the in fishes ofthe fork length range (>5-104 mm. fecundity as ranging from about 7 950 to Maximum length recorded was I52 mm. The 28 430 with an average of 13 530 in the Gulf most important food items were Pleurosigma, of Mannar. Triceratium. Coscinodiscus, nematodes, From Porto Novo, Jayabalan (l988b) copepods and foratniitifcrans. determined the spawning period as August Leiognarhus splendens: From Porto February. The length at first maturity in males Novo, J ayabalan (1986) reported that spawn was estimated as 99 mm and in females as 102 ing takes place almost throughout the year mm. Fecundity was estimated as ranging from with two peaks during April-May and Oc about 11 650 to 26 750 in 15 fishes of the tober-December. Length at first maturity was length range 110-114 mm. estimated as 89-90 mm in males and 89-94 The results, therefore, show that silver mm in females. The relationship between bellies are fractional spawners spawning fecundity and total length was determined as: throughout the year with one or two peaks or Log r== -7.4891 + 6.6910 log 1. over longer durations each year; the estimates MURTYBTAL. lVol.39,Na 1,2 Leiognamus bindus, Visakhaparnam 1937 Stock assessment ' I I 1 Growth parameters: The smallest and I I- 0I r largest L‘ values and their associated K values of the four species under study along w 'Iii’: E .: with the corresponding Phi values (Pauly and O "-Q‘ I ' __]_I I | l= ' Munro 1984) are shown in Table 2; the cor L. blndus. Vlsakhapatnam 1987 responding length frequency (restructured) 120 data withgrowtlrcurvesareshown in figures 6-9. In L. bindus (Table 2). the estimated I I I Lafognarhus bindus, Madras 1984 60 .~ ‘FF, : .:P 120 ' "' 0 Ii‘' ' 4.1 liiiII' so _ L. bindus, Kakinada 1955 - 120| I I LI r 0 B |]II L. bindus, Madras 1986 . pI- eI -I I. l. 120 ~ O 601an nE ri 60 L. bindus, Kakinada 1988 , 1 20 O smrormramor, Vlsakhapatnam was 60' O §£§§§§§5§ so- '| 0I I|. Fig. 6. Rertrucnrred length frequency data (ELEFAN l) and growth curves of Lciognarluu ' birrdru. Visnldraputnam 1937: L. =1 I51 mm, K an 0.95 per year, SS-=9, SL=6$ mm; Vinklu.pet S. Insldiafor, Vlsakhapatnam 1987 nnm I987: 1... I I63 turn, K=0.95 per year, 100 SS=7, SL=45 mm; Kaltlnade I988: L..=l$4 mm, K=0.77 per year, SS=9, SL=30 mm; 60 Kaldnida l988: L..=l65 mm, K=0.70 per year, %l0.’SL=l00 mm. 20 of length at first maturity are within 63-102 assaigiissés mm with majority of the values falling in the Fig. 7. Rertnremred length frequency data length 80-9S mm; these fishes are mainly (ELEFAN 1) and growth curves of Laiognalhus zooplankton feeders; and -though. some es bindus. Madras 1984: I...=l$3 mm, K=0.90 per timates of fecundity are niade; in view of the year, SS=l, SI;-55 mm; Madras 1986: [..=l67 mm, K=0.96 per year, SS=8, SL=90 mm. fractional spawning habits in these fishes, the Sccuror in.n'dialor. Viukhapetnam 1988: estimates cannot be taken as total annual L..=l20mm, l(=l.2peryear, SS=7,SL--90 mm; fecundity, and can at best be referred to as Viukhapetnern 1987: L...=l30 mm, K=0.8$ per batch fecunditles. year, SS=7, SL-95 mm. al engih mm N Q —_ -Q _ Ifili ..od=l— _ E51_ WIFIIMIDI! inn: TOM length mm} é _l -3I-Fa_f Mard\.Iuna rm] svocx ASSBSSMENTOPSILVHRBELLIES Secutor msldiator. Kaklnada 1987 lier by Murty (l986a) were closer to the values of this study but those estimamd from Calicut 1 00 (Pauly and David 1981), Samar sea (Silvestre 1986) and Java sea (Dwiponggo ct aI., 1986) 50 were different: the values of L... were much 0 smaller (Tables 2 and 3). In L. jonesi (Table 2), the L. values were S. lnsldlator. Kaklnada 1988 slightly larger than Lm known. While the Lafognathus jonosl, Ftameswaram 1988 I v F! O .. ill . . 1°01 120* 5 5 J I H Z S. lrulohtor, Madras ‘I986 il'lIi' ' 0L. jonosi. Rameswaram 11984 “0 I 'III||||l|| Iml I I ' I_ ‘ 120 w" S. lnaldafor, Madraa. 1987 L. dussumfod, Parnban 1984 1. 40 I' I I_-8I -' U5 t 'a' ' '' °;aa2§§§arars 70O I. . Fig. 3. Reltmctured length frequency data (ELEFAN I) and growth curve: of Sccutor ia L. duaaurnlerl. Pamban 1988 sidiator. Kakinada 1987: 1.. = I25 mm, K = I13 per year, SS =1, SL = 85 mm; Kakinada “O .' if is 1988: L. = 130 mm, K = 0.85 per year, SS = 7, SL = 65 mm; Madras 1986: I, = 125.5 mm, K = 1.22 per‘ year, SS = 9, SL = 80 rnm; Madras I937: |__ = 138 mm, K = 1.30 per year, SS = 10-o I ' ' . 4, SL I 65 mm. Fig.9. Restructured length frequency data values of L... and K in both the sets ranged (ELEFAN l)and growth wrves of Leiognathus from 151 mm to 167 mm and from 0.70to0.96 jonesi. Rameawaram 1988: L..= 155 mm, respectively. The maximum known length of K=0.70 per year, SS-=3, SL-=50 mm; Runes this species was l55 mm (Anonymous 1977) wararn I984: I-= 160 mm, K=O.6 per year, from Madras. The estimated values within SS2], SI.-70 mm. Leiognalhus du.m0m'¢r|'. Pamban 1984: L. = 162 mm, K=l.2 per year, each set (lower or higher) were found to be SS=7, SL=85 mm; Pamban 1986: L_= 175 close to each other. The values estimated ear mm, K=0.80 per year, SS:-7, SL==60 mm. 53 Totallangth mm S Totalongthlmt Jan l “M8A, inn! II‘ If Jtno-~MINI! ll ll‘ lflj MINHI -n_.| sq, -11 -111 W :~ nut;tug-1; wllfllN... aunt; 2"WN9”3fin(VIMHY1RUM$2 85: E b__£ 9&0? E83 5 §_; 0 ______“__%_“______%3|5mE_ HO ngmg as D U5 N M3 "8508 Uta £88 BE____8____m5_ 3 E558 U85 an “U3; Ufi _5g now“ Us EM 2903 usufi $02 3;_v3EH“2“adQ:3“Q A8“gfl2 A2:andCNN:3Edad2“2:“ad2“Q,"mg8““NdNQN“__N_NOWNmgNW"8:“#323HQNHO _ Q_H3608;Q56_N“__v_dmg_ _Q_O2 __N8;CS6$2“Q2N $6sad2N6N36ad28QhdP: 6mm H6O86:2and56O36andN: 6N% 6P86MU __©adQ2£6$6$6adEN2“mumad2*QQM36$68“onOSas0:O2SNS:SN%W_Nad2“ma$__£2fig8_NNfi@03X 8$62;3;$6Q;Q2ad368686860:‘acInQ2O2Q;Q2s_Q:“H2O5 : 93_:§_ESR_ _§_a M “gs: J Saw: $6Om;£6262“gm£6:6N“ H8__O“ _O“ fi26OQQ:6mg“W:n_O2N2m_EW2_2fig;QQQ6‘SS6om 2“Q: NM“gmiN28“QGQN25%’_H:__H_%|ggkkl8°86‘H§8fi'gr?‘§_p_Y8:_N_.Tqk~_§i “£8 ‘SM “as: ‘E ‘Q ‘£3 Q2F:O:H2N22*N:O2“:32E3§E&§>__£___&gagsE32333EE_a_%_fl;“EYEgga__R5&~6_3; EggEE~33E&“CR28556*cH5aS3a_>LSq_i______VA _E____§___Q‘ 4 __3D3933 J__§__i__E__ Baug__=___§§q {N w_ac°_____H 3%EggsV52EaOu__ __ % m _§ ______£83 ngmG505 Om: “E 32; g _5__§Q 2: B; ma \A=u£O>_G “O smug: H__B£_€ Baas Em Q5 _~ 3”" “V5 _E__wE_ J88 DEEOE éaoflaa gem ‘O U3; 3% _N O3; March, June 1992] STOCK ASSESSMENT OF SILVERBIZLLIES estimates of Venkatraman er al. (1981) were timated yield of these two species is 3 680 close to the estimates of this study, those ob tonnes. Ilence, the increase in yield by tained by Karthikeyan er al. (I989) were not decreasing the effort by 20% will not be sig so (Table 3); the Lu. was much smaller than nificant. these estimates. In northern Tamil Nadu (Fig. l1.A), the In L. du.r.smnicrt' the 1.... was closer to the maximum yield of 1 860 tonnes of L. bindus Linux (Table 2). corresponds to 120% of present effort. In S. In S. insidialor the estimates obtained insidiator the yield increases to about 2 270 were close to each other (Table 2). The lone tonnes at 200% of present effort. The com earlier estimate (Marty 1991 ) was closer to the bined yield of these two species increasesto present estimated values (Tables 2 and 3). 4 100 tonnes at 200% of present effort. The Mortality rates: Taking the two sets of present yield of these two species is estimated parameters (Table 2), the total mortality rates to be 3 930 tonnes. Thus, a 100% increase in were estimated using the length-converted effort can result in about 4% increase in yield. catch curve. in L. bindus, the estimated values ln southern Tamil Nadu (Fig. 12) the of Z varied from 4.14 to 5.26 under ‘lower yield of L. dussumieri increases to 5 720 ton parameters’ and -from 4.72 to 7.44 under nes at 200% of present effort whereas the ‘higher parameters’ (Table 2). In L. jonesi, the MSY of 16 500 tonnes of L. jonesi cor Z values were 4.95 and 5.36 under ‘higher’ responds to 120% of present effort. The max and ‘lower’ parameters respectively. In L. imum combined yield of 22 100 tonnes of dussumieri, they were 5.46 and 6.70 (Table 2). these two species corresponds to 140% of In S. insidiaror under ‘lower parameters’, the present effort. The estimated yield of these Z values varied from 4.69 to 5.67 and from species during the study period was 21 800 4.36 to 8.72 under ‘higher parameters’ at dif tonnes. Thus a 20% increase in effort will ferent centres (Table 2). result in about 1.3% increase in yield of the The estimated valuesof natural mortality two species and 40% increase in effort will rate (M), under both the sets of parameters increase the yield by about 1.5%. ranged from 1.64 to 2.05 in L. bindus, from Cod end mesh size of trawl and yield: In 1.50 to 1.67 in L. jonesi, from 1.76 to 2.35" in Andhm Pradesh, the yield of L. bindus in L. dussumieri and from 1.99 to 2.59 in S. creases up to 2(X)% of present ts. In S. tn insidiaror. The M/K values (Table 2) in all the sidiator, on the other hand the MSY corres cases showed that they were well within the ponds to 60% of the present tc (Fig. 10.8). The range of 1.0-2.5 (Beverton and Holt 1959) situation thus, shows that under the current known in fishes. ‘ effort level there isneedtoreduce thecodend Effort and yield: In Andhra Pradesh, mesh size by 40% to get MSY of one species maximum yield of about 2 500 tonnes of L. and to increase the same by at least 100% for bindus is obtainable at 60% of thepresent another species. The combined maximum effort whereas the yield of S. insidiator in yield of the two species, however, cor creases to 1 560 tonnes at.200% of present responds to 60% of present tc. This implies effort. The mixed fisheriesassessment of that the present cod end mesh size which is these two species showed that maximum yield already small (15-20 em) has to be reduced of 3 700 tonnes will be obtained at 80% of the further by 40% (to 9-12 mm). This reduction present effort (Fig. 10.A). The present es can only result in l-6% increase in yield. QN9_3MWVlLATh_YW“U1Aadfig2“3“_nQ__NOWNNi"G _ ‘N:3ON“__ inanM “NEd2Ngfl:___2:2 6ad8;2;s_N_::3HodEdEH:6SN3;on8;Q:adma8““HA“Ndgd_gQ326£6268“CNNK6863%Q6ananad26ON“3' I OI Q3“ O O| nN© O___ mg QI “Q0 OO8__ad86On“@2_862;g_ _cg%__‘__‘ “ad ‘ a 2 Ed£0 3 l ' ____o and 2“ __ Omg an ___ Ed‘ M;2;ad%d8628_R_86:838_$N8_G_8_$_8;“:8;:8_Q_ _S6:8__£O_NN_asas‘Q2as iscg82 gm8°_E3'56§_ 4‘ _”°as gnaw£2 “Q 30%82 pang“U $2_____“a“_as __§Egfigas __§sE%>$2 _EA_is ram82 ____ _ucg£2 E_n>_w82 :52gin8. E£5'3“aifiIa“8“ hflhlmfig _°_6z 88“ _€___ _H__&_§_§ £5 ______%_H2 $3 J83ggU“ :5_%___ ’____aIdM Egg JQ__&__3_u Q 33*‘ 4aiauq J___a_a___d%______4_____\__“°_3 °_w__flN’_JJ____ E5 cg AEFQ ca;3 E;AEVJ858€8é_3_<“£8”gm? “swag ED: 360% hmggmm __Eo§_U __O Baum Eu E PG” us £_w5_ _b=“8E £2" ngfiam 6 U3“? March, June I992] STOCK ASSFSSMIZNT‘ OF SlLVl£RBl£l.LII':S I Q‘ so wr In northern Tamil Nadu (Fig. ll. B) the I I "1 ‘*1 3 "7 O (‘*1 N on § N MSY corresponds to 80% of present tc for L. blndus and to 60% of present tc for S. in O\ I“ I-Li "1 $. ~11 sidiator. The combined maximum yield of Q v V1 I these two species corresponds to 60% of 0 on O\ present t¢. Here also, the implication is reduc ‘*3 N 9! Z ea 3 wt to l tion in cod end mesh size by 40% which o~ O I-1 ‘<0 results in 13% increase in yield. l‘. O-d of “Z N 4-»: so 00 oo I In southem Tamil Nadu (Fig. 13) the MSY of the two species corresponds to ~0 “Z present tc only suggesting that under the O I t present effort level and in the presentfish O Q O Q ing grounds, mesh regulation is not neces --I 3 ~45 as I %JE F 00 co v sary. /-\ DISCUSSION i _,-5 z> Two species (L. bindus and S. insidiazor) J were considered for the study from Andhra E Pradesh and northem Tamil Nadu coasts and two other species (L.jonest' and L. dussumieri) 5 Q @ ‘F from southem Tamil Nadu. As these species formed about 60% by welight of silverbelly in Q V1V catches in the respective regions, assessment at 0 O—_ Q 2 § T of these species could be taken as nearly l L reflecting the situation in the silverbelly 8. 8. 3 8. 8 J 2 fisheries of the regions. E 3 3 .3. The problems in arriving at realistic es 9 timates of growth parameters and the conse quent need to take into account at least two P'— it PII —_. sets of growth parameters (lowest and highest O 3 ‘O I-0: and related K) from among many sets of I values estimated and the types of conflicting management options one would encounter in mixed fisheries assessments, have been dis Z-0>5 N cussed in the paper on thteadfin breams in this issue. As these are common to most of the 1‘> E G multi-species/mixed fisheries, they are not E v-u dealt with here. By the very abundance of silverbellies, both in terms of number of species as well as '-v quantities landed, and the species dominant in Iu-Q the fishery, the southem Tamil Nadu is dis tinct and requires separate treatment for Tab e3 (Could) Spec cs A1114/L06 K(P=1'lo I-= E yw) (Yw) (yflf) L. brevirostris Dwiponggo etal. 986 Secular nsiziialor Kakinada, India Murry 99 27.0) 0.20 350 S. ruconiu: Dwiponggo ct al. 986 Cazza minutzf Porto Xovo Iayabahn and 0.8649 -0.Bl6 Ramamunhi 986 MURTY EFAL [Vol 39, No. 1, 2 Andhra Pradesh n B100 3960 ® 80”’ - 1. 396OF- 3520 sp°°'°$ -J 1200 80”-, sped93 l. 3520 ‘T, 5 aoeo1~_\ t -Jsaoo ‘X? 3080 °\.°¢~> ~t\°" F ..2640 Lii 0° F\ i Tr| \. 2640} \ -1 ‘"' : ,_2200L‘ lf- '|4 p_\ 9/%. ‘IV -1 4 2200 i» K 2 ii l \ 0%"~*o. T, -0% | L‘-»‘_ ' ‘\ \| 0%“ 760 '" 1 __ 760 wlssoo_J _ .- \ Secutor if1$5d'a'°' ‘+ 2 | \ \ G) 1320 fl \‘ \ eT -42700 ->; 1320» 35ot-El\ \ ‘\\ \ \:07 __ t.Spec’, -#1800 J . it-l $\ \ ""‘\_\ - S;"”5/‘7'?'tlor | K saw i we 440 j“ \ O//rdus900 440i¢q i \ QJ_?&n-Q-~ ‘ Q _-4_....-4 _._t_._.._L ._a_i__.t.___t_...t O O» -J ;_)_ _.J_..._..l__..l 20 40 60 80 100120140 160180 200 .20 40 60 80 100120140Q 160180 200 Ettort as % or present t¢ as % ofpresent Fig. 10. Yield of Leiognarhtts bindus and Secutor insidiator f rorn Andhra Pradesh. A. At different effort levels expressed as percentage of present effort. B. At different t, levels expressed as percentage of present t, (the small vertical lines on the curves indicate MSY in the present fishing ground and the long vertical liner the current effort or I, levels and yields). fisheries management. Northern Tamil Nadu quired to harvest MSY but the levels of effort and Andltra Pratlesh, however, do not show required to get the same were different in both greater difference with regard to the species the species. In southern Tamil Nadu, in both composition and dominant species. The as the species (Fig. 12), increased effort was sessments were. however, treated separately necessary to get MSY but at different maxi for the three regions due to the above reasons mum levels. The combined assessment of the and mainly Because the fisheries management two species (in each region) lead to a still is within the administrative control of mari different situation in that the effort cor time states. responding to maximum combined yield was The Thompson and Bell long-term different from the effort corresponding to forecast in Andhra Pradesh indicated the need MSY of constituent species. A more or less to decrease the present effort level for one similar situation was seen in case of yield species and increase the same for another mesh curves of the species from the three species in the same fishery to get MSY (Fig. regions making the task of formulating effec l0.A). In northern Tamil Nadu (Fig. ll.A), tive management measures difficult. lf all situation was that increased effort was re other species in the mixed fishery are also Y'e d 8t» 8it Biomass orm DRUGS —L .e . <2‘-’ s°$ March, June 1992] STOCK ASSFSSMENT OF SILVERBELLIES Northern Tamil Nadu 4600 " 4600 _* “B 4 t 40 - goth sr>e¢'°5 -[ 5850 4140 ~> ® t 3680 QSBOTt l \ I "1 5200 t 4-v' 3220 *_l\ -1-tsso 't ._ ' 3; 3220 .. \ _t é4-I 2760 -- 390 2760 .* l \ 1 30° " t \ \ , $eCulor insidiator ‘i 3250 23OO +- ‘ :2 \ t _ . 2. 840 \ _; 1840 d. J:—\\|\‘l \ 4Le:ognamus ~I1 —-_ bindus ~ 2600 i P» / 1380 \\ \ \i i-§ l~tQ50 ' aaot-/ \ ‘T \ ni/d/;.”O, ~- 920 * \__\ t -~___ _-ttaoo 92o~ ‘f % 1 bllfkfuc 460 Ar ~~~tIt -ieso-A ‘T-' 46 " l Q L_, I _l .a eL._e _u___t.___r .._|___l_.l O Oe it, _r_ .1 __.t___L _p_.Ls,_r__ L,_i 20 40 60 BO 100 120140160189 200 20 40 60 BO too 120 140160180 200 Effort as % of present tc as % ot present Fig. ll. Yield of Leiognarhus bindus and Secular frtridiator from northern Tamil Nadu. A. At different effort levels expressed as percentage of present effort. B. At different t, levels expressed as percentage of present 1,. considered, the situation will only become importance of stock assessment lies in making more complex. This is the real problem faced available strategies for regulating fisheries of in fisheries resources management particular several species stocks so that the fishery ly in tropical countries like India. While managers can select the strategy mostrequired knowledge of the biological interactions be for the industry. In the case of silverbelly tween species contributing to the multi resources considered here, the present effon species/mixed fisheries is essential for can be maintained in the present fishing effectively formulating regulatory measures, grounds, because in cases where increase in on the basis of available knowledge, the only cf fort to get MSY is warranted the increase in option appears to be fit is to regulate the effort yield will be very marginal and can result in at a level where MSY (or MSE.) of the most reduction in catch rates. Only in Andhra economically important species is obtained. Pradcsh there is need to decrease the effort by As long as the effort is stabilized at a required about 20%; here also the increase in yield and level (in the well-defined fishing grounds), the catch rates is not significantwarranting such yield of all the species including the targettcd a reduction in effort. Though the analysis in species, also gets stabilized as long" as the certain instances indicated the need to reduce steady state assumption is fulfilled. Thus the cod end mesh sire of trawl net, particularly in 59 Yeld Ol'lfl8S N O Biomass Ol'lI'l Y. 8 Kl On ll 95 D T_ _ r__ F "1 fl "“l 90»: /24,8 ’/0% . 6,602/8 9/0’ MURTY ETAL. [Vol 39,No. l, 2 Southern Tamll Nadu 24 -148 l \ BO") $p9 ‘ ‘ 22 7' \ _ __§I§_ CIBS€___“__ ..; 44 Ll l J 2o»- \ ’ -§ 40 itT \\ 18*\\ \ | -- as _\\ ‘ =* t .is g-» _ _ Qiognarhusjonesi _ ‘ 4 ‘P ‘I -it L \ 4 20 1 4 \ \ F| 2 - \\ \ \ ‘Bil \ \ "N 24 _ L \ \ \ l " \ \ \\ 0°/3 l 7 4 .. 111 \ . 1 l it 8 ; \ \I ul \\ \ \ 6 Ir" V\\\ A‘~__ -_&*\__:~ - L. \ dussumieri :_ .._ _ ' 12 .. I ‘M 1 \ #1 4 . X. *5'%,-*i¢ I \ S §‘*1 "'—' 8 \ x‘ "i J 2 I E-‘#1“ —~ -i 4. __ L. dus.:umien' .-t4 1 hi i _.~1;' ._... Q _t_.. 1____.t___l20 40 __ so tags t___-t_~t_._l_._..i.1__.l___.1_...so 100 120 140 ..__4_160 .1... tao .'_.. .1.._...-l.. 200 __‘ 0 Ellort as % of present Fig. 12. Yield_of Lgiognathusjonesi and L. dussumieri at different effort levels expressed as percentage of present effort in southem Tamil Nadu. northern Tamil Nadu, such a regulation will where active fishing both by mechanized and not result in substantial increase in yield and non-mechanized gears is taking place. Con even if so, the contribution will be from much siderable caution is necessary before any cl‘ smaller fish (of the already small, considered fort increase in the present fishing grounds is as trash fish) not valued by the industry in any thought of because of its possible impact on significant manner. other resources. Moreover, silverbelly land It is known that silverbellies are predo ings are showing declining trends in recent minantly inhabitants_of shallower regions years. Yea X1000 onnes} 8~‘ 5 r //\///v / 0° / // an / 6’ //Q5? / L 3 Bzomass X 1000 on nes March, June I‘)‘)."!| S'l‘O(_‘K AS3155 .\-IIi.\"l'()l-' SlLVIiRlli-Il.l.lI-IS 22 ‘W Southern Tamil Nadu 20*‘ T 18' I 5:‘ 16U-P <3’.‘Q 14|-—+I I /i\ 1 1 .22 107' A > 8& L. dus$\1'“‘°Ii o+ 1 4-no 2!! 0 O . o -L_-20 4 A 40 ‘lo 4,?60 L 80 1 l____JJ 1 00 on1 ,420 ,1o,_4o 1 40 1____nu_14o__4o 1 60 1 BO 200 P4 le as % ol present Fig. I3. Yield of Le|'0gn.a!hu.r jonesi and L. dusswnicri at different It levels expressed as percentage of present 1,, in souLhcm Tamil Nada. ACKNOWLEDGEMENTS the course of analysis of data at lhc Computer We [hank Dr P S B R James, Ex-Dircqor, Ccnlrc; the authors arc thankful lo them. CMFRI, Cochin, for encouraging Lhc study. REFERENCES Mr K Namyana Kurup' Mr K Bahm and kn. Alagaraja K. 1984. Simple methods for estimation of T V smhianandam Scientists’ CMFRL ' parameters for assessing exploited fish stocks. In Cochin, cxlcndcd help in many ways during am Journal ofFish¢ries an = 171-95. 61 (x 1000 tonnes O5 6 i'“l 1 (0 9% Go“ 6‘ Q30‘? 09% l\lUR'l'Y l;'l'AL. [Vol 39, l\'o. 1,2 /\nn:tm V l’ and l)lt:mnar;i_j:i 5 K. 1981. Ttentls in the James 1’ S ll R. 1975. A systematic review of the fishes catch of silvethellies by mechanized boats in Tamil of the family l.eiognathidae. Journal of Marine I\':tdu during I971 -75. lnilian Journal ofl"isltcries Biological Association oflnrlia 17(1) : 138-72. 28 (1 & 2) : 87-95. James PS B R. 1986. liiology and fishery of Leiognathus /tnonyrnous.1‘)77. Annual Report 1977. Central Marine jonesilamcs from the Pallt Bay and Gulf of Mannar. Fisheries Research Institute, Cochin, I48 pp. Recent Advances in Marine Biology. pp 29-101. Anonytrtous. 1991. Annual Report 1990-91. Central (Iid.) James I’ S ll R. Today and Tomorrow publish Marine I-‘isherics Research Institute, ICAR, Cochin, ers, New Delhi. 1 ll pp. Jmnes I’ S ll R and llntlrttdeen M. I975. lliolugy and Arora ll L. I952. Contrihution to the biology of the f isltety of Leiognutlius bre virostris (Vulenciennes) silverbelly Leiognatlius splenrlens Cuv. Proceed from the Pallt Bay and Gulf of Mtmnar. lndion ings oflrulo-Pacific Fisheries Council 3, Technical Journal of Marine Sciences 4 1 50-59. l’nper 4, pp. 75-80. James P S B R and lluilrudeett M. 1981. lliology and llalan V. 1967. Biology of silvcrhelly, Leiognatltus bin fishery of silvcrhclly Leingnatlms ilussmnieri dus (Val.) of the Calicut coast. lndian Journal of (Valencicnnes) from (iulf of Mannar. Indian Jour Fisheries 10(1) : 1 18-34. nal ofFisheries 28(1 & 2) : 154-82. James l’ S B R and Badrudeen M. 1986. Studies on Bevcrton R I ll and Ilolt S J. 1957. On the dynamics of exploited fish populations. Fishery investigation maturation and spawning of the fishes of the family Series, London 19 : 533. Leiognathidae from the seas around India. Indian Journal ofl"isheries 33(1) I l-26. Bcverton R J ll and llolt S J. 1959. A review oflifc-spans James I’ S I3 R and liadrudeen M. 1991. A new species of and mortality rates of fish in nature and their relation silverhelly Leiognothus striatus (Family Leiog to growth and other physiological characteristics. nathidae : Pisces) from the Gulfof Mannarlndia and Ciba foundation eolloquia on ageing. The Life-span redescription of L"eiognothusfasciatus (Iacepede). of/1nirnal.r.5.pp 142-77. (li.d.) \V0lsenholmy(i Ii \V and Conor M O. Journal of Marine Biological Association of India Chan E ll and Liew ll C. 1986. Characteristics of an 32 (1 & 2) : 217-I-26. James 1’ S B R, Alagarswamy K, Rao K V N, Muthu M exploited tropical shallow waterdemersal fish com munity in Malaysia. The First /tsion Fisheries S, Rajagopalan M S, Alagaraja K and Mukundan C. 1987. Potential Marine Fishery Resources of Forum. pp 349-52. (lids) Maclean J 1., Dizon I. ll India. CMFRI Special Publication No. 30. pp. and llosillos I. V. Asian liisheries Society, Manila, 44-74. Philippines. 727 pp. James 1’ S B R, Badrudeen M and lidwin Joseph V. 1992. Dwiponggo A, Ilariati '1', Barton S, Palmares M L and An annotated bibliography of the silverbellies. (Pis Pauly D. 1986. Growth, mortality and recruitments ces : family Lciognalhidae) CMFRI Special Publi of Commercially important fishes and pcnaeid cation No. 50. 220 pp. shrimps in lntltmesian waters. JCLARM Technical Jayabulan N. 1985. A new species of silycrbelly, Garza Report 17 1 91 pp. sltcttyi (Pisces : Lciognalhidae) from the Bay of Qayanilo F C Jr, Soriano M and Pauly D. 1988. A draft Bengal. Matsya ll :42-45. guide to COM I’l.F.A'l' ELIZFAN. ICLARM Jayabalan N. 1986. Reproductive biology of silverbelly Software Project 2 : 65 pp. Leiognathus splendens (Cuviet) at Porto Novo. In James P S B R. 1967. Leiognathus leuciscus (Gunther) dian Journal of F isheries 33(2) : 171-79. and Leiognathus smithur.t'ti (Ramsay and Ogilby) Jayahalim, N. 1988a. Age and growth of the ponyfish, (Family Leiognathidae : Pisces) - Two new records Leiognathus splendens (Cuvier) caught off Porto from the Indian seas. Journal of Marine Biological Notio coast. The first Indian Fisheries Forum Association oflndia 9(2): 300-02. Proceedings. (Bd.) Mohan Joseph M. Asian Fisheries Society, Indian Branch, Mangalove, pp James P S B R. 1969. A new species of silverbelly XV + 494. Leiognathusjonesi (Family beiognathidac : Pisces) Jayabalan N. 1988 b. Reproductive biology of the from the Indian se1ts.Joi.-rnalofMarlne Biological ponyfish Gazza minuta (Bloch) from Porto Novo, Association oflndia ll (1 & 2) : 316-19. cast coast of India. Indian Journal of Marine Scien James PS B R. I973. The fishery potential ofsilverbcllies. ces l7(l):51-54. _ The proceedings of Symposium of Living Resou r Jayabalan N and Ramamoonhi K. 1985 a. Sexual dimor ces of the Seas around India. CMFRI Special Pub phism in the ponyfish Leiognothus bindus (Val.). lication. pp 439-44. Current Science 54 (22) : 1191~92. March, lune 19921 S'l‘U(fK ASS]-BS)-lliN'1'()1:Sll.\'liRIlliI.I.lI{S .I;iy:ih:il:|n N and R.'ttlt:tmtmttlti K. 198$ I). Matti ration and Kakinada. Journal of Marine Biological Associa sp:iwr|it1|1 of silvculiclly .$'ecut0r inxidiatur from tion nflruiia 32 (I & 2): I0-24. Porto 1\'uvnco:tsl. lnrliart Journal ofllfarine .'icit'n Pauly I). I977 a. The l.ciognatltid:rt-. (l'elt'ostr-.i), their ces I4: I05-()9. species, stocks and fisheries in Indonesia with notes Iayabalan N and Ramamoorthi K. I985 e. liood and on biology of Leiognathu: splendens (Cm/ier). feeding habits of the silverbelly (Jazzo minuta Marine Research in Indonesia" I9 : 79-93. (llloch) in Porto Novo waters. Indian Journal of Pauly D. I977 b. The Leiognathidae (Teleostei) : A Marine Sciences 14 : I ll)-I2. hypothesis relating their mean depth of occurrence .layaba1anN and Ramamoorthi K. I986. Determination of to the intensity of their countershading hioIuminis age and growth in the toothed ponyfish Gazza cence. Marine Researclr in Indonesia 19 : 137-46. minuta (Bloch) from Porto Novo. Mahasagar Pauly D. I930. On the interrelationships between natural 19(3) : 217-20. moitality, growth parameters and mean environ Kartltikeyan M, Pillai N G K and Iladrudeen M. I989. mental temperature in I75 fish stocks. Journal du Population dynamics of silverbelly Leiognathus Conseil 39(3): I75-92. jonesi James i‘n the trawling grounds off Ramos Pauly D. I982. Studying single-species dynamics in a waram. lndian Journal ofFisherie.r 36(2) : I03-O6. tropical multi-species context. Theoryand Manage Kurup B Madhusoodana and Samuel C T. I983. Sys ment ofTropical Fisheries. pp 33 -70. (Eds) Pauly D tematics and distribution of fishes of the family and Murphy C I. ICLARM, ISIRO. Leiognathidae (Pisces) of the Vembanad Lake, Pauly D and David N. I981. ELEFAN-I a BASIC Kerala. Records of Zoological S urvey oflndia 80 (3 programme for the objective extraction of growth & 4) : 387-411. parameters from length frequency data. Meere.s Murty V S. I983. Observations on some aspects of biol forschung 28 : 20$-I I. ogy of silverbelly Leiognathus bindus (Valeneicn Pauly D and Pauly S W. 1981 ./in Annotateldliibliography nos) f ront Kak inadn. Indian Journal ofl~'i.slterie.s 30 ofSlipmoutir.s (Pisces z Leiognathidae). ICI./\R.M, (I) : 61-68. Manila (Philippines), 62 pp. Muny V S. 1985. Multispecies stock assessment with Pauly D and Munro J J. 1984. Once more on the cont particular reference to major dcmcrsal fish species parison ofgnowth in fish and invertebrates. Fishbyte in the trawling grounds off Kakinada. Journal of 2(1) : 21. Marine Biological Association oflndia 27 (I 8:. 2) : Pillai N G K and Dorairaj K. I985. Results of trawling 3‘)-48. survey by an Institutional boat Cadalrnin II in the Murty V S. I986 a. Studies on growth and population Palk Bay of Gulf of Manner, Mandapam, during dynamics of silverbclly Leiognathus bindus (Valeri I977-80. Indian Journal of Fisheries 32 (I) 1 I23 eiennes) in the trawling grounds off Knkinada. in '32. rlian Journal of!-'i.\"lrerie.t' 33 (3) : 277-ll-1. Pillni P K Malntdt-.van. I972. Iiccumlity and spawning Minty V S. 1986 b. Popttlntion characteristics of the habits of some silverhellies. Indian Journal of silverbelly Leiognathus bindus (valencicnnes) Fisheries 19 : 196-99. along West Bengal coast. Journal of Marine Rani Singh and Talwar P K. I978 a. Species of silverbclly, Biological Association of India 28 (1 & Z) : Leiognathus indicus, Pisces : Leiognathidae (From 41-47. the Bay of Bengal). Bulletin oflooiogical Survey of Murty V S 1989. Mixed fisheries assessment with refer India 1(3) : 275-77. ence to five important demcrsal fish species landed Rani Singh and Talwar P K. 1978 b. Oh the little known by shrimp trawlers at Kakinada. pp. 69-86. Con ponyfish Garza achlamys Jordan and Starks tributiortr to Tropical Fish Stock Assessment in (Pisces : Leiognathidae) in the Indian waters. Cur India. (lids) Venema S C and Van Zalinge P N. rent Science 47 (23) : 930-31. Paper prepared by the participants at the Reuben S, Sudhakararao G, Luther G, Apparao T, Rad FAO/DANIDA/ICAR National training course on hakrishna K, Appanna Sastry Y and Radhalrrishna fish stock assessment: Cochin, India, 2-28 Nov. G. I989. An assessment of the bottom trawl fishery I987. FI: GCP/INT/392/DEN/1: 1989. 157 pp. resources of the northeast coast of India. Bulletin of Murty V S. 1991. Biology and population dynamics of the Central Marine Fisheries Research institute 44 silverbelly Secutor insidiator (Bloch) from (Part I) : $9-77. MURTY ETAL. [V0]. 39, No. 1, 2 Siivesln: G T. I986. Yield-per-Recruit Anniysis of Ten praisul of the marine fishery resources oflhc Indian l)emcrs:|1 fish species from the smnar sen, Iixclusivc Iiconomic Zone. Bufletin offishery Sur l’l:ilippincs. pp 5()l-504. Procn'd1'ngs of Firs! vey oflndia I3 : 85. Asian I-'is'her£e: Forum, Manila, Philippines. 727 Thompson W F and Bell F ll. 1934. Biological studies of pp. (lids) Macle:m .11., Dixon I. H and llosillos the halibut fishery. 2. Iiffecl of changes in intensity I. V. upon total yield and yield per unil of gear. Report of Sivaprnkasnm '1' ii, l'arnsur:|m:m I’ S, l’|cmchun MURTY, V. SRIRAMACI-IANDRA, M. KUMARAN AND R. S. LAL MORAN. 1989. Resources of ornamental fishes. égz Marine Livi ng resources of the Union Territory of Lakshadweep An Indicative Survey with Suggestions for"Deve1opment. §'_i_s_120P§5_Q_ I'l_l§_E-0; 43: 46‘-640 CMFRI|e'¢Q~;;1B@¢eO~ R 25 bulletin 43 APRIL 1989 MARINE LIVING RESOURCES --OF THE UNION TERRITORY OF LAKSHADWEEP — An Indicative Survey With Suggestions For Development §' 1 s Q’Q'“‘.‘('1‘I ';>Q\ '3\\\) ‘-9If \ . -.16'\ 1,.;/ 5'; 3 \ ‘<1,' 30 ».~> E E11?‘ ' " CENTRAL MARINE FISHERIES RESEARCH INSTITUTE (Indian Council of--Agricultural Research) P B N0. 2704, E. R. G. Road, 682031, India Bulletins are issued periodically by Central Marine Fisheries Research institute to interpret current knowledge in the various fields of research on marine fisheries and allied subjects in lndia ‘\ Copyright Reserved Published by P. S. B. R. JAMES Director Central Marine Fisheries Research Institute Cochin 682031, India Edfled by C. SUSEELAN Scientist Central Marine Fisheries Research Institute Cochin 682031, India Limited Circulation CONTENTS Preface Introduction P. S. B. R. James HistoryP. of MarineS, B. Research R. James in Lakshadweep \ Some Observations on the Fisheries of Lakshadweep P. S. B. R. James, P. P. Plllal and A. A. Jayaprakash Tuna Resources and Plan for Development P. S. B. R.James, P. P. Pillai and K. P. S. Koya Live-Bait Resources and Development M. Kumaran, and 4 olhers Resources of Ornamental Fishes V, S. Murthy, M, Kumaran and R. S. Lalmohan Other Finfish Resources M. Kumaran, R. S. Lalmohan and V. S. Murthy Crustacean Resources G. S. Rao, C. Suseclan and M. Kathirvel Mollusean Resources K. K. Appukuttan and 4 Others Potential for Development of Pearl Culture K. Alagarswami, A. Chellam and A. C. C. Victor EchinodermsD. of LakshadweepB, James and their Zoogeography Beche-de-mer Resources D. B. James Q I Sponge Fauna P. A. Thomas Seaweed and Seagrass Resources N. Kaliaperumal, P. Kaladharan and S. Kalimuthu Turtle ResourcesR. S. Lalmohan . . .. The Coral Fauna C. S. G. Pillal and S. Jasmine Some Observations on the Marine Mammals and Marine Birds R, S. Lalmohan 19s Hydrobiology of the Lagoons K. G. Girijavallahhan, L Davidraj and S. V, Alavandl zoo Environmental Damage and Consequences P. S. B. R. James and 4 others 212 Underwater Observations in the Lagoons A. C, C, Victor, A. Chellam and K. Ramadoss 227 Mariculture Potential R. S. Lalmohan, D. B. James and S_. Kalimuthu 243 Suggestions for Establishing a National Marine Park P. S. B. R. James and C. S. G. Pillai ' 243 Development of Fisheries---Recommendations P. S. B. R. James and 3 others zss 6. RESOURCES OF ORNAMENT/\l_ FlSHES f V. Sriramachandra Murthy, M. Kumaran and Fl. S. Lalmohan INTRODUCTION lllteam: Androth, Kavaratti, Suheli, Kalpeni Among the fishes of Lakshadweep islands, and1987. Minicoy during 6.3.1987-1.4. ' those of ornamental value (aquarium fishes) are very abundant: of the 601 species of marine In all the islands the fishes were collected fishes belonging to 126 families reported from using drag net. encircling net and cast net. In these Islands (Jones and Kumaran, 1980). at the lagoons, the collections were made by en least 300 species belonging to over 40 families circling nets Fig. 15 A-D and those in the reef are ornamental fishes. In addition to the taxo flats with drag nets Fig. 15. E: the drag net nomic account of fishes of Lakshadweep islands was laid in a semicircular fashion on the flats by Jones and Kumaran (1980), information on in suitable areashnd stones were placed in the ornamental fishes of these islands is restricted net to provide hiding space for fishes; the fishes to the works of Pillaietal. (1983). M“adan were driveneinto the net from the open end and Mohan eta! (1986). and Kumaran and Gopa then the net was hauled. Every effort was made kumar (1986). There is, however, no infor to collect all the species available in the area. mation on the relative abundance or areas of Cast net was also operated on the reef flats. abundance of different species of ornamental during low tide periods : the net was laid over a fishes from different islands. There is con big stone and then the stone was moved several siderable demand for live ornamental fishes in times or lifted up, the fishes underneath the several countries (Tomey 1985, 1986) and the stone get entangled in the net and thus caught. present export market price of each fish, Observations on the distribution and abundance depending on the species, ranges from Rs. 16.10 of ornamental fishes were also made visually to Rs. 272.25 with an average of Rs. 90.60 in and through underwater surveys in deeper areas Netherlands and from Rs. 4.96 to Rs. 148 with of the lagoons. an average of Rs. 34.85 in South East Asian Countries. ln West Germany, each specimen of Collections were made from the lagoons some of the species of ornamental fishes from and reef flats by dividing them into arbitrary India can fetch from Rs. 99to Rs. 810 (Anon zones so that representative samples of the species inhabiting the "zones" could be colle 1986). ln view of the demand for the ornamental cted, Each zone was intensively studied: speci fishes and the possible earning of foreign mens were collected from different areas ineach exchange through export of live ornamental fishes and also in view of the lack of adequate "zone" to get a general picture of distribution information on distribution and abundance of and abundance of different groups of fishes in the lagoons and reef flats. Alter collection, the different species in different islands, a survey fishes were taken to the shore, identified" in was conducted during ..lanuary-March 1987 and the results with reference to ornamental fresh condition, photographs tak_en and then. fishes are presented here. preserved in 5°/0 formalin. All the collections were brought to the main land. MATERIAL AND M ETHODS ORNAMENTAL FlSHES OF LAKSHADWEEP The survey was conducted by three teams lSLANDS as follows: Jones and Kumaran (1980) recorded about l team: Chetlat. Kiltan, Kadmat and Amini 300 species of ornamental fishes belonging to islands during 5.1 .1987-6.2.1987. over 40 families (Fig. 1). The most dominant llteam: Bitra, Thinnakara, Bangaram and group is Labridae with 45 species, followed by Agatti islands during 9.2.1987-25.2. Pomacen'tridae 135). Apogonidae (22), l\/luraeni~ 1987. dae (22) Serfanidae (21). Blenniidae <20)» 46 . CMFRI w___Q__§2Zw__2 w * ———— 1—— -_" ' ,_ |3's 72 O41E \ "°i. ‘ I Fig. 3. Map of Chetlat island showing the distribution by shaded Ireaa. Of ornamental fishes. Acanthuridae (19), Chaetodontidae (16), Mu llidae (14) Callyo dontidae (14), Gobiidae (14), Scorpaenidae (14), Balistidae (10), Ho|ocentri dae (9) and others. The above 14 families are r _____*__—__ ~~; -' __—A_ __ ~~— —_ -7 V — 251% (T so‘i- 4 i Lk _ ’ ill I r€("I 11°? ““-\ 5 X’ i’ i(I, 4 “i '.¢';~"'a\ \ ‘ I1i ‘bu\-R‘ 5 ~‘.9’,1 t x J:‘ 1“ 1|i ----»___L____ I7 U .1 2 -__ e. i . 12°45? 46- 47. Fig. 5. Map of Kedamet island showing the distribution, by shaded areas, of ornamental fishes. 2.9: ‘T_ DISTRIBUTION AND ABUNDANCE OF ORNAMENTAL FISHES During the three-month survey, a - total of 139 species belonging to 33 families were collected from different islands (Fig 2). Among ay;LoIl 5 ' ‘.0’I them, the fishes of the family Pomacentridae are -"$10 or-I3‘ — mostdominant (22 species) followed by Labri 11* i_ __2___r 2 _ dae (21), Apogonidae (10). Mullidae (9). 73°E P Muraenidae (9) Chaetodontidae (8), Callyo Fig. 4. Map of Kiltan island showing the distribution, dontidae (6), Acanthuridae (6) and others; the by shaded areas, of ornamental fishes. species of these eight famiiiies together con -48 CMFRI ru Q. _.‘I___i. -=“"°fT.‘.‘-iiafr %f-3"\ ~ '5'" \\\ "’ ll \LT“N \ \\ (\\ t\\\\\*\\\ .'I_ Z R3 \ _\\ 1\l_~ \ :___w ' - \ "*'/¥%':LEa, -~' . \ °'*"'~?-;@Q_\\ - .. 0*‘ I u9V Q . Q ‘A e.“-vv ¢'¢‘r\.' .6C: .~ ‘KKK s‘-z,H’-‘i:-r”--z:-'% -;a":,% I 14*.’-\s‘."I%~" ‘v Q2115 ‘ass’ a*'J' "" on __ ‘2 _ :_____"_ --'— ' ‘;;_;~ _ ;——~ . if-‘ ‘:__ _i' -' _ ‘_*__ '—_:i:o;i:_-- 7*“. ,1: | 805,6In AI‘ A‘ ~ 5?‘Fr "44"‘t ”\~,.=::_Q: ‘Q5‘#: rrfl,w"' “M 1 7 5’ “°"~rq-.. rf0" - Z. o {(1,' V en rah!‘ We '"\'** A ,‘;4*"“ "?..'l-.".'!-Q:A L A s 0 or N / M ’ . ;; - 4 I 56|_ - :__:_-TINNAKARA Q3! e er; ' I I;-i BANGARAM -_ ./.1’ 1 5*’ ‘b . I 1.17 ‘$3 . -J’ ‘ > r _. I it ‘ x’: f . l Q:v%€/%% @»1-::s:<$§¢’fi’! I T~-_- e_.72°16‘ Ks-_~, ,_.___|_ E 1-7’ _W____ re‘ r < '_ I . Fig. 8. Mlp ot Ylnnekera and Bengarem islands showing I l the distribution of ornamental fishes. I “E9”lvuvvuvvvo .r~l~)"°gd r l L J rl 7 _ , ' _____ f _ ---—-----§---.s Z Ti? 4, " c_ J. 72 43E ' 44" ' Z 7 ‘ l Fig. 6. Map of Amini island showing the distribution, ‘l \ by shaded areas, of ornamental fishes. r _ j ' "'1 i‘ T “*5 I I . .) nf‘p “'6 /% F 40%nrpn nnflnflan | _ 36:L|1r ¢rpP0ti/l §2>/ //4§;;2;; I nfionq8,‘ ' %%a01% T ((//4, / Q 0'71 N ! (/'/ " /I r 6;2”/ 7 51' l_ //' i _> 1O°l / J‘ | |, .- _, LAGOON | ,_LL » ’ \l ‘-w..~»*’r'§ALPITTI LQ ,-I 4. t. 1. t. Qt L1i~1i---n---—-._.._.i_..-.-.- - - - \ .- -mi-.- .l_..-,___. .___.,___,,,_ _ ,._.%.,,_¢._p-¢.@i.—. t. 72°11'E' 5c LL <. Q Fig. 9. Map of Agetti and Kelpitti islands showing the L l| t. distribution of ornamental fishes. H wwwvvwvwvl wvuuooouw-'°°X ‘JO' N Q . stitute about 64% of all ornamental fish species 30' 11° - H t ' "L ~ collected. Z2O" iO‘E *— —-7 77-, ':' - --*—;;~ ~ s 7i _ Fig, 7. Map of Bitre island showing the distribution of The distribution and abundance of different ornamental fishes species of ornamental fishes in the reef flats and BULLETIN43 49 1 “-" 1 fir‘ ‘I \ M--"' "M 1-“'-'0‘, "I.-‘I-\"_"‘4\-q:\a\ fi~fi "N ~‘l ‘\ .‘fi '\ n 0”” ( ~ V ‘\ 6‘ O L 0 "( Q 4/ D ." J 5'» .'.)’ \ \ “"'Q90. I J \ 0v“qJ' > \ ~N_,.,-P’ > {J .0;0":-“:~. 1. 0 3-? H. L A G O O N "'—>::\w \\~\\“‘§\:<-__.,;-.r \ . 0 fin‘ ‘ '1" ' ' ' ~ —ifi-— —— . |_,.—___a;:_.I1'-_ ___—I--- apogonids and holocentrids. Pomacentridao are abundant both in the lagoon and reef flat, acanthurids in the reef flat and Holo oentridae and Apogonidae are abundant in the lagoon. 49-_ Nfff/f////.4’//'////////////////////////////,.. - . .. V‘ '_ _ A___. _r, ‘ Kiltanz At this island Pomacentridae. Labridae, Holocentridae and Acanthuridae are abundant. Of these pomacentrids are more abundant in the lagoon whereas ‘L A N D R0 TH - g, Labrids in the reef flat. -,-. 4e‘ ,,"- --.---- -_-. .. --'>>/// "**—-F'—""i|" ' *F—— "1 "1 -~ --1 10°Q .. ‘O ‘. -J L VALIYA KARA.,"T7\f'4'. ‘f Common 8' - 5;". Q Abundant 'r'; —t I | I O 73 40E O ° 41 ‘ . Fig. 10. Map oi Androth island showing the distribution it- / o'\ /. ll’ . 0 of ornamental fishes. I | Ir 5 , / ‘ ' I 1 I \- . o lagoons of different islands are shownlin table 4I ;...:;$~ .O.Q . _ <9 .l 1 and in Figures 3-14 (the areas of abundance o‘o\\‘0‘\.::.:.:Q Q Y‘\ --tII“t‘. of ornamental fishes are shown by shaded _ | , Q:O:\.§~‘ ‘ Q \. ‘ -I3! I areas) ‘.§ ‘Q ‘lg. 0 J,1 l / 0.0‘.' I _ 0:0’ 1’ J l 1. Chetlar: At this island, pomacentrids are +, / _ cg._ ‘.0;’_, J: J en?-RN“ma ;:=:=E$‘ -~'=‘=" most dominant followed by acanthurids, ~° _._;f fa‘ -v-‘ | !'l-i777 ‘A777 ' 7 _“‘ ‘—‘_“T_" "”' 7 _7- __e . ii l t0°'"-1;‘ ' ' U -_‘*~'\‘-1':r::.'-‘-‘ ‘ ' l an Q' 59"‘, Common t I 4O E Abundant . '0 O T 34'1 ’O:O:O O O .0 ' Q, __.__ _;~_%_,_ ,1 L e - "_1__._-s-W ,1 _ .1_.___ _ I — o. i ?2°|2’£ ta‘ 14' 15‘ 16' n'__',_ is‘ W 12. Map of Suhelipar showing the distribution of is . &\ ~'0_ 50 0 ornamental fishes. ~00‘‘1»:0'o ‘ v’\ 0-4.5’o'0 1- 00 l | Abundant 3 Bitra: Labridae, and Scorpaenidae are most l abundant in the reef flat. Only one species to -1_ r w film] ___ V_ _ , i_i 72°35'|: 36' 31‘ each of the first two families is abundant Fig. 11. Map of Kavaratti island showing the distribution in the lagoon whereas scorpaenids were not of ornamental fishes seen in the lagoon. 50 CMFRI O . . AAQall-;4-an-we-s,‘ 1|-n gnu‘ H ¢ \ .‘:.Q. . As ~I\ » .0:O:60 0. O 0 0 Q ya‘ \ st; \|~‘.‘ \\ 0.0 . \ 5 0. k "6:::0.0 0 0 Q . . .0 Q0 $‘ '~$:;;G \ . 0}_ s \ O 0 {'60:3'1 :1‘. ~.,\ kg‘ \ 0 . .O:s% 0:. .9,¢1s’\ ‘O0 O 0.0;3'0. 0‘ "" .... t9:0‘o\Q 0 Q0 ‘tI: ' ~“- 0..:::::‘ 0.:‘.' _ 1 '- . ~51 .5‘; 3 Js ,0 “*5 \'\-M usss-~\q.~.~.;-"' 0’:f:"1’-9.“.-"% ’ \\ x 1'. P '1: £0‘I ‘\ 1 \‘,0 /,0 ' §743$,-; Q 0 ‘ Q .'::.x.O"; xi\ +:-. O ~\ /V F. 41¢"in‘. up \\\= 0-1'::::l 1.0-ii‘ ‘I’. ‘ - ‘ 03:. Cw "‘ _1 _ Q‘ r _ ---. _ __ 91 1 q——- s----F-pr_.¢:._;;_R_.,_.__._,\ 10. Kavaratti: Only Labridae and Acanthuridaa p are abundant, particularly on the reef flat of this island. 'I(.0/I0, Iv . . Q: II 11. Suheli: Labrids and apogonids are abund Q V , .~ vi OI . l ant in this island. Q fil 8'@ I ? “‘ ' i. 12. Kalpeni: Labridae is the only abundant 1-J J ‘ Q005 _: i group here both in the lagoon and reef flat. OOO09 ‘Q. ,0 Q 13. Minicoy: Pomacentridae, Labridae and 1 I * Acanthuridae are abundant both in the reef flat and lagoon of this island. I A The above observations show the following: O *1 a. ln 9 of the 13 islands surveyed, there are i more number of ornamental fish species in ; the reef flats than in the lagoons, though l ¢'¢ , some species are abundant in the lagoon _t and some in the reef flat, in almost all the 5 T ":?P|tT..__ | . islands reef flat is richer in ornamental lll g-%,'"T.'lLAKl(Al&lu . _ -___ I .. \ fishes than the lagoon. N, -‘ t at-‘l@¢'_ P‘lg. l '.;.-I ‘I ,'-0:a:a i » ' 4, - ‘i . 1:3:\_‘I '_.. 'o.- ‘.1.0-‘b , . ,I ‘.1 b. Species of Pomacentridae and Labridae are lo "k ‘:23.‘ '..3 I‘! JI not only more in number but they are also Q fig! Common ;, abundant in almost all the islands. l‘ _'i " 7- f -i -—~e~ —--~_*_,1: . .. _ _ __ 1 _g_Lgit1:. 1;. Q Abundant ~ “°"ii~L*»’*' H ' Rare ~‘ ‘ ‘ 7303-('_EN_i38 if 1 ' ' Ii J i ‘mi39 ill“ 40‘ ‘ I Fig. 13. Map of Kalpeni island showing tha distribution of ornamental fishaa. i ,.¢-*"",‘.’,'_:-4--a~'>r\' av" 2O'i- W‘0 T , 6’:’p,-fl_r . .. lll r" F 1-"‘Fnil’Ora” Thinnakara: Pomacentridae, Mullidae ff , Fr’:fr;-' Labridae and Acanthuridae are abundant in '9-r—1 ' PI’¢ -J this island: three species of Pomacentridae. J .- ‘ 2 each of Mullidae and Acanthuridae are 7 . ' . a a abundant in the lagoon whereas two species .l ..vo..','.'I..-"..”.Q. ’Q O Q ...... 0 90% ‘o‘I Q . _ O I each of the above four families are abundant ‘B P , O. O 59.0; 0.0, .. Q, _ . O.Q,O Q OO O, 4. . 0 V‘ ’..:..'0 :o:o:O0‘ 9 V 0... . _ Tl in the reef flat. , .0. 0 Bangaram: Pomacentridae, Labridae, Cha etodontidae, Mullidae, and Balistidae are abundant in this island; except pomacent ridae, the fishes of all the above families are abundant in the reefs. l Agati: Pomacentrds are the most abundant l group here followed by Labridae. $00fD6— enidae and others. ln all these cases. reef N jp _ flat is richer in ornamental fishes than the ‘Sf Common 4; lagoon. * @ Abundant i _ _A__g ____g l Androth: Only two species of pomacen i g?3°i'i: L _ 2' J 3' Rore Q is “ .i tridae and one species of Labridae are Fig. 14. Map of Minicoy island showing the distribution abundant in the reef flat. of ornamental fishes. BULLETIN 43 51 O3 ~.| 4.4 4 _ a._'_ _ l __ F l _ M _ A I - Q‘' 0. .0 0 ‘Q \-. .‘ - n. ° 0 _ -_ .a:0'o:o.o.9.,,~ _- _~:a_ _ ...... Q.Q.Q...‘Q.....Q.‘¢o0oQod?¢.$, ‘ ' .3.‘ . 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Pmacronemus Agati and Bitra have very rich resources of C. ternatens/‘s, C. chrysurus., Dascy//us ornamental fishes as revealed by the total aruanus, Ha/ichoeres gscapu/aris, Stetho number andabundance of species followed julis axillaris, S. strigiventer, S, a/bow'ttata_ by the group of four islands Kadmat, Chet Thalassoma hardwickii, Labroides d/‘mid/3 lat, Kiltan and Amini. Agatti and Androth atus, Acanthurus triostegus. A. lineatus. respectively are the richest and poorest H0/ocentrus diadema, Ostorhynchus no islands in regard to the abundance of vemfasciatus, O. endekataenia, Archam/‘a ornamental fish species. It is also clear fucata, Chaetodon auriga, Aspidcnorus that the western and northern group of tractus, Mu/loidichthys samoensis, M. islands are rich in ornamental fishes. aurif/ammo, Pterois vo/itns Dendrochirus zebra, Rhineacan/hus acu/eatus and R The abundant species are: Abudefduf rectangulus. All these fishes range in sordidus, A. sexfasciatus, A. cingulum, A. length from 2.5 cm to 22.0 cm. Some bioce//atus, A. unioce//atus, A. xanthozona, species of ornamental fishes collected from A. zonarus, A. glaucus, Chromis caeruleus, different islands are shown in Figs. 16-21. BU LLETIN 43 53 . . " ;-___ ‘>-Q.» _-c ‘Y-'9 . 5 , -'-.- '-univm. -~ Fig. 17. A. Pempheris owalensis, B- Chaetodon lunula, C. C. xamhocephalus D. C. auriga, E. C. citrinellus, F. Heniochus acuminatus 54O cmm Fql; - .. _--,__-7".-i. .-_ ._ Iv-@_-,-q._. . ..- _\I,.... _. . -p-w-_ I-v\_\- -;\ 71;‘? .¢_._. ._- 4§_-p-9 '4 i | | > E . I ? ?_;:' 1. . ‘f - 'f:§--_: 1.1: .;§";. - -I :-:".1.E1:i I-.11‘ ~‘-.J-'-.;;_ :-_;>;:--;; -I -1;‘-._.-3?.-. 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'_ < \ :j¢‘?;.m..€%e5sa§%§%%%e%e%ee@%;%e§;g;e%g§$e;;;e§£;;;;eeiggesenses,» ' ...' .':.:':. .. ::-:41-'-:3:-,3; . ...1._..._._ 11 ' ; -_ ;_ -.I ._. '_ " - ' I E3 _ s fii?T*?*f"1HY' 3 -* P i I.-' ~Jn"Q .H.“¢m,.H}"f"-+'-vitYHg;;;g,M,, .- §jg5j+@;I{ai£;m§gf4f115%aiiy*¥TF*jyfifH§K={iF¥g§j§g§ugq§ ,..__ __.4..__ . _,L - . . . - - - - 3. - ' _- __ _------:-':;.-:;i$_"_:;;-_€_____,_._ - - ' '-‘ _'___,______''-I :-:-. ' ;I;‘-' - -'_'-_!-- :'- __, -."~—__ -- .‘ .-: '.\, -. V-“->——4>4‘—‘-“Ill ..1‘ ‘ ‘-1-'11:-1'-:"'-"-~---T"-"-1':'.3:' :3-3. 3 -.-_ :3. ..-.-.. -. T—-_-__-_____-,_-_ '-‘I’-IL-I-:3: "rs?----<5 - V. _— ,\A__ ... .___.;iii.‘f“"'-: A-_ .: _'.T' , -, Fig. 21. A. /{cant/auras Iinealus, B. A. matofdes, C. Rhineacanthus aculeatus D. D. R. reclangulus, E Pterois volitans, F. Canllrigaster mgrgariiarus HABITAT OF IMPORTANT GROUPS fish fauna is also poor along the near-shore It is observed that labrids and callyodontids sandy portions of the lagoons. The reef flats are abundant in areas where sea grass is abund= are particularly rich in pomacentrids, serranids, ant; thus the reef flat along the eastern side of holocentrids,acanthurids and in some islands Amini these fishes are very abundant. Pome labrids. The different species of eels are centrids, particularly Chrom/‘s caeruleus and residents of crevices in the reef flats.‘ Pome Dascy//us aruanus and some labrids are abun centrids represented by Abudefduf sordius, A. dant in the lagoons where corals are abundant. saxati/is, A. sexfasciatus and A. g/aucus and Lagoons with sandy bottom are generally poor chaetodontids,_ ostraciontids, canthigasterids in ornamental fishes but goat fishes are available and some acanthurids are abundant in areas in considerable quantities during night time under the-Jettys and in areas protected by large particularly in Kadmat and Chetlat. Ornamental rocks. 58 .CMFRI 3%‘: i"~"*%.4<~ -$3.. 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C8:v_Hm__H2_0 gmgam ‘dz>_mEm“_ __m 53 Hg t 03¢v_ EOEEOU H xx UCw_U_5n< “ xxx 5"KgfigxxU2“QKiIIIIiKKIIEIIIIIIIiIFIIIIIII5?IIIIIII KKI figl 5“I XXXI‘ _ XXI K"* ‘K KK MKXX KE XI I*I II IK K_X XX1KKXxU2XXKXXIKKi_ KKKXIlI1lKXXXXIIIIIIIIIIII15QKXXKIiIIlI>00E__>_ ___wv_ E3_Ew_ F_Hp_ Em“ em“GE HmV_ __< _Ewm< '_~9__Wm |_wC____£ g_ _C_E Um Eg_v_ I0 O __2__w ‘gg -_UC _m < v_ r_ Q:§_8°“_ __‘ g8U=S_E_u 2__:____S_m__~5‘ gb_aME ‘R“‘_=2_&m_E __N h_8a“EaQSu_E s_b2S£ __Q_a%qSm_M_Q\E W%_§_gQQw g_2_E_9_”E _Bu6Q_=bQ@U _=°\3 QQEONEQQQOQ ___'s__§2m_g__ c°_8____E_O age Q_c__cQ_\\&\< %=0Q_fi__Ub_:_; _3b__S&Fm Wsamgga om “_am_&8N gs=82____=E “_=~£=Um_E 6 g_E__Q._§ aégga macs: “__§___\ Qggfim gag %E__%2b§Q “___g_wEgq %%O§m_S8m 26_:wCC®HC< gEEo_E_g£$mU:N£QQO°m@A m__w2_2m_wmEEQU mv§E%O_om_%_£gU_w5O %_U_§__Wm gE___E8gwU Q:5_@®_H:QM;MM"N9‘SFOm;GNPQ:FNPmVN__@@_§__MN"NNF_285585 _°_“£025>__Em“_‘oz.5 REMARKS REFERENCES The survey as mentioned above was con ducted during a short period of three months ANNON. 1986. Report on the training mission and thirteen islands "were covered during the on ornamental fish _export to the Ne survey. The results are very useful for an therlands. Marine Products Export appraisal of the availability of different species Development Authority, Cochin. 24 pp of ornamental fishes in different islands and for planing a comprehensive future research on JONES, S and M. KUMARAN. 1980. Fishes of the resources of ornamental fishes of different the Laccadiva Archipelago. The Nature islands. The data collected, however, are not Conservation and Aquatic Sciences sufficient for estimation of resource potential Service, Trivandrum. 760 pp. of these fishes. ln this connection the following points need consideration: KUMARAN, M and G. GOPAKUMAR. 1986. Potential resources of fishes other than i. Thelnformation on population characteris tuna in Lakshadweep. Mar Fish. lnfor. tics is restricted to one or two species Serv. T 8* E. Ser., 68-: 41 -45. that too from Minicoy only. There is also no information on seasonal variatiohs of important species. There is therefore need to MADAN MOHAN. C. S. GOPINAOHA PILLAI study various aspects of biology of dominant and K. K. KUNHIKOYA. 1986. Biology species of ornamental fishes from different of the blue puller, Chromis caeruleus islands to enable a detailed study of stock (Cuvier), from the Minocoy atoll. Indian assessment of these fishes. initially, the J. Fish., 33 (4) : 457-4_70. study should be undertaken for at least two years to enable advice on the exploitation PILLAI, C. S. GOPlNADl-lA, MADAN MOHAN pattern. AND K. K. KUNHl KOYA. 1983. On an unusual massive recruitment of the ii. Presently the exploitation of ornamental reef fish Crenochaetus strigosus (Be fishes is only on a sustenance basis and nnet) Perciformes: Acanthuridae) to there is no organised exploitation for co the Minicoy atoll and its significance. mmercial purpose. Since the ornamental fishes are associated with corals and asso Indian J. Fis/1., 30 (2) 261-268. ciated fauna and flora in the islands, any exploitation on a commercial scale can TOMEY, W. A. 1985. Survey in the Union result in destruction of the environment Territory of Lakshadweep, the Bombay which in turn can also eventually affect the and Madras area: Promotion of export fish populations inhabiting these areas. trade Indian ornamental fishes from Further, sincethe areas are easily accessible, M marine as-well as freshwater origin and the exploitation of reef fishes is likely to ornamental plants. Report .to CBl., the quickly lead to depletion of stocks and Netherlands and the Marine Products therefore utmost caution has to be exercised Export Development Authority. Cochin. before planning exploitation and export trade of ornamental fishes. Fishing with traps is suitable for ornamental fishes; this TOMEY, W. A. 1986. Promotion of Export trade is not likely to lead to destruction of habitat Indian ornamental fishes from Marine and therefore can be encouraged. However as well as freshwater origin and aquatic exploitation of ornamental fish species from plants for theaquarium industry: The the lagoons and reef flats can be undertaken pilot project : Conclusions and reco on a smaller scale, and the same should be mendations. Report on the project closely monitored. results to CBI/MPEDA. 64 CMFRI ,et_l_iT:-lsii_s {CONTRIBUTION~;;_ -1 —_ —.__s—; - —4_,; _24¢ ;__J RADHAKRISHNA, K. AND V4 SRIRAMACHANDRA MURTY. 1993. Present trends in marine fisheries management and catch forecasting. Paper presented at the International workshop on application of satellite remote sensing for identifying and forecasting potential fishing zones in developing countries: Hyderabad, India, 7-11 December, 1993. National Remote sensing agency, Department of space, Hyderabad India; Committee on science and.Technology in Develop ing countries of the International Council of Scientific Unions, Madras, India, 20 pp. ,i _ ___ ,7-A is ' ' V \ cowrnxeurxon 24 ,__-_--1 — -— .:—; F -: n 1" IN TE RNA TIONAL WORKSHOP , ON APPLICATION OF SATELLITE REMOTE SENSING FOR IDENTIFYING AND FORECASTING POTENTIAL FISHING ZONES IN DEVELOPING COUNTRIES HYDERABAD, INDIA 7 -11 DECEMBER, 1993 LECTURE NOTES JOINTLY ORGANISED BY NATIONAL REMOTE SENSING AGENCY (NRSA), DEPT. OF SPACE, HYDERABAD, INDIA AND COMMITTEE ON SCIENCE AND TECHNOLOGY IN DEVELOPING COUNTRIES OF THE INTERNATIONAL COUNCIL OF SCIENTIFIC UNIONS (COSTED I ICSU), MADRAS, INDIA COSPONSORED BY Centre for Science 8. Technology of the Non-aligned and other Developing Countries(NAM S&T), New Delhi, India Committee On Space Research(COSPAR) Panel on Space Research in Developing Countries, Paris, France Asian Network tor Biological Sciences(ANBS), Singapore Third World Academy of Sciences(TWAS), Trieste, Italy South East Asian Fisheries Development Centre(SEAFDC), Bangkok Dept. Of Space (DOS, Govt.of India), Bangalore, India Dept. of Ocean Development (DOD, Govt.ot India), New Delhi, India Fisheries Survey of India(FSl, Govt.ot India), Bombay, India Council of Scientific and Industrial Research (CSIR, G0vt.0f India), New Delhi, India Dept. of Science and Technology (DST, Govt.oi India), New Delhi, India Directorate of Fisheries, Karnataka State Govt., Bangalore, India Directorate of Fisheries, A.P. State Govt., Hyderabad, India Orissa Remote Sensing Applications Centre (ORSAC, Govt.of Orissa), Bhubaneshwar, India BENFISH, Calcutta, India CONTENTS 1. RETRIEVAL OF SEA SURFACE TEMPERATURES USING NOAA—AVHRR DATA FOR IDENTIFICATION OF POTENTIAL FISHING ZONES — DISSEMINATION & VALIDATION A.NARENDRA NATH, NRSA, HYDERABAD, INDIA 2. PRESENT TRENDS IN MARINE FISHERIES MANAGEMENT AND CATCH FORECASTING K.RADHAKRI8HNA, ICAR , NEW DELHI, INDIA V.SRIRAMACHANDRA MURTHY, CMFRI, COCHIN, INDIA J0'7 ELECTRONIC INSTRUMENTS REQUIRED ON BOARD FISHING VESSELS DR.T.K.SIVADAS, CIFT, COCHIN, INDIA 4. POTENTIAL FISHING ZONE FORECAST DISSEMINATION: USER INTER ACTION WITH FISHERMEN COMMUNITIES CREATING TECHNOLOGY AWARENESS ALONG THE INDIAN COAST 0.33322 NATHANIEL, NRSA, HYDERABAD,\ INDIA 5. INTEGRATION OF VARIOUS SATELLITE—DERIVED OCEANOGRAPHY INFORMATION FOR THE IDENTIFICATION OF POTENTIAL FISHING ZONES R.MICHAEL LAURS, u.s. NMFS, LA JOLLA, U.S.A. 6. FORECASTING TUNA FISHERIES AREAS IN TROPICAL ATLANTIC OCEAN 2 WHAT PARAMETERS? WHAT MODELS? THE PRAXEOLOGICAL RESPONSE JEAN-MICHEL STRETTA, CENTRE ORSTOM, MONTPELLIER, FRANCE 7. POTENTIAL FISHING ZONE CHART PREPARATION AND DISTRIBUTION SYSTEM FOR REAL TIME HAN SHIXIN, ECSFI, SHANGHAI, CHINA 8. FISH STOCK LOCATION AND ABUNDANCE ESTIMATES BY FISHING SONAR — A SUPPLEMENT TO SATELLITE REMOTE SENSING OF FISHING GROUNDS D.SRINIVASAN, IIT, MADRAS, INDIA 9. INFLUENCE OF THE VARIOUS OCEANOGRAPHIC PARAMETERS ON THE ABUNDANCE OF FISH CATCH PROF.M.P.M.REDDY, U.A.S., MANGALORE, INDIA 4 / O CHLOROPHYLL STUDIES USING REMOTE SENSING AISHWARYA NARAIN, SAC, AHMEDABAD, INDIA REMOTE SENSING IN CHINESE FISHERIES HAN SHIXIN, SHEN JIANHUA, LIU SHUXUN ECSFI, SHANGHAI, CHINA CHARACTERISATION OF MARINE ENVIRONMENT FOR FISHERIES P.S.B.R.JAMES, CMFRI, COCHIN, INDIA FISHERY TACTIC AND TUNA STOCK EVALUATION WITH AIRBORNE REMOTE SENSING SYSTEM JEAN—MICHEL STRETTA, MICHEL PETIT CENTRE ORSTOM, MONTPELLIER, FRANCE REMOTE SENSING AND FISHERIES EXPLORATION: CASE STUDIES AISHWARYA NARAIN, SAC, AHMEDABAD, INDIA\ UTILIZATION OF SATELLITE DATA FOR MONITORING OF FISHERIES GROUND IN JAPAN SHIROH UNO, SNFRI, JAPAN REMOTE SENSING ACTIVITIES IN RECENT JAPAN SHIROH UNO, SNFRI, JAPAN APPLICATION OF REMOTE SENSING TECHNOLOGIES FOR MONITORING OF COASTAL ENVIRONMENT SHIROH UNO, SNFRI, JAPAN REMOTE SENSING APPLICATION AND INTEGRATED MISSION FOR SUSTAINABLE DEVELOPMENT DR.D.P.RAO, NRSA, HYDERABAD, INDIA MARINE RESOURCES EXPLOITATION IN THE INDIAN EEZ DR.D.SUDARSAN, FSI, INDIA AN OVERVIEW OF OCEAN REMOTE SENSING INFORMATION MODELS PROF.MA AI NAI, PU, CHINA ,// /I REMOTE SENSING INFORMATION MODEL OF 3D SEA WATER TEMPERA TURE AND OCEANIC INFORMATION SYSTEM PROF.MA AI NAI, PU, CHINA EARTH OBSERVATION PROGRAMS IN JAPAN AND DATA POLICY DR. YUKIO HARUYAMA, NASDA, JAPAN BRIEF INTRODUCTION ABOUT SATELLITE REMOTE SENSING ON MARINE FISHERY IN CHINA DR. ZHANG JIANGUO, CAS, CHINA REMOTE SENSING APPLICATIONS IN BAY OF BENGAL WITH SPECIAL REFERENCE TO BANGLADESH DR. MD OBAIDUL QUADER, SPARRSO, BANGLADESH OPERATIONAL USE OF SATELLITE-DERIVED DATA IN u.s. FISHERIES R.MICHAEL LAURS, u.s. NMFS, LA JOLLA, U.S.A. JAN svnaxovsxv, 01c, CALIFORNIA STATUS ON APPLICATION OF REMOTE SENSING TO MARINE FISHERY STUDIES IN MALAYSIA ABDUL HAMID YASIN MANSOR MAT ISA PRESENT TRENDS IN MARINE FISHERIES MANAGEMENT AND CATCH FORECASTING K. RADHAKRISHNA AND V. SRIRAMACHANDRA MURTY (Indian Council of Agricultural Research, New Delhi- lio 001 and Central Marine Fisheries Research Institute, Cochin ~ 14) ABSTRACT Marine fish catch forecasting is m<.2 on a short term or long term basis for purposes of explo _ation and management. Among the short term forecasts, two approaches need serious consideration in India: 1. to'improve the methods of understanding the influence of environmental characteristics on the abundance or availability of fish in different areas in different periods and to make the forecasts of the same, 2. to make analysis of time series catch data (ARIMA mod— els) to make forecasts of catch in the next year or in a particular period during next year. There is some evidence of suitability of these approaches to Indian marine fisher ies but attempts aiming at comprehensive studies should be made. in the area of long term forecasts, considerable work is done in India on single species asses ments but in the context of multispecies, multigear nature of Indian marine fisheries, assessments of all species together in a mixed fisheryfisheries. are urgently required for effective managements of INTRODUCTION India, with a long coastline, is one of the major marine fish producing countries and occupies 7th position in the world in regard to the quantity of fish harvested. Of the total of 3.84 million tonnes harvested in 1990-91, 2.3 million tonnes forming about 60% of the total fish produc tion is contributed hy the marine capture sector. The exploitation of marine fishes has so far been restricted to about 50—60m depth. The declaration of Exclusive Economic Zone (EEZ) in 1977 for exploration, exploitation and utili zation of the living resources in the sea upto 200 nautical miles from the shore has given exclusive rights to the country to formulate its policies for the development and use of the fisheries resources in an area of 2017900 sq. km. This extended jurisdiction, provides a challenge for a new and improved basis for rational exploitation and utilisation of the resources and to enhance opportunities for fisheries Lecture note, "Workshop on Application of Satellite Remote Sensing for Identifying and forecasting Potential Fishing Zones inn Developing Countries", National Remote Sensing Agency, Hyderabad, India, 7-11 December 1993. 1 to play a greater role in increasing food production so as to help minimise protein malnutrition and contribute to the betterment of the socioeconomic conditions of the poorest sections of the population. Though it is nearly one and half decades since this extended jurisdiction has become available to the country, for various reasons (including shrimp-oriented development of the marine fishery), the progress in the exploitation of the resources in the entire EEZ region has not been satisfactory and the fishery has only been taking the resource available in the inner conti nental shelf up to about 50 m depth. Only a small number of larger vessels have been introduced to exploit the resources in the relatively deeper waters. By and large the re sources available in the areas beyond 50m depth still remain unexploited. ,The situation, hence, calls for a reassessment of the strategies and policies for marine fisheries development and management in India. From the presently exploited regions in the Indian seas, vast information on craft and gear, state—wise and species~ wise production and on various aspects of biology of con stituent major fish and shell fish species is gathered. Based on such information, attempts at stock assessment of some species from particular regions and at the development of mathematical models and methods for estimation of parame ters are made (Alagaraja 1983, 1984; Alagaraja and Srinath, 1981, 1987; Alagaraja et al. 1982, 1986, 1988; Annigeri 1972, 1987; Chakraborthy 1989; Dan 1982, Devaraj and Gulati 1988; James et al. 1989; Karthikeyan et al. 1989; Kasim 1987, Kasim et al. 1981, Kasim and Hamsa 1989; Krishna moorthi 1978, 1980; Krishnamoorthi and Jagdish 1986; Kurup and Rao 1975; Lalithadevi 1986, 1987; Murty 1983, 1985, 19888, 1986b, 1987, 1988, 1989, 1990, 1991; Narasimham 1983, 1987, 1988; Nair 1972; Ramamurthy et al 1981; Rao 1971; Reuben et al, 1989; Sekharan 1975; Silas et al 1985a, 1985b; Silas and Pillai 1985; Srinath 1986; Srinath and Alagaraja 1982; Sudarsan et al 1990; Sukumaran 1983; Vivekanandan and Krishnamoorthi 1985; Vivekanandan and James 1986; Venkatra— man et al 1982; Yohannan 1983). However, in view of the various problems involved in the acquisition of data and estimation of parameters, the progress in this direction aiming at a plausible advice to the industry has only been fragmentary. Moreover, in the context of multigear multis pecies nature of the tropical marine fisheries like those of India, steps to make assessments to advise the industry or developmental agencies on the required measures are but very scanty. Though some assessments of mixed fisheries are attempted (Murthy, 1985,1989), they have been only prelimi naryartisanal and detailed fisheries assessments of trawl on,fisheries for example, of a maritime management state of or the country are not attempted. In the context of manage ment of fisheries resources, major thrust has been on possi ble measures to regulate the effort or mesh size of the gear with reference 'to particular species in the mixed fisheries 2 . and attempts at forecasting the catches or the abundance of stocks in the fishing grounds are not made in any serious manner, except a few preliminary studies (Noble and Sathia— nandan 1991 and Sathianandan and Srinath MS). The present paperscenario attempts in India at giving with annotes overview on current of the trendsmarine infisheries catch forecasting. MARINE FISHERIES OF INDIA : Fishing and Landings: The fishing in the Indian seas, re stricted as it was, to the use of artisanal gear and craft in the nearshore waters during forties has improved vastly later by introducing and popularising mechanised vessels with trawl nets. By seventies, purse seines were introduced along the west coast (first in Goa and later in Karnataka and Kerala). This development has resulted in increase in the area of fishing and increase in the production of demer— sal resources along both the coasts and pelagic resources along the west coast. with increasing demand for fish and with improved technologies, the indigenous craft are moto rised to reach fishing grounds quickly and to operate drift/gill nets, hooks and lines, ring seines etc. Present ly about 1,68,100 traditional non—mechanised craft, 15,300 motorised indigenous craft and 22,900 mechanised craft are engaged in marine fishing in the country. All these operate in the inner continental shelf upto about 50m depth and during 1988-1992 an estimated annual average of 2.15 million tonnes of marine fish are.landed in the country. Maximum catches are obtained from off Kerala which contributes about 27% of total catch followed by Gujarat, Maharashtra, Tamil Nadu, Karnataka, Andhra Pradesh, Goa, Orissa, West Bengal, Pondicherry, Andaman and Lakshadweep Islands (table.1). Prawns form the most dominant component in the marine land— ings in India followed by oil sardine, other clupeoids, mackerel, carangids, croakers, Bombay duck, perches (predom inantly threadfin breams), ribbon fish, anchovies, catfish etc. (Table 2). 4 Potential yield : Based on the researches on primary and datasecondary on exploited production, stocks, survey bythe exploratory potential fishing yield andin the the presently fished grounds upto 50m depth along both coasts of India is estimated as 2.21 million tonnes (Anon 1991) (Table 1). Of this, the maximum quantity is available off Kerala coast with an estimated 571317 tonnes forming 25.8% of the total country's-potential. Next in importance is Tamilnadu (16.3%) followed by Maharashtra (16.1%), Gujarat (13.3%), Karnataka (12.2%), Andhra Pradesh (6.4%) and others (Table 1). The present landings (Average of 1990, 1991 and 1992: scope2.23 million to increasetonnes), clearly from show these that there areas. is not ~ much 3 ./' The potential yield of the resources in the EEZ beyond 50m depth is estimated as 1.69 million tonnes (Anon 1991) and this region is virtually unexploited. The potential of pelagic resources is estimated at 10.4 lakh tonnes of which about 4 lakh tonnes is available in the 50-100m depth_zone, 3.42 lakh tonnes in the 100—200m depth zone and 2.95 lakh tonnes beyond 200m depth zone. The major components are carangids, coastal and oceanic tunas, ribbonfish, pelagic sharks and mackerel which have considerable value for export as well as for domestic consumption. The potential yield of demersal resources is estimated as 4.2 lakh tonnes in the 50—l00m depth range, 2.0 lakh tonnes in the l00—200m depth range and 0.3 lakh tonnes in the depths beyond 200m in_the EEZ. The major constituents of the demersal resources in the 50-200m depth zone are thread fin breams, catfish, bull's eye, croakers and lizard fish. Thetions: above information thus leads to the following considera* \ —increase in production can be achieved only by deploying additional effort in the depths beyond 50m as there is not much scope to increase production from the presently exploit ed grounds, the strategy in this area should be for a sound and pragmatic management with forecasts of maximum sustainable yield of individual species stock and all the stocks together and, to regulate the effort to harvest the MSY. FORECASTING AND MANAGEMENT" Fish being a dynamic aquatic resource, the ability to fore cast the catches or variations in the seasonal abundance of the stocks in different areas assumes great importance in the development and management of fisheries of exploited stocks. Principally two types viz; l.Short term and 2. Long term forecasts are recognised (Shepherd 1988). SHORT TERM FORECAST Short term forecasts of catch are required for management of fisheries, for setting total allowable catches in a year and to guide the industry on the likely catches or catch ratesi In these assessments, forecasts of catch, catch rates, stock size, level of effort required and immediate effects of measures such as mesh regulation or closed season are made (Shepherd, 1988). These largely depend upon the current state of the stock and the likely changes in the stock in the near future. Short term forecasts are made using dif— ferent approaches: l. analytical approach (virtual popula tion analysis — VPA), 2. analysis of time series data.on catch, 3. influence of environment on the availability or abundances, 4. changes in fishing pattern and 5. remote sensing and PFZs. 4 1. Analytical approach : The virtual population analysis (Gulland 1965; Murphy 1965; Pope 1972), is a procedure for determining how many individ— uals there must have been in the sea to account for a known catch as well as natural losses. This analysis which also helps a forecast of the catch next year, can be carried out with data on, among others, catch~at—age and an estimate of recruitment of the stock in question. However, in Indian marine fishes, techniques for ageing individuals are not yet developed and therefore data on catch—at—age are not avail able. Similarly an estimate of recruitment too is not possi ble on the basis of available data. Hence short term fore cast using VPA cannot be made for Indian marine fisheries. This technique is used in higher latitudes, particularly in the North Sea to forecast the catch next year and allocating quotes to different fleets. 2. Analysis of time—series data : 1 Though analytical methods such as VPA take several factors into account and lead to better predictions of catch and catch rates, they are time~consuming and demand extensive data. This has lead to development of simpler methods that are less demanding on data and still yield reasonably ac ceptable results for forecasting catch and biomass. Among these, time—series methods employing ARIMA (Auto Regressive Integrated Moving Average) models (Box and Jenkins 1976; Saila et al. 1980; Mendelssohn 1981; Stocker and Hilborn 1981) are helpful in catch forecasting. For example in the case of Pilchard from Greek waters, Stergiou (1989) applied ARIMA model to the monthly catch data of 17 years and found that the mean error was 14.6% or 12% (with two equations). About the forecast value of the catch and the actual esti mated catch (after one year) the author remarked that "ARIMA procedures are capable of describing and forecasting the complex dynamics of the Greek pilchard fishery which have hitherto been regarded as difficult to predict....". In the case of sardine and anchovy in the Eastern Mediterranean, Stergiou (1991) applied Vector Auto Regressive Model to»the catch data of these two species, obtained during 1964—87 and stated that the model "produced accurate and unbiased fits and forecasts". In India forecasting using ARIMA models have been made only recently; Nobel and Santhiandan (1991) analysed the annual catch data of mackerel of the period 1950-1989 and found that ARIMA (1,0,0) to be suitable for forecasting. The catch predictions by this method "hinted at 10 years cycle but seemed to lack seasonal term". Sathianandan and Srinath (MS) analysed the annual data, for the period 1950-91, of total catch and catches of three important groups: penaeid prawns, silver bellies and cat fish. They found that ARIMA (2,2,1) to be suitable for predicting total landings. ARIMA (1,2,1) 5 for penaeid prawn landings and ARIMA (3,2,l) for cat fish and silver belly landings. Thus, forecasting using ARIMA models is still in its beginning in India; as the basic requirement is only the annual estimate of catch for over a long period, say a few decades, it is imperative that fur ther studies on the efficacy of ARIMA models to Indian forecastingsituated are.made using in thesea big way methods. to be able H to attempt catch 3. Environmental influence on abundance : Certain environmental parameters as limiting factors on the availability of stocks for exploitation is‘well known and the study of environmental factors for the prediction of availability or abundance of fish stocks in the fishing grounds is gaining momentum. According to Banse (1959,l968), the deoxygenation of the near—bottom water during the period of upwelling, results in regular disappearance of demersal fishes and in unprofitable trawling in a belt between the aerated water nearshore and the relatively new bottom water in the outershelf off Cochin. He (Banse, 1959) observed that Oxygen concentrations of 0.25-0.50 ml/l were critical for Nemipterus japonicus. Further, Banse (1968) stated that the drop of Oxygen content to Zero in near—bottom waters off Bombay and Calicut "suggests that there may possibly be a vast area in the outer shelf (and perhaps also in the middle shelf) approximately from Cochin to Karachi that is devoid of commercially exploitable concentrations of demersal fishes during southwest monsoon. The fishes very likely disappear before the oxygen has completely vanished". During the post monsoon period also, the near—bottom areas are known to be devoid of fishes because poorly aerated water persists on the shelf between Bombay_and Karachi (Carruthers et al 1959; Doe 1965). The threadfin breams which are more abundant in the 100—200m depth zone (Silas 1969, Silas et al. 1976, Vijayakumaran and Philip 1991, Sudarsan et al. 1990) are known to move into relatively shallower depths of 35-40m during the southwest monsoon period to avoid oxygen deficient layers in deeper waters (Nair and Jayaprakash, 1986). This enables exploita— tion of this resource from relatively shallower areas during monsoon period which during other periods is available only beyond, a good fishery exists for this resource off Kerala during July—September. Along the central east coast also, a similar situation of the so-called "cold water fishes" (eg. Psenes sp) moving into nearshore waters from deeper waters during upwelling in April-May has been observed (Reuben et al. 1989). Thus, oxygen—deficient layers in near—bottom areas of deeper waters and upwelling indicate disappearance of demersal fishes from deeper waters and their abundance in inshore areas. 6 _/' showedIn the case that of the oil successsardine, ofLonghurst recruitment and isWooster related (1990) to sea level prior to onset of monsoon. According to them, the sea level just prior to monsoon, indicates remote forcing of upwelling (other than the wind driven upwelling that occurs during monsoon) and "Unusually early remote forcing (of this upwelling) appears to inhibit subsequent recruitment, per— haps through exclusion of spawning fish from the neretic zone by oxygen—deficient upwelled water. Critically study ing the data on oil sardine landings and sea level during 1900-1987, these authors could establish a relationship between sea level just prior to the onset of monsoon and the summerrecruitment monsoon. to the oil sardine . fishery towards the end of A_peculiar phenomenon, known as "mudbanks" or chakara (in Malayalam language) occurs along southwest coast particular~ ly along Kerala coast. Though the origin and nature of dissipation of these mudbanks are not fully understood, their formation enables a good fishery to develop in the coastal area during the peak southwest monsoon period. The waters of mudbank are very calm compared to the very turbu lent conditions prevailing outside these areas during the same period. This calmness facilitates operation of artisa nal craft and gear which are brought from several distant places (Silas, 1984). Several species of shrimp and finfish particularly Metapenaeus dobsoni, Penaeus indicus, Sardinel— la longiceps, Leiognathus spp, Stolephorus spp are known-to be abundant in the mudbank regions (Regunathan et al., 1984) and support a very lucrative fishery. On the basis of fishery data for ten years from the mudbank and non mudbank regions of Kerala, Regunathan et al. (1984) made the following observations: 1. The abundance of some species in the mudbanks during July—August is not an exclusive feature for the mudbank alone but such abundance is seen all along the coast during southwest monsoon because, along with good catches in the mudbank region, similar catches are also obtained from non mudbank regions on days when weather is suitable for operation in the inshore waters. 2. During monsoon, the current is southerly and fish moving in schools in northerly direction (swimming against the current), pass through the mudbanks and contribute to the catches there. The composition of catch in the mudbank area shows variation on a daily basis indicating that different shoals move, one after the other on different days, into the bank area and support fishery. Thus, whatever may be the reason for a lucrative fishery in the mudbanks during southwest monsoon period, the mere formation of the banks makes the area calm (unlike the rough weather conditions in the non bank areas) and facilitates 7 operationshell fish orwhich cannoes cannot and be harvest obtained bumper otherwise. catches Thereforeof fin and mudbank formation serves as an indicator of a good fishery during monsoon period. 4.Change in fishing pattern: Regulation of fishing by imple menting closed season or closed area is a major short—term management strategy. In the tropics, annual or seasonal bans on trawling are known to have been implemented for rebuilding exploited stocks (Naamin 1984, Garcia 1986). Similarly, ban on bottom trawling in certain instances is resorted to, to protect ripe running fish on spawning grounds and to protect young fish on nursery grounds. In recent years, trawling bans are implemented along Indian west coast particularly along Kerala coast during monsoon period because 1. due to rough sea conditions during the monsoon period, the fishing by artisanal gear is restricted to nearshore waters whereas the trawlers operate in the waters which are accessible to artisanal fishermen during fair season and exploit shrimp, and 2. the traditional fishermen believe that trawling during monsoon‘results in the destruction of spawners of important fishes and affect the recruitment adversely. According to James (1992), the studies made so far do not indicate any adverse effect of trawling during monsoon on various stocks. He, however recommended, among others, that 1. urgent stops should be taken to regulate the number of ring seines and their fur ther entry into the fishery; as this gear catches apprecia ble quantities of young fish, it was also recommended that the mesh size of this gear should be increased to not less than 35mm and, 2. bottom trawling during monsoon is allowed strictly only beyond territorial waters all along west coast, perhaps to prevent possible growth overfishing in the nursery grounds by the first measure and to prevent clashes between fishermen of mechanised and artisanal gears by the second measure. 5. Remote Sensing and potential fishing zones Identification of potential fishing zones (PFZs) using Sea Sur face Temperature (SST) data derived from Satellite imageries-and forecasting the same are receiving attention. The data from the Thermal infrared sensor of the satellite are processed at the National Remote Sensing Agency (NRSA) to retrieve information on SST which is used to locate thermal boundaries, upwelling areas and eddies where maximum pelagic fish populations are found to occur (Narendra Nath et al., 1992). The data on the thermal imageries obtained by the satellite are transformed onto scaled base maps to obtained maps showing PFZs. These maps are trans mitted by FAX to fishermen associations and to maritime-state fisheries departments-; where FAX facility is not available, the information on the exact location of the PFZ is sent by Telex/Telegram also. 8 ./' The forecasting of PFZ initiated on an experimental basis in 1991 along Karnataka coast has been extended to coasts of all maritime states including Lakshadweep and Andamans. Along Karnataka coast, in one instance, the fish catch was reported to be 71.4 t from 102 boats from the PFZ where as only 52.4 t from 192 boats from other areas. In another instance along Karnataka coast, it was observed that the catch per unit effort at the PFZ was more than twice that obtained from other areas (Narendra Nath et al., 1992). The data on PFZs provided by NRSA are being increasingly made use of by the fishing industry; from Orissa coast during February—April 1992, it was reported that the catch in more than 80% of the cases was " above average or very good" in the PFZs when compared to other ares (Narendra Nath et al. 1992). Similar encouraging reports were also ob tained from some other areas. It is thus clear that the Satellite derived SST values can be utilized to forecast potential fishing zones not only to help fishermen save time searching productive grounds but also help increase production with less effort. LONG TERM FORECAST A long term forecast such as estimating maximum sustainable yield (MSY) depends on the factors such as recruitment, growth, mortality etc. which maintain the stock in the long run. Such an assessment is relevant to the strategy of management and is generally a part of an attempt to deter mine some long term goals or targets for management. It may involve estimation of fishing mortality (or the fishing effort) consistent with MSY or a minimum tolerable stock size to avoid the undue risk of stock collapse. Long term forecasts can be divided into two: 1. macro and 2. micro analytical models and the most common valuable result of these assessments is an estimate of the maximum quantity that can be harvested annually, year after year. In prac tice, however, the greatest possible yield may not be taken because greater economic benefit can often be obtained by taking slightly less catch at considerably less cost or because the greatest theoretically achieved yield requires anstrictly impracticable controlled combination selectivity of aof high fish level of the of fishingright size and (Gulland 1983). N CROANALYTIC MODEbS 2 These models also called as production models, do not con— sider the events such as recruitment, growth,_mortality in a population. They take into account the population biomass, the catch, the fishing effort (in terms of boat-days, number 9 of units etc.) and the natural rate of increase in the population. In these models (eg. Schaefer 1954) all the species together are treated as one and the data required are only effort and catch over a number of years and the assessment leads to an estimate of MSY and the effort re quired to take it. Though this is very simple for assessment of stocks, the assumptions on the dynamics of the stocks cannot be fulfilled (Larking 1982, Gulland 1983, Sparre 1985) and therefore this model is of limited value. It can be used only as a first approximation, when data on various stock parameters of constituent species are not available, to be above to provide a provisional advice on the maximum quantity that can be taken and the effort re— quired for the same. HICROANALYTIC MODELS modelsAs opposed consider to the themacroanalytic various events models, in the the stockmicroanalytic such as recruitment, growth and natural mortality. The most widely used model is that of Beverton and Holt (1957 which is based on the assumptions that recruitment, growth and rate of natural mortality are constant. In the absence of tech niques for determining age of individuals on a routine basis, methods of estimation of parameters of growth and mortality using length frequency data are developed in the tropics (Pauly 1980 Pauly and David 1981, Jones 1984, Gaya— nilo et al. 1988, Sparre 1987). In many stocks, recruitment is found to be highly variable and these variations are found to be independent of adult stock being determined mainly by environmental factors. Beverton and Hold (1957), therefore, developed a method of estimation yield~per— recruit, taking into account the growth parameters, natural and fishing mortality rates and selectivity of the gear and this method has become very popular in tropical countries to make assessments. Mainly two types of assessments viz; yield per recruit as a function of fishing mortality rate and as a function of age at first capture are made which lead to an advice on the pattern of fishing effort that will give the greatest yield from the fish that is recruited. The Beverton and Holt model deals with single species stocks and therefore advice on the effort or mesh regulation in a multi species fishery is not possible. It however, leads to an understanding of the state of single species stocks in a multispecies fishery. Of the several studies on pelagic and demersal fin fish and shrimp species made in India using microanalytic models (vide supra), in majority of the cases the fishing mortality is found to be close to the one that gives maximum yield and in the case of trawl, the cod end mesh size is found to be smaller indicating that additional fishing pressure in the currently fished grounds will not lead to any further increase in production and that the cod end mesh size of trawl has to be increased. However, since l0 ,/" all these assessments are based on individual species in a mixed fishery, a proper advice to the managers or the indus try on the effort or mesh regulation has not been possible There is therefore urgent need to develop methods of multis pecies stock assessment to be able to manage the exploited marine fisheries resources effectively Table 1: Marine Fish landings and potential yield in different maritime state of India from the presently fished areas in the O—50m depth range. iiitiiiiifliiiiii-—qijg.gi1¢i 141.0-11113.-n Goa 89,899 4.2 l,O8,522 4.9 ‘ Maharashtra 3,47,022 16.2 3,56,043 16.1 Gujarat 3,52,879- 16.5 2,93,929 13. 3 Andaman & Nicobar Islands 13,324 0.6 Lakshadweep Islands 6,809 O. 3 I-we-FQIUIII-Qwuuw Z-oi‘.-in-QQQQQIQ-ii—. 21,45,122 22,09,842 zntnji jiiiibji Q-pqnnq-Qcmiijjilv-It-II Q) o\° o\° Table 2 : Estimates of present yield and potential yield of different groups in the O—50m depth range of potential yield beyond 50m depth. //' Potential Potential Present" Y ield yield yield Resource (‘O00 t) ('oqo t) ('0on t) 1990 1991 1992 indepth O—5Om depth beyond 50m —-*¢~--iccioqg-Q0-01:1-—-i--g._¢-*q_.-_1,, Quin-can-n.-iii‘; 1.-gqgpg-q-Q.-1-Q-zyizpzzn-Q‘qnniQI—Ql1lI-Q|. Elasmobranchs 51 51 62 65 103 Eels 5 7 7 7 _ Cat fiah 38 39 36 60 63 Oil Sardine 261 177 104 191 Other Sardines 77 86 93 L 96 ~ Anchovies 59 86 81 53 * Other Clvpeoids 136 188 191 196 14 Bombay Duel; 130 136 127 104 Lizard Fish 25 I8 29 27 21 Perchov 121 103 114 114 125 Sciaenids 119 146 162 120 22 Ribbon Fish 74 95 111 95 216 Caranqids 142 169 190 143 304 Silverbellies 54 52 51 82 4 Pomfrets 4O 42 34 42 12 Mackerel 184 114 134 162 62 Seer fish 30 37 43 42 Tunas 52 36 42 37 451 Flat Fish 30 37 63 38 Penaeid Prawn 165 190 187 178 " Non Penaeid Prawn 80 101 91 54 Cephalopods 56 65 89 50 21 Otluwrs 233 255 244 254 272 ___ i‘--Z ______,______.1 ____ I is — — ..-.-in TOTAL 2162 2240 2285 2210 1690 13 REFERENCES Alagaraja, K. 1983, Mathematical models in Fish Stock as sessment, J.mar.biol.Ass.India 25(1&2):142-157 Alagaraja, K. 1984, Simple methods for estimation of parame ters for assessing exploited fish stocks, Indian J. fish. 31(2): 177-194. Alagaraja, K. and M. 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Narasimham, K.A. 1987, Fishery and population dynamics of the windowpane oyster} Placenta placenta (linnaeus) from Kakinada Bay, Indian J. Fish., 34(3): 277-282. Narasimha, K.A. 1988, Fishery and population dynamics of the Blood clam, Anadara granosa (linnaeus) in the Kakinada Bay. Bull Cent. Mar.Fish.Inst., 42:130-135. Nair, K.V.S. and A.A. Jayaprakash, 1986, A note on monsoon fishery for threadfin bream off Cochin, Indian J.Fisk., 33: 106-112. Narendranath, A. M.V. Rao, K.H. Rao, D.E. Nathaniel, T.V. Ramana, T.D. Suhasini, G. Venugopal and D. Jogendranath, 1992, Satellite forecasting for marine Fishery resources exploitation along Indian coast, Interface 3(4): 1-3. Noble, A. and T.V. Sathianandan, 1991. Trend analysis in all India mackerel catches using ARIMA model. Indian J. Fish., 38(2): 119-122. Pauly, D. 1980, On the interrelationships between natural mortality, growth parameters and mean environmental tempera ture in 175 Fist Stocks, J. Cons.int.Explor.Mer. 39: 175 192. (' Pauly, D. and N. David, 1981, ELEFAN I-A BASIC programme for the objective extraction of growth parameters from length frequency data. Meeresforschung, 28: 205-211. 0 Pope, J.G. 1972, An investigation of the accuracy of virtual population analysis using cohort analysis, Res. Bull ICNAF, (9): 65-74. Ramamurty, S., G.G. Annigeri and N.S. Kurup, l981, Resource assessment of the penaeid prawn Metapenaeus dobsoni (Miers) along Mangalore coast. India J. Fish., 25(1&2):52—66. Rao, K.V.S., 1971, Estimates of mortality and yield per recruit of ‘Ghol', Pseudosciaena diacanthus (Lacepede). Indian J.Fish., 15(l&2): 88-98. 18 Regunathan, A., K.J. Mathew, D.S. Rao, C.P. Gopinathan, N. Surendranatha Kurup and A.V.S. Murty, 1984, Fish and Fisher— ies of mudbanks, 60-71, in: Kartha, K.N.R. (ed). Coastal Zone Management - Mudbanks of Kerala Coast, Bu1l.cent.mar.Fish.REs.Inst., 31:i—vi, 74pp. ' Reuben, S., G.S. Rao, G. Luther, T. Appa Rao, K. Radhakrish— na, Y.A. Sastry and G. 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SRIRAMACHANDRA MURTY. 1993 Complexities of Management of Inshore Fishery Resources of India. §j_igh§.ng Cl11mq§,_ 13 (8): 5-9 QL._._.__:~ comigmiw i - A '2-3 _ f Global Fishing Chlmee (Pvt! Ltd. rtChimee Houee | e \ t Sector 12, Plot 178, MVP Colony Vleskhepatnam - 5'30 O17 Andhra Predeeh. Indie ' Tel : [891] 54142, 55171, 54319 Telex : 495-450 DIXI IN l Telofex : 91-891-54142 Reghtered ee e Journal In Indle INo.377!-50/811 Publlehed twelve time e yeet i Annual Subscription II Inland 110.360! Abroed US O 45 Place of Publloetlon : Chlmee Houee Sector 12. Plot No.1 78 M.V.P.Colony Vlealhepetnem - 530 O1 7 Managing Director Editor 6| Pubileher J.V.H. DIXITULU Executive Editor Q. PAPA RAO Production Manager A AB. MOI-IAN RAD Hepreeentatlvee : l I Oelli : R.N. Seigal ' CoclinKerneteh : H.N. : T.P.V. Chandreeekherieh Nair I J Nellove : M. Bhimareju \ Blhar : A.K. Singh PariahLeeer :Typeeettlng Anieh at Due I CHIMES LASER PRINT ChimeeHOUSE Houee I Sector 12, Plot No.176 F Vleekhepetnem - 17. 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During 1970-80, the marine of India, accommodating the technological changes, fishing activities expanded rapidly harvesting the socio-economic objectives, interaction of different resources upto about 50 m depth zone in the users of the resources and other activities which Continental Shelf. influence the fisheries, has been a matter of great concern for the policy makers, planners, scientists In the early seventies, purse-seines were and maritime State Fisheries Departments in the introduced on the South-West coast for the last decade. It appears to dominate the scene in exploitation of pelagic fishes. The pattern of the current decade as well. A review of the present fishing also changed from single day fishing to state of the inshore fisheries by Experts has stay-over fishing. Since the last decade. concluded that the catchable potential of different motorisation of country craft got momentum, and groups of fishes in the 0~50 m depth zone, estimated employing these craft, gears such as ring seines at 2.21 million tonnes, is very close to the present and “'minitrawls" were used for fishing in the production level of almost the same quantity. inshore waters. These inputs have helped the Added to this depressing note, the fishing marine fish production of lndia to increase steadily technological developments, which are perceived to the level of two million tpnnes by the turn of the as panacea for augmenting production and economic last decade. ' gains, have given rise to the formation of sectoral groups among the fishing communities exploiting the resource, and the consequent social and Fishing Pressure and Chasing Crisis professional conflicts. The various controversies and complexities of these issues are discussed As the catching capacity of the fishing units here in an attempt to help in the development of a increased but confined to a narrow belt of 0-50/60 balanced management strategy in consideration of m depth zone in the Continental Shelf, and the the administrative, social, economic resource competition among the resource users for conservation, technological and political objectives. maximising their share of opportunities to step up harvests, the exploitation pressure on the stocks in these grounds increased. Several studies made on The Beginnings and Growth Thereafter the production trend and the fishing effort put in to realise the production. and the studies made on the The emphasis on the marine fisheries population characteristics of the important individual development of India at the start of the planning fish and shellfish stocks constituting the fisheries, process in the fifties and sixties has been on the have indicated that increased effort in these grounds introduction of mechanised fishing vessels. may not produce enhanced yield or proportionate improved gears and gear material. The location of increase in production as the exploitation has lucrative shrimp grounds in the inshore waters, reached the optimum or near optimum level. This establishment of an export trade for shrimps and its is particularly so in respect of the shrimp fishery, accelerated expansion, gave a fillip to the which due to its value and importance in the export progressive addition of mechanised fishing vessels trade, is playing a pivotal role in stoking the and popularisation of bottom trawling, which co aspirations and also precipitating a crisis in the existed with the traditional fishing, exploiting the Indian marine fishing industry. same resources almost in the same area. These activities were supported by modern methods of Juvenile Exploitation : Besides the difficulties of handling, processing, preservation and utilisation of the catch, and establishment of other onshore resource sustainability, the increase in number of fishing fleet, use of least selective fishing gears infrastructural facilities with considerable financial @“ having relatively small mesh size, the changing and ring seines, and ivl closed fishing season and pattern of fishing methods and the increasing areas. competition to catch asmuch quantity as possible to realise better economic returns, resulted in the Catch limitation : catch limitation and control of catch of considerable quantities of juveniles. Large fishing effort are among the most common methods quantities of juvenile fishes and prawns, are also used in the management of fisheries, particularly in caught from the estuaries and backwaters. The their developed state. This technique is based on increasedicatch of juveniles of potentially high estimations of Maximum Sustainable Yield lMSYl commercial value fishes has brought intense and determination of Total allowable Catch (TACl pressure on the resources. indicating the quantum of catch that could be taken annually without disturbing the replenishment ability Neglect of By - Catch of the stock and, the optimum effort needed to exploit this quantum of catch. However, as the Similarly, the trawl fishery of our country is, estimations of MSY and maximum effort are by and large, interested in exploiting only the dependent on a number of variables and the quality shrimps and a large quantity (about 75-90% of of the commercial catch and effort data used for trawl catchl of fishes and other shellfishes is the estimation, the management strategy based on landed as by-catch. This by-catch is not properly this technique is often criticised for being too cared for and often, discarded to facilitate proper narrow in its objectives. preservation and landing of shrimps. According to one estimate, about 1,30,000 t of by—catch were Similarly, the changing seasonal pattern of discarded in the north-east coast of India alone by the fishery as well as the fishing methods, rapid the large trawlers in 1988. Such huge discards in generation of improved gears and ineffective system the sea pose severe problems for the resource of surveillance are the other problems of its practical scientists to get a correct and reliable picture of the application. Besides, the regulation of fishing species composition, seasonal variation, biology of effort is difficult in the context of multigear and the constituent species in the catch, estimation of multispecies nature of the fishery and the natural and fishing mortality rates and other competitive attitude of the resource users, enjoying population characteristics of the exploited resources. common property rights of fishing. it is observed Besides, in the critical situation of protein fish food that for species which have short life span and supply shortage the country cannot afford wastage exhibit intense recruitment variability, it is difficult of fish biomass in this way. This, coupled with the to base the management strategy on catch quotas. lack of involvement of the fishing industry in This strategy would also attract opposition from generation of data on exploited stocks places economic and political angles. ln view of these severe constraints on the fisheries managers. complexities, although this management technique should receive further consideration for dealing Modules in Fishery Resource Management with excess fishing effort, its practical success cannot be achieved in the present situation, and perhaps, continuous education of the resource Recognising the adverse effects of the above users on the deleterious effects of excess fishing activities on the resources over the years, and the effort on resources needs to be undertaken before urgent need to maintain a sustainable resource its application. base and stock conservation, the management strategy advocated for adoption in this zone has been towards the management of resources that Young Fish Conservation : Restrictions on the are over-exploited or have reached the optimum exploitation of juveniles of commercially important level of exploitation. The management measures fishes and shellfishes in the inshore waters, discussed and suggested in this context are : il estuaries and backwaters to conserve the stocks regulation of fishing effort and catch limitation, are in application in the coastal fishery of the mainly of the shrimps, iil restriction of fishing gears country. Licensing of fishing gears such as stake which exploit the juveniles in the inshore waters, nets and Chinese dip nets in the estuarine/back water estuaries and backwaters, iiil mesh size regulation fisheries of Kerala is in force. Similarly, the of fishing gears such as trawl nets, purse-seines operation of gears during high tides is also prohibited. These measures are meant to protect certain life of the net to catch even small fish in more numbers stages of the exploited stocks, mainly the shrimps, which gradually resulted in the reduction oi size of that spend a part of the life cycle in these the fish or in catching greater proportion of small ecosystems. Their implementation, however, has sized fish and shrimps. Over the years, the cod-end not been successful mainly due to the socio mesh size of the shrimp trawl nets was reduced economic constraints. The estuarine fisheries from 25 mm to 8-20 mm and that of purse-seine contribute significantly not only to the sustenance from 10/18 mm to 7/15 mm. Studies carried out of the fisher population living on the banks of these on mesh selectivity in relation to populations of water bodies, but also offers" gainful employment shrimps exploited from the inshore waters of the opportunities. The increasing demand for even tiny country have shown that there is an urgent necessity shrimps and the absence of regulations on the for increasing the cod-end mesh size of shrimp minimum size of species for capture as well as for trawl nets to atleast 30 mm to save the stocks export, have prompted the use of several hundreds from the danger of over-exploitation. However, in of unlicenced gears along with the licenced gears. recommending an appropriate mesh size of the net, Further, the exploitation of smailer individuals of there should be a realistic relationship between the certain culturable species such as Penaeus monodon size of the fish and the performance of the fishing and P.indicus for purpose of seed in certain parts of gear used to catch the fish. Further, in the the lndian Coast is causing concern to the already operation of demersal trawling and purse-seining, existing problem of over-exploitation of shrimps in often large quantities of fish are caught which the nursery ground. In respect of shrimps, there is virtually seal off the net meshes resulting in the one school, however, which believes that retention of undersized fish. For a multispecles exploitation of iuvenile prawns in the estuaries and fishery of the type prevailing in our waters, selection backwaters is the best way of utilisation of the of gear by mesh size would be difficult. From the resource because all the juveniles which enter the investment point of view, a regulation based on estuaries as larvae may not return to the sea even mesh size will not be appreciated by the fishermen in the absence of fishing due to heavy natural as they may have to sacrifice the present nets mortality during post-larval and iuvenile phases. In incurring loss and requiring additional investment any case this unrestricted exploitation has led to for the new nets. Nevertheless, studies carried out the necessity of controlling the fishing to ensure have indicated that it is worthwhile to encourage safeguarding of the resource without sacrificing adoption of more selective gears for stabilised the social and economic benefits. The regulation of harvest of the resource, although the benefits are this practice, therefore, cannot be achieved slow to be realised. Recently, the UK Government immediately, unless an alternate workable policy has insisted that square meshed panels with a cod for rehabilitation of the affected fishermen in gainful end mesh size of 75 mm shall be used for trawl fishery related avocations is incorporated in the nets, as it permits greater escapement of juvenile management strategy recommended for the fish than the normal mesh nets. purpose. Closed seasons and areas : Closed season, as a Mesh regulation and gear selectivity :Mesh size fishery management technique, is well known in regulation for the capture of marine fishes-has been many parts of the world. For example, in UK, one of the traditional methods of conservation and closed season is practised to protect Salmon and management of fisheries resources used in several Coarse fish breeding stocks. Similarly, in some of parts of the world. The use of nets with large mesh the world penaeid shrimp fisheries such as in Gulf size would permit the escapement of juvenile of California, it is used for the protection of spawning fishes enabling them to grow to larger size, mature stock. Besides helping in the protection of breeding and contribute to the maintenance of spawning stocks or juveniles in the nursery grounds, it also biomass. lt is also observed that by allowing the limits the fishery at certain level of the total catch. fish to grow to larger size, the market value of the Closed fishing season for shrimps is observed at catch would be improved and growth overfishing present in India during April-June by the larger averted. As the fishing effort in the marine fishery trawlers operating from Visekhapatnam on the of the country increased, the catch distribution east—coast. As this is a voluntary action, no among the fishing units dwindled, and consequently, problem is encountered at present. Otherwise, the the resource users started reducing the mesh size main constraints of this system would be, when the fishing season changes it would adversely Monsoon Trawling conflicts : ln the complexity of affect the industry as the vessels and the crew may issues causing the conflicts between the traditional have to be laid off for longer period. Consequently, and mechanised fishing sectors, the monsoon the supply of raw material would fluctuate. fishing practised in certain states, particularly in Kerala since the last decade, has become a critical. Conflicts : The system of fisheries management issue 0‘ e°nt_l°Vet$V- opposition to lnenseen throughfishing zone demarcation tTerritorialuse of tlshlng eelnee ttetn ht the nleehentled tlehlng Rights in Fisheries) is a recent thinking in India. As "e$5e|5 5he'ln9 the teeeutees in the tnehete Wete'5 the fishing activities by the traditional and the normally held for the traditionalfishing, (ii) fears of mechanised fishing vessel operators in the inshore Peeslhte edvelse etteete Qt nlenseen ttehlng en the fishing groundsiricreased,competition to maximise leselltt-‘he egetnet the e"eedV deepening “lets of the rent from the fesoufce ensued_ has resource and COnSeQUenflY, the urgent graduauy |ed to Conflicts between the two sectors r‘l88d fOf C0nS6l'V8tiOI‘I Of the reSOUrC6, aCUte for the control of the fishing grounds. Similarly, as oomoetitioo for the harvest of shrimos available in the mechanised .vesse| Opefatofs CQU|d the inshofe Watefs and the widfinirlg 8COr10r'iliC harvest fesoufce more effectively than the‘ imbalt-N109 between the Sectors. the Same time, traditional fishermen, the social and economic ene eeheet betlel/es that the tneneeen ttehlng status between them widened and this irnba|anCe WOU|d bettef Utilisation Of the TGSOUTCQS $UCh caused dissatisfaction among the traditional es Shnlnpe Whleh otherwise lnell net he eveltehte fishermen. This conflict between thetwo sectors, tet exilleltetlen it not henfested When evettehte often becoming violent, necessitated safeguarding dUlln9 the nl0n800l"l D8fi0d- The ditelnlnfl Whethel thefishermen interest of the within Small-scale a ehti management Medium-scale this policyproblem can which be suooesstullv seeks accommodated to place the stock conservation at the top without unduly fishing zone , The management policy which has restricting the utilisation of the resource or risking serious dislocation_of the fishing industry, has been been adopted to tacklethis problema matter of great has concern been for several the Committees _ demarcationdifferent types of fishing of vessels fishing in the inshorezone and for C°mm's$'°ns the operation appomted by ofthe Govemmento_ _ _ - f fishing ground. Accordingly, certain regions of the Kama to 9° into the issue of trawlmg q“'i"9_ the mshofe area based either on distance from the monsoon period. After considerable deliberations shore or on bathymetric disposition, are set apart on the eubtech it was decided to ban bouem exciusivew for the operation of traditional fishing trawling in the territorial waters of the State during units;from theOperation mechanised in thisfishing zone vessels However’ are prohibited the 1988, JUne‘AU9L"15t' wit relaxationin "'t"_°“‘tl" certain this 5,5areas implemented and duration, stnce statedemarcation to state of and fishing often, zone within is round the sameto vary state, "Om as thetcontroversystillpersists tot e confhcts does not seemand ahworktable to ave ea" W0’solution ed in Kerala. This ‘arbitrary nature of fishing zone out‘ demarcation and the pressure of increased fishing effort, technical modernisation and exploitation Rem8r| 5:» _ _-L ._ 4 a sustainable resource base with adequate stock users has given rise to many of the unwanted and conservation measures. in this context, catch destructive features leading» to the failure of limitation and control of fishing effort are the most implementation of the regulations. As observed effelstive ways to manage the fisheries and conserve ‘Experience, when resource sharing becomes an the stocks. But in practice, it is difficult to maintain issue, has shown that unless all parties agree to a the fishing effort at desired level. The new rational system for sharing, sooner or later the technologies (fishing capacity of vessels, engine debate ends up in court. If this happens, expensive size, gear dimensions, improvised gears, methods court cases replace fisheries management, of operation) would effect the catching process expensive lawyers replace fisheries managers and often yielding higher catch and leading to increased fishers, the resource suffers and nobody wins’. In level of fishing effort beyond that which gives MSY. consideration of these, several administrators and Similarly, implementation of catch limitation requires fishery managers now assert that the resource accurate and reliable data both from the biological users organisations must play an active role in observations and commercial fisheries sources. policy making and be made responsible for its Although a very reliable method of sampling the implementation. This strategy would also result in commercial landings, within the overall limitations fewer social, political and conservation-led problems of Governmental set-up, availability of funds and that are to be addressed by the Government. In adefiuate number of trained personnel is in vogue fact, such strategies/tactics have helped to reduce! at the Central Marine Fisheries Research Institute, redress several of the controversies encountered in the sampling system without the involvement of the purse-seine fisheries of Karnataka and the fishing vessel operators gives room for one to mechanised fisheries in certain areas of Tamil doubt the validity of conclusions drawn from these Nadu. data. If the fishing industry furnishes all the relevant data in a prescribed format to the Data Against the background of heavy fishing Centre of the institute at the end of each cruise, pressure in the inshore fisheries of the country, its that will go a long way not only in understanding impact on sustainability of resource and deepening many things which are hitherto not understood conflicts among the resources users, the policy to well but also in the proper management of the be evolved should meet the requirements of fisheries. Further, catch limitation/fishing effort conservation of stocks taking into account the are set for individual species stocks, whereas, the social and economic background and the livelihood gears catch not just one species but several species, of the local communities dependent on fisheries. thereby making it difficult to uniformly apply the Accordingly, the appropriate management system catch-limitation based management system in such that could be considered may multispecies fishery. TAC should be fixed for the multispecies groups taking into account the bio > provide increased role to the local or regional economic considerations. The problems of fishing communities in the formulation of management by mesh regulation and closed seasons regulatory measures and their managerial have already been indicated. ln the context of responsibility; discarding fish by-catch by trawlers appropriate method of collecting the same would play a significant role in the better utilisation of this > ensure positive access in favour of local protein rich resource. fishing communities: Thus, practical implementation of > formulate regulatory measures with a strong management policy in coastal fisheries is a complex conservation policy through careful and‘a difficult task. It is generally observed that the regulation of fishing effort and restrictions Government formulates the regulatory and on gears; and legislative measures to safeguard the resource or for ‘resolving the issue affecting the fisheries and > incorporate a system o_f fishing zones within force the resource users to abide by or adopt these the regional management scheme regulations. However, the resource users try to transmuting-the conflict to c_o-existence or break the regulations to stay in the business. This even symbiosis. poor relationship between the regulations and the o o 0 o 0' .-A ... V~.- 3 -~."'~.r- '-\-. -. - --‘ -'».1 T-="_\u"‘ ~""' T‘; = . »=-=-1‘:' a., 3 YI .7’ _» \'.7:':-:!-t.'L’,.-,»?;¢---1 _-'1 \- . 1-°''- ___.' "-.~~-"\,—3'a *"'~'-,~"¢‘.‘/s. _ -:\ ._~ >=-;§'.i"'-"Es-r'i:"7 t --‘-4. _. g 1>- .1 -". ,--v_,-_:,_. """‘-' -'7. .'- '1 "-" '.“-I»-Y"-‘ . -_\ Vi ' _.-.I~'!'l “I _-- <'-7'"""}' -. 1 - '5I»V -' 2 _,~ V T. ' H -' ~2:- ’1‘- t»l . ‘T'- "' -'7'. ' 7» ~ i'~"- '".‘>." --I...’ _. "- ’. »'. V. _. '"‘ r _( _, F _. _ J.‘ . 5;‘ _ _\._,y ,_._ at ‘,5 ‘__ burs, >, Q. . L‘ ,._\__ ._._.______; y _ .( __l,,- ._, H, .. “V . V IV > . - ..>\ . _-1, >- -g 1,‘. ,-V, -ll; V \ \ :3?-or:-’$$"'fa-1.L"‘1!:-i'~5$=:;i-~==- - '- 5 ~'=- 4 " ’ -__‘~-..- l' r‘e.i_--'1 Q} ~>af..-»»r~.-"siIF§~.>.;-=¢#?’o~i-aha.»--:3.H»-:‘?;E-i‘\!T»7'5-.i,i'(r‘~" ' " -‘V?-ll-"'!'i-("A "V "'1 ~ \»'--‘"2’-' '* " -.'. -.-..;'Li>".(-.1 ‘l ' r ’ »f"' ._“--v.\. ' .( = ".=.=:~e.~_._-'=.-A I V‘ ‘ _ _Jo “ 1-P/is .; K .; . :-2 -r‘.~w.r-" "' ' ' _.~' .¢<».;?l»-".=<-'- Q3‘? * Li." .' - - ‘~ ;-". -.1---1 ' " ' LIST OF RESEARCH PAPERS PUBLISHED BY V. SRIRAMACHANDRA MURTY LIST OF RESEQRCH PAPERS PUBLISHED BY DR.V.SRIRAMACHfiNDRA MURTY 1. MURTY,V.SRIRAMACHANDRA.1967. Notes on hyperostosis in the fish Drepane punctata (Linnaeus).J.mar.bi01.A55.India, 9:323—326. 2. MURTY,V.SRIRAMACHANDRA. 1969. On some interesting and new records of marine fishes from India. J. mar. biol. Ass. India, 10: 126— 132 (1968). 3. MURTY,V.SRIRAMACHANDRA.the laccadives) in the Reference 1969. Catalogue collection of fishes of (excluding the Central from Marine Fisheries Research Institute. Bull. Cent. mar. Fish. Res. Inst., 10:36 pp. 4. MURTY,V.SRIRAMACHANDRA. 1972. On a specimen of Caranx carangus BlochAse. (carangidae, India, Pisces)14:884~885. without a pelvic “ fin. J. mar. biol. 5. MURTY,V.SRIRAMACHANDRA. 1975. Studies on the maturation, spawning, fecundity and sex ratio in Berbus (Puntius) serene (Hamilton— Buchanan) from lake Holleru, Andhra Pradesh. Fish. TechnoZ.. 12: 131-144. 6. MURTY,V.SRIRAMACHANDRA. 1976. Studies on growth checks on the scales of Barbus (Puntiu5) serene (Hamilton~Buchanan) from lake Holleru, Andhra Pradesh with comments on growth checks reported on some hard parts of Indian fishes. Proc. Indian Acad. Sci., 83 B: 85—102. 7. MURTY,V.SRIRAMACHANDRA.relative condition factor 1976. inOn Barbusthe 1ength—weight (Puntius) relationship serene and (Ha1milton—Buchanan) from the lake Holleru, Andhra Pradesh. Hem. 30¢’. F.'c‘.)<'.>l. G(.IT!¢'U)"_. 13 9C'>""1OQ. B. HURTY,V.SRIRAMACHANDRA. 1976. Note on the natural_ pearl in Placenta placenta (Linnaeus). Indian. J. Fish., 23: 243-246. 9. HURTY,V.SRIRANACHANDRA. 1977. Taxonomic studies on the fishes of the family Cyprinidae from lake Kolleru, Andhra Pradesh. Proc. Indian Acad. 3ci., 858: 107~146. 10. MURTY,V.SRIRAMACHANDRA. 1981. Nemipterus mesoprion (Bleeker) (Nemipteridae, Pisces) a new record from the seas around India. Indian J. Fish., 25: 207~213 (1978). 11. MURTY,V.SRIRAMflCHANDRA. 1981. Observations on the biology of black croaker, Atrobucca nibe (Jordon and Thompson) from Hakinada. Indian J. Fish., 27: 66-76 (1980). 12. MURTY,V.SRIRAMRCHANDRA. 1982. Nemipterus Iuteus (Schneider,1801) (Nemipteridae, Pisces) the valid name for a threadfin bream from the Indo—Pacific region. J. mar. biol. Ass. India, 19: 107~1l4 (1977). 2 MURTY,V.SRIRAMACHANDRA. 1982. Observations on some aspects of biology of threadfin bream Nemipterus mesoprion (Bleeker) from Kakinada . Indian J. Fish., 28: 199-207 (1981). MURTY,V.SRIRQMACHfiNDRA. 1982. On ‘the fishes of the family Platycephalidae of the seas around India. J. mar. biol. Ass. India, 17: 679-694 (1975). NURTY,V.SRIRQMQCHQNDRQ. 1983. Observations on some aspects of biology of the silverbelly Leiognathus bindus (Valenciennes) from Kakinada. Indian J. Fish., 30: 61-69. MURTY,V.SRIRAMACHANDRfi. 1983. Estimates of mortality, population size and yield per recruit of Nemipterus Japonicus (Bloch) in the trawling grounds off Kakinada. Indian J. Fisn., 30: 255-260. MURTY,V.SRIRfiMQCHANDRQ. 1984. Observations on the fisheries of threadfin breams (Nemipteridae) and on the biology of Nemipterus Japonicus (Bloch) from Kakinada. Indian J. Fisha 31: 1-18. MURTY,V.SRIRAMACHANDRQ. 1984. Observations on the biology of the croakers Jonnius (Johneiops) dussumieri (Cuvier) and Johnius (Johnius) carutta Bloch from Kakinada. J. mar. bio]. Ass. India, 21: 77-85 (1979). MURTY,V.SRIRQMfiCHANDRA. 1986. The threadfin bream resources. R&D series for Marine Fishery Resource Management. No.8: 4pp, CMFRI, Cochin. MURTY,V.SRIRAMACHANDRA. 1986. Growth and yield per recruit of Kakinada.Johnius (Jonnius) Indian carutta J. BlochFish., in 33: the trawling163-170. grounds ' off MURTY,V.SRIRAMfiCHANDRA. 1986. Studies on the growth and population dynamics of silverbelly Leiognathus bindus (valenciennes) in the trawling grounds off Kakinada. Indian J. Fish., 33: 277-284. MURTY,V.SRIRAMACHfiNDRA. 1987. Further studies on the growth and yield per recruit of Nemipterus japonicus (Bloch) from the trawling grounds off Kakinada. Indian J. Fish., 34: 265-276. MURTY,V.SRIRAMACHANDRA.particular reference to major 1987. demersal Multispecies fish stock species assessment in withthe trawling grounds off Kakinada. J. mar. bio]. Ass. India, 27: 39 48 (1985). MURTY,V.SRIRAMACHANDRQ. 1988. Population characteristics of the silverbelly Leiognathus bindus (Valenciennes) along the west Bengal coast. J. mar. bio]. Ass. India, 28: 41-47 (1986). MURTY,V.SRIRQMfiCHQNDRA. 1989. Mixed Fisheries Assessment with referencethe shrimp to trawlers five important at Kakinada, demersal p69-86 fish in: resources Venema,S.C. landed and by N.P. van Zalinge (eds). Contributions to the tropical fish stock assessment in India. Papers prepared by participants at the FQO/DQNIDQ/ICAR National followup training course in fish stock assessment, Cochin, India, 2 -28 November 1987. Fl: 3 MURTY,V.SRIRQMfiCHANDRA- 1991. Biology and population dynamics of the silverbelly Secutor insidiator (Bloch) from Kakinada. J. mar. bio]. Ass. India, 32: 10-24 (1990). MURTY,V.SRIRAMACHANDRQ. 1991. Observaticns on some aspects of biology and population dynamics of scad, Decapterus russelli (Ruppell) (Carangidae) in the trawling grounds off Kakinada. J. mar. bio]. Ass. India, 33: 396-408. NURTY,V.SRIRAMACHQNDRA. 1994. Contribution of CMFRI to research and development in marine fisheries of Andhra Pradesh. Central Marine Fisheries Research Institute, Cochin, India, 26pp. MURTY,V.SRIRAMACHANDRA,D.C.V.EASTERSON,Q.B.FERNANDD,K.K.APPUKUTTQN and K.M.S.AMEER HQMSQ. 1968. Bibliography of marine fisheries and oceanography of Indian ocean 1962-1967. Bull. cent. mar. Fish. Res. Inst. 1: 208pp. MURTY, V.SRIRAMACHANDRA, D.C.V.EfiSTERSON, fi.B.FERNANDO. 1969. Bibliography of Indian Ocean 1968 (with suppliment for 1962 1967). Bull. cent. mar. Fish. Res. Inst. 5: 146pp. MURTY, V.SRIRAMACHQNDRA, K.A.NARASIMHAM and W.VENUGOPALfiM. 1979. Survey of window — pane oyster (Placenta placenta) resources in the Kakinada bay. Indian J. Fish, 26: 125-132. MURTY, V.SRIRAMQCHANDRA AND N.G.MENON. 1986. The silverbelly resources. R&D series for Marine Fishery Resource Management. No.7: 3pp. CMFRI, Cochin. MURTY,V.SRIRfiMACHQNDRA AND P.RAMALINBAM. 1988. Observations on some aspects of biology of Johnius (Johneiops) vogleri (8leeker) and Pennahia macrophthalmus (Bleeker) in the Kakinada region. J. mar. bio}. Qss. India, 28: 57-62 (1986). MURTY,V.SRIRAMACHANDRA,Marine fish calendar V.Kakinada. M.K.BANDYOPADHYAY Mar. Fish. AND Infor. P.RAMALINGAM. Serv. Tech 1988. & Extn. Ser., 83: 1-17. MURTY,V.SRIRfiMACHfiNDRA, M.KUMARAN AND R.S.LfiLMDHAN. 1989.Resources of ornamental fishes. in: Marine Living Resources of the Union Teritory of Lakshadweep - An indicative survey with suggestions for development. Bull. cent. mar. Fish. Res. Inst., 43: 46-64. MURTY,V.SRIRAMfiCHANDRA, K.V.S.NAIR, P.A-THOMAS, S.LAZARUS, S.K.CHAKRABORTHY, S.6.RAJE, C.GOPAL, P.U.ZACHARIA AND A.K.VELAYUDHQN. 1992. Persent status of exploitation of fish and shellfish resources - Threadfin breams. in: RQD.P.V., V.SRIRQHACHANDRA MURTY AND K.RENGQRAJAN (eds). Monsoon Fisheries of the west Coast if India - Prospects, Problems and Management. Bull. cent. mar. Fish. Res. Inst., 43: 154-168. MURTY,V.SRIRAMQCHANDRA, R.S.LALMOHAN AND G.BOPAKUMAR. 1994. Marine Ornamental Fish Resources of India, Department of Environment and Forests, Government of India, New Delhi. MURTY,V.SRIRAMACHANDRA, T.APPRA RAD, M.SRINATH, E.VIVEKANANDAN, S.K.CHAKRABORTHY, S.G.RAJE AND P.U.ZACHARIA. 1994. Stock Assessment of Threadfin breams (Nemipterus spp) of India. Indian J. Fish., 39: 9—41 (1992). MURTY,V.SRIRAHACHANDRA, M.SRINATH, P.LIVINGSTON, Y.APPANNA SASTRY AND S.5RINIVASA RENGAN. 1994. Stock Assessment of Silverbellies of India with particular reference to Andhra Pradesh and Tamil Nadu. Indian J. Fish., 39: 42-64 (1992). MURTY,V.SRIRAMACHANDRA AND P.RAMALINBAM.(in Press>.Characteristics of exploited stock of Nibea maculata (Schneider)(SciaenidaeJ as revealed by trawl landings at Kakinada. J. mar. bio]. Ass. India, 37: MURTY,V.5RIRAMACHANDRA AND P.VEDAVYASA RAD. (in Press). Marine Fishery Resources of India — present status and management concerns. Sp]. pub. CMFRI, Cochin. RAJAPANDIAN, M.E. AND V.SRIRAMACHANDRA MURTY. 1966. On the occurrence of spotted threadfin Polynemus microstoma Bleeker in the Gulf of Mannar. J. mar. bio]. Ass. India. 8: 365-367. DUTT,S. AND V.SRIRAMACHANDRA MURTT. 1971. On the fishes of the genus Cirrhinus Cuvier (Family Cyprinidae) from lake Kolleru, Andhra Pradesh. Bull. Dept. mar. bio]. Uceanogr. Univ. Cochin, 5: 39-48. KUTHALINGAM,M.D.K., G.LUTHER, P.LIVINGSTON AND V.SRIRAMACHANDRA MURTY. 1973. Further occurrences of the whale shark Rhincodon typus Smith in the Indian Coastal waters. Indian J. Fish., 20: 646~651. DUTT,S. AND V.SRIRAMACHANDRA MURTY. 1976. On the Fish and Fisheries of lake Kolleru, Andhra Pradesh. Mem. Soc. Z001. Guntur, 1: 17-27. DUTT,S.diagnostic AND V.SRIRAMACHANDRAMURTY.characters used in the taxonomic 1976. Remarksstudies onon some the cyprinid fishes with special reference to those of lake Kolleru, Andhra Pradesh. Hem. Soc. Zoo]. Guntur, 1: 70-75. RAO,B.S., K.A.NARASIMHAM AND V.SRIRAMACHANDRA MURTY. 1988. Pwawn culture in salt pans in East Godavari District (Andhra Pradesh). J. mar. bio]. Ass. India, 30: 151-156. KUMARAN,M., P.P.PILLAI, R.S.LALMDHAN, V.SRIRAMACHANDRA MURTY AND B.GDPAKUMAR. 1989. Live-bait resources and development. in: Marine Living Resources of the Union Territory of Lakshadweep — An indicative survey with suggestions for development. Bull. cent. mar. Fish. Res. Inst., 43: 39~45. KUMARAN,M., R.S.LALMOHAN, V.SRIRAMACHANDRA MURTY. 1989. Other Finfish Resources. in: Marine Living Resources of the Union Territory of Lakshadweep ~ An indicative survey with suggestions for development. Bull. cent. mar. Fish. Res. Inst., 43: 65-72. 5 RQD,T.A., R.S.LALMDHAN, S.K.CHAKRABDRTHY, V.SRIRAHACHANDRA MURTY, ofK.V.S.NAIR, sciaenid E.VIVEKANANDAN resources of India. AND Indian S.G.RAJE. J. 1994.Fish., Stock 39: assessment 85-103 (1992). RAU,P.VEDAVYASA AND V.SRIRAHACHANDRA MURTY. 1993. Complexities of Management of inshore fishery resources of India. Fishing Chinnes, 13 (8): 5-9. RADHAKRISHNA, K. AND V.SRIRAHACHANDRA MURTY. 1993. Present trends in marine fisheries management and catch forecasting. Paper presented at the International workshop on Remote Sensing applications to Fisheries, 7~9 December 1993; NRSA, Hyderabad, 2Opp. IAMES,P.S.B.R.Snappers of AND India V.SRIRfiHACHANDRA — their distribution, NURTY. exploitation 1993. Groupers and and biology. Paper presented at the International Workshop on Tropical Groupers and Snappers; Campeche, Mexico; 26-29 October 1993. JAMES,P.S.B.R., K.fi. NARASIMHAM AND V.SRIRAMfiCHANDRQ MURTY. 1994. Technology for improving Marine Fishery Production in: D.L.DEB (ed). Sustaining crop and animal productivity. p2o1~283; Associated Publishing company, New Delhi."-ilI _~‘ I \-- ,1_ _>'_-.‘- > *" _ .'f_\l‘”' . -u I--1' ‘i /I.J r~.14u..\‘r.-1“A? '-I"? : V‘ . .-‘ it. -rt.'~. ‘Qt-. '\'lI~'‘talk .-mm‘; I‘-;-=:'1 ui; ' "ID ‘I’