(C) JULY, ]-994 Wæ^W Nationallibrary Bibliothèque Nationale Ffi \+¿ Lí3 of Canada Du Canada

$(C) JULY, ]-994 Wæ^W Nationallibrary Bibliothèque Nationale Ffi \+¿ Lí3 of Canada Du Canada$

THE ITNTVERSITY OF MANITOBA

A STUDY ON THE ECOLOGY OF KATLE,

NEOLTSSOCHTLUS HEXAGONOLEPIS (McCLELLAND),

IN A NEPALESE RESERVOIR AND RTVER

DEEP B. SVüAR

A THESIS SUBMITTED TO THE FACULTY OF GRÄDUATE STUDTES IN PARTTAL FULFTLMENT OF THE REQUIREMENTS FOR THE DEGREE OF

DOCTOR OF PHTLOSOPHY

DEPARTMENT OF ZOOLOGY WINNÏPEG, }ÍÄNTTOBA CANADA (c) JULY, ]-994 Wæ^W NationalLibrary Bibliothèque nationale ffi \+¿ lí3 of Canada du Canada

Acquisitions and Direction des acquisitions et Bibliographic Services Branch des services bibliographiques

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SE¡EN€85 ET INGÉNIER¡F Çèolçie. . . 0372 S(IINCTS PHYSIOUTS Bioméd]co|e...... 05al Sciences Pu¡es Choleur ei ther o473 Hvd;ol6oiå. ... o38s modvnomioue...... Chìmie . .. .03¿8 0285 Mi',¿¡olåoie or'ì ì Condirìonne"i.* Genê¡ol'rés...... Ocèonosiophie physique ...... 0415 ...... 0¿85 |oqel Biochimie ...... ¿87 {Embo ...... 05¿9 P.lèôhôrõ¡idL,ê O3¿5 . .. Gèñie oèroiooriol ...... 0s38 Poleðko|ooii...... 0¿2ó Chi¡nie ooricole...... 07a9 Chimie 0Á86 P.lÉÒ¡r.ld:è or'l8 oñol¡io¡e Génie civil .:...... 05¿3 Chimie min¿'rolå...... O¿8e Polèozooloäie...... 0985 (hrm Génie élecìronioue et Polynolosie-...... 0427 e nucl-ÀoÍe ... . O/34 Chim;e o¡oonioue ...... 0490 elê(k;a!e . . .054a Chimieohãrmoceurioue. 0491 Génie inJurriel...... 05¡ó s(lt (ts Dt ta saNli It Dt Gènie mèconioue...... 05a8 Phvsiouå... : oÄ9a çenenucleorre...... u5ll rrNvtR0 Ntft$Nr PofvmCres ...... 0¿95 Économie dome!rioue...... 038ó Rodrolron.. .. O/54 . Meconroùe l)5Á/ 5c ences de I envroñnement 0/óa Molhémo1ioues...... 0¿05 ¡ôvôlê Sciences de lo sontê Mèro lurbie . .. .. o7Á3 Générolirés ...... 05óó ' c¿nè,olirés ...... oóos Science ðes rnorériou^ ...... 079a Technioue du oèlrole a765 A¿minislrorion des hìóitôux O7ó9 AcoulioLre...... O98ó . Alimenrôlionelnukilitn . ..0570 le.hnr.re mrnrÞrê (ì551 Ìê.hni;1,ê( (ô.ir^i,êr pt audiolø;e.... . o3oo 0ó0ó orroohvlioue.-..... muni¿iooles...... oss¿ chimiôrÊ'érÒôie o99) Elecrroniqire èr élecrricir€ ...... Oó07 . T€chnoloiie hvd¡oLJlioue.. . osa5 Dênriterie..:...... 05ó7 rru des el Dlosmo...... o/5y Mèconiouê ôåôliiuéê o:]r'¿, Déveloooementhrmoin 073A Méréo¡olobie ...... qéaq Enseioååmenr...... 0350 upnqu€,.,, -...... u/J2 Céorechnoìosii ...... O¿28 l.-,;"|""i. oga? Porlicules {Phy!ique a7e5 1or5rrs...... (J5/5 nucleonel...... 0798 fTê¿h""!"l,i.l Recheiche ooé¡ãtiónnelle...... 079ó Médecine du hovoilel Phvsioue orôñioùe 07 Ág Tenieserris!us (Tech¡olosie) ....079¿ thérôó;e 035¿ Phisiciue de l étår solide oól I Mede¿ile er ¡hnu¡oie 05ó¿ Phísiciue moleculoire ...... oó09 Obsréhioùe er ovñËcôlôôiê 0380 PSY(H0t0GtI Pl,i¡iciuenuclæire.... 0ólo (Jenerolrles |J621 oohrolmhlôore:i...... :...... 038ì Roijioi;on...... 025ó . Pe¡sonnoliré...... 0ó25 Ohhoohonie-...... Oaóo Sloliliques ...... 04ó3 Porhofooie O57l Psvchobiolooie.... o3¿9 Phormocre ...... u5/2 5ciences Appliqués Et Psicholøie-cl;nioue aó?? Pho¡mocolooie ...... 0a19 Psicholdie d! c¿moo¡remenr o3B¿ Phv

IIü A I{EPALESE RESERVOIR AI{D RIVER

DEEP B" SWAR

A Thesis submitted to the Faculty of Graduate Studies of the UniversiÇ of Manitoba in partial fulfillment of the requirements for the degree of

DOCTOR OF PEILOSOPEY

@ 1994

Persrission has been granted åo the LIBRARY OF THE UNIVERSITY OF MAIJITOBA to lend or sell copies of this thesis, to the NATIONAL LIBRARY OF CAI{ADA to micofihn this thesis and to lend or sell copies of the film, and UIJIYERSITY MICROFILMS to publish an abstract of this thesis. Ttre author reseryes other publications rÍghts, and neither the thesis nor extensive extracb fton it may be printed or otherwise repmduced without the autho/s perrrission ÐEDTCATTON

r would like to dedicate this thesis to my late parents, veer Bahadur and Bhagirathi swar, who could not see this end of my academic journey. ÃBSTRÃCT

A study on feeding, âgê, growth and reproductive biology of katle , NeolissochiTus hexagonoTepis, \^¡as conducted in the newly created rndrasarobar Reservoir and in the Tadi River in Nepal during ,-Tanuary, 1988, to December, 1,ggI. The objective hras to assess katle's adaptability from a riverine to a lacustrine environment. Monthly samples of katl-e \^¡ere collect.ed. volumetric gut contenL analysis revealed katle's eurlzphagous nature. Animal matter, plant matter and detritus and soil const.ituted 2l-.9, 68.8 and 9.4% respectively of the gut contents of fish from the river, and 29 .0, 56. 0 and 1-5 . 0z in the reservoir. one annual peak of feeding intensity was observed in both systems, as well as seasonal variation in diet composition. The cont.ribution of plant food increased with the size of the fish. The gut length of katle was allometrically related t.o its total length in both habitats, more strongly in the reservoir population. This appears to be a major adaptation to the reservoir in the f eeding ecology of katl_e. Age determinat.ions showed that one annulus was formed in the bony parts of katle annually. oxytetracycline marking confirmed t.he validity of ages derived from pectoral fin rays. Females at.tained a larger size t.han males. The annual length increment r/vas high f or the f irst four years of lif e and. decl-ined after maturity. Growth dat.a lvere fit.Led t.o the von l- l-

Bertalanffy growth model. The est.imated maximum lengths L_ for females (73 cm for the reservoir and 45 cm. for t.he river) \ivere higher than those for mal-es (41_ and 26 cm) . The K values rnrere higher in males (0.1-95 yr-1 for the river and 0.135 yr-1 for the reservoir) than in females (0.089 and O.LZO yr-t). A positive correlation was observed between the average area of the reservoir during the warm months (April to october) and annual length increments in reservoir katle of specified age. Radío t.elemet.ry studies of female katl-e revealed their upstream pre-spawning migration. euantitat.ive studies on the gonadal maturation cycle reveared that katle are partial spawners of low fecundity. This study has shown t.hat kat.le is a eurlphagous, slow growing, long living and multiply spawning hill stream cyprinid that has adapted well to the lacustrine environment of the Indrasarobar Reservoir. ]-l-r-

åCKNOWLEÐGENfrEMTS

Af t.er several years in t.he Freshwat.er Institute, Department of Fisheries and Oceans (Canada) , t.he Department of Zoology, University of Manitoba, the Fisheries Development Division, Kathmandu, and the School of Biological and Molecular Sciences, Oxford Brookes University, U. K., I have had the opportunity to meet many people who have made my tenure most enjoyable and at times, bearable. I take great pleasure at this time in thanking those people. First. and foremost, I would like to e)

Development Research Cent.re, Canada (fDRC) for providing me with the opportunity of pursuing higher studies in Canada.

I would like to take this opportunity to express my appreciation to Dr. B.F. Dawy and Mr. A. McNaughton of rDRC for their support toward the completion of my degree. The Nepal Electricity Authorit.y, Kulekhani Division, provided housing and valuable data on meLeorology and water fluctuation in the Indrasarobar Reservoir. v f thank the following personnel from the oxford Brookes university, uK: Mrs. Diana cox for providing raboratory assist.ance, Mr . Derek whit.eley f or assisting me in illustrat.ion and Dr. Tomek Brus f or helping me in dat.a analysis. Dr. J. Shrestha and Mrs. A. Tamrakar, Department, of zoorogy, Tribhuvan university, Kathmandu, provided valuable suggestions and literature, and assisted in identifying the aquatic insects, respectively. Dr. M. Nakanishi, centre for Ecological Research, KyoLo University, .Tapan, provided constant encouragement throughout the study period. I am grat.eful to Messrs. M.B. pantha, B.C. Shrestha, A.K. Rai, P.L..loshi, K.R. Bastola, R.M. Mulmi, B. Silwal. H.N. Manandhar, B.R. Pradhan, Gagan B.N. pradhan, Mr. D.M. Singh, T.B. Gurung, Mrs. N. Pradhan and Mrs. S. Rana, Fisheries Development Division, Kathmand.u, for their support. Mrs. Hilary Craig proofread the thesis; Dr. J.A. Mathias, Mr. L. P. Tripathy, Mrs . s. Tripathy and Ms . Martha Janzen provided support for me and my family during our stay in winnipeg. r express my sincere appreciation for their kindness, r also benefited from the computer expertise of Mr. Bhaskar Tripathy in preparing some of the graphs. Mr. R.B. Singh and Mrs. Sushila Singh, my parents-in-1aw, provided great support for pursuing this study in a variety of lvays. Their kind assistance will never be forgotten. vi Last. but not least, I would like to e)tpress my sincere appreciat.ion to my dear wife Bijaya, son Shikhar and daughter Smriti who are the main driving force behind my motivation and enthusiasm. vii

rÃaLE oF CO3üTE$WrS

ABSTRå.CT l_

ACKNOWLEDGEMENTS l- l- l_ TABLE OF CONTENTS vii

LIST OF TABLES xl_

FTGURES LÏST OF xl- l- l_

CHAPTER T: GENERÄL TNTRODUCTTON Katle, Neolissochilus hexagonolepis

Main characteristics B

Dist.ribution t-0

Biology L2

C}ÍAPTER TI: GENERÀL MATERTALS AND METHODS 1,7

Description of the study area 1,1 Indrasarobar Reservoir I1

Tadi River 20

Collection technigues 22 cllAPTER rrr: soME ASPEcrs oF THE FEEDïNG Brol,ocy oF KATLE TN THE TNDR.A,SA,ROBAR RESERVOTR AND THE TADI RIVER. 24

TNTRODUCTTON 24 }4ÀTERIALS AI\TD METHODS z6

RESULTS 3l-

The gut 31

Gut content analysis 33

Seasonal variation in diet composition 3B

Seasonal feeding intensity 41- V]-]- I

Change in food with size of fish 44

Relative length of the gut of katle A'l

DISCUSSION 50

CHAPTER IV: STUDIES ON THE AGE AND GROWTH OF KATLE IN THE TNDRASÀROBAR RESERVOIR AND THE TADT RTVER. 5l

INTRODUCTION 57

MATERIALS AND METHODS 6¿ Ageing methodology

Validat.ion of ageing method 66

Back-calculation of lengths at age 6B

Instantaneous or specific growth rate 69

Fitting of the von Bertalanffy growth model_ 10 Effect. of temperature and drawdown on annual growth '72 Length-weight relationship l3

RESULTS 74

Evaluat.ion of pectoral fin ray ageing met.hod 74

Nature of t.he checks 14

Agreement. between readers 11

Age validat.ion 11 Annual f ormation of transparent zones and checks 11 Marking with t.etracycline t9 Fin ray radius - t otal lengt.h relationship o1 Size composit.ion o f qill net catches and effect. of mes h size B5 Age composition of the reservoir and river populat.ions B9 l-x Growth of katle in the first. three years of life 91

Adult growt.h in katle 96

The reservoir population 96

The river population 96

Dr-tterences between populations 99

fnstantaneous rate of growth 100

The von Bert.alanffy growth curve l_05 Variation in growt.h in different years and its correl-ation with abiotic factors tO7 Effect of temperature variation between years I)j Effect of variation in surface area due to drawdown l-t-0

Lengt.h-weight relationship 1,1,2

DTSCUSSION 1-1.6

CHAPTER ASPECTS OF THE REPRODUCTIVE BIOLOGY OF KATLE TN THE ÏNDRASAROBAR RESERVOIR AND THE TADT RÏVER L25 ÏNTRODUCTION 125

MATERIALS A}JD METHODS 1,29

Radio tagging 130

Observation of spawning movements 1-3 3 Ova diameter measurement L34

Fecundity assessment 1,3 4

Collection of abiotic data ]-37

RESULTS 138

Sex ralio t_3 B Maturity stages t4L Cycle of maturat.ion 14L

Age at first. maturity 1,49

Fish movement 1,52

Visual observations of spawning of katle ]-51

Ova diameter 158

Fecundity 1,64

Seasonal variation in abiotic factors ]-66

DÏSCUSSION ]-69

CHAPTER VT GENERAL SIIM}{ÄRY A¡TD DTSCUSSTON 182 Recommendations 191

REFERENCES 1-9 s

APPENDIX 1 A short discussion on the taxonomy of kat1e. 221-

..t APPENDIX Mean maximum depth of the reservoir 236

APPENDIX 3 Mean monthly discharge of the Tadi River 231 APPENDTX 4 fitting of the von Bert.alanffy growth model 238 APPENDIX 5 Effect of reservoir area on annual growt.h 250 APPENDIX Variability of fin ray age determinations 253 APPENDTX 1 Log a (length vs. weight.) for reservoir fish 254 APPENDTX I Log a (length vs. weight) for river físh 256 APPENDTX 9 Total and somatic weights (reservoir d) 258

APPENDÏX 1-0 : Total and somatic weights (reservoir g) 259 APPENDTX LL : Total and somatic weights (river d) 26L APPENDTX L2 : Total and somatic weight.s (river 9) 263 xl_

r,TST OF råBTJES

Table Classification of gut fullness. 30 Table ¿. Seasonal f eeding int.ensity of katle reflected in the prevalence of different degrees of fullness of guts in the Indrasarobar Reservoir. 42 Table 3 Seasonal feeding intensity of katle reflected in the prevalence of different degrees of fullness of guts in the Tadi River. 42 Table 3 4. Va1ues of the coefficients b and intercepts 1og a for the regressions of the weight of gut contents on the total length for reservoir ma1es. A1 Tab1e 3 5. Values of the coefficients b and intercepts 1og a for t.he regressions of t.he weight of gut contents on the tot.al length for river fish. 43 Table 3 6. Val-ues of regression coefficients b and intercepts log a for length of gut on t.otal body length for kat.l-e from the Indrasarobar Reservoir and Tadi River. 49 Table 4 1,- Summary of completed oxytetracycline marking experiments. 81- Table 4 ¿. Levels of significance of t.he differences between exponent. b values for the relationships between fish length and fin ray radius. B6 Table 4 ïntercept and slope values for the regressions of the total lengths of katle on their fin ray radii. 87 Table 4 Mean total lengths of Indrasarobar Reservoir male katle grouped by age at capture. 92

Table 4 5. Mean total lengths of Indrasarobar Reservoir female katle grouped by age at capLure. 93

Tab]e 4 6. Mean total lengths of Tadi River mal-e katle grouped by age at capture. .94 xii Table 4 7 . Mean t.otal lengths of Tadi River fema1e katle grouped by age at capt.ure. 95 Table 4 B. Intercept and slope values for regressions of instantaneous growth rates on 1og age. ]-04 Table 4 9. Values for von Bertalanffy growth parameters estimated by the graphic method for fitting growth curves for katle from the Indrasarobar Reservoir and Tadi River 106 Table 4 l-0 . Age-specif ic regressions of katl_e,s average annual length increment on logro of the average surface area A of^L the Indrasarobar Reservoir for years

from L982-1-989 l_ 1_ 1_ Table 5 L. Data on transmit.ters and kat.Ie tagged in the Indrasarobar Reservoir, August-September , 1,990. L3Z Table 5 2. The sex ratio of katle in the two habitat.s i_3 9 Table 5 3. Distinctive features of the ovaries of katle at different stages of gonadal maturation L44

Table 5 4. Distinctive features of the testes of kat.le at different stages of gonadal maturation 145 Table 5 5. Summary of t.he movement of kat.le as determined by radio tagging in Indrasarobar Reservoir, 26 August to l_5 September, l-990. ]-54

Table 5 6. Results of analysis of variance on egg: diameters of katle 1- 63

Table 5 7 . Re1ative fecundity and recorded age of some clprinids 1_80 xIl- l_

LTST OF FTGT'RES

Figure l-: 1 . A f emale katle f rom t.he Tadi River. g Figure L:2. Distribution of the kat.le in south Asia indicated by hatched areas. 1_I Figure l- 3. Distribution of the kat.le in Nepa1 indicated by stippling along the river courses. 13 Figure 2 l-. Map of the Indrasarobar Reservoir showing the gi11 net sampling stations (L-7). j-B Figure 2 2. Map of the Tadi River showing the sampling area from A to B. 2I Figure 3 1-. Alimentary canal of a female katle from the Tadi River. 32 l'r_g'ure J 2. Percentage diet. composition of katle in the Indrasarobar Reservoir and the Tadi River. 34 t'r-g'ure J 3. Monthly variation in the percentage value of food items of kat.le in the Indrasarobar Reservoir and Tadi River. 39 Figure 3 4. Monthly averag'e gut contenL weight of a standard (237.6 mm) katle from the Indrasarobar Reservoir and Tadi River. 45 Figure 3 5. Food composition of various sizes of katle in the Indrasarobar Reservoir and the Tadi River. 46 Figure 3 6. Relationship between gut length and tot.a1 length of katle in the reservoir and the river. 48 Figure 4 1-. Cross section of a pectoral fin ray of a katle showing annuli and. the axis of measurement. 65 Figure 4 2. Transverse section of the pectoral fin ray of a reservoir female katle showing eleven annuli. j5 Figure 4 3. Transverse section of the pectoral fin ray of a reservoir female katle showing eight annuli. 76 xl-v

¡'r-giure 4 4. Percentage of katle with a transparent zone at the edge of the pectoral fin ray in each monthly sample, from ,ïanuary to December. 7 g Figure 4 5. Cross-section through an OTC-marked pectoral fin ray of a katle injected in ,-Tu1y, 1-990, and recaptured in October, 1_991-. B0 Figure 4 6. Relationships between the totat lengths of male katle and their pectoral fin ray radii. 83 Figure 4 7 . Relationships between the t.otal lengths of female kat.le and their pectoral fin ray radii. 84 Figure 4 B. Size composition of katle samples caught. by gi1I net panels of 25, 50, 75 and 100 mm mesh size. BB Figure 4 9. Age composit.ion of katle populations by sex and habitat, âs sampled in this study. 90 Figure 4 1-0. Average total- lengths of male katle from the reservoir and the river at age. 97 Figure 4 LL. Average total lengths of femal-e katle from the reservoir and the river at age. 98 Figure 4 1-2. fnstantaneous rate of growth of katle in the reservoir for male and female f ish of various ages. 10 j_ Figure 4 1-3. Inst.antaneous rate of growt.h of katle in . the river for male and female fish of various ag'es. . L02 Figure 4 1,4. Growth curves for male katle from the Indrasarobar Reservoir and Tadi River. l-08 Figure 4 l-5. Growth curves f or female katle from the Indrasarobar Reservoir and Tadi River. l_09 Figure 4 :-.6. Monthly average total weight and somatic weight of the standard male katle from the reservoir and the river. 113 Figure 42L7. Monthry average total weight and somatic weight of the standard female katle from the reservoir and the river. LL4 Figure 5 l-. Number of ma1e, female and juvenile katle in t.he river and the reservoir. t4O Figure 5 2. Diagrammatic drawings of the ovaries at different stages of maturation. L42 Figure 5 3. Diagrammatic drawings of testes at different stages of maturation. !43 Figure 5 4. Monthly change in the reservoir catch frequency (as percent,agTes of the total female cat.ch) of female katle at different stages of mat.urity (f to 7) . ]-47 Figure 5 5. Monthly change in the reservoir catch frequency (as percentages of the total male catch) of male katle at different stages of maturity (f to 7). 1,48 Fígure 5 6. Monthly change in the river catch frequency (as percentagTes of the t.ot.al female catch) of female katle at different stages of maturity (j_ to 7) . j_50 Figure 5 '7 . Monthly change in t.he river cat.ch frequency (as percenLages of the total male catch) of male kat.le at different stages of maturity (j_ to 7). 15j-

Figure 5 B. Map of the Indrasarobar Reservoir showing the locations of tagged fish. j_53 Figure 5 9. Egg size distribution in the ovaries of katle at stages 2 Lo 4 of maturation, combined for river and reservoir fish. i_59 Figure 5 1-0. Egg size distribution in the mature ovaries (stage 5) of the katle: a. Reservoir,. b. River. 1,6L Figure 5:1-l-. variation of mean egg diameter in mature katle from the reservoir and river during ,Ju1y to October. 1_62 Figure 52L2" Relationship between fecundity and fish length in katle in the reservoir and river. t_65 )

Figure 5 l-3. Seasonal variat.ion in surface water temperature (oC) in the Tndrasarobar Reservoir and the Tadi River. L6i Figure 5 L4. Lengt.h of daylight hours in the study area during the year. j-68 Figure 5 l-5. Monthly precipitation (mm) in the Indrasarobar Reservoir area throughout the study period (1998-1990). tjT Figure 5 L6. Monthly precipitation (run) in the Tad.i River area throughout the stud.y period. 111_ l_

CTTAPTER T

GENERÃL TNüTROÐUCTTOST

The impoundment. of a river can cause substantial qualitative and quantitative changes in the limnological conditions of the water body (Lewis, 1-974) . The aquatic environment provided by the semi-static waters of the reservoir differs markedly from t.hat which prevailed before inundation. one immediate consequence is the conversion of a naturall-y lotic environment to a lentic habitat which affects several abiotic factors such as temperaLure, f1ow, substrate, dissolved and suspended substances and the chemical properties of the water. such changes in t.he hydrological eguilibrium have a profound influence on the aguatic environment. Generally, format.ion of a reservoir leads to an increase in the amount of inorganic and organic nutrients in the water derived from the catchment area. These nutrients support the development of abundant populations of phyto- and zoopl-ankton in the new waLer body. The formation of the reservoir also destroys many invert.ebrate species that. are suit.ed to running waLer. This is partially due to siltation, an anoxic bottom and the pronounced drawdown that affects the l_ittoral production. when a river environment is alt.ered through impoundment, certain changes in the structure of the físh population have al-so been observed (Crisp et al-., l_983; Eley 2 et al., l-981_; Motwani and Saigal , 1_9jj; Singit et a1., j_gBB). Those fish requiring moving water, riffle areas or holes with rock and gravel subst.rate will be reduced in number or lost entirely. other fish which prefer bodies of stationary water will increase in numbers. The changes in the composition and abundance of both planktonic and benthic communities also affect the food supply to many species of fish. Besides the food resources and living conditions, the fish community in the reservoir is strongly influenced. by changes in the available spawning habitats and by blockage of upstream or downstream migrations caused by dam st.ructures across the river (Benson, 1980; Cain, L974; Beam, j_983; Gasaway, j_970) . The impact of reservoir construction on fish populations in temperate countries has been well documented and several recommendations have been put forward to mitigate the effect on the fish fauna (Craig and Boda1y, 19BB; paxton et al., 1-9Bl-; Walburg, 1-976, L9'7'l; Lusk, l_991) . However, only limited informat.ion is availab]e on tropical reservoirs (Tansakur et â1. , L992; Sreenivasan , ]-97 6; Hamman, 1980; pet.r , Lg67) . In Nepal, biological invest.igations on reservoirs started only ten years ago.

Nepal (26o20'-30o1_0, N and B0ol-5-gBo19, E) has common frontiers with the Tibetan Àutonomous Region of china in the north and with the Republic of rndia in the west, east and south. rL has an area of 1-47,181 km2 and is divided into three physiographic regions, from south to north: t.he Terai plain, 3 the mid hills and the Himal (Central Bureau of Statistics, 1'992). The Terai lies between l-30 m and 500 m elevation, the lower hills up to 2,700 m, the upper hiIIs up to 4,ooo m and the greater Himalayas are located above the tree line (>4,600 m). Mountains and hills make up B3B of the area of Nepal while the Terai occupies only t7z. The Himalayas in the north st.rongly inf luence the climate of Nepa1. The count.ry may be divided into three climatic zones according to altitude: subtropical in the Terai, temperate in the hiIls and alpine in the mountains. The climate varies little from east to west The geographic and climatic range influences the diversity of the flora and fauna of Nepal. There are many suitable habitats for native f ishes. A total of 1-'12 indigenous and 10 exotic fish species has been recorded from different rivers, 1akes, reservoirs and other water bodies (Edds, L986; Rajbanshi, 1-982; Shrestha, l-981- , 1-990a, Igg2; Terashima,

L984) . Rivers, lakes and reservoirs make up approximately 558 of the total water area; the rest is in the form of flood plains and irrigat.ed rice fields. The rivers represent most of this area. Rivers and sLreams, numbering more than 6,000 and with a total length of about 2l-,000 km, flow generally from north to south (Shrestha, 1983). There are three major river systems in Nepal, each with seven main tributaries: sapta Koshi in the east, sapta Gandaki in the centre and sapt.a Karnali in t.he west. rn addition the Mahakari, the Babai, the Rapti, the Bagrmati, Lhe Kamala and the Mechi rivers are 4 sizeable. These river systems drain into t.he River Ganges . The combined run-off from Nepalese rivers contributes a substantial percentage to the annual flow of the River Ganges.

Lakes are scattered throughout t.he country and have a total area of c. 5,000 ha. These lakes have different origins: g1acial, tectonic and ox-bow (Sharma, ]977) . Lakes located above 4,000 m (in the north) are mostly glacial in origin. These glacial lakes are the source of t.he count.ry, s major rivers. The majority of tectonic lakes occur in the mid hill region. Most of these lakes have been d.rained and used for agricult.ure (Malla and Shrestha, l-983 ) . The ox-bow lakes are locat.ed in the sout.hern flood plain of the country. They are the dead arms of rivers in t.he Terai region and provide suitable habitats for various species of aguatic fauna and f1ora. To produce adequate electricity for its reguirements, Nepal must harness its water resources. rt has a long-term pran to create several multipurpose reservoirs by damming rivers at appropriate points. pradhan (1987) has estimated that. the potent.ial area for reservoir development is c. 152,220 ha. At. present, there are only nine reservoirs in Nepal with a total area of 1,500 ha. These reservoirs have been constructed mainly for hydroelectric porvver and irrigat.ion

(Pradhan, L987) . They include Indrasarobar (226 ha) , (125 .Tagdishpur ha), Trisuli (16 ha) , Marsyangdi (62 ha) , 5

Panauti (50 ha), Gandak (100 ha), Sunkoshi (60 ha) and Andhikhola (90 ha). The rndrasarobar Reservoir \,vas formed in i-ggi- by the construction of a dam (height l_j-4 m) on the Kulekhani River. This reservoir serves as a water st.orage basin for hydroelectric power. The filring of the reservoir started in June, !98]-, but the peak waLer level (100.j_ m) was reached only in November, 1983. since then the annual drawdown has resulted in water Ievel fluctuations between l-7 and 46 m below the peak level. The first documented survey of the fish species composition of the stretch of river no\À/ occupied by the reservoir hias conducted in l-980 (s.9. shrest.ha, personal communication) . rt r,vas reported that the clprinidae \,vas the most abundant family by number of species, represented by Garra Tamta (Gray) , NeoTíssochilus hexagono|epis (McClelland), Puntius chiTinoides (Ham) , Schizothorax richardsonii (Gray), Puntius ticto (Ham) and puntius spp. The famiries cobitidae and channidae were represenLed by Noemacheilus spp. anð. channa gachua (Ham) respectively. The f amily Sisoridae \^ras represented by GTlptosternurn spp. and coragJanis spp. A survey of t.he f ish f auna of the Kulekhani River upstream of t.he reservoir was carried out during r9B4/gs by the rnland Fisheries Project assisted by the rnternational Development Research Centre (IDRC) of Canada. It revealed that the clprinidae v¡as the most abundant family (no figures given) 6 followed in order of import.ance by the sisoridae, cobit.idae and Channaidae (Pradhan, 1-986). A further comprehensive investigation of the f ish populat.ions in t.he rndrasarobar Reservoir r,vas made from ,January, l-985, to .Tune, 1989. Monthly experimental fishing tvas carried out from seven stations distributed throughout the reservoir, using multipanel gri11 neLs. The catch composition showed that. the cyprinidae was the only family which remained in the reservoir. The other families had disappeared. Katle, NeolissochiTus hexagonoTepis, u/as the dominant species in the reservoir throughout the study period. The mean percentage by weight and number of katle in the total catch for the whole period of 1-985 to 1,989 rivas 69.3s% and 49.g% respectively. Karange, Puntius chilinoides, was the second most dominant. species, comprising 22.052 by weight and 44.2eo by number of the total catch throughout the study period.. Asal-a, schizothorax richardsoni, the dominant. species by number in the pre-impounded river, formed a very smal-l part. of gil] neL catches in the reservoir, never more than 2% by weight, and 6% by number throughout the study period (Swar,

L992) . The consLruction of the Kulekhani Dam result.ed in the conversion of 7 km of the river into a lake. This transformed a varied but unstable riverine environment. into a relatively stable lacustrine one although subject to extensive drawdown. A profound change in the relat.ive abundance of many species 7 occurred within a short time of the lake's formation. This included: a. a drastic decline in the number of asala; and b. the disappearance of puntius spp., G. l-amta, Noemacheilus spp., C. gachua, Glptosternum spp. and CoragJanis spp, Katle and karangê, two indigenous species, remained. dominant. rt is reasonable to infer that the katle and karange can adapt from conditions ín a river to those in a l-acustrine habitat. The main objective of this study is to assess the adaptability of the katle by comparing food and feed.ing, age and growth and reproductive biology in the rndrasarobar Reservoir with that in a nearby river, the Tadi River.

KaLle NeoTíssochíLus hexagonolepís (McClelj.and) vaLid, name: fveo-7.issochiTus hexagonoJepis (Mcclelland 1-839), Rainboth (1-985) . tveol.issochirus hexagonolepis, the

Nepalese " kat1i " or " katle', , has had a very conf using nomenclature since it was first named. A short d.iscussion on the taxonomy of katle is given in Append.ix i-. The f ish was originally included under the gienus Barbus by Mcclelland in l-839. IrVeber and de Beaufort (19 j_6) cal1ed this f ish LissochiTus. oshima (191-9) created a new genus AcrossocheiLus. Recentry, Rainboth (1985) renamed the genus NeoLjssochijus. similarly katle ís described under different specj-es names. Mcclelland (1839) was the original author t.o describe this fish as Barbus hexagonoJepis from Assam. Later several authors I described it under different names from different. regions. Day (1878) call-ed it narbus dukai. other authors who referred to this fish as B. dukai \^¡ere Boulanger (189g) and Annandal_e (191-8 f ) rom Burma, and Hora (1923 ) from Siam (Thailand) . Duncker (1904) reported katle as B. soroides from sumat.ra and Penang and the Malay peninsula. The t,axonomy of katle is as follows: Kingdom - Animal, phylum - Chordata, Subphylum vertebrat,a, superclass - Gnathostomata, class - TeleosLomi, Subclass - Actinopterygii, Order - Cypriniformes, Suborder _ clprinoidei, Family - clzprinidae, subfamily - clprinini, Genus - NeoLissochiTus, Species - hexagonoJepis.

Vernacular Names: Katle (Nepali), Bhorkol and Buluk (Bengali), Mirpunia

(Lepcha), Boka or Bokar and Boolooah (Assamese) .

Maín characterÍstícs of, Neoríssoc/níLus hexagonorepís The fish is olive-green on the dorsal side and. silvery- white on the abdomen. The bod.y is elongated and compressed with a deep copper-coloured band above the lat.eral rine. The snout, obtusely rounded, slightly overhangs the jaw (Fig. 1-:1). The mouth is horizontal and subterminal. Eyes are more anterior towards the snouL and laterar in position, The lips are t.hick and cont,inuous around t.he angle of the mouth and the lower jaw has a sharp horny covering. There are four barbels, Figure l-:1. A f emale katle from the Tad.i River.

i_0 a pair each in t.he rostral and maxillary regions. The caudal fin is deeply forked with poínted r-obes. The lateral line is complete with twenty-seven scales, and seven scales run in an oblique line from the base of the ventral fin to the ridge of the back. Males are smaller than females. The length of the head in proportion to that of the body is one to four. on the anterior part. of the body the exposed. surfaces of the scal_es represent. hexagonal outlines. The fin ray counts are D.L2: P.16: V.9: 4.7: C.L0/9.

rn large*sized individuals, scales are blackish grey on the back, the head and the base of the fins, while the fins and the scales on the opercurar plates are tipped with ye11ow. rn young fish the fins are edged with black. This species is simil-ar in appearance to Tor tor (Ham) , mahseer, but can be dist.inguished at once by the interrupt.ed. giroove behind the lower lip and it also differs in the lengt.h of its head. Head.- length is shorter than the height of t.he body in mahseer but. almost equal in katle (Hora , ]-940; Hora and. Misra, 1,941) . shaw and shebbeare (L931 ) have distinguished mahseer and. katle on the basis of coloration. The katle is deep copper-coloured while mahseer is golden.

ÐíEtsråbutíon

Katle is dist.ributed in a broad geographic and environmental rangie (Fig. r:2). rt has been described as a hill stream fish which is distributed in southern Asian 1-1

Figure L:2. Distribution of the katle in south Asia indicated by hatched areas.

1_2 countries such as china, rndia (Tami1 Nadu, Meghalaya, Arunachal- Pradesh, Assam, East Bengal, Darjeeling, Eastern Himalayas), Nepal, pakistan, Burma, Malaysia, Sumatra, Thailand and Vietnam (Day, 1B7B; Herre and Myers, l_931-; Myers, t93L; shaw and shebbeare, L937; Herre, 1,940; Hora and Misra,

1941"; Chacko et a7., 1,954; Misra, L959; ,Jayaram, l-ggl) . Katre is abundant. in most of the big rivers, lakes and reservoirs of Nepal between 250 m and 1,500 m above MSL and in a Lemperature range of 15-30'C (Rajbanshi, 1,992; Shrestha, i-g8l-; Ferro, l-980; Rai and Swar, t9g9) (rig. j_:3) . This fish has been reported from the Koshi drainage mainly from the sunkoshi, rndrawati, Tamor and Arun rivers up to 1-,220 m (shrestha, l-990a) . rt is cornmon in several rivers like the Narayani, Tadi, Trishuli and the Kali Gandaki drainage from an elevation of 50 m, near Nepal's southern border, to 1,440 m in the mid hills (Edds , L986). Katle has also been caught from t.he Bagimati and mid hill region of the Karnali river system (Shrestha, 1-990a)

BÍoJ.o96¡

KaLle, a large scaled clprinid, is well known as an excellent game f ish in t.he mounLain streams of Nepal. The largest fish recorded so far is about 1-1 kg, from Assam, rndia (Shaw and Shebberae, 1937) . Fish of total_ length >600 mm are common in the rocky, clean, hill streams and rivers of Nepal and India (Misra, 1959; Shrestha, 1"992) . ft is a popular fish 1_3

Figure l-:3 . Distribution of t.he kat.le in Nepal indicated by stippling along the river courses. N t

TADI RIVER KATHMANDU

N @ 0 50 100 km E INDRASAROBAR RESERVOIR t4 for angling. This is probably t.he reason katle has attracted the attention of naturalists and anglers like Mcclell_and (l-839), wood (1933) and Langdale smith (r944), who wrore several art.icles on the taxonomy, dist.inguishing characteristics, races and colour variations of kat.l-e. However, the biology of the katle remains poorly underst.ood. Mr. D. E. B. Manning, Divisional Forest officer ín Burma, had 'observed this fish in the hill streams of Burma and supplied the following notes on its habitat to Hora and Misra (1,94L): "The fish normally lie up in the deep still_ pools and only exceptionally will they be taken in rapid water. shoal_s roam round the pools preferring t.hose that are deep, black and rocky. The fish normally avoid the rocky, fast head waters but drop down to the s1ow, deep, rocky pools. They run up to spawn about the end of May to .Tune and stay up till the end of september when they go down on one of the l-ate rises. At these times they are found in the rocky swift head water streams. Throughout the year t.hey appear to be in grand condition and appear to be very fat. in comparison with the rndian mahseers. " The first. aut.hent.ic account of the spawning habits of katle was recorded by Langdale Smith (L944) who observed. the spawning movement, of katle in August in his tea estate ponds in the Darjeeling district of rndia. Few batches of spawners v¡ere observed by him. Katle seems to have a prolonged spawning period from April to October (Hora and Nair, Lg43; Hora and Ahmad, L946, cited in Ahmad, t94B; Ahmad, LïAB; Rai, 1,978; 1_5

Jhingran, L982) . According to Ahmad (l-g4}) , katle can be stripped like trout and, by providing suitable conditions, can be induced to breed in tanks like common carp. sometimes ripe females yielded relatively few ova at a time by stripping although innumerable ova in various st,ages of d.evelopment were found in the ovaries. rt follows that all the ova in an ovary do not. become mature at the same time. Ahmad (L}AB) incubated the fertilized ova of katle and described their embryonic development. The incubation períod lasted from j_03.5 to j-90 hours depending on the water temperature. Dasgupt.a (19BBa) considered the katle to be a prolific breeder though less fecund in comparison to species of mahseer. According t.o him, the fecundity of this fish in the simang River (in Meghalaya, rndia, latitude 25030" N, longitude 9ooltQrr E and altitude 347 m above MSL) varied considerably from individual to individual and ranged from 533 eggs in a specimen measuring tg6 mm total- length and 74.4 g in weíght to 11,659 in a specimen measuring

442 Írm and weighing 1,000 g. The average number of eggs g-1 body weight and the number of eggs cm-1 body length were found to be 1-2.49 and 10.93, respectively. The kat.le is omnivorous, feeding on plants, small- fish, gastropods and insects (wood, l-933,. Ferro and Badagami l_980;

,Jhingran, L9B2; Dasgupta, j-988b) . An initial study u¡as carried out on katle from the Tndrasarobar Reservoir during 1985 to j_996 (Kalkman, 1986). she briefly described their feeding, reprod.uction and growt.h, L6 using scales to est.imat.e age. rn recognit.ion of the need for detailed scientific information on the biology of the katIe, the present investigation \¡¡as carried out under the rnland Fisheries Project of Nepal assisted by ÏDRC. rt is hoped that the findings of this research will provid.e the scientific basis for the management of this fish and so increase production of katle in Nepa1. L]

ElTåPTER

GESTERAr, M}ÀTERTAES &3ED MET}ÍOÐS

Descråptsåon of tshe study area Ind.rasarobar Resewoir

The rndrasarobar Reservoir at Kulekhani was formed by damming Lhe Kulekhani River (Fig. 2:t). The reservoir is situated on the sout.hern slopes of the Mahabharat Range at an altitude of 1,430 m above MSL and about 30 km south of t.he Kathmandu Va11ey. The catchment area of t.he reservoir is about 1'26 kmz. At fu1l water capacity, rndrasarobar Reservoir is approximately 7 km long and 380 m wide and has a maximum depth of 1-05 m and a volume of 85.3 x 106 m3. The surface area of the reservoir at. full pool is about 226 ha. The valley in which the reservoir is located is steep-sided. Rapid changes in depth occur with filling and drawdown. For example, the water drawdown in June , 1986, resulted in a maximum r¡¡ater depth of 78 m, a volume of less than half (39 x 106 m3) and a surface area of only 1-30 ha. The major rivers and streams draining into the reservoir throughout the year are the Kulekhani (Palung) River, the chakhel River, the Thado stream, the chalkhu stream and the chitlang stream. rn addition there is the run-off water from the catchment area during the monsoon period (,Ju1y-September) . t-8

Figure 2zL. Map of the rndrasarobar Reservoir showing the gil1 net sampling stations (L-7) . 0 lkm L-=_-r-J K,ULEKHANI RIVER f BHISINGKHEL KHOLA

CHITLANG KHOLA

l- INLAND FISHEFIES CENTRE ".,1

,/ THADO KHOLA

î ,,I

DAM L9 The reservoir is normally at ful1 capacity in the winter months of November and December (Appendiy- 2) . From December to May the discharge of the Kulekhani River is minimal, about l_.2 m3 s-1. Normally the rainy season begins in ,June and. lasts until october, and the river discharge increases al_most tenfold t.o a peak of 10-11 m3 s-1 in ,Ju1y and August.

The rndrasarobar Reservoir is almost isothermal to a depth of 60 m during the winter months of November to February. rt undergoes progressive stratification during the warm months from March to ,June, when the water level falls.

Although the reservoír continues to \^iarm d.uring ,Jury and. August, its temperature stratification is partially broken down by the enormous volume of water entering during the ,Ju1y to sept.ember rains. rn the short period of stratif icat.ion, the thermocline is found between depths of g-r2 m. Dissol_ved o)fygen concentration in the top 3 m of the reservoir remains >6 mg 1-1 throughout the year except in ,June and ,July, when it is >4 mg l-t. rn contrast, oxygen concentration below 5 m dept.h declines to <3 mg 1-1 from May to october. when the water temperature is >20 oC below 20 m (May to October), the oxygen concentration fa1ls to only 1-*2 mg 1-1. The total bicarbonat.e alkalinity of the reservoir water rises from 62 mg 1-1 in December Lo 75 mg 1-1 inJune, and then drops duríng the rainy season to 36 mg l-t by November. The pH in the top 2 m varies from 7.8 (December to February) to j-0.0 (May to August) . The annual average conductivity of the top 10 m of Lhe reservoir 20 is 87 mhos cm-2 (pradhan and Swar, 1_g}l.).

Tadi Råver

This ríver was se]ected as a study site f or several_ reasons: it is similar in physicar and chemical characteristics to the Kulekhani River before damming, it is a natural habitat for katle and it is accessible by vehicl_es and by foot. However, it is is not in the same catchment. area as the the Indrasarobar Reservoír and therefore comparisons between katle populations in the two systems are confounded by probably different gene pools. The Tadi river, which is glacier-fed, arises from "surya Kunda", Lamtang Himal (Fig, 222). This is a tributary of the Gandak system. The river has an approximate lengt.h of 60 km and a catchment. area of 653 km2. rt originates at about 4,609 m above MSL and joins the Trishuli River at Devighat at 463 m. The river water is clear throughout the year except during the rainy season (,luly to september) . The river has deep pools at j-rregular intervals. The bottom of the river consists mainly of big rocks, boulders, gravel and sand. The averagie slope of the river over the first 20 km from Ghyangfedi to Bokedhunga is about j-:0. L81 . The slope of the river in the rest of its length is about l-: 0 . 0l-4. The Tadi River receives several seasonal and perennial streams. The chake Khola, Khahare Khola and Likhu Khola (Khola = stream) join at Bokedhunga, chaughoda and Dhikure, respectively. From Dhikure, the Tadi runs towards 2L

Figure 2:2. Map of the Tadi River showing the sampling area from A t.o B. KHAHARE KHOLA

LIKHU KTOLA 22

Devighat through shera Beshi, Malakot and Majhitar, T\¡yo more perennial streams named sindure Khola and Bel_kot. Khola join the river between Dhikure and Devighat. Average discharge for B years (1969-1,976) \,vas 43.L6 m3 s-t (Appendix 3). The maximum recorded discharge rvvas 1-,625 m3 s-1 on 18 ,Jury, Lg73, and the minimum discharge \^/as l-.40 m3 s-l on 22 NLay, Lg6g, and 14 and (Department. 15 May, 1,970 of Hydrology and Meteorology, 1_gg2) . The surface water's physical- and. chemical characteristics vary as follows: temperature 1-5.5 oc - 29.1- oc; depLh 39.0 - 63.0 cm; pH 6.8 to 7.2; dissolved oxygen j.O to 8.4 mg I-r; and tot.al alkalinity 1_3.9 CaCo, mg 1-1 xo 29.9 CaCo. mg 1-1.

CoL lect,íon techsríques

The rndrasarobar Reservoir was divided into seven sampling areas (Fig. 2:1,). A multípanel gi1l net of 50 x 5 m with floats on the top and lead-Iines on the botLom, having stretched mesh sizes of 25, 50, 75 and 100 mm, was set once a month at every station to cat.ch fish over a wide range of sizes. Each panel of the 50 m long and 5 m deep net was about. L2.5 m in length. The nets u¡ere usually set in the evening at l-9:00 hours ánd lifted at about 08:00 hour in the morning, but when fish hrere sampled to study their food and feeding habits, nets \À¡ere checked at four hour int.ervals to minimise both regurgitat.ion and digestion of food in t.he fish,s gut. Fish in the Tadi River were sampled at monthly intervals with cast nets, trammel nets, fyke neLs, hook and line and oLher local 23 Lechniques such as paso (loca1ly made loops using horse hair) and fishing traps. Fish were collect.ed from different sites of the Tadi River within the st.retch of about 20 km from Devighat to Gadkhar (Fig. 2:2). Fish samples \^/ere also purchased from local- fishermen along the Tadi River. Bot.h reservoir and river were sampled for three years from January, 1gg8, to December, ]-990. Katle lvere examined externally and. internally to separate males and females by using the method described by Lagler (1-978). Measurements of t.otal length, standard length, girth and weight were recorded. Different bony structures such

as scales, opercula, and pectoral and dorsal fin rays \,vere removed for ageing the fish. rnformation on feeding, reproduction and growth of katle was gathered by using these monthly samples. specific details are given in each of the fo11owíng chapt.ers. 24

CEÃPTER TT

SOME ASPECTS @F TEE FEEDÍ3{G tsTOT,OGY OF KAB'EE T3q' gÃÐT ï3{ÐR.&SÃROBÃR RESERVOIR Ã3üÐ WHE RTVER " r3ürRoDtrcTIoN

Feeding is one of the most important functions of a heterotrophic organism and all other activities stem from the food consumed by the organism (Nikolsky, 1963). Therefore Èhe study of food and feedíng habits forms one of the main investigations in any biotogical study of an animal. Investigations on the food and feeding habits of a particular fish population include detailed observation of its diet, both in quality and quänt,ity, availabílity of the different food items in the environment, and the intensity or rate of feeding. These studies provide valuable information on the seasonal util-isation of natural resources by fish and how these change during their life cyc1e" Data of this kind are helpful to the fishery biologist in the efficient management and optimum production of fish. Despite the use of several species of clprinids in aquaculture and commercial fisheries, investigations on their food and feeding behaviour have not received sufficient aÈtention in the Indian sub-continent" Most of the previous studies are linited to the examination of çfut contents of 25 conmercially important. clrprinids (Khanu L934; Mookerjee et ã7. o lr947; Menon and Chacko, L958; Chakrabarty and Singhu L967; Bhatnagar and Karamchandaní, L97O; Desai u I97O; Jyoti, Lg76; Sunder and BhagaÈ, LgTg; Sharma, LgB6/LgB7) " Some workers have contributed by deternining the relationship betr,¡een the type of food and the sj-ze of the alimentary canal (Das and Moitra, L955, 1956a, 1956b, 1-956c , L963 i Das and Nath, 1965; Das and Pathani, l97B; Das and Srivastava, L979i Nath, Lg82) and the change in food itens witn the size of the fish (Pisolkar and Karamchandani, l-98i-) " The role of certain abiotic factors, such as t,emperature and turbídity, in regulating food intake as well as the nature and composition of the fish diet was described by Nautiyal and Lal (1995) " Feeding habits are also frequently associated with particular body forms and functional morphologies of skull, jaws and aliment,ary tract (Alikuni and Rao, l-951; Barrington, t9S7;

Keast and Webb, L966; Kapoor et ãI., L975; Hyatt, L979) " Comparative studies on food and feeding habits of several species of cyprinids co-existing in Sri Lankan çraters described the relationships between their feeding habits and their morphologicat features (such as the shape and position of the mouth, the nature, number, size and spacing of gi1l rakers and teeth and mean relative length of the gut (RLG, the ratio of gruÈ length to body length) (De Silva et ã1. ,

L977, 1980) " 26 Little is known about, the feeding biology of kat,Ie" Biswas (1985) measured gut, length in relation to the nature of the food items ingested at different life stages of five commercially important, fish including katle" He observed that kat.le were carnivorous at the fry stage but, the juveniles and adults ate plants as well as animals" The alimentary canal of katle is not as coiled as that of true herbivorous fish and consequently the RLG values are lower" Other studies (Jhingran, L982; Ferro and Badagarni, L980; Dasgupta, 19ggb) have indicated the change from a rnainly carnivorous diet (insect.s) during the early fingerling stage to an omnivorous (gastropods, algae and vascular plants) diet in adult katIe" This present study investigates the feeding of katle in the Tadi River and in the Indrasarobar Reservoir and aims at assessing a) if the composition of prey items differs between the reservoir and the river, b) if there are any seasonal differences in prey, and c) if these adaptations in feeding habits affect their Life histories such as growÈh and reproduction"

34åTERTAÏJS AND 3{ETEODS

Fish for the present study were collected from the Indrasarobar Reservoir and the Tadi River during JuIy I LgBg, to December, 1990, and treated as descrÍbed in Ch" If" The mouth position and the structure of the alinentary canal were 27 examined and recorded for each fish. Soon after collect,ion, specimens were dissected and the aliment,ary tracts were removed and unravelled Èo facilitate measuremenÈs of their length (ÄI-Hussaini I L949). Length measurements (cm) and weights (g) of the alimentary canals were taken before they Idere preserved in 5å formaldehyde solution. For the analysis of grut contents, four different methods have been used in previous work: the numerical, volumetric, gravimetric and points methods (reviewed in Hynes, L95Q¡ Pillay, L952; Rounsefell and Everhart, L953; HoIt, L959; Windell and Bowen I L978 and Hyslop, l-98o) . The appropriateness of each method depends on the feeding habits of the fish and the objectives of the study (Beyerle and tr{illiams, 1968; Guma'a, 1978; Crisp et ã7", 1978; Mann and Orr, L969r" Stickney, 1976; Arawomo, L976) " The volumetríc and points methods were selected as best suited to the present study. To determine the cornposition of the gut content and its seasonal variation, the vol,umetric method of analysis Ia¡as employed (McComish, 1966; Karlberg and Benson, L9751 " The contents of the intestinal bulb were enptied into 10 mI of water and stirred. If any large organÍsms &rere present such as insects and fish fry they þJere rernoved from the rest" One mI of the remaining suspension was withdravrn and the food items contained in it r*ere examined under a WiId Stereo M8 binocular microscope" A compound microscope (G921100 Olympusu H.S"C", Japan) Ìdas also used for detailed identification" The 28 organisms found Ín the food rdere ident,ified t,o order, family or generic level-s depending on their condition. Keys used for the identification of different organisms included pennak (l-953), I{ard and I{hippre (19i-g), Mar}a et ar" (Lg7B) 0 swar (L979) swar and Fernando (Lg7g) , and Nakanishi (1986) " Assist.ance with the identification of the phytoprankton and aquatíc insects !ìras given by Dr. M" Nakanishi, Kyoto university, Kyoto, and Mrs. A. Tamrakar, Tribhuvan university, Kathmandu, respectivery. After identification, each group rras sorted out and its vol-ume estimated by allowing it to settle in a graduated measuring vessel (Jude, L}TLî Mccomish, Lg66ì Karlberg and Benson, L975) " centrifugation was also ernployed to separate contents into distinguishabre rayers thereby allowing estimation of the volumes of dífferent groups (Bonneau et a7. , r97z) . The volume of each food itern found in the intestinar bulb h¡as presented as a percentage of the total vorume of the contents" The corresponding percent,age for the total fish population !¡as estimated by averaging the volume percentage of that item over art individual_ fish examined (Hunt and Jones, L972). seasonar variat.ion in the proportions of different items in the gut contents tdere sinitarly measured by using the volumet.ric method. Feeding intensity hras estirnated in two ways. First, the points method (Robotham, Lg77) was employed to estimate seasonal feeding intensity by ctassifying the fulrness of the alirnentary canal (ranging from enpty to fuJ_r) . since katle 29

have no well-defined stomach, the furrness of the whole grut. rdas assessed" The gut of katle r*/as divided into ten equal parts and the number of full sectíons estimated. The grut fullness was given a 'mark out of ten' (Robotham, Lg77) " All_ the points all-ocated to each section of the alimentary canal v¡ere summed and expressed as a percentage of total possible points (l-00) " Guts scored as oeo srere categorÍsed as empty

(Table 3:1) . The feeding intensity of katle was also estimated through an indirect calculation of the monthry average weight of the gut contents of a ¡rst.andardle fish for each of the reservoir and the river" After estimat.ion of the fulrness of the grut of an individual fish, its contents ü/ere removed and the empty gut reweighed. The weight of the gut contents was carcurated from the difference in weight of the gut with and without contents. weights of gut content were protted against weights and total ì-engths of fish for different months. A great variability was apparent among individual fish. The estimation of reqression equations reLating weight, of food agaÍnst weight or total- length of fish from both locations, both on arithmetic and roglo scales, lras attempt,ed but these rdere significant onry in some cases. As it was observed from the initial plots that there were no apparent differences for the same months between different years, data for each system tdere pooJ-ed over al-I years. No difference between sexes could be detected" The relaÈionship between the total length of the 30

Table 3:1. Classificat,ion of gut fullness.

Gut Description Points (å)

Full Gut The gut bulges considerably 76-LOO with food" Intestinal bulb wall transparent" 3 / 4 FUII The gut is almost full 5l--75 t/2 FulI Food occupies about fifty 26-50 percent of the gut volune" Ll4 Full WaIl of the intestinal 01-25 bulb very flabby, some food remains present" Hnpty Gut No visible food in the gut O rrrhen dissected " 3i-

fish (t) and the weight of its gut contents (G) at each of 4 different stages of gut, fullness (L/4 full to full) !ilas estimated by using the least sçFtares method after transformation to fít the data to the equat,ion: G = aÏ,bi hence, log G = log a + b log L where a and b are constant,s. A etstandard fisht¡ trdas now defined for each habitato with a total length equal to the mean of the total lengths of fish in all sampÌes from that habitat. To estimate the monthly mean weights of the gut contents of this standard fish, the percentage of the fish in each habitat at, each of the four states of fullness bras calculated" For each of the four states, the weight of the gut contents corresponding to the length of the standard fish was calculated from the regression equation established for that stat.e. These weÍghts \dere then averaged using the ¡nonthly percentage of fish at that state of ful-l-ness as a weighting factor (Craig, 1978) "

RESULTS

The gut, The oesophag'us is the most anterior part of the aJ-imentary canal" ft is narrow, tubular, short and rather muscular" On entering the body cavity, the oesophagus expands into a thick-walted intestinal bulb (Fig. 3:i-)" posteríor1y the intestinal butb curves t,o the left and passes into a 32

Figure 3:l-. Alimentary canal of a female katle (total length 365 nn) from the Tadi River. Oesophagus

lntestinal bulb

lntestine

Rectum

Anus 33 coíled intest.ine which overlies the intestinal bulb ventratly. The waII of the coired portion of the íntestine is quit,e thin and of an armost uniform diameter. The íntestine widens slightly at the posterior end to form the thin-walled rectum whÍch opens ventrally at the anus.

Gut, eontent, analysis Quaritative analysis of the gut contents of katre from the Tadi River and the rndrasarobar Reservoir caught during L989 and 1-990 revealed that this fish consumes many food items and is omnivorous. The total animal food, plant food and detritus and soil were calculated to be 21.g, 69.g and 9.42 respectively of the totar volume of the gut contents of alr the examined fish from the Tadi River and 29.0, 56.0 and 15.0g respectively in the rndrasarobar Reservoir katle (Fig. 322). The food eaten by katre can be divided into six broad groups: phytoplankton, vascular plants, zooprankton, benthic animals, detritus and sand and soil:

1. Phyt,oprankton: This group formed 39.la and 29"33 in the gut content of katle from the river and the reservoir, respective]-y " rt \^/as represented by chrorophyceae, Bacill-ariophyceae, Cyanophyceae and Euglenophyceae. a. chlorophyceae: The genera included were chramydomonas, zygenema sp., crosterium, oedogoníum, Idicrospora, HydrodÍctyon, cosmarium, pedíastrum" Eremospheran scenedesmus 34

Figure 322" Percentage diet composition of katle in the Indrasarobar Reservoir and the Tadi River" A. Reservoir

15% Detritus & Soil

560/o Plant 29% Animal matter matter

B. River

9% Detritus & Soil

22o/o Animal matter

69% Plant matter 35 and Spjrogyra of ç¡hich ChTamydomonas, Spirogyra and CosmarÍum were the mosL cornmon in Èhe gut content of the river fish. Oedogonium and Closterium were more freguent in the diet of the reservoir fish" b. BaeilXriophyeeae: Twelve genera rdere identifíed in the dietz Amphorao Cynhe77a" Pínnularíu Pleurosígfrão Cocconeis" Cocconemao FragiTaria, Navicula, Synendra, I{eLosira, and TabeTTaría" Among them Fragí7aria, Navicula, Synendra, I{eLosira, Cymbe7La, Peridiníum and Tebellaría were most conmon in the gut contents of the reservoir fish" The presence of the diatoms was not so frequent ín the diet of the river fish" c. Euglenophyceae: This group was represented by TracheTomonas and -E'uglena and was observed only in the grut of freshly killed fish" d. Gyanophyceae: From this group Oscí7Latoria, Anabaena and U-Z.othrix h¡ere eaten"

2" Vascular planÈs: These were also important food iterns forming 32"72 and 26"48 of the giut content of katle from the river and reservoir respectively. They could be divided into a. Maerovegetati.on: This was usually found in a masticated and semi-digested condition. It formed one of the main items of the gut contents, and was encountered more frequenÈly in the river samples than those from the reservoir.

b. GrêEs: Occurrence and bulk of this iten rdas particularly high during JuIy to September, when the marginal 36

growth of grass was submerged and uprooted grass &¡as erashed down in the reservoir and the river during morÌsoon floods" c" Bwågrs: These were the small shoots of macro-veget,ation ingested by the fÍsh" d. ÞLant, seeds: This item comprised small seeds of aquatic p1ant.s" Its contribution was insignificant in the diet of katle from both systems.

3" Zoopl.ankton: This made up 7"8å and J-7"32 of the gut content of fish from the river and the reservoir respectively" ft was represented by Rotifera, Cladocera and Copepoda. Keratei-:,,ao

Polyarthrao Asplanchana and Bracchíonus rúere more conmon among the rotifers" The cladocerans were represented by Daphnia" Bosmína" Diaphanosoma, I{oína and -LepËodora" The copepods k¡ere represented by adults and copepodids of Cyclopoida and Calanoida" Chaoborus larvae were also very conmon in the gut contents" Zooplankton was observed only in the freshly killed f ish"

4" Benthos: Benthic animals formed l-3"98 and 11"58 of the gut content of katle from the river and the reservoir" This group was represent.ed by aquatic insects, oligochaetes, Hirudinea, MoLlusca and water mites. a " Aquat,5.e insect,s: This group was represented by Coleoptera, Odonata, Ephemeroptera, PlecopÈera, Trichoptera, Hemiptera, DipÈera and Chjronomous. 37 b. 01åEoehaeÈes: Among the oligochaetes, Branchiura, LímnodríLuso BranchíodriTuso Procladiusu poTypediTumo Tubificidae, Naidídaeo Lumbriculídae and Enchytraeidae were

colnmon " c" Kírudinea s¡as represented by Erpobdellidae d" MoLLusea: Gastropods were present, from the molluscs, and e. Wat,er mít,es hrere represented by Hydracarina. Among the benthic fauna, Odonata, Trichoptera, Plecoptera, Hemiptera and Chironomidae occurred more frequently and in higher percentages in the diet of the river katle" Tubificidae, Branchiura, LímnodriTus, Naidídae, Polypedium and Procladíus $¡ere observed rnainly in the gut contents of the reservoir populat.ion; i"e., annelids were more abundant in the reservoir and aquatic insects in the river.

5" Detrítus and Debris (decayed organic matt,er): This nainly consisted of unidentifiable plant matt.er in a digested state" It occurred regularly in the guts of katle from the river and the reservoir throughout the year, and on an average constituted 6"9* and 13"5å by volume of the gut content,s in Èhe two habitats respectively"

6" SoíL and Eand: This ítem occurred in the guts of the river katle throughout the year except in the March samples. On average, it formed 1.8å by volume. The largest, quantity was 38 encountered in May. In the reservoir samples ít, &Ías not encountered so frequent,ly and the gut conÈent,s of the fish during January, March, May, JuIy and October did not have any mud or sand in them. It was found during the rest of the months and formed < 2Z of the gut contents by volume" Besides the items listed aboveo nematodes v¿ere found in the intestinal bulb of katle from the river and the reservoir occasionally. These nematodes &¡ere not considered in the measurement of the volume of the gut contents of katle"

Seasonal variat,i-on in díet eomBosít,íon The percentages of dif ferent it,ems in the gut contents of katle in different months are shown in Figrure 3:3. It can be seen that there were considerable variations in the percentage of different items among the different months of the year and between the river and the reservoir. The phytoplankton group forned a rnajor source of food for katle in both the river and reservoir populations throughout the year" It constituted the highesÈ percentage (86.42) by volume of the gut contents of the riverine population in January and the lowest percentage (8.9å) in Ju1y. In the reservoir fish, the highest percentage (4O"92) of phytoplankton occurred in February and the lowest percentage (L2"52) in October. The vascular vegetable matter seemed to be another major food source of katle in both systems" The quantity of vascular 39

Figrure 3:3" Monthly variation in the percentage value of food items of katle in the fndrasarobar Reservoir (Â) and the Tadi River (B) " E so;t & sand

il[ Detritus

¡ Benthic fauna

ø Zooplânklon

E Vascular planl

øl Phloptankton

ffi 50il ö sano il üü Der¡tus tr Benlhic fauna

gl Zooplankton

planl = vâscular El Phfoplanklon 40 plants also varied from month t,o month" rn the gut cont,ents of the river fish, vascular prant.s formed the highest percentage (74"52) in sept.enber and the lowest guant,ity (så) in December. In the reservoir fish, the highest, quantíty (62.SZ) was observed in Jury and the lo¡*est (6"8?) rdas recorded in March" In the river fish, the maximum amount of zooplankton was observed in February when it constituted about z9z of the total vorurne of their grut content, whereas zooplankton was absent in the sampres collected during March and June. rn the reservoir population, zooplankton rdere encountered throughout the year" The maxirnurn (292) occurred in September and the minimum (12.82) was encountered in August. The benthic fauna formed significant percentages of the totar diet of katle in the reservoir and the river with varying amounts in different months" å,nother important food item was detritus" The highest percentages were observed in fish from the reservoir during March, April and May (42"7, 29 "7 and 262 respectively) , whereas detritus formed a rower percentage in the river katlers diet. except in.August (22.322) " soil and sand occurred in the gut of river fish in all months except March, but it constituted a very smal1 percentage (< 22) of the total grut content. perhaps it was taken up by accident" 4t Seasonal feeéång ånt,ensåÈy Seasonal feedÍnE intensity was est,imated first by classificat,ion of the fullness of the alimentary canal (Tables 322 and 3:3) " In a considerable percent.age of the f ish examined from both systerns during the study perÍodo the gut was either enpty or contained little food (< L/Z futl) " The percentage of fish with enpty guts during springu sunmer, auLumn and r+inter was 35 "7 Z , 3OZ , L5 " 42 and 42 .32 , respectively for the Tadi River, and 332,2O2, Lgå and 362, respectively for the reservoir. Fish with a full gut r{ere observed during spring, sunmer and autu¡nn in the river system and during surmer and autumn in the reservoir" The feeding intensity of katle rdas also estimated (as descríbed in Materials and Methods) through the indirect calculation of the monthly average weight of the gut contents of a ¡¡standard¡t fish for each of the reservoi-r and the river (no difference could be detected between sexes). Values for fitting the regression equations between the logs of gut contents and tot.al length are shown in Table 3:4 and 3:5" AIl regression coefficients for the pooled data krere highly significant (P < 0"001). The total length of the standard fish for the reservoir was calculated as 237 "6 nm. From the regression equations, the estimated weight of the gut contents (with 958 confidence intervals) for this standard fish was 0.5 + 0.85, 2.48 + 0.33 r 6.59 t 0.18 and !3.29 ! O.Z3 g with the g\t l/4 fulÌ, L/2 full, 3/4 full and full, respectively. The 42

Tabl-e 322. Seasonal feeding intensity of katle reflected in the prevalence of different degrees of fullness of guts in the Indrasarobar neservóir.

Season Nunber Empty Ll4 Ll2 3/4 Full of gut fulL full fuI1 grut fish z E * I z

Spring 88 33 "7 35. O 25"O 7.O Summer 9L 20"0 25"O 20 "o 13.0 22 "O Autumn L03 18. 0 23 "O 28"O 9"0 22"6 Winter 84 36"0 40"0 22"O 2"O 0"0

Table 3:3" Seasonal feeding intensity of katle reflected in the prevalence of different degrees of fullness of guts in the Tadi River"

Season Number Empty r/4 tl2 3/4 FuIl of gut fuÌ1 fulI fu11 gut fish z z z z z

Spring 83 35 "7 42.5 L2 "7 4"6 4"5 Summer 86 30"0 27 "O 23"O 10"0 l_0"0 Autumn 86 15"4 27 "O 27 "O 8.6 22"O Winter 77 42 "3 35 " 3 2L"4 0"o 1"O 43

Table 3:4. Values of the coefficients b and intercepts log a for the regressions of the weight of gut contents (Gu in g) on the total tength (in mn) for fish with I/4 fuIl o L/2 fuII o 3/4 full and full gut. Also given are the number of degrees of freedom (d.f.), the S"E. for G estimates from the regression, and the estimated G (with 95 Z confidence linits) for the standard reservoir katle ot 237.6 m:n length.

Statistic Ll4 Ll2 3/4 Full fuI1 full- full gut b 2 "786 3 "L37 3,253 3.2L3 log a -7 "07 -7 " 060 -6 " 910 -6 " 510 d"f. 66 76 26 L2 S " E. of G"". o"436 o. 166 0. 088 o. 105 Gest (standard) 0.534 2 "479 6"586 L3 "292 + +0 +0. 952 CL " 854 10 " 32s 180 +o.228

Table 3:5" Val-ues of the coefficients b and intercepts log a for the regressions of the weight of gut contents (G, in g) on the total length (in nn) for fish with LlA full , L/2 fuIl , 3/4 full and fulI grut. Also given are the number of degrees of freedom (d"f"), the S"E. for G estirnates from the regression, and the estimated G (with 95 Z confidence linits) for the standard river katle of 163"9 mm length"

Statistic L/4 Ll2 3/4 FuI1 fu11 fu11 fu11 gut b 2.98 2 "96 2 "992 L "994 1og a -7 "37 -6"63 -6.31 -3"88 d" f. 49 67 10 10 S"E" of G"". 0.34 0"16 o"07 o. 15 Gest (standard) 0. 169 o "932 2"070 3"434 +0. +0 t 952 CL 683 " 320 t0 " L56 +0"367 44 total length of the st,andard river f ish was 163.9 mm, and the estimaÈed weight of its gut contents r*as O.l-7 + 0"69, 0.93 + O"32t 2.O7 + 0.16 and 3 "43 ! O"37 g with the gut J_/4 fulI o LlZ full, 3/4 fu}l and full, respectively" Monthly average weights of the gut. contents of the st.andard katle from the reservoir and river were then calculated from these values, usingr the monthly percentage of fish at each state of fullness as a weighting factor" It was clear that there is one annual peak in both systems" The weight of the gut content was highest in August and remained higher until November in the reservoir (Fig" 3z4), but in the river the peak was observed in September" The average weight of gut contents was relatively low during winter and spring"

Changes ín food with Eíze of f,ísh Analysis of the food data for the entire year fron both systems indicated that both qualitaÈive and quantitative differences existed among the various length groups (Fig" 3:5)" In the river, phytoplankt,on was dominant in the gut content of fish from 45 to 145 rtm, vascular plant tissue dominated in fish fron L46 to 2g5 ¡nm, and detritus was dominant in the gut of katle longer than 296 mm. In reservoir fish, phytoplankton was present in all groups but its contribution &ras very low in físh above 396 nm in length. vascurar plant tissue was dominant ín the fish longer than 246 lnm" Among the benthic aniurals, annelids were dominant. in the 45

Figure 324. Monthly average gut content weight (g) (with t 95 I CL) of a standard (237.6 mm) katle from the Indrasarobar Reservoir (a) and Tadi River (b) " 1

I T ritl I tr+l:l

I I

llta EIrl

T ïi I TiillT'

Ju Ëb M3r Atr May Ju! Jul Aug Sg-DL Ocr Nov D€

t_I ;l tlt- åtttl ltJlEl ilii

lll I

Ja¡ Èb M.d AFr À4¡y Ju¡ Jut Aug Scpr Oc" Næ Dæ 46

Figure 3:5. Food composition of various sizes of katle in the Indrasarobar Reservoir (å) and the Tadi River (B) " 100 G80 ã60 I ;40 3zoo 0 96-1 45 14G'195 246-295 395< Fish length group (mm)

@phytoplankton @l Zooplankton ¡Benth¡cfauna lllflDetr¡tus iffiSoil &sand =Vascutarptant

96-1 45 246-295

&l Phytoptankton vascular plant W zooplankton n Benthic fauna ffi Detritus @ Soil & sand = 47 reservoir fish while aquatic insects were quite common in the guts of ríver fish" No zooplankton rdas present in the fish longer than 396 mm. It seemed that the contribut,ion of plant food increased with the size of the fish" In the reservoir, animal food constituted the najor percentage (53.83) of the tot.al gut content of fish of length 95 t,o L45 hñ, while it formed only 6.62 I of the gut content of large fish of 346 m¡r to 395 mm. Sirnilarly in the river system, animal food formed 32"72 of the total gut content in smaller fish (45 95 mrn), but only 13 " 333 in the gut of larger fish (296 345 mrn) .

Relative S.ength of the gut, of kat,le The relationship between the gut length and the total body length was found to be allometric" The values for fitting the regression equations are given in Table 3:6 and the best fits for the relationship between logro gut length and loglo total length of the river and the reservoir katle are shown in Figure 3:6. Both the regression coefficients rdere highly significant (P < 0.001) " Student t tests carried out t,o test differences in b values indicated a significantly higher value (P < 0"05) for the reservoir population than for that of the river" 48

Figure 3:6. Relationship between gut rength and total length of katl-e. (-a- and solid 1ine = reservoir fish; and -ø- stippled 1ine = rÍver fish) " E ct

6t Ctt .a o L'L J

1.2 1.4 1.6 1.8 2 2.2 2.4 z.o 2.8 Log total length of fish (mm) 49

Table 3:6. Values of regression coefficients b and intercepts log a for length of gut (nn) on total body tength (run) for kat,Ie from the fndrasarobar Reservoir and Tadi River"

Statistic Reservoir RiVei b l-.465 1,.267 a Iog -0 " 810 -o " 453 d"f" L95 2L2 S"E" for logro (gut length) 0"099 0"099 F value 872 "2 L564 "2 12 0 " 81_7 0.881 50

Ðr6eusgrCI3ð

Nikolsky (1963) recognísed three main categories of food on the basis of their importance ín the díets of fish" They are (a) basic food, which is normally eaten by fish and includes most of the gut contenÈs, (b) secondary food, r¡hich is frequently found in the grut, but in snaller amounts and (c) incidental food, which is found rarely in the gut" In accordance with the definition given by Nikolsky (L963) , algae and vegetable matter, which formed 68.8 and 55 "6 Z of the gut contents in the river and the reservoir fish, can be considered as basic food" Benthie fauna, Rotifera, Crustacea and other animal matter together constituting 2L.82 and 29"0å in the river and the reservoir fish, was the secondary food"

Soil and sand particles which formed 2"L4 and O "472 of the gut contents in the river and the reservoir fish was an incidental item and has no food value at, all" On the basis of feeding habits, fish are broadly classified as herbivores, omnivores and carnivores. The various degrees of specialisation in food habits allow their further categorisation as monophagous (consuming just one kind of food), stenophagous (a linited range of foods), and euryphagous (nixed diet) (Nikolsky, 1963; tdeatherl.ey and Gill, 1987). fÈ is evident that the relat,ive gut length value, RLG, has a close relationship with the nature of the food of the fishî e.9", vegetable matter reguires more tine for digestion" 5l- This ís why herbivorous fish like Labeo rohita and Labeo goníus (Das and Moit,ra, L956 a, b, c, l-963) have hÍgh RLG values (about 12"O and 9.5) respect.ívely. In omnivorous fish, the RLc values are lo*¡er (Das and Îitrath, 1965; Síngh j L966, 1967) " Weatherley and GilI (1987) compared relaÈive gut lengths of several species and described the grut. length as a major adaptive specialisation in the feeding ecology of fish. The relative gut. length of katle falls in between those of omnivores and herbivores" It is also evident from this study that katle consumes a variety of food items and can therefore be classified as an omnivorous and euryphagous fish" According to Biswas (1985), katle is carnivorous in the fry stage, but juveniles and the maturing adults subsist on both plant and animal matt,er. The results of the present study support this observation" This is probably why the increase in RLG value from fry to juvenile stages is not so sharp in katle as in Labeo and Cirrhina spp" Jhingran (1-975) and Dasgupta (1988b) described katl-e as a voracious feeder as indicated by the high values of its gastrosomatic indices (GSI) in the Indian waters. However, the present study revealed that a considerable percentage of the examined fish from both the rÍver and the reservoir had enpty or almost empty guts" The diet composition of katle in the present study agreed with the results of previous workers (Jhingran, L975; Dasgupta, 1988b) except that the fish bones and scales encountered by Ferro and Badagarni (l_980) in fish 52 from the lakes of PokTrara Valleyu Nepal, were noL observed" Beyond these report,s, there is litt1e ¡rrevious information in the l-iterature on the feeding biology of kat,Ie, The food consumption of çrild fish is affected by a J-arge number of factors inctuding the size of the fish, water temperature, activity of the fish, and availability of food organisms (EIIiots, L975; Lagardere, L987) " Water temperature affects food consumption of fish by inftuencing the metabotic rate of the fish and the primary production of the ecosystem (Angerneier, 1982) " Surface water temperature in the Tadi River and the Indrasarobar Reservoir followed a seasonal pattern with the lowest values recorded during winter (December - February) and the highest values in summer (June - August; Figure 5:L3) " The pattern of gut fullness and average weight of gut content recorded in this study suggest that the intensity of feeding also followed a seasonal pattern, being relativeÌy intense in sunmer and autumn and low during winter and spring. The temperature variation through the period may have affected the feeding intensity of katle in the reservoir and river" Any seasonal changes in the conposition of the gut content.s probably reflect the abundance and availability of each item. Besides temperature, dissolved oxygen, pH and alkalinity also fluctuated throughout the year but none of these factors appeared to be limiting (Singh and Virdi, L983; Soemarwoto et a7", 1990). The raínfalt was highest during the sunmer months: about 7oz of the annual rainfal-r during the 53 study period occurred (Figs then 5:15 and 5:L6) " rn both systems plant matt,er formed the highest percentage of the totar volume of the gut, contents, followed by animar rnatter and then by detritus and soir. rt is evident from the study that, the relative contribution of ptant food increased with the size of the fish in both popuraÈions. Accompanying this switch to plant matter, ârr increase in the length of the gut relative to body length was observed. This increase is refrected in the fact that the b varues in the logarithmic rerationships between the gut length and the total length of fish hrere greater than j- for both habitats (Tabre 3:6); further, the b varue rc/as greater in the reservoir, where plant food constituted a higher percentage of the diet, than in the river"

Besides these general similarities, some differences $rere observed in the food and feeding trabits between river and reservoir katle" Detailed analysis of plant food revealed that the gut contents of river katle bras domínated by crushed vascular tissue and filamentous argae; these items are attributed to the submerged rooted vegetation found in the marginal shallow portions of the river r*here the filamentous algae also remains attached to the rocks. Reservoir katle were found to be ingesting more planktonic blue-green algae and diatoms and occasj-onaIly terrestrial grass during the period of high water l-evel. These food items are attributed to the nutrient enrichment in the reservoir from the agricultural 54 lands ín the watershed area of the reservoir and availability of grass when the water covers the marginal land during the high water levels of the sunmer season. The differences rdere also evj-dent in the variety of animal food. rn the reservoir, the percentage of zooprankton in the diet, r*as quite high, and the benthic animal,s were represented mainry by annelids. rn the river, zooplankton rdere sparse in the diet,, and most, of the benthic fauna v/ere nymphs of aquatic insects. The dominance of zooptankton in the reservoir diet is probabry due to the abundance of linnetic zooprankton in the water corumn, which is not so common in the ríver system. simirarly the fornation of the reservoir from a fast flowíng river has destroyed the habitat of aquatic insects, and their community has been replaced by different species in the reservoir (Yadav, t-999) " The percentage of detritus in the gut content of reservoir katle was higher, whereas it made up only a smalr percentage of the total- voLume of the gut content of the river katre. rn addition to the difference in food composition, there is an apparent difference in feeding Íntensity between the two populations. The reservoir population attains its peak consumption in July and maintains quíte a high level untir November. July is the spawning period of katte (see chapter v). The occurrence of higher feeding íntensity during the post-spawning period was also recorded by sharma (],9g6/87), Malhotra (L967), Jyoti and Malhotra (Lg7s) and Jyoti (Lg76) for Tor" The river katle attain their peak intake only in 55 september" This delay can probably be attributed to high turbidity due to monsoon rain during June and Jury. The j-nfluence negative of turbidity has also been recorded in Tor putitora by NautÍya1 (19BSa) and Lal " The average weight of gut contenÈs (in ¡lercenÈage of the body weight) for different rength groups in the reservoir is higher than in the river. perhaps this is due to the higher avairability of food and relatively stabte condit.íons during the summer season in the reservoir. sirnirarry, as noted above, the increment in gut length r¡ith length of the fÍsh is also greater in the reservoir. since the percentage of animal- food in the gut content of katre from the reservoir is ress than the percentage of the animal food found in the gut content of fish from the river, it is probable that this increased gut length is related to a switch to rnainry plant matter. prant matter is generarry higher in fibre and rower in energy. Therefore, a larger 9ut, perrnitt.ing digestion of a larger quantÍty of food over a ronger tine period, is required in a herbivore to achieve the same rate of energy intake as a carnÍvore. Katle's ability to increase its rerative gut length may thus be a major adaptive specialisation in its feeding ecology under reservoir conditions.

Three attempts were made to assess the effect of drawdown in the reservoir on the feeding behaviour and growth of katle. unfortunatery the experiment could not be cornpreted due to the high mort.al-ity of fish within a week of the experiments being 56 st.arted " After careful examination of the gut cont,ent.s of katle from the river and reservoir and comparison of these data with those from previous work, it seems reasonable to suggest that the basic feeding behaviour of katle in both systems is sÍrnilar" Apparent differences can be eNplained by the dif ferent environmentar condit,ions in their respect,ive habitats; consequently, reduced density of food may generarry Lead to lower fecundity and sl-ower growth of katre in Neparese waters" These possibilities are explored in chs. rv and v. 57

CKÃPEER TV

STUDTES O38 trHE ÃGE A3{'D GR,OWT& OF KåTTJE TW BEE

g}gÞRågÃAOBÃ&, R,ESERVOTR, å3üD THE TÃÞT RTVER"

TNTRODTICFTO¡g

Age and growth data are needed for efficient físh stock assessment and fisheries management" The evaluation of age provides a means for understandíng the conposition of fish populations with regard to year classes and for finding the role of part.icular year classes in the fluctuations of the stock. The study of the growth rate of fish leads to an effective and conclusive assessment of the sustaining pourer of the stock in a fishery. The von Bertalanffy growÈh modeL (von Bertal-anffy, 1938) is used in the analytícal methods (Beverton and Holt, L957 ) enployed today" The principle of age determination in fish depends on the 'annual' growth marks that are formed in certain skeretal parts such as the scales, otoliths, spines, opercula and vertebrae" The growth of fish is not normalJ-y uniforrn throughout the year" The fish may grow quickly during a certain part of the year and more s1owly or even not at all during another pa5t. This fluctuation of growth expresses itserf on the skeletal parts of the fish as v¡ide and narroÞil zones" rt is important to verify that the deposition of these distinct bands or checks is annual or can 58

be rel-ated to a distinct seasonar event such as a rainy or a dry season " Annual marks may also be relat,ed t.o spawning activities of the fish. Studies on the age and growÈh rate of conrmercial físh such as cod, herring and sal-mon were initially developed by Norwegian scientists (chevey, 1930). This was folrowed by detailed investigations on many species, especiarry commercial fish, in Europe and America (Menon, 1950, 1953). These studies have been confined to temperate regions which have well defined seasons" There have been a few indivÍduar attempt,s to determine the age and growth rate of some fish ín tropical and sub-tropical waters" Mohr (Lg2t) was one of the first biologists to examj-ne growth checks in skeretar parts of tropicar and sub-tropicar fish incruding Rasbora vuTgaris, R. eregans, Trichopodus trichopterus, Barírrus guttatus, Ambassis commersonií, poTynemus indicus from Malaya and R. daniconius from sri Lanka" He found distinct and welr defined zones ín the scares of the fish from both Localities even though the crimatic conditions between sri Lanka and Malaya are different" sri Lanka has rainy and dry perÍods whereas the climate in Maraya is fairry uniform throughout the year. Distinct growth marks on the scales and other bony structures were arso observed in freshwater and marine tropicar and subtropical fish by whitehouse (tgz3), Hornelr and Naidu (rgz4) | Devanesan (1943) , Nair (t949) and chidambaram (1950). They investigated the age and rate of growth of the oit sardine, 59 Sardínella Tongíeeps/ by the Peterson method v¡hich was further subsÈantiat,ed by scale readíng. However, validation and interpret.ation Btere lackinE in the above aEeinE studíes. Ïdone of the workers addressed the problemo as outlined by Graham (L929) and von Oosten (L929), of validating the annual nature growb,h of the checks that they all assumed in their studies " Several other investigators such as Hora and Nair (1940), Chacko et a7" (1948), Chacko and Krishinamurti (1950), Chacko and Dixitulu (1951), Sunderaj (1951) and Jones and Menon (1951) examined growth marks on the scales of hilsa, Hí7sa ilísha" and linked the fornation of the radii to the physiological rhyÈhm related to tidal periodicity. Uair (1949) used the otolith in his age studies of the oit sardine and observed growth bands as alternating translucent dark zones and opaque white ones, paralle1 to the margin of the otolith. He presumed that these rings vrere annual" Chidambaram and Krishnamurty (1951) used the otolith in studies of age and growth rate of the Indian mackerel, RastreTTiger kanagurta" They observed a close relationship between the number of growth rings on the otolith and the size groups of the fish. It was found to be too difficutt to read Èhe number of rings in the otolith of specimens > 20 cm. Seshappa and Bhimachar (195L) observed scales with transparent margins in Malabar sole, CynogTossus semÍfascíatus, caught during the monsoon. The authors assumed that there was an annual interval between najor growth checks. 60 They concluded thaÈ the rings were formed under the ínfluence of the south-west, monsoon season and referred to them as monsoon rings. They correlated the check ín growth to the depletion of benthic organisms and proposed that the lack of food ç¡as the main factor in the formation of the ring" This was the first investigation in which occurrence of transparent margins in the scales of tropical fish was correlated with the depletion of food" The studies on age and growth of.cyprinids, in particular the major carp group, started in the late 1950ts with the advancement of aquaculture. Several authors have studied the age and growth of. Cirrhina nrígaJ,a from different habitats and used the von Bertalanffy growth model to describe its length at different ages (Jhingran, L957, L959; Kama1, L969i Hanurnantha, L974), Natarajan and Jhingran (i-963) investigated the growth of Catla catLa" The age and growth of different species of Labeo have been exarnined in several Indian waters, for example -L. fimbriatus in the Narbada River by Bhatnagar (Lg7s) and in the Godawari Ríver by Rao (Ig74) " Chatterji et a7" (L979) and Chatterjí (t992) studied the age and growÈh of L" goníus and L" bata respectively in the Kali River. Das

(L960) conpared the growth rate of -L " rohita and CatTa eatla in ponds. The growth of L" rohíta has also been examined by Klran and Siddiqui (J-973) in a pond and in the rivers Ganga and Vamuna. Gupta and Jhingran (L973) used scales Èo study the age and growth of I" calbasu. 6L HíII stream-inhabit,ing cyprinid species like Tor spp (mahseer) have also attracted the atLent.ion of several biologist,s" Pathani (198la) and Tandon and Johal (1983) studied the age and grow'th of Tor tor and ?or putitorau and observed the highest growth in the first, year of life with a steady decrease in growth thereafter. Nautiyal (1990) used the scal-es to study the age and growth of mahseer from two ecologically different fluvial systens, one torrential and stenothermal and the other placid and eurythermal" His resurts were in agreement with the findings of pathani (1981a) and

Tandon and Johal (1983) " Besides the above authors, several workers studied the growth of freshwater and marine fish from tropical and

subtropical regions using their scales (Thakur , L967 ¡ Rangaswami, 1973; Pi1lay, 1958; Pillay and Rao, 1962¡ Khumar and Siddiqui, 1990) " Most of those workers eNamined the formation of annular bands on the scales of fish and used the von Bertalanffy growth model to eNplain the tife history of the fish. The oÈolith was used in only a few studies. Pantulu (1961, 1962 and 1963) used a different structure, the pectoral fin rays, to determine the age of three species, Ìíystus gulioo Pangasius pangasjus and Osteogeíosus míLitaris" His findings rdere validated with results obtained by Petersonts method.

Despite the involvement of so many researchers over an extended períod, the technique of direct validation of the age 62 of fish has not. been applied in the Indian subcont,inent, nor have age and grourth ínvestigations apparently been attempted wiÈh katle" Litt,le is known about, this fishrs age, Ìife span and growth rate" The aims of the present investigation on Nepalese katl-e ares a) t,o work out a suitable method for age and growth deterrnination and a t,echnique for validation; b) to estimate length at age and annual growth rates; and c) t,o determine the katle's adaptabilíty to two different habitats by comparing its growth in the reservoir to that in the river"

¡4Ã,TERTAÍJS .A3qD MESEODS

Ãgeing methodology Fish samples f or this study rqrere coilected from the Indrasarobar Reservoir and the Tadi River as described in Ch. If" Both the reservoir and the river rdere sampled for three years, from January, 1988, to December, 1990, For comparison of ageing methods, calcified structures such as scales, fin rays (pectoral, dorsal, anal) and opercula were collected fron all fish sampled in L988 as described by LeCren (L947), Pantulu (1961), Bagenal and Tesch (1978) and Casselman (l-98?). One hundred of each of these structures were examined to determine which best reflected the age of the fish (Canpbell and Babaluk, L979). The cross sections of pectoral fin rays brere found to provide relatively easily recognÍsable patterns under the microscope and these were used for ageing kaÈIe in 63 Èhis study.

A total ot 2046L pectoraÌ fins ínctuding the i_OO used in comparison of aEeing methods (2,O6L from the reservoir popuJ-at,ion, 400 from the river population) were processed and examined" A complet.e fin was removed from cl-ose t.o the body of the fish using surgíca1 bone cutters" This was necessary in order to incorporate the first year's growth" Fin rays \dere spread out and placed in a flattened position in envelopes" They were left to dry for 2-3 weeks" The pectoral fin rays stere then embedded in epoNy resin" The blocks were then trirnmed into rectangular shapes, using a pair of scÍssors, and the distal ends of the rays rdere also taken off. "4, low speed ISOMET circular saw wíth a diamond blade was used to section the blocks of pectoral fin rays" Three sections (0"6, 0"65 and 0.70 nm thick) were cut at the point of termination of the basal triangular noÈch. These sect,ions were nounted on microscope sJ-ides with Diatex. The slides were left to set for

2-3 days" The prepared sections were then examined under a compound microscope (X 100 magnification). Measurements on sections of pectoral spines &¡ere made with the aid of an ocular microrneter. An examination of the cross sections of fin rays revealed the existence of alternating opaque and transparent zones around the central medullary cavity. One opaque and one transparent zone rdere taken to indicaÈe one yearrs Erowth. The border between a transparent zone and the succeeding opaque 64 zone ís referred to as a e'check'' " All measurements of the tot,aÌ radius of the f in ray and of the radii up to the termination of different transparent, zones in the spine section were made from the centrar meduttary cavity arong the line of maximum growth (Fig. 4:1). The line of maximum Erowth usually lay at about a 600 angle to a defined reference line which passes through the poínÈ of divergence of the two projections and through the central medurlary cavity of the spine. The precise line along which radii were measured was selected a) t,o lie within the zone of maximu:n growth and b) to show the most crearly defined growth rings" At first, thirty pectoral fin ray sections were examined under reflected light, with a binocular microscope. Ages were det,er¡ained by Dr" K" Milts (Freshwater rnsÈitute, canadian Department of Fisheries and oceans) and by the author without reference to the fish length or weight" These sections then received a third reading from another colleague in Nepar" rndependentry assigned ages were compared and discrepancies were resolved by re- examinat,ion and discussion of ring characteristics" Any sections with confusing or unclear bands were excluded from the study. All of the remaining (2043:'.') fin ray sections of mare and female katle from the river and reservoir &¡ere aged by the author by counting of the annuli. sect,ions from 30 fish for each age group of each sex and for the two habitats were randoinly selected for further measurements of theír annular radii for back-calcurations of rength at age. .å,rr the sections 65

Figure 4:1" Cross section of a pectoral fin ray of a katle showing annuli and the axis of measurement. R1, Rz, R3, &, R5, & radii of respective annual rings; Radius total radius of the section. À reference line passing through the central nedullary cavity and the point of divergence of the two project,ions of the spine is also shown" &Kw 66 ín a subgrou¡r rdere measured if. the number of físh was less than thirty.

Valåda&,ion of ageång' method The object,ive of the validation procedure was to deternine r*hether or not the increnents on the pect,orar fin ray sections were in facÈ annuar increments (i.e", whether or not age deternination from the pectorar fin ray was accurate). To make this deternination a tetracycrine compound (orc) was injected into katre to produce marks at a specific date in bony parts of the body. Tetracycline is known t,o be incorporated quickly into calcifying tissues of fish during growth and to form a fruorescent band that is vísibre under urtravioret tight (Beverander and Gross I Lg6z) " campana and Neilson (L982) recorded that injected tetracycrine was incorporated into carcifying tissues within 24 hours" rt is non-toNic to fish at doses required for marking (Harris, 1960) and has been used previousry in fish age validation studies (Holden and Vince, 1973; Casselman, L974; Babaluk and Campbell, L987; McFarlane and Bearuish, t9B7; Babaluk and Craig, 1990). Five hundred katle of different, sizes (61 to 450 g) were collected with a cast net between L7 May and 2s June , LgBg, from the rndrasarobar Reservoir. They brere kept Ín a nylon cage for one day prior to injection and were rereased inÈo the reservoir v¡ithin tv¡o hours of receiving tetracycl-ine 67 inject,ions adninistered as described below" A separate group of fift.een fish of dífferenÈ sizes were collected with a fyke net, between 22 and 25 August, L99o, from the Tadi River" They trere kept in cement, tanks until 26 Aug:ust , Lggo, and then released after injection into an earthen pond of about, o"5 ha at Gadkhar near the Tadí River" Ã,It the f ish were- anaesthetized with benzocaine (zs mg 1-1) using the nethod described by Laird and Oswald (L975) and weighed to the nearest 0.5 g" They ranged in weight from 80 to ZBZ g" OTC was ¡rurchased under the brand name Liquamycin" Liquamycin is oxytetracycline hydrochJ-oride díssolved ín an establishing agent and suppried in vorumes of 250 nr at a concentration of 1OO mg m1-1, Using the method outlined by Kobayashi et at. (L964') , all 515 fish Ìcere injected íntraperit.oneally with a dose of 50 ng tetracycline kg-1 body weight, a dose used in other studies (l{eber and Ridgway, L96Z; Holden and Vince, t973 r" Babaluk and Craig, 1-990). A floy tag was attached with polyethyrene filament to each injected fish. a,fter processing, arl fish were herd in a recovery tank for one hour prior to release into the rndrasarobar Reservoir or into the earthen pond" Atternpts were made to recapture the injected and tagged fish from the reservoir by experimental fishing and by offering a reward to the locar fishermen for recaptured fish returned to the rnland Fisheries centre" None of the tagged fish had been recaptured from the reservoir by the end of this study in L992" Fíve t,agged and orc-marked katte from the 68 earthen pond at, Gadkhar near the Tadi River were recaptured on 9 oct,obero L991. These fish were remeasured and reweighedu and their pectoral fins were collected and sect,ioned as described above. "A'ges were estimated using a courpound microscope wíth bright and dark field light,ing. To ascertain the presence or absence of a tetracycrine mark, âD urtravíolet right source ç¡as used. AIso, the presence or absence of a check outside any tetracyclíne mark sras noted" photographs were taken on Fujichrome (i"00 å,sA) filn with a 35 mm camera attachment,.

Baek-ealcuLat,íon of Xengths at age To be abl-e to back-calculate the length of the fish from the spine secÈions, it rdas necessary to establish a rerationship between the radíus of the spine and totar length of the fish. The total length (in cn) for each individuar fish (Y axis) was plotted against each spine radius (in nicrometer divisions) (x axis) to establish the relationship. The rerationship between the spine radius and total tength was found to be rinear in all- groups and could be expressed as: Y:a+bX where Y is the total- rength of físh in cr¡ x is the spine radius in micrometer divisions and a and b are constants. Back-carcurations of lengths at ages of annulus formation could therefore be made according to the nodified direct, proport,ionatity formul-a (Bagena1 and Tesch, L97B) z Y¡-a=Xi/X (Y-a) 69 where v¡ : length of fish in cm when annulus i was formed, Y = total length of fish in cm aÈ time fin ray was removedu X¡ : radius of annulus i on the f ín ray in micronet.er

divisions (1 division : O"O37O mn) , X = t,otaI radius of f in ray in nicrometer divisions, and a = intercept on Y axis. Mean rengths at each age were obtained fron the back- cal-culated lengths of individual- f ish, and annual- length increments &¡ere cal-cul-ated as the successive dif f erences between these means" preriminary examination of the mean length for different age groups of katle showed that there q¡ere like1y to be differences between cohorts and sexes within the popuration" The data for these different groups r.rere thus kept separate through the process of corlection and analysis. rn the finar analysis of the data the mean length of young fish was first, examined separately fron the burk of the data on mature adult fish

Instantaneous or speeífíe growth rat,e

The instantaneous growth rate ín length G,- can be defined by the equation dL/dT : GlL. This assumes that. the rate of growth increases in direct proportion to present length, with GL as the proportionality constant" GL Ìdas calcurated separately for the mates and females from both habitats for each age group by using the foltowing fornura (Ricker, L97E;

Ball and Jones, 1960; Bagenal and Tesch, L97g) z 70

Logu 12 - Logu L1 TJL _ Tz-Tr where L2 and L1 are the lengths at tímes T2 and T1 respectively. The increment of tí¡ne, Tz-Tr, is usually taken as one year" Therefore, GL is eNpressed as the specific rate of growth per annum, in cn cm'î yE-1, or * yr-1.

FíÈt5.ng of, the voa BerÈal,anffy gnow€h model The best-known growth model used in fisheries assessment is that, of von Bertaranffy (1939), røho based his formulation on physiological considerations. The von Bertalanffy expression for length t(t) at age t is usuarly written as

(Dickie, L978) z

L (t) = L' { 1-et-K(t-tol: t (1) where L- : the asymptotic length at t = æ (often referred to as final maximum J-ength), K = the growth coefficient, and to = a time scarer equivarent to the (hypothetical) starting tine at which the fish would have been zero-sized if they had always grown according to the equation" The different parameters of this eguation for the reservoir and the river katle were calculated in two ways. The first h/as a mathematical method relying on regression analysis (Ricker, L975) " To estimate r-6, Equation (1) was rearranged in the form: L(t + 1) = l- tl -e(-K)l + e<-xr t(t) (Z) Then, a regression of L(t + 1) on L(t,) was performed, in which 7L

the intercept (a) = f,* [ l-e<-rl ] u and the sloPe (b) = s(-K) lø could then be cal-culated as: f* = a/ (1-b) (3) once rø had been estimatedo another regression model was used to estimate K and to" Equation (1) vras rearranged as: Iogu(r--L(t,)) = (Iog"Ia+Kto) -Kt (4) Ã, simple regression of tog"(l- L(t)) on tine t was then performed, using the previously calculated value of I-, from s¡hich: K : -sIope, and (logelå + Kto) : intercept, so that to : (int.ercept - 1og It)/K. The second method of estinating the parameters L,,o K and to utilized the graphical representaÈion dever-oped by Ford (l-933) and warford (1946) " Plots of lengths at, age (t) against lengths at age (t + 1) gave a straight-line rerationship for each group of fish, as Eq. 2 predicts, The line was fitt.ed by the least squares method" The point on the x axis where this line cuts the 45o diagonal through the origin yielded r,. (walford, L946) " K and to were then deternined as in the first methodo except that the slope of the graph of ]ogu(l* - L(t) ) against tine t was determined graphicarly rather than by regression analysis. 72

Effeet, sf ÈemperaÈure and drawdovra @n &&&&r&J- grrowÈh The ef f ect of drawdos¡n of the ç¡ater level_ in the reservoir on the annual total length increment, was examined for the years !9Bz to 1999. The area of the reservoir, which is dependent on the annual precipitation and denand for erectricity in the country, showed a great variation from 63 ha in r9B2 to Lzz ha during 1986. since availability of natural food in the reservoir varies vrith the area of the reservoirn it !ùas hypothesised that growth rate might be positively associated with the average area during the &¡arm months. Detailed records were kept on the maximum depth of the reservoir throughout the study period (Äppendix z) . .a few paired measurements of surface area (A) and maximum reservoir depth (D) h/ere al-so available. The relationship between them was found to be a l-inear one and courd be fitted by the rnethod of least squares as: A:a+bD where the val-ues of constants a and bwere - Lsz.63 and 3.61, respectively. This equation could then be used to carèulate the area of the reservoir precisely at any depth (swar t Lggz). The average area of the reservoÍr during the ldarm months (April to october) was thus calcurated for each year from Lggz to l-989 " Attenpts were made to fit a regression model to exprain the growth of fish as a function of both age and the water surface area avail-abre during the growing season. several 73

model-s as described by weisberg and Frie (Lgg7) and Maceina (L992) were considered (Appendix 5). of these, the only significant dependence was demonstrated by a model- evaluated separately for every age X: AL=a+b]ogA

where aL = annual total length increment, of the fish, and A = average area of the reservoir.

Length-weight, reIat,íonshíEr The length-weight rerationship in fish can be represented by the following equaLion (LeCren, 1951; Craig, L974) z T{=aLb or by its logarithmic form: logW=Ioga+blogL where w is the weight of the fish, L is the total length of the fish and a and b are constants. Data of total length and weight, both total and somatic (total weight gonad weight), for both sexes, colrected monthly for three years, were used to study the length-weight relationship of the katle from the fndrasarobar Reservoir and the Tadi River" Regression rines for the reservoir and river populations hrere calcul-ated by the ¡nethod of least squares for log of totar weight and the 1og of somatic weight against rog total length for each sex and for each rnonth of colrection. Comparisons were rnade between regression coefficients for each month.Therev/erenosignificantdifferences(p> 74 between the same months in dif f erent, years for t.ot,al and somatic weight regression slopes (b varues) " Therefore, data for the same month ÌArere poored over arr years, and b vaLues recalculated (Lecrenu 1951-; craig, L97a) " The slopes for each sexrilerenotsignificant,1ydifferentfromeachother(p> O"05) and krere not significantly different from 3"0" Therefore, tat values &¡ere calculated for different nonths and different sexes aÈ different stages of gonadal rnaturity (ch" 5) using the b value of 3.0 throughout" The mean length of all fish of each sex at naturity stage 1 and st.ages 22 o caught from both systems, Irere calculated" These values were taken as the st,andard rength of a ¡estandard¡¡ fish. Total and somatic weights for the standard male and female of stages >Z were cal-culated at each stage of maturity for twelve months, usingi the b value of 3.0 and calculated a values. These weights were then averaged over aII stages of maturity using the monthly percentages of fish at each stage as weighting factors.

RESULTS

Eval.ua8åon of peetoral fin nay ageing meÈhoé &{ature of the ehecks Most of the pect,orar fin ray cross sect,ions revealed the exisÈence of alternating opague and transparent rings around the central medullary cavity (Fig" 422 and 4:3). The sequence of one opaque and one transparent zone ¡øas taken to indicat.e 75

Figure 422. Transverse.section of the pectoral fin ray of a reservoir female katle showing eleven annuli" Annuli are marked with white dots" w

',&.t.,

;,,,,.. &' '.. .::ll:6t.'.:.:'-# ffi_ì*ñ w 76

Figure 4:3" lransverse section of the pectoral fin ray of a reservoir female katle showing eight annuli" Ã,nnuli are marked with white dots.

one year's gro\.,rth and 1ùas classified t,o be a true annulus" A few sections with patchy rings were also encountered. Rings that' were pat,chy or broken were shortu and. were considered as false annuli" Further, in a true annulus çrhích was comparatively broad, the change fron transparency t,o opacity r*as gradual, whereas in a farse annulus the change was abrupt. The nunber of farse annuri was l-ess than 5g of the total.

Ãgreement, between readers Determinations of the age of kat.le usinE the pectoral fin ray ï¡ere reasonably consistent: the three readers agreed in 24 out of 30 cases" variability of three successive pectoral fin ray age determinations of katle from the rndrasarobar

Reservoir is shown in Appendix 6. where there &rere disagreements, final fin ray agles were assigned by several readings and consultation between the second and thírd reader because the first reader was not available.

Age valídatíon

.Annual formation of t,ransparent, u ones anð ehecks: Est.írnation of the age of the fish depended on the assumption that an annuar band was laid down in the bone. To test this assumption, a sample of thirty fin ray sections for each month was examined for a transparent zone appearing towards the edge of the section" The percentage of each month's sampre having transparent bands laid down on the edge is shown in Fig. 424. 7B

Figure 424" Percentage of katle þrith a transparent zone at the edge of the pectoral fin ray in each monthly sample, from January to December. -@- - reservoir katleî @ - river katle. Percenloge o{ number èE

g (_ o 3 (t, (_ 79

rt Ís evident, from the figure that there Ís an opaque band at. the edge of the fin ray sect,ion of katre during most months of the year" The opaque zone is presumed to represent fast growth and the t,ransparent zone, slow growth" rt, shourd be noted that the presence of a t,ransparent zone cannot be determined until the next opaque zone has begun to form" Thus when a band is recorded, it is an indication that growth has started again. The data presented in Figrure 424 indicate that a pair of growth increments, one clear and one opaque, are deposited annuarry" Riverine fish usually laid down the opaque check in March, and in the reservoir popuration checks rdere formed during the period of T{arch to &fay" Markíng wiÈh ÈetraeyeLíne: Examinatíon of the cross sections of pectoral fin rays from the five recaptured fish with uIÈraviolet light revealed that an orc check, indicated by fluorescence, was present in three of the fish (Fig. 4zS, top). No tetracycrine marks were visibre on the pectorar fin rays of two fish, probabry because the orc was not properly injected" The details of the observations on each físh are given in Table 4:1" one annurus raíd dorsn after an orc mark was clearly visibre in the pectorar fin rays of two of the three marked. fish" No check outside the tetracycline mark was found in the third fish" since arl- the fish rrere recaptured and eNamined over one year (about 13 nonths) after the orc inject,ion, it is cl-ear that onl-y one annul-us is 1aíd down on the pectoral fin 80

Figrure 425 Cross-section through an OTC-marked pectoral " fin ray of a katle injected in AugusÈ, 1gg}, and recaptured in October I L99L" Top: transmitted ultraviolet light shows the oxytetracycline mark (oTc) " Bottom: transmitted white Iight shows the annuti (índicated by dots; not all annuli are shown), ffiæ* 81-

Table 4"1. Summary of completed oxytetracycline-marking eNperíments. Katl-e nere injected with OTC, tagged and released into an earthen pond on 27 Aug:ust, 1990; they were recaptured on 15 October, L99L and their pectoral fin ray cross sections were examined for a fluorescent OTC mark and for growbh checks outside the OTC mark"

Fj-sh No. Presence (strength) Age Number of checks of OTC mark (yr) outside OTC mark

347 Yes (strong) 5 l_ 348 Yes (strong) 7 349 No5 : 350 No5 351 Yes (weak) 6 o 82 rays of katle per year" This support,s Èhe conclusions drawn above from the annual- fornat.ion of the transparent zones and checks " The ¡rect,orar f in ray agies of four of the f ive recaptured fish were one year greater than their pectoral fin ray ages at the tine of marking. The recaptured físh ranged in age fron 5 to 7 years" A strong check on the fin ray sect,ions corresponding in ti¡re to the orc injection was observed in all five fish, probabry as a result. of the stress of marking, tagging and handring (Fig. Azs, bott,om) " rt is suggested that this should be taken into consideration during age determination of previously tagged or marked fish" rn addition to these fish recovered from the earthen pond, a large number of katl-e over a wide size range were arso marked with orc and released into the reservoir. None of these fish rüere recovered by the end of this study, but since the fish are relativery long-tived, possibre recapture of these katle from the reservoir in the future may allow future valid.ation for more than one age group over a greater span of time.

Fån ray raéíus-È,ot,a1 trength relaÈåo¡¡shíp: The relationship betr+een fin ray radius and t,otal length was found to be linear for all groups of katle. scatter ¡llots for individuar fish and best fit regression lines through the points are shorsn ín Fig. 426 for males in both habitats, and in Fig " 427 for femares. Analyses of variance were carried out 83

Figure 426" Relationships between the total lengths of male katle and their pectoral fin ray radii. &u Reservoir" b" River. The fitted reg'ression line of Table 4:3 is shoç.¡n for each gioup" Toîol lenglh of fish (cm) Totol length of lish (cm) p \ 9po çl eõ88à C) AOö c) oc)t)t)t) () c)oÕ O

CI () F df o\66 eÂ\ @ EE\ EI qa-E q EãIIq EI N) NI \ E N) E¡II6 E O O tsq@ EEE .À et \ cÉ¡ 8t \ EE \EI E 3'! Etq EI a 8!8ÍE @ EIEÑI 6I \Þ N @ü18¡ EE\ EI E¡ (f) €B Eü. ñ O IEE@ q\ i¡rw¡ o E6M8I8 6tE o \srE 8iN @ Q, o\ r¡ilbg tnc g@¡& eN Et ! lÉE¡@ cEl !B¡N¡ @\ EI! BE o q\ d[i! e E.E À ttÀ EE\ U =(f \ o @6 'a

I I

! O ! 84

Figure 427. Relatíonships between the total lengths of fe¡na1e katle and their pectoral fin raf radii" &, Reservoir" b" River" The fitted regression line of Table 4:3 is shown for each group, a: Reservoir f'emale

60 b50

.9 40 c3oo ct) ãzo fú 810 t- 0 30 40 50 60 70 Fin ray radius (arbitrary)

b: R.iver female

60 b50 ; 940 o -e 3o ot ãzo Ë ro

0 30 40 50 60 70 Fin ray radius (arbitrary) 85

on the b (slope) val-ues between the varíous groups (sokaJ_ and Rohrf 0 ]-967) " The significances of these analyses are shown in Table 4 i 2 " rn cases where there were two set,s of data o student's t tests were performed (Bailey, i_ggr-). There were no signifÍcant differences in the val-ues of b for dífferent yearso but the values of b compared between sexes and habitats &rere significantly different from each other. rn particul_ar, b was greater for females than for males within and between habiÈats - A,s there \üas no signif icant dif ference in the varue of b between years, regressíon rines for different sexes and habitats hrere calcurated from the poored data for the years 1988, L989 and l-990, and back-calculation of length was done by using 'a' (intercept) var-ues for the respective groups (Table 4:3 ) . size composition of gíLl net. eatches and ef,feet, of mesh såze: To ascertain whether the gilt nets used in the reservoir captured a representative sampre of the population, an analysis of the sizes of fish caught by each of the four mesh sizes b/as carried out (Fig. 4:B). Most of the fish were found to be caught by the 50 mm mesh sÍze panel of the gilr net, whereas the paneJ-s with 25, 75 and r-oo m¡n mesh sizes caught relatively smarr- numbers of fish throughout the study period (Fig. 4:B). The fish caught in the 25 mm mesh ranged from 1i- cm to L5 cm in totaL tength, with the largest nurnber at 13 cm. No físh l-ess than t-l- cm in length (or less than three years of 86

Table 422. Leve1s of significance of the differences between exponent b values for the rerationships between fish length and fin ray radius (Ns = non-significant, *.- P < 0"05, ** - P < 0"01).

(a) I d Reservoir between years Ns Ns River between years Ns Ns 1988 between habitats +¿ 1989 between habitats 1990 between habitats t Pooled years betç¡een habitats * * (b) Pooled years river o to g Pooled years reservoir d to ç * 87

Tabl-e 4:3 " Intercept and slope values for the regressions of the t.otal lengths of katle on their fin ray radii"

o Reservoir s"07 0"523 0 " 930 L461_ Reservoir d 7 "77 0"405 0.875 127 River o 4"45 o"482 0"948 150 River d 5 "32 0"451 o"838 l_9 1 88

Figure 428" Size composition of katle samples caught by gill net panels of 25, 50, 75 and 1OO ¡nm mesñ size. All fish caught in the fndrasarobar Reservoir during 1988 to 1990 are included. 60 +0 20 0 +óu ++o +20 400 380 J60 340 320 300

_c 280 C) 'ç lou rts o 240 L a) _o 220 E f 200 z. 180 160 1+0 120 100 80 bU 40 20 0 20 0 20 100 0 20 30 40 Totol body length (cm) 89 age) Þrere caught; this represents a siEnificant, bías in the gill net samples" The 50 mm mesh caught. a wide size range of kat'le, from 13 to 34 cm in totaL lengtho with a peak at 22 c;m. The 75 mm mesh size paner of the gilr net cauEht, físh between 22 cm and 45 cm in totar- rength" The contribut,ion of the 1oo nm mesh size panel was numericalry smar-r, Èhe largest fish caught being 54 cm in total length and 11 years old. Ã,s these data show, the catches in Èhe four ¡ranels overlap each other substantiaLJ-y in the total lengths of the fish. Thus, even though each mesh size is shown to be somewhat selective in its catch, the four mesh sizes combined would not have missed any size class compÌeteÌy, except for the very smar-r fish ress than l-1 cm in 1ength.

Ãge composit,ion of t,he reservoir and ríver populat,i.ons: The samples corr-ected in this study gave an approximate age composition of the male and female populations in the tv¡o systems (Fig. 4:9) , even though the youngest age group is inadeguatery represented, as shown in the preceding sectíon. rn the reservoir mare population, the five-year-ord group formed the highest percentage (38"2å) and ol_der groups formed only small percentages of the totar catch (Fig. 4;9a). rn the sample of the reservoir femal-es, four-year-old fish formed 42"22 of the total, and the contribution of the order fish decLined successivery (Fig. 4:9c). rn river males, the catch was dominated by three-year-old fish, whích constituted 4 L.gz 90

Figure 429. Age cornposition of katle populations by sex and habitat, as sarnpled in-ttiis study. a" Reservoir males (n = LZ7). b. River males (n = L5O) c. Reservoir females (n =" 1461). d" : River females (n 191) " b: River Male

40 45 35 40 30 35 S30 ìzso CJ ?Ã c"" 6zo c) 20 rs =o tl-I Ë15 io 10 5 5 o 0 c*l(Ð$rO(o CÐStO Age (years) Age{years}

c: Reservoir Female d: River Female

45 35 40 30 35 25 s30 o\-o ?, 25 àzo 0) 20 0) =o 3 15 Ë 15 rr-E 10 10 5 5 o o _-*w. -Nc)stto(ol-@o)OF c{(Y)$tO(o1.. co o) Age {years) 9t_ of the totaf catch (Fig" 4z9b); order fish formed a rel_at.ively small percentage of the t.otal fish catch. For river females, two- and three-year-ol_d fish formed 24.22 and 3o.72 of the total catch (Fig" 4:9d), and the contribution of older fish again decreased successively. Ïitro river female was caught at, the age of eight, whi-le nine-year-ord fish formed 28 of the total catch of female katle"

Growfh of kat,le ín t,he f írst t,hree years of }ífe: the data for the back-carculated mean rengths at the end of the first year of life sho¡r¡ed no consistent differences between sexes and locations. The average lengths at age one year v/ere 7 .68 and I " l-7 cm for the females from the reservoír and the river respectivery. The one-year-old males from the reservoj-r and the river vrere 9"33 and g.03 cm long on average (TabJ-es 4i4 and 4:6). The slight average rength difference betv¡een males in the two habítats was not significant. rn the second year, the annual rength increment in river femares was slightly higher than that of their reservoir counterparts. rn the third year, however, the reservoir femalesr length increment exceeded that of the river females (Tabres 4zs and 4t7). rn the case of males the rength increment, during the first' three years hras almost ídentical in both ¡lopulations. 92

Table 424" Mean total lengths (cn) of rndrasarobar Reservoir male kat,le grouped by age (yr) at capture (Age at Capt): E (bold ÍtaX.áes) - rnean X_engfth c,bsewed at. eapture¡ Bç (1iæ) mean tength back-calculated to year n of life" BC - mean value of BC at year n for fisn; I annual length (BCn=tf - increnent for alL fish - ecn_,¡ "

Age No" Age at fin ray annuJ-us@ at of Capt Fish

L+ 2+ 3+ 30 8"55 13"34 75,67 4+ 47 8 "32 13.00 t5 "97 20.38 5+ 60 8"27 12"56 15" 59 19 "32 21-.72 6+ l-6 8 " 66 L2.98 15.96 L9 "45 2L "52 23 "74 7+ o4 7 "90 11.81 l_6.30 21,"25 24.82 28 "75 33 .9s BC 8"33 L2"75 15"80 L9"44 22 "18 28.75 I 4.43 3"05 3"64 2"74 6"57

SD of BC 0"80 1_"1_1 0"97 0.94 l_.58 2 "29 SDofE 1"29 t_ -42 o .87 i_.37 2.5L Table 425" Mean total lengths (cm) of Indrasarobar Reservoir female katle grouped by age (yr) at capture (Age at Capt): E (boLd ítaLícs) - mean tength obse-oed at eaptúrti Bc (liqht) - mean length back-carculated to yäar n of rife. BC - mean value of BC at year n for all fi-sh; ï - annual length increment for all fish (BCn - nCn_,¡.

at of Capt Fish

l_+ 2+ 3+ 30 7 "69 LL"75 L6.E5 4+ 89 8"06 LL"79 18"70 20 "88 5+ \o 90 7 "8L 1,L " 44 16"83 2L.92 24.75 ar) 6+ 90 7 "53 L7"T2 17"50 24"35 24 86 29.90 7+ E9 7 "47 11"48 L6 "23 2L"22 28 00 29 "99 33 "8L 8+ 29 7 1-L "L5 " 69 L6 "75 22 "33 28 16 32"44 34 "04 37.8V 9+ L4 7 "76 L1"98 16"95 22 "99 27 89 32"47 34"00 36"6L 47 -31 10+ 2 7.76 L2 "3L L7 "63 22.53 26 85 32 "77 34.LL 35.97 4L"69 5i".a@ 1L+ 3 1-l-.83 8"37 16"90 23 "3L 28 36 32 "95 34"15 36.39 44"6\ 47 "95 53.48 BC 7 11_ 50 77 22 "68 " "26 .5L 26 76 30"87 34 "04 36"sL 43"44 47 "95 I 3 5 "82 "76 5"26 4"25 4"11 3 "I7 2 "47 6"94 4"51_ SD of BC o 0.85 7 1_0,92 "67 "79 13"52 2"43 l_ " 01 1-. 13 3"59 2"70 SD of E 3.5 x 1- 3 .16 "27 ,34 3.87 2.29 i..58 i_.4X t "3. 94

Tabre 426" Mean t,ot,al rengths (cm) of Tadi River maLe katle grouped by age (yr) at ca¡rture (Äge at Capt): E þond Å-taJ-åes) - MeaÍì. I-engtk obserøed at capture; BC (1iæ) mean length back-calculated to year n of life. BC - mean value of BC at year n for aJ_t fish; I - annual length increment, for alt fish (BCn - BCn_r).

Age No" Age at fin ray annulus formation at of ltÐ Capt Fish

l-+ 2+ 30 7 .59 1_O .97 3+ 30 8 " 08 11. O0 X-3 .3X_ 4+ 30 8.35 11 " 39 L3.97 16.78 5+ L2 8.09 10 " 63 L3 "24 15. 39 1-8 "42 6+ L2 8 "12 11.36 75 "L7 t6 "57 L7 "92 22 .CIX_ 7+ 3 8 " 09 LL.47 L4 "56 16 " 84 L7 "92 20 "70 23 .90 BC 8"03 1l_.1-5 14.10 ]-6"O7 L7"92 20"70 I 3"L2 2"95 L"97 1"84 2"7A

SD of BC o"52 0"46 0.36 0.33 0"33 0"15 SÐoTE 1.48 i- -2i_ i- " 4x- x-.48 3-.38 a.s6 Table 427 " Mean total lengths (cm) of radi River female katle Erouped by age (yr) at capture (Age at Capt): E (bold ítalícs) - nean Tength obserlrzed at capture¡ Bc (right,) - mean length back-calculated to yãar n of life. Bc - mean value of BC at year n for all fish; T - annual length increment for all fish (BCn - ACn-,¡¡.

Age No" ge at n ray annu ormat on (yr) at of Capt Fish

1+ 2+ 30 8 "32 i_3.OO 3+ 30 8 " 1-4 L2.53 x,5.25 4+ 2L 72 8.09 "58 16.04 L8.75 \o 5+ 1_9 8"01 L2"58 L5"42 ]-8"32 2L "7V ur 6+ l_1 8. 04 72 "7L L6.7L L9"57 22 "22 26.96 7+ 9 8"49 L2"53 l-6 " 03 20 "2L 22 "03 24.60 29 "63 8+ 0 9+ 3 7 "98 L2 "84 L6.87 2L"04 22.90 25 "92 28.77 30 "94 36.46 BC 8.L7 12.60 16.01 L9 "25 22 "23 24 "93 28 "77 30.94 T 4 "43 3.4L 3 "23 2 "98 2 "69 3.84 2 "76 SD of BC 0.56 0.83 l_.1_8 1"67 0"84 1"17 l_"1_3 0.62 SD of E i_"72 X_"39 1.43 2"1_3 1_"O9 3-.55 0 "95 96

&d¡¿1ê, grow&,h ån kaÈ,&e

E'he rescrveår popuåaËåonl ïn nearly every ease the mean length at the end of the third and subsequent years was

smaller for males (Fig" 4:1-0a) than for femal-es of the same age (Fig. 4:11a)" This difference rdas also obvious in annual

increments" The annual increments ín adult, mal-es were 3.o5 cm between Lhe ages of 3 and 4, 3"64 crn between 4 and s and 2"74 cm between 5 and 6 years (Table 424) " These were rower than those in females, which were 5,75, 5.26 and 4.ZS cm over the same periods of life (Table 4:5). Male katle above the age of seven rdere not observed throughout the study period, Average totar lengths at age deternined by back-calcuration were in agreement with those observed at capture in most cases, but for the four-year-old age group the back-calculated average length vras significantly higher than the length at capture in both sexes. A sinirar discrepancy vras found for six-year-oId ma1es, but the back-calculated average length for this group was based only on a small sample (4). The ríver populat,íon: Similar trends of mean length and annual increments were found in ríver fish as had been seen in the reservoir popuration" The length increments in mar-es in years 3, 4, and 5 were 2"95, L"97 and 1.94 cm respect,ively (Tabre 4:6) " The length increments in those years for fenares rdere 3.41- , 3.23 and 2 "98 cm respectively (Table 4z7l " The rength increments in the fish (mare and female) above sìx years of age seem guite hiqho but these aeans were based on 97

Figure 4: 10. .ê,verage totar lengths of male katre from the reservoir (a) and the river (b) at, age. Lengths observed at capture - back-calculated lengths @. ^; + 95 Z confidence liniÈs are shown. Avcrugc total lcrrgtlr (crrr) Avcragc tolal lcngtlr (cnr)

Pþ ¡'6 æèo itli ll

i Jli : lh åP: P i'iH

(Oè (D ilj i ao A) Jb Lit it"t'i u ri I

t-t' i "il----l

....>. .. . t I !""""""

t_ 98

Figure 42L7. Average total rengths of femare katre from the reservoir (a) and the river (b) at age. Lengths observed at capture - back-calculated lengths w. ^", + 95 Z confidence linit,s are shown. e

s 3CTr-

^ OETL I .. r.. I ¡ I rìii I rl 1r

-T-

q ECTL

¡ OBTL b -"t- -t- 95% c.,.

I I .-J-- E -JU ¡:rl ..,t - I èo ¡l () Y

a C) -

-I-

:j-

5 Age (yeaQ 99 only t'hree fish of each sex so these data &¡ere not. Èaken int.o account in the estimation of asynptot.ic growÈ,h and other parameters of the von Bert.alanf fy equation" Ã,s in the reservoir popuration, average tot,al lengths at. age observed at capture agreed røith the back-calculated values in mosL cases. ïn mareso the back-calculated rength was significant,ry higher Ín the three-year-ord age group and lower in the six-year-old age group (rig" 4:10b). rn femaleso the observed averagie total length rdas found Èo be significantly higher than the back- calculated one for the six-year-ord age group (Fig" 4:11b).

comparison of average total lengths back-calculated to a particurar age from fish of dÍfferent ages at capture were in good agreement for arr groups. specificarlyo there Þras no consistent decrease in back-carculated length with increasing age at capture, a tendency frequently noted in other studies and known as Lee's phenomenon (Ricker, L969; Bagenal and

Tesch, L978) "

Díf,f,erences between t,he populat,åons Mean lengths of male katre at the end of their first year rdere not sÍgnif icant.ry dif ferent between habitats. The reservoir mares greid faster than the river males fron the second year on" The oldest males encountered in the catches frorn both the reservoir and the river krere 7 years old. There eras a significant dÍfferenee of 10 cm between their average total lengths, Èhe 7-year-old reservoir mares being larger 1_O0 (33.93 cm) than the river ones (23.90 cm). Againo these average lengths are derived fron smal-l sampre sizes (3 fish from the river and 4 fish from the reservoir) " The mean lengths of the reservoir femates at the end of the first and second years rdere rower than those of the river femares at the sâme age" Howevero the average total lengths (and the annuar Íncrement,s) in female fish older than 4 years !¡ere significantry higher in the reservoir ¡lopulation than in the river. The ordest femares in the river were nine years old while three 1L-year-o1d fish were encountered in the reservoir samples.

Inst,antaneous raÈe of growth rn the reservoir popuration, the instantaneous rates of growth per annum (Gl) between the ages of 1 and 2 years srere o"4o and 0"43 cm cm-1 yr-1 respectively in mar-es and femares (Fig. 4:12). rn the next year the growth rate remained more or less the same (0"4i- cm cn-î yr-1) in females but dropped to o"2L cm cm-1 yr-1 in mares. The grourth rate continued to decrease with increasing age in both sexes and urtinat.ely it was onry o"o7 cm cn-1 yr-1 between the ages of 7 and. g years in females and 0"13 cm cm-1 yr-1 between the ages of 4 and s years in mares" The growth rate J¡etween ages g and 9 years in females and 5 and 6 in mal-es shov¡ed some apparent increase, hrr# 4-lâ^ aaanì i 1 .l vqe e¡¡s Èq¡tty¡g ^ Þ¿¿¡gÞ- -^^ WglE ÞfUClJ-I-*^ The instant,aneous growth rates in Èhe river popuration 10L

Figure 42L2. Instantaneous rate of growth (cm cm-1 yr-t) of katle in the reservoir for male (-r- ) and f emale (--{]_ ) f ish of various ages. lnsfonfoneous lqle of growlh ç) cf l., ¿o LO2

Figure 4:13" Instantaneous rate of growth (cn cm-1 yr-l) of katle in the river for male (@-) and female (+) f ish of various agies. lnslonfoneous rote of Growth 9o lt, ¿Þ l_03 showed a simirar decline with age. The híghest valuesu 0"43 cm cm-1 yr-1 in females and 0.33 cm cm'1 yr:l in maleso occurred. between the ages of l- and 2 (rig" 4:13) " The rat,e dropped to o"24 cm cn-1 yr-1 in females and o.23 cm em-1 yr-r in males in the neNt year and urtímateJ-y to o. 07 cm cm-l yr-l in femares and 0'14 cm cm-1 ys-l in mares between the ages of g and 9 and 5 and 6 years respectively A sirnpre linear regression nodel- was fítted to the data for instantaneous growth rate against 1og age: GL = (slope) log age + intercept" The slo¡res and intercept,s (Tabre 4:B) &¡ere compared between sexes within the same location and for the same seN between the locations" rn the case of male versus femare in the reservoir, the slope and the intercept of the mare moder differed from those for the femare by approximatery 0.6 and 0.9 standard errors respectívely" The decline in growth rate with age eras not significantly different between the two sexes in the reservoir. The slopes and intercepts for males and females in the river differed by approximatery 1.1- and 1"5 standard errors and were arso not significantry different at the 5å revel. rn the case of the females compared between the two habitats, the slopes and intercepts differed by about 2 and 3 standard errors. The difference betvreen the slopes was noÈ statistically signíficant whÍre the intercepts frorrroc.on'l- i nrv #ha (=- r¡r'l rra a# 1 tvass ¡-^ì v sÁsç se 4 J sqÀ v!^â cryg,, wgJ- Ë significantly different (p LO4

Table 418" Intercept and slope values for regressions of insÈantaneous growth rat,es on log age "

Intercept (SE)

Reservoir ç 0 " s86 (0 " 064) -o.217 (0"037) 0.83 Reservoir d 0.483 (0.141-) -0" 179 (0" 102) 0"50 River o 0.383 (0. o32) -0.155 (O"O22) 0"89 River ct o"443 (0"065) -0.1e3 (0.047) 0"84 l_05 the slopes and íntercepts v¡ere not signifícant between males from the river and reservoir. Tt appears that the regression noders were all within a dist,ance from each other that could be explained by random variation. Only one comparison, Èhe intercepts between females from Èhe river and reservoir, showed significance" Overallo the data suggested that the habitat and sex factors do not influence the decline in the instantaneous growth rate of katle with age.

The von Eertalanffy growth eurve The mathematical and graphical methods for estimating I+, K and to yielded very sinrilar values within each group of fish, although they differed between groups" The val-ues of I+ for male and female katle from the reservoir and river indicate their predicted maximum size in both habitats" The predicted maNimum sizes for males in the reservoir and the river were calcul-ated to be 4L and 26 cm respectively" Similarly, the predicted maximum sizes for the females in the reservoir and the river were 73 and 45 cm respectively (Tab1e 429) " The highest K value (the growth coefficient) was calculated for the males from the river (0"196) and the lowest was for the reservoir females (0"087) " The values for the von Bertalanffy growth pararneters indicated that males grew faster than the females but to a smaller maxinum size. r.06

Table 429" values for von Bertalanffy growth parameters estirnated by the graphic nethod for ËitÉing groitn curves for katle from the Indrasarobar Reservoir anâ Tadi River. Also shown are the maximum ages of fish captured"

Maximum Iþ K lo Habitat Sex Age (yr") ( cn) (yr-1) (vr)

o Reservoir 1l_ 73 0"0 -o "LL7 Reservoir d 7 4t 0"135 -0 650 River o " 9 45 0"120 -o " 682 River d 7 26 0"195 -0 " 875 3-07 The observed growth curves for male and female kat,l-e from both systems (back-carculated rength agaínst age) are shor*n in Fig" 4zL4 and 4:l-50 along with the rnathenaticall_y fitted von Bertalanffy growth curves ín each case. The mathematicat curves can be seen to fit, the data quite werL, passing within the 95å confidence rirnits of almost arl data points. The fev¡ exceptions riüere rnostÌy for the larger, order fish with smarl sampJ-e sizes " variatíon in growth ín different years aud åts come1atåon wít,h abíot,íc factors Ef f ect' of t,emperaÈure varíat,ío¡r betwee¡¡ years: Prelirninary examination of the growth of the reservoir katre showed quite clearry that there was a year-to-year variation in the annual totar length increment within the same age groups" As it was observed that most of the transparent zones in the fin ray cross-sections (indicating slow growth) were laid down during winter or earry spring (rig. 434), it appears that nehr growth of the fish in the reservoir starts about in April" Most of the annual growth was achíeved between April and october, the warmer months. Katle are knoçrn to rive in a wide temperature range from 15 to 3ooc (Rajbanshi, rgg2) and breed naturally in temperatures between zo - 23oc (Rai, lgTg) oc or between 2L to 26 "7 (Ahnad, 1948) . rt vras thus hypothesised that temperature above 2ooc night. be optirnal_ for iÈs growth" 1_08

Figrure 4274" Growth curves for nale katle from the Indrasarobar Reservoir (¿) and the Tadi River (tr) " So1id synbols show average back- calculated lengths for each age with gíeo confidence lirnits (dashes). Curves and hollow symbols show predicted lengths at each age calculated from the von Bertalanffy growLh equations fitted Èo the dat,a. Total length (cm) oN 1_09

Figure 4:15" Growth curves for female katle from the Indrasarobar Reservoir (a) and the Tadi River (tr) . Solid slnnbols show average back- calculated lengths for each age with 9SZ confidence Linits (dashes). Curves and hollow symbols show predicted lengths at each age calculated from the von Bertalanffy growth equations fitted to the dat.a" E (J o¡ ^^ gcóu E o f/- 110 Therefore, an attempt was made t.o eNamine the effect of t,emperature variat,ion beÈween different years on the annual growth of katle in the reservoir" surface water temperature q¡as taken aÈ L0:00 h each day beginning in l-982 by personner from the rndrasarobar Hydroerectricíty sub-statíono and after 1985 by personnel fron the rnland Fisheries centre. These temperature data were used to carcurate the number of degree days above 20oc (the sum over arr days of the difference between the daily temperature and 2o"c) for the period of April to ocÈober from L9B2 to l-989" rt was found that the number of degree days above zooc between Lggz and 1989 ranged between 595"7 in 1984 and 611"2 in i-985" This smarl variationn by only 15.5 degree days or less than 3Z of the total, seems unlikely to have infl-uenced the growth rate of katle. Effect, of varåatíon ín surf,ace &trea, 6ue t,o 6randowne The regression described in the Materials and Methods: AL:a*bJ_ogA where a¡ = annual total length increment. of the fish, and A : average area of the reservoir, kras evaluated separately for every age x, to determine whether growth varied v¡íth drawdown and, if so, whether the dependence of growth on area differs from one açfe to another. The results demonstrat,ed a dÍstinct positive linear rerationshíp between tot,at length increments and average reservoir area for arr ages (Table 4:1,0) o but it is difficurt to see any pattern from one age group to the next as slopes differed significant,ly among thern" l_ 1- l_

Table 4: l-0. .A,ge-specif ic regressions of katlets average annual length increment, AI, on logls of the average surface area A of the fndrasarobar Reservoir for years from L982-L989"

Age Regression equation r' P value No.

Age l_ AL = *26"8 + 1-1" 0 IogA 0"78 o. 006 35 Age 2 AL = -38.9 + L5"2 logA 0.85 0. 001 45 Age 3 AL : -55"9 + 21"5 logA o "79 0"003 30 Age 4 AI, = -36.O + L7 "L logA 0"55 0"034 30 Age 5 ÂI = -99"6 + 28"1 logA o.7r 0"015 30 Age 6 : + A¡ -86.7 26 "2 logA 0.95 o " o0l- 30 Age 7 AL : -57"3 + 20.6 logA 0. 65 0"098 30 Age I AT : -30"9 + 10"8 IogA o.79 0.107 30 LL2 l,engËh-weíght, relatåonshige : As described in the Mat.erials and Methodso the length_ weighÈ relationship was appried in iÈs logarithmic form: logW=loga+blogL where w and L are the weight and the tot,ar rength of the físh. The constant b did not differ significant,ly fron 3.0 for any group, so this val-ue of b was used t,o calculate values of rog a from the regression eguations for reservoir and river popurations (Appendices 7 and 8). The mean lengths of alr fish caught from the reservoir were: 19.0 cm for males at stage 1 of gonadal maturity (see ch" 5); 22.L cm for males at stages 22¡ L9.3 cm for females at stage J_; and 24.5 cm for femares of stages >2" similarly the mean lengths of aIr the fish caught. from the river were l-l-.6 cm for mal_es at stage 1, 16.9 cm for mares at stages >2, rz.9 cm for fernales at stage l and 20.g cm for females at stage >2. These varues have been taken as t¡standardf¡ lengths of standard fish in further analyses, Monthly total and somatic weights (+ gS g CL) of standard males and femares from both locaÈions at their different stages of gonadaÌ maturity through a year were calculat,ed from monthly regression equations. These are presented in g, Appendices 10, L!, 12 and illustrated in rig. 4z] 6 and 4217 " rn the reservoir standard male the total weight ranged between 94"08 + 0"86 g in Jury and 104.68 + 2.96 g in June (Fig. 4: i-6a) " The average total weight, of the reservoir standard female ranged between J.oB.Az t o"z4 g in July and l-i_3

Figure 4zL6 " ÞÍonthly averagie total weight and somatic weight (g) of the st.andard (ZZ "I cn) male katle from the reservoir (a) and of the standard (L6.9 cn) male from the river (b), + 952 conf idence lirnit,s " " Toni weigni i " Somatic weignl I

I --l I ø .tlrf Ë? t_1 :i géa I -:1t= T ;r ¿ll? E li I I I _-¡ I I è¡ ,Lt:o rl tt T oola lltt i -'j-

; I T ! I

I I

I -..1- l I

Jo Ëb lvls AF Ìr'f.ay Ju Jul Au5 Sæt Oc' N@ Dd

u Toral weight b . Somaric weight

T Tl_ lâllll ti Illït-tå

ulllr:¡l èO I t l-L- o ¿l:tll tri+lrllll t-t? TItl rllo

Jæ Êb Mã Âr lvlay JE Jul Aug Sø! Ocr Nw Dc Month 11_4

Figure 4zL7 " Monthly average total weight and somatic weight (g) of the standard (24"5 cm) female katle from the reservoir (a) and of the standard (20.8 cn) female fron the river (b), + 952 confidence linits. ø

qæ :-e

'õèo È ir6

Jæ Fcb Àáä At Ì'{a1 Ju lu) ,{uE SrPl Ocr Nov D-

" Toial weight " Somatic weighl -i

-c ,| -ï-

g : Il -l I

-a- -l I E:I j l;ll¡l i -:-ril ¿' ert "ì- :- +I r_l i lrÌ I ll_ I¡l_

1 +

Js FeD i'tã AFr ì'l¿: iu Juì lru6 S?i Oci ¡ìõ'D€ Month l_t_5 L26"r5 t o.Ls g ín December (r'ig. 4zr7a)" The fact, that the reservoir fish eNperienced their l-owest weight. in July was probabry due to the effect. of reproductive activities, despite rel-at,ively higher feeding intensity ín reservoir fish during Jury (ch" 3) " The ninimum value of average total weight, in the river males was observed in October (40"45 + 1.38 g), and was. irnnediately followed by the highest value (4g.01 + 0.75 g) in November (Fig" 4:16b) " rn the case of the river females the values of average total weight ranged betvreen 76"76 t O"OB g in January and 91.33 + 0"75 g April (Fig. 4:17b). No definite trend kras observed in the variation o.f total weight of the fish between the locations and sexes. ft was also obvious from Fig" 4:16 and 421,7 that the toÈal and somatic weights of kat.le did not differ significantly during the winter months (November to February). significant differences between total and somatic weight, reflecting the weight of the gonad, v/ere observed from March to october in both systems, but the dífferences were not very large. The low gonadal weight that this impties is probabty due to the fact that katle are partial spawners. 116 ÐrscussloN

The for¡nation of marks on bony structures such as scales, fin rays, otoliths and opercuJ-a is werl document,ed for fish from t'ernperate waters" such annurus production is usualry the result of periods of slow wínter and fast su¡ntner growth during the course of a year" The present study has estabrished for the first time the occurrence of growth checks in katle similar to those found previousry in both t,emperate and tropicar fish (see rntroduction). This study has furthermore provided validating evidence that the observed annuri are indeed annual- growth rings. carefur examination of the transparent margins of fin ray sections reveared that the highest percentages of werl- defined rings or annuLi ç¡ere laid down during March and Àpri1" rt seems that the new growth begins at that time and that the preceding transparent bands are laid down in the previous months (January to March). This interpretation is supported by the resurts of oxytètracycline marking: onJ-y one growth check rdas found to be laid down during the 15 months between the tine of administration of the orc (indicated by a sharp fluorescent ring in the fín ray cross-section) and the recapture of the fish. These resul_ts therefore provide evidence that age can be deterrnined reliably from the pectora] fin rays of katre. This is not unexpected: being situated above 26 o zo, N, Nepal exhibits four distinct seasons in a year with temperature variation of about 140c. Lr_7 The average surface wat,er temperature ín the rndrasarobar Reservoír and the Tadi River ranges from i-3.soc in February to 27oc in Jury (Fig 5:16). The format,ion of checks in both habiÈats in the spring v¡ould then arise from an acceleration of growth due directly or indirectly to rising temperature or other seasonar effects, and srower growth çrourd be expected in the cooler wi-nter season. Growth is generally defined as a change in the length of fish over time. several general features were observed for the growth of katre in boÈh the river and the reservoir populations. Females attain a rarger size than the mares" comparison of the von Bertaranffy equations for each sex from the reservoir and the river reveared that r," for females is greater than that for males and that K values are higher for mares than for females, even though the differences are not signif icant, in arr cases (A,ppendix 4 ) " The mares tend to mature when a year or more younger than the females, and faster-growing individuals mature earlíer than sl-ou¡ grovrers. A comparison of growth rate in various age groups of katre from the river and the reservoir shows that. the growth in length was rapid during the first three or four years. Thereafter the growth rate declines and, during old âgê, growth in length practically ceases. A complicating factor in these resurts is that a wide range of sizes is observed among fish of the same age or agie crasses. As suggested by Frost and Kiplíng (tg67), this may be l-l_8 because spawning of alr the indivíduals of the population does not, take place at, one Èime" rn katre the spawning season lasts for about seven months (April to oct,ober), The fish that. hatch earlier than the others may have an advant,age ín getting plenty of food and having comparativery ress competition" Kat'Ie popuÌations in the Indrasarobar Reservoir and the Tadi River face heavy nort,ality due to íntensive fishing and poor environrnental conditions" Most, of the fish are either fished out or die as a resulÈ of heavy monsoon floods, sirtat,ion from soil erosion in the river, heavy draq¡doçrn in the reservoir, or other unfavourable conditions. Thís may be the reason for meagre sarnpres in the larger size groups from both loeations. A related cornplication is that the samples from both habitats do not. represent those populations with complete accuracy. The scarcity of one- and two-year-ol-d fish from the fndrasarobar Reservoir may be because of the setective action of the nulti-panel gill net whose rneshes were too large to catch the smaller katle (Fig. 4:8), Biological segregation according to maturity (HiIe and Frank, Lg4L) also may have contributed to the scarcity of katle of the younger age groups from both habitats" siurirarly, the catch of juveniles (one- year-ord katle) from the ríver wilr also have been affected by the use of selective gear" Craig (1-987) has described the physiological process of growth, the various stages Èhat intervene between feeding and eventual tissue depositionu and the effects of abiotic factors l_L9 such as t,em¡rerature and tight, on growth of tenperat,e-zone f ish. The growth ¡rattern observed is the result of an interact,ion between a potentiar for growLh defíned. by the genotlpe of the fish and the envÍronmental conditions experienced by the fish (wootton, L9g2). Three main reasons have been advanced in this study for the arresting of growLh during several months of the year: 1" Reproduction, 2" Temperature, and 3. Effects associated with drawdown. Fish use a certain port,ion of the energy gained through food consumption for gonad deveLopment; as the gonads increase in size with increasing age, maturation of the gonads requires an increasing amount of energy at the expense of somatic growth (Craig, Lg77'). However, the proportion of the energry diverted to the gonad depends on the spawning pattern of the fish" The najority of the clprinids that are single spawners spend a considerable amount of energy ín gonadar deveropment. During the spawning season of these species, the gonads enlarge and most of the growth potential is directed towards this developrnent (Biswas et a7. u 1982). The space for the gut is arso reduced through enrargement of the gonads, and this results in low feeding and sl-ower growth" The eraboration of gonadar ¡rroduction during the fasting periods probabJ-y accererates the depletion of fat reserves and exaggerates the low physical condition which is refrect,ed in the bony 420 structures of the fish (Das and Fot.edar, L96S; Jhíngran, L97L¡ Payne , ifg76). It, is doubt.ful whether gonadal ínvestment is the prime reason for growth checksr âS maturat,ion is frequentty preceded by a long period of negligible feeding in many species (wercornme, 1985) " Many clpriníds inctudíng katle are partial spa\dners and have an extended spawninE period (Aprit- OcÈober); these species do not, seem to put, a large fraction of theír energy into gonad development at this tiure. Katle produce only a few eggs at one tine and the average weight of the mature gonad is < 10 å of the total body weight. However, it ís very likely that acÈivities relaLed to reproduction such as moving away from feeding grounds, involvement in spawning rather than in feeding, and diversion of energry to migrations and gonadaÌ development u¡ould reduce the annual growth rate of katle " The most irnportant external factor in influencing fish growth is ternperature (LeCren, L955, 1958; Craig, 19gO) " The formation of annuar checks in the bony structures of katle demonstrated in the present investigation suggests that temperature is arso of great importance in the growth of arl ages of katle" rt is most rikely that reduced temperature influences the growth of katre in two krays. First, it nay srorø dot¡n metaboric activitieso incruding feeding. Even though katle is reported to survive in a wide temperature range between l-5 and 30oC (Rajbanshi, L9BZ) | the fact that it has only been observed to breed at temperatures above 2ooc L2L sugEests that, Èhe optimum for growth ís probably also above 2OoC. Secondlyo ít, may also be possible that, lower t,emperatures alonE with other physical factors have a negative effect. on the whole bíot,a and thus on the food supply of the fish, which røi1l eventually lead to the scarcity of food. Besides the influence of t,emperature reflected in the annual growth cycle of katle, âD attenpt was made to examine the effect of temperature on the year-to-year variation in growth (LeCren 1958; Mann, L976) between 1982 and L989" There did not appear to be enough variation in the number of degree days above zOoC in the Indrasarobar Reservoir during these years to influence the int.erannual variation in growth of katle. Nonetheless, studies of the growth of katle in the reservoir show that there are considerabl-e year-to-year variations in growth. This study has shown that. the Íntensity and the duration of dra¡*down can account for much of this variation. Ã,naIysis of age data and annual drawdown on growth of katle revealed a distinct inverse effect of drawdown of water level in the reservoir on the total length increment of katle" A negatíve impact of wat.er draçrdown on the growth of two species of Hydrocynuso H. brevis and f/" forskahTíí" has also been observed in the Neiger River (Dansoko, LgTs¡ Dansoko et aI" o L976) " These workers studied the growth of these two species during r97L and ]-972 when there &ras an extensive drawdoç¡n in the river and found that growth, particurarly of L22 the younE of the year in both specíes, vtras poor during these Èwo years. such year-to-year variat,ion ín grow'th within the same species has arso been observed for some cichrid species in the Kafue River in central Africa. Here, Dudley (Lg7A) and

Kapet,sky (L97 4 ) found signif icant, correlat.ions betvreen some physical variables and the main growth increment. The intensity and duration of flooding in combinat,ion with lorø temperature in the dry season accounted for the year-to-year variation in the growth of year class 1 and 2 of TíIapia rendaTTio Oreochromis andersoní and O. macrochír" In most, situations, drawdown is also responsible for creating crowded conditions for the fish population, reducing the amount of food per individual and eventually reducing the growth rate of the fish. However, there is not enough information to determine the effects of populatíon density on the growth of katle in this study This study did reveal a strong effect of riverine versus lacustrine habitat on growth patterns over the lifetirne of katle" comparison of the von Bertaranffy equations showed that L. is larger for reservoir katle than for river kat1e, and that K varues are greater for river katle of both sexes" The higher values of L. in the reservoir can probably be attributed to higher feeding intensity observed there throughout the greater part of the year (Ch" 3) " Fish with higher K and rower Tö values approach their ultinate size faster than those with lower K and higher r,," Therefore, the L23 reservoir female wourd need t,o live longer than the ríver female t,o achíeve ít.s ult,ímate size.

.AccordinE to Bevert,on (Lggl') 0 the level- of feeding has a powerfur infruence on the urt,imate size T-s, whereas K is much more strongly ínfluenced by genetics (unless the shape of the growth curve is distort,ed by marked chanEes in the availabirity of food during life) " rn the present studyu there is not enough information to distinguish between genotlpic and phenotypic effects between these two popurat,ions, deríved from different, gene pools. Beverton (L987) consíders that there is good evídence in several species for growth and rongevity being phenotypic responses to the environment. This is supported by differences in the correlations of rongevity with growth in cohorts of a single perch population (Craig et aI., 1979; craig, L982) and by intraspecific variation in the life history tactics of Atlant.ic herrÍng (CLupea harengus L. ) stocks (Jennings and Beverton, L99L) " rt is most rikely that the observed differences in growth between the reservoír and the river popurat,ions of katle are largely a response to environmental factors. Effects of regulation of the River Tees upon growth and reproduction of bulrhead (cottus gobío L" ) were observed by crisp et a7" (1983), who studied the ¡lopulation before and after impoundment. rnvestigations on the fish population in the Indrasarobar Reservoir area before as well as after its formation would have provided vaLuabl_e information to help isoLate the genotlpic and phenotlpic 124 influences on dífferential grovrth of kat,re ín the river and reservoir populat,ions . 1,25

CÏ{FÀPTER V

ÃSPECTS OF TITE REPRODUCTTVE BTO&OGY OF' KÃTLE T}ü TNE

Ï3{DRÃ,SÃROBÃR RESERVOTR A3ÛD TÞTDT THE R,IVER "

INTRODUCTION

studies on the reproduction of cyprinids in the rndian subcontinent have concentrated mainly on two groups. The first group is that of the rndian major carp, which comprise Labeo spp" , cirrhina spp. and catla catra. The second group is híll stream f ish which include Tor spp. , Neorissochil_us hexagonolepis and Schizothorax spp. Tor spp. and /veo-z.issochiLus hexagonolepís are commonly caIled the large- scal-ed barbels or the mahseers, and schizothorax spp. is called by the popular name of snow-trout. These studies have been stimulated by the desire to understand and control the reproductive processes in these species which are used extensively in aquaculture and sport fishing" scientific observations on the reproduction of rndian cyprinids started in the l-940's (Hora, Lg4s). on the basis of their spawning frequencies, rndian cyprinids are divided j_nto two broad categories (sathyanesan, ag6L, 1-962; prabhu, 1_9s6¡ Qasim and Qayyum, L962, 1963¡ parameswaran et aI., 1970): a) single spawners: those which possess a wel_l_ marked s j_ze group of oocytes and have a short breeding season which rasts ]-26 for 2 to 4 months" All the rndian rnajor carp farl into this category " b) Multiple spahrners: those which conÈaj-n oocytes of various sizes with no well marked bat.ches. Gravid individuals occur over the greater part of the year" rt seems that if conditions for spawning are favourabre, the cycre can occur at any tirne of the year" spawning in each individuar is not synchronous with those of other individuals of the population. The mahseers belong to this category. The spawning behaviour of the cyprinids in natural and controlled conditions has been investigated by several workers and the rol-es of different abiotic factors have been described. rntensive floods, caused either by rainfarl or artificiarly, which inundate sharrow areas are essential to j-nduce spawning in many carp (Hora, Lg4s). Floodwater has been considered to assist the fish in migrating to their shalrow spawni-ng grounds (Ganapati and Alikuni, Lgso; Arikuni and Rao, 1-951-; Ganapati et a7., t_95j_; David, l_955). shaha et aL. (l-957) investigated the spawni-ng behaviour of carp in controlled cond.itions and found that floodwater played a rol-e in lowering the pH of the water to a favourable level- to induce spawning. Dubey and Tuli ( j_961_) observed the breeding of arr three major carp species, Labeo rohita (rohu), catl-a catl-a (catla), and cirrhína mrigara (mrigal), in Madhya Pradesh, rndia. They found that rohu and mrigar breed in flooded areas with a depth range of 0.46 m to 0.9j_ m, while L27 the catla requires a spawning ground with a v¿ater depth greater than a"zA m. Al-r fish spahrn within a pll range of 7.2 to 8"2 and a temperature range from 26 t,o 33oC. sinilarly the reproductive bÍorogy of different species of hill stream fishes has been sÈudied by many ç¡orkers and the role of water temperature has been emphasized. The optimurn temperature for the mahseers was found to be from zo Eo 2goc wit'h >6 ng-1'1 dissolved oxygen content (David, 19s3; Desai, t973; Pathani, L978, r-98r-b, rgg2; sunder and Joshi , l.977 ; chaturvedi, L976; Kulkarni, rgTo; Kulkarni and ogale, LITB), whereas the snow-trouts (schizothorax longipinnÍs Heckel, schizothorax essocinus Heckel, schizothorax ríchardsonì Grap and Hard and schizothorax niger Heckel) ürere described as spring spav'¡ners at a temperature range of LA-L7oc (sunder, 1984, t9B6; Raina, tg77; eadri et ãI., 1983; Jyoti and Ma1hotra, 1972; Malhotra, L}TO). Ä'mong the rndian cyprínids, carp have the highest relative fecundity (chonder, lgTo; Hanumantharao, LgTt; sinha, L975; singh and shrivastava, Lggz). The snow-trouts have rower fecundity than that of the carp species (Jyot,i and Mal_hotra," a972, Raina, 1977) , whire the mahseers are the Least fecund of the three groups (Desai, Lg73; Dasguptâ, 19gBb; Nautiyar, L984; NautiyaL and Lat, l_995) " Arl these studies on cyprinids have been performed in rndian waters" simirar studies in Nepal brere sÈarted only in the late L97o's. Masuda (L985) bred Tor putitora by corlecting 428 mature fish from the Tadi River in the month of .Augrust, rg7g. simil-ar work v/as carried out by shrestha (r-986) in the Tadi River during the nid-19Bors. rn addition to breeding Tor putitora, shrestha (i-990) investigated the spawning period and l-ocation of this species in the Tadi River and its feeder streams. shrestha et at" (i_990) successfurÌy conducted the induced breeding of Tor tor" using hormonar injection. The fish were initialry caught from Lake phewa and herd in floating net cages for two years. The femares $/ere injected with an extract of the pituitary grands of conmon carp in sz sodj-um chloride solution (6 mg kg-1 per dose) three tj_mes at o | 6 , and r-8 h intervals. The males rdere given only one injection (3 mg kg-1). These workers were able to stríp about 4'5oo eggs from a femaLe of 2 kg weight. Hatching occurred in 64 hours with a 972 survival rate. Despite the interest of several v¡orkers in economically irnportant cyprinids, the reproductive biorogy of katre is poorly known. one of the earliest and most irnportant documented observations on the reproductive ecorogy of katre ü¡as carried out by Langdare srnith (Lg44) " He observed the spawning movements of katle in his tea estate pond at Darjeeling during earry autumn and collected some eggs from the pond. Ahrnad (l-948) collected and incubated the fertilized eggs of katle and studied their embryonic development. Rai (1-978) collected mature katle from Trishuri River in central Nepar and stripped eggs from them. The eggs were fertilized. L29

and incubated at temperatures of 1g to 2l-oc. Dasgupta (l_98ga) collected 24 female katre from the simsang River, Meghalaya, rndÍa, and estimated their fecundity. He considered the katre as a prolific breeder but less fecund than other species of mahseers. No further information is avail_able about the reproductive biology of katle in Nepalese rivers and reservoirs. The present study is an attempt: a) to investigate the reproductive adaptabitity of katte by comparing its reproductive season, spawning behaviour and movements, and fecundity in the Tadi River with fish in the rndrasarobar Reservoirr' and b) to assess the infruence of abiotic factors such as temperature, daylight rength and annual- precipitation on reproductive biology of katle.

MATERTALS AND METHODS

Two thousand two hundred and seventy three (2,273) katle ranging from 8o nm to 553 nm s/ere colrected from the rndrasarobar Reservoir (i,ts72) and The Tadi River (701) frorn January, l-9gg to December, l-990 as described in ch. rr. Katle from both sites srere examined externarly and j_nternalry to separate males from females. Measurements of total length, standard length, girth and weight were recorded. The gonads t/ere removed and weighed " ovaries brere stored in Gi Ison, s fluid for fecundity estimates. rnformation on gonad development was noted. The gonads $/ere crassified according to 130 their stage of development as suggested by Laevastu (1965) "

Radío t,aggíng Radio tags \dere used to investigate the spawning migration and l-ocate the breeding sites of reservoir femare katle" Radio teremetry equipment rdas obtained from Austec Erectronics Ltd", Älberta, canada. Low frequency (4g ¡mz) radio transmitters hrere used in the study. Each tag had a unique frequency in the 49"1- to 4g.g wz range. The specific requirements for the tags included: 1,4O days, l_ife span; lithiun battery pov/er for reliability; - tag weight (I4 g in air) suítab1e for adult fish; external type with whip antenna. out of 6 radio tags received two v/ere defective. An ATS ¡fchal]-enger 2oorr model- radio receiver was used to detect and locate tagged fish.

rnitially, the radio tags were tested on three colnmon carp (cyprinus earpio) in a pond of area 0.5 ha at Godawary Fishery Development centre near Kathmandu during August 7-1,s, 1-990" That experi-ment provided the forlowing key information on equipment performancet a. The range of reception of a transmitter submerged l- m in a pond varied between 200 m and 1 km. b. The carp v/ere recaptured after a week and it was found that the transrnit.ters h¡ere stirl securery in place. L3l_ c" Experience lvas gained in using the receiver and antenna"

The katle for the experiment were capÈured durinE August, 26 and 27 0 ]-990 ' with gilI nets set. in the area of stat,íon number 1 (Fig " 2zL) " sexuarly mature, spawning females were serected by eNt,ernal examination for radio tagging, Tagged fish were 360-520 rnm in totar length and 450-1400 g in weight. The fish rdere anaesthetized with benzocaine (25 rng t-l) usinE the method described by Laird and osward (1975). .A,naesthesia usualty took L-2 minutes. Transmitters Ìdere praced beside the dorsal fin following the sub-dorsar- fin mount procedure described by winters (1'978) " After the Teflon-coated wire rdas threaded. through the tissue under the dorsar fin with the aid of a L6 gauge hypodermic needre, the transmitter ú¡as secured to the fish with a neoprene disc followed by a prastic disk on the opposite side of the fish" Both disks were 1 cm in diameter. The fish hrere usuarly out of the water for about one rninute for the att.achment of the transmitter. when the fish were placed in a tub of fresh water, they recovered in 5-10 minutes. They v/ere then placed in the reservoir. The fish rÀ/ere hand-held until they courd break away and swim off. The tag signal outpút rvas continually monitored during tagging and aft.er rerease" All the 4 fish were released at st,ation number 2 (see Table 5:1-)" Tracking of the fish was done either from land, walking along the shore of the reservoir and upstream, or from a boat. Forty-five tracking trips rrere made between å,ugust 26 and September IS, l_990. L32

Table 5: l-. Data on transmitters and katle tagged in the Indrasarobar Reservoir, August-Septernber, l_990.

F Tag Release Rel-ease Total- I{eig No Channel Date Location Length (s) No (mm)

L 8 Àug" 26 Station 2 360 450 2 1_ Aug. 26 Station 2 470 4-ì O 3 6 Aug" 27 Station 2 520 l_400 4 9 Aug" 27 Station 2 380 550 1_3 3

Observat,íon of sglavrning movemenËs Besides following ripe femare fish by radio tracking in the reservoir, an atteinpt h/as made to observe the spawning behaviour of katre in the Tadi River in August, Lggj-. Preliminary information on the spawning location and behaviour of katl-e hras provided by technicians of The Trishuri Fishery Research centre and l-ocal fishermen" The Khahare Khora was identified as one of the spawning sites of katre. The Khahare Khola is one of the feeder streams of the Tadi River. A fierd station of the Trishuli Fishery Research Centre is 1ocated at the confl-uence of the Tadi River and the Khahare Khora (Fig" 222) " According to the locar people and information from the literature, the second harf of August !/as considered as an appropriate period for observation. fntensive observation was conducted from 1-5 August, l-99t-, untir 7 september, 1-ggl_. The movement of fish in the Khahare Khola from the Tadi River was watched continuousJ-y. Four fishermen (from the Fishery Research centre) h¡ere ernployed to do this. Diurnal movements of the fish h/ere observed by men sitting beside the stream. Fyke nets were set at the Khahare Khola near its confruence with the Tadi River every evening at about 19:oo hours to measure the nocturnal- upstream and downstream movements of the fish. The nets were checked at intervals of 4 hours until 06.00 hours. physicar features of the v¡ater such as temperature, pH, turbidity and dissol-ved oxygen were measured during the period of observation. The shal-row areas with 1"34

gravel bott.oms were surveyed for fish eggs once a day using a rong-handled dip net. This net rdas thought to cause rninimum disturbance.

Ova díamet,er measuremenÈ

The ova diameters &¡ere measured for two purposes. The first was to determine the size of ova at different stages of maturity. For this, zoo preserved eggs s¡ere randomly serected from both the anterior and posterior parts of the ovary of fish in the second, third, and fourth stages of maturity from both the reservoir and ríver. The eggs rúere spread out evenly on a slide and their diameters were measured using an ocul_ar micrometer in a G92l_l_O monocular microscope, Olympus, H.S.C., Japan. The scal-e of the micrometer at the magnification used rùas l- minor divi-sion : 0.037037 mm. The second purpose of ova diameter measurements was to examine the size range of ova in mature ovaries. one hundred eggs from each fraction v/ere measured giving a total of 3oo eggs from each fish. The ova from each fraction !¡ere spread out evenly on the slide and diameters s/ere taken from randomly selected eggs"

Fecundity assessment Bagenal (J,971,) reviewed the rnajor methods avail_able for the estimation of absolute fecundity in fish. He defined fecundity as the number of ripening eggs in the female prior 1_3 5 to the next spawning" These methods and this definitíon are not, however, readily applicable to many tropical species. As pointed out by Bagenar (ag7r), such fish are frequently multipre spartrners and., as a result, a gronad rnay contain a wide range of egg sizes and maturity stages" This complicates both the assessment of totar egg numbers and the recognition of ¡rmaturetu egg sizes. To partly avoid these problems, the following rnethod described by Brake (1,977) was used in this study" The ovary was removed and weighed. The outer ovarian walr \,/as removed and the gonads split longitudinally and preserved in Gilson's ftuid (Bagenar, LgTa). The jars containing the eggs and fl,uid were agitated at regular intervals to facilitate egg separation. Microscopic investigatj-ons revealed the presence of many very smalr eggs, and the decanting of the supernatant fluid during washing required great care. rt trdas, therefore, inevitabl-e that some ovarian tissue debris remaíned in the sampre, but egg separation in general was satisfactory and counting was not impeded. After one month in Gilson,s fruid the eggs were sufficientry hardened to arLow handling and the estimation of numbers and sizes. At l-east three size ranges s/ere present, in two of which the eggs rdere yer-Iow and yolky, and in the third, small and white" Eggs in the first and second groups rdere considered to be developing ova and those in the third were consi-dered to be oocytes. As sub-sampling was necessary it was 136 desirabre to separate the eggs int.o the three fract.ions

according to diameter. The entire sample $¡as poured into a sieve of i-o cm diameter and with 17oo ¡rm apertures. The eggs q¡ere copiously washed and the residue retained. The filtrate eggs &¡ere then washed through a similar diameter sieve with apertures t-000 pm and the firtrate and residue retained separately. For each fraction, four subsampres of one thousand eggs each u/ere taken and placed in separate petri d.ishes. The remainder of the eggs !'Íere spread on a large pan. Ar1 these f ive containers rrere air-dri-ed for 4g hours. Atr four subsamples of one thousand eggs and the remainder \dere weighed to the nearest 0.0ool- g. Total numbers of eggs r¡ere calculated by the weight of known numbers of eggs (average weight of 1000 eggs) and the weight of the remainder. The number of eggs in the gonad, absol-ute fecundity, was estimated by the formula:

l_000 Eg: xWg D (ws) /N where Eg : total number of eggs in the ovaries, ws : weight of sample mean, Wg: weight of the total eggs, and N : number of sub-sampl-es. (!.tg = Wr + Ð (Ws) /N, where Wr : weight of remainder. )

The total- number of eggs Bras counted if the number Ìdas less than 4ooo" The fecundity was determined from g4 ripe females from the rndrasarobar reservoir and 35 from the Tadi River during l-990 and i-991" They ranged in tot.aI length from l-55 to 535 mm. Generarry the egg number (absolute fecundity) ]-37 ú/as related to the fish length by the expression (Bagenal,

a967) z F=aLb røhere F : absolute fecundity (no of eggs) n L : fish length (nm) and a and b are constants" rn the logarithmic form this expression becomes: logF:loga+b1ogL rn order to make a comparative study of fecundity of the katre in the river and the reservoir, the number of eggs g-1 of fish

(relative fecundity) v/as estimated (Das I Lg64) .

Collect,ion of abiot,íc data Surface water temperatures of the reservoir and the river srere measured once every day during the study period. The readings v¡ere taken at o9:oo with a yerlow springs rnstrument

(YSr) Model s4 temperature probe. The ysr s4 instrument Ìùas regularly caribrated using a standard grass thermometer. The reservoir temperature v/as measured at station 5 (Fig. 2zL) and the temperature of the river Tdas measured. near the fierd station of the Trishuli Fishery Research centre (Fig. 2:2). DaiJ-y data on precipitation at both rocations and rength of daylight in Kathmandu were obtained from the Department of Hydrology and MeteoroÌogy, Ministry of water Resources, His Majesty's Government of Nepal. The mean monthly temperature and length of daylight and total nonthly precipitation were cal-cul-ated from the daily data for the respective parameter. 1_3 I RESULTS

Sex rat,ås

The sex ratios between females and males are summarised in Table 522. rn the reservoir the femare to male ratios during 1988 to 1990 were 1:0.05, L:0.06 and 1:0.3r- respectively" rn contrast the ratios in the river were 1:2.08, 1:l-.15 and 1:0.95 during the same years. rt was observed that

during the whole study period the reservoir populatj_on rdas dominated by femal-es, and that mares were more abundant in the river" The sampling areas in both the habitats were extended during the second half of l-989 and in 1990. The upper area of the Indrasarobar Reservoir b/as sampled with different fishing g'ears and the sarnpling area in the Tadi River was extended by 2 km to the north and south beyond the usual l_o km sampling area of the river. As the sex ratios show, the abundance of the mal-es in the reservoir increased slightly during t-989 /90, and the proportion of femares increased in catches from the river during LgBg /gO (Fig. 5: i-) . However, overalI, the reservoir fish population was doninated by femares while males made up more than half of the total adult fish specimens from the river" A statistical test of proportion indicated that the proportion of femares v/as significantJ-y higher than that of males (p < 0.os) in the samples collected from the reservoir throughout the study period. Mares rdere significantry dominant in the river samples of the year l-9gg. However, the proportion l_3 9

Table 5:2 The sex ratio of katle in the two habitats.

HABTTAT NUMBER OF NIIMBER OF FEMALES MALES

1_988 Reservoi-r 535 26 l_: 0. 05 l_9 88 River 1-3 27 1: 2.08 l-989 Reservoir 482 32 1_ 0. o6 t_989 River 34 39 l- 1. i_5 1990 Reservoir 379 1_l-8 t_ 0"31 l-99 0 River 30r_ 287 1 0"95 l_4 0

Figure 5:1.. Number of mar-e, femal-e and juvenile katle in the river and the reservoir. R[wer

350

2æ

2æ 'tæ

ræ

Reservoir

ó00

5æ

4æ

3æ

2æ

ræ

0 t4L of males and females rdas not significantly different (p

MaturiÈy stages The ovary \das observed at seven different stages of development in femal-e katre from the reservoir and river (Fig. 522) " At the first and second stages of rnaturation, the ovary Ì,¡as like two small- pieces of compact tissue under the air bradder, and the oocytes were not visibre to the naked eye. The oocytes became visibre at stage three. The ovaries gradually increased in size and the oocytes became more distinct and translucent at the successive stages (Tabre 5:3). seven different stages of testes vrere al_so observed in mare katl-e from both systems (Fig. 5:3). At stage L, the testes were very thin thread-like paired organs under the vertebral_ column. They graduarly increased in size and urtimately occupied about two thirds of the ventral cavj-ty (Table 5:4).

The margj-n became hravy with transverse grooves. At stages 5 and 6, testes \Ä/ere pinkish white and turgid, and mil-t ran with slight pressure. The 'partly spent, stagie of gonads expected to be f ound in a partiar spakrner like katl_e was not encountered in the present study.

Cyc1e of maturat,ion since the annual maturation cycre of the katre in both habitats was similar in each year of the study period, aì_1_ the monthly samples from 19gg to 1990 for each sex and each L42

Figure 522" Diagrammatic drawings of the ovaries at different stagies of maturation: l-. virgin; 2" recovering spent; 3. developing; 4. developed; 5 gravid 6 spawning " r" " "

1-4 3

Figure 5:3 " Diagrammatic draruings of testes at different stages of maturation: l-" virgin; 2. recovering spent; 3. developing; 4" developed; 5" gravid; 6" spawning"

1,4 4

Table 5:3" Distinctive features of the ovaries of katle at different stages of gonadal maturati-on.

1-. Virgin Thin, smal-I, two pieces of compact tissue underneath the air bladder. Grey in col-our, oocytes not visibl_e to naked êyê, 30 to 6O ¡lm in diarneter.

2. Maturing Ovaries with compact 1obes, creamy to virgj-n and pale yellow in colour, ova spherical, recovering particularly laden with yoIk, egg visible spent with magnifying glass.Oocytes SO-fOO pm in diameter.

3. Developing Ovaries light yellow in colour with distÍnct btood capillaries, eggs completely opaque under microscope. Visible to naked êyê, whitish ánd granuLar. Oocytes 2OO-3OO pm in diameter.

4. Developed Ovaries large, bright yel1ow in colour with conspicuous blood capillaries and with distinct oval- shaped oocytes, 3OO- 2000 Í¿m in diameter.

5" Gravid ovaries enlarged and fi1l ventral cavity, yelIow eggs completely round and semi- transparent. Primary oocytes as in stage l- and 2 present" Eggs 3OO to 28OO pm in diameter "

6. Spawning Ovaries much distended, yellowish white, jel1y-Iike, eggs run with sl-ight. pressure, most eggs translucent.

7. Spent Ovary enpty, shrunken, bag-Iike, a few residual oocytes may be visibte. ]-45

Table 5:4" Distinctive features of the testes of katle at different stages of gonadal maturation"

1- " Virgin Very sma11 paired organs, close under the vertebral_ column, connected to air bladder, transparent.

2" Maturing virgin Slightty larger than stage L, length and recovering about half of the ventral cavity, spent transparent, reddish grey in colour.

3. DeveJ_oping Opaque and reddish with blood capillaries. They occupy about half of the length of the ventral cavity.

4. Developed Reddish white with s/avy margin and distinct blood capillarieã" rhey occupy about two thirds of the ventral êavity.-

5" Gravid White, wavy margin with transverse grooves and occupy the length of the ventral cavity" Drops of nilt exuded on pressure.

6" Spawning The testes occupy the length of the ventral cavity. They are pinkish white, turgid and nilt runs with slight pressure "

7 " Spent Flaccid, grey in colour with blood capillaries, without urilt. :J.46 habitat !ùere pooÌed to describe the cycle of maturation" Reservoir females in stages i- and 2 were found throughout the year (Fig" 5:4). From March, stages 3 and 4 began to deverop and all stages, 1 to 6, lrere observed in the samples from April to october" More than 60z of the total catch rdere at stage 2 except in March. Females at stage 3 were next in freguency, the percentage varying from 9"62 in May to 37"8å in March. Femal-es of stage 4 were found in the monthly reservoir samples from March to october" Their percentag.e r^ras 1owest in (4.82 May ) and highest in september (i-z "2e") " Gravid femal_es T,üere caught from April to october but formed a smaIl percentage of the total- catch" No running' or spent femal_es were caught throughout the study period" The number of males caught was very row in the reservoir samples (n : 176). stage 2 development was dominant among the reservoir mares caught throughout the study period (Fig. 5:5). stage 3 was observed every month from March to october except during May" Mares at stage 4 were present in the reservoir samples in April, July and August" Males of stage 5 were found onry in Jury and Äugust" No mares of stages 6 and 7 were ever observed in the samples from the reservoir. No mares above stage 2 of maturity rr¡ere caught from November to February. The general cycle of gonadar maturation of the katte in the Tadi river r^ras simirar to that in the rndrasarobar Reservoir except that stage t- constituted the highest percentage of the total nonthÌy catch in both sexes except in L47

Figure 524. Monthly change in the reservoir catch frequency (as percentages of the total female catch) of female katle at different staqes of maturity (l- t.o 7). ðg ou ro .g E stoge z U' q, o stoge o tt % ? 6a% W soge s f E ffi stoge a E E soge g 3 40% co o ffi stoge z õ= o ffi soge I EL 2OT" L48

Figure 5:5. Monthly change in the reservoir catch frequency (as percentages of the total male catch) of male katle at different stages of inaturity (1 t,o 7) " totr/o

òe 80ï" .E at, E Stoge z (0 o % stogeo ! 60% W soge 5 f b E ffil sose a

40% E stoge 3 o9. (¡) ffi stoge e ,ø(, ffi stoge t r& 2A% 1,49 september. Femares at stage z e¡ere found throughouL, ranging from 77 "3? in December to 3L"zz in september. Femares at stage 3 appeared in the catch in March and were frequently caught until- october (Fíg. 5:6) " Their proportion varied from 1,z.sz in Jury to 252 in May" stage s was observed only in the sampres from July to october, the highest percentage being observed in september (2o"3e") and the lowest in october (7.72) " stage 6 was observed in september and october, whire spent females hrere encountered onry in the month of october. Males at stage 2 frequently occurred throughout the study period" Their percentage occurrence varied from Lg.gz in June t-o 63.62 in December. stages 3, 4 and 5 appeared in March and T¡/ere observed until october (Fig" sz7). stage 6 fish s/ere found from June to october. spent males were observed only in the month of September. The occurrence of different stages over a greater part of the year (March-october) indicated the ext.ended spawning season of the katle in both systems.

Ãge at first maturity Among the cyprinids, mares are frequentry smaller than f emal-es, and f emares become sexually mature 1- year later than males (Mann , i,99J-) " Katle are no exception to this general rul-e. More than 50å of the river males caught during their second year $/ere mature (in the sense of having maturing gonads), and more than 9o? had reached maturity by their third 150

Figure 5:6. Monthly change in the rj-ver catch frequency (as percentages of the total female catch) of female katle at different stages of maturity (r_ to 7). 10070

òe 80% g stoge z ql, E od¡ ö % stoge o þ óo% Ë W soges 5 b Effi Stoge a E E ;. 40% E Stoge s co (0 lllll sose 2 Ea (l) ffi stoge t 'E 20% 151

Figure 527. Monthly change in the river catch frequency (as percentages of the total male catch) of male katle at different stages of maturity (l_ to 7) " àe B0% ,ãL E Stoge z (û o) o % stoge o v, ó0% Þ W stoge J s b E ffi Stogea o 40y" [tr stose o s tr c, lllll stoge 2 (t= d) l! 20% ffi soge t

JFMAMJJASOND L52 year of l-ife" Only 5? of river females were mature at the age of 2 years but al-most al-l of them were mature at the age of three years" Most of the three-year-old reservoir males krere mature" No fish less then 3 years old was caught from the reservoir, mainly because of the use of relatively large-meshed giIl nets (25-l-00 nm mesh). In the reservoir about 50å of the three- year-o1d females !,¡ere mature, and almost all fish in their fourth year of life had maturing gonads. The immature fish hlere significantly smaller than the mature ones of the same age in both sexes in both reservoir and the river populations. Maturation appears to be correlated with both size and age but the analysis of the rel-ative irnportance of the two factors is cornplicated because, while size and growth rate can vary continuously, the method of assessment allows age to vary only in units of a whole year. It was therefore considered beyond the scope of this study to distinguish the effect.s of age and size more precisely than has been described"

Fish movement Four mature fernale fish fitted with radio tags, released at Markhu (A) on 26 and 27 August, 1-990 | remained near the release site (A) for two days (Fig" 5:8 and Table 5:5)" Fish number l- moved towards site B on the third day (28 August) and hlas located around site B on 29 August" ft moved towards site C on 30 August where the Chitlang Khola joins the reservoir. l_53

Figure 5:8. Map of the rndrasarobar Reservoir showing the locatj-ons of tagged fish" 1-54

Table 5:5. Summary of the movement of katle as determined by radj-o tagging in Indrasarobar Reservoir, 1-5 : 26 August to September, l_990 (- not located) "

Date Location Location Location Location of fish L of fish 2 of fish 3 of fish 4

26 Aug. A (release) A (release) 27 Aug. B A A lreiease¡ A (release) 28 Aug" B c A A 29 Àug. B c D A 30 Aug. D D 31- Àug" : A c c 0l- Sept " A c c 02 Sept. D D G 03 Sept. D E G 04 Sept. D E D H 05 Sept. A F E H 06 Sept" c F F r 07 Sept. c I G I 08 Sept. c H I 09 Sept. c H ï 10 Sept. c I J l-1- Sept. c I J 1,2 Sept. c 13 Sept. c l 1,4 Sept. l-5 Sept. KULEKHAN¡ RIVER

INLAND FISHEFIIES CENTRE

CHITLANG KHOLA

THADO KHOLA 1-55

This fish could not be located on 31- August and 1- september but the radio receiver indicated its presence near site D on the morning of 2 september. rt was l-ocated in that vicinity from 2 septernber to 4 september" The fish returned to the area A on 5 september and again moved to site c on 6 september. The presence of the fish at location C lùas observed and recorded tv¡ice a day from the 7th to the 13th of september. when it was realised that the fish was not moving from the area, giII nets and cast nets were used to try and capture the fish. However, neither the tag nor the fish were recovered.. Fish number 2 moved towards site c on 2g August and remained in that area until 29 August" The fish courd not be located on 30 August but the radio receiver indicated its presence near site A on 31- August and l septernber. on 2 september the fish moved towards site D and then it nigrated to site E. After being located in that area for one more day it moved to site F on the s september. rt remained in that

location on 6 september and then travelred to area r on 7 september" The fish remained in area r until_ I september and thereafter could no longer be located. Fish number 3 moved towards site D on 29 August and remained there on 30 August" rt travel-Ìed towards site c on 3l-

August. rt was located in the same area on l- september but v¡as not found during 2-3 september" rt v¡as rerocated at site D on 4 september and in area E on 5 septernber. The fish reached siÈe F on 6 september and site c on 7 september. rt moved l-56 towards site H on I september and passed into the Kulekhani

River area r on l-o september and rernained at that site on l_j_ september" The presence of fish number 3 in area J was recorded on l-l- september but it could not be traced after this date" Fish number 4 was recorded near area A until 29 August. then it moved towards area D on 30 september and to c on 31 september. rt travelled from areas c to G on 2 september. From area G the fish travel-Ied towards H on 4 september, continued

its upstream journey and passed into the Kulekhani River on 6 septernber. rt spent three days in area r and then it, moved towards site J on 10 september and rdas recorded in that area until 1-2 september" The location of fish number 4 courd not be traced after that date.

Äbout a 1-5 km stretch of the Kulekhani River rdas regularly surveyed from area A to palung untir l_5 september, l-990, but no signars were received. All the mature females, after being tagged, migrated upstream. Three spav¡ners moved towards the Kulekhani RÍver and the fourth towards chitlang Khola" rt seems likely that a1l the ripe fish migrated upstream in search of appropriate breeding grounds. However, none of them !/ere recaptured. There are six fu1l-tine and twenty part-tirne fishermen engaged in fishing in the reservoir and in the upstream river (personal observat.ion) " since fishing pressure in the rndrasarobar and Kurekhani River was quite high, the fish numbered 2, 3 and 4 may have been caught r57 by local fishermen who may then have thrown the radio tags away. rt was surprisi-ng to receive a strong signar frorn fish number 1- in area c without any sign of movement of the fish. rt is possibre that either the fish had been captured by a fisherman and the tag was thros¡n arday in that area or the fish had died at that location and the tag remained on the bott.om.

VÍsua1 observat,ions of spawníng of katLe upstream movement of 3 fish to the Khahare Khora stream from the Tadi River was observed on 2o August at about. j-6:oo. The fish h¡ere followed. They appeared to move rapidly for the first 300 m. They sl-owed down after they reached the sharlow and slow moving part of the stream" The targest fish, probably femal-e, vtas leading and two small-er fish, presumably ma1es, followed her. As soon as they found a wide, shallow pool with

a gravel bottom, they stopped" They then started to swirn in a non-directionar manner, over and around the spawning substrate. some movements v/ere circular (anti-crockwise and clockwise), whereas others v¡ere spiral and upward. Both the males were seen to be equalry active and swirnming arongside the femal-e. Unfortunately further under-water movement was not visibl-e from the bank of the stream partry due to darkness and partly due to the turbidity of the water, A torch was used but with littre success. After harf an hour the same f ish r,,rere noticed entering the Khahare Khola. A fyke net, facing towards the stream, was set near the confruence of the river and 158 stream. The net was watched from the shore. Two spent fish (one female and one male) v¡ere caught in the net at about 0l-:00. Both f ish Þrere examined externalry and internarly. Their rength, weight and gonadal condition were measured and recorded. The total length of the female u¡as 365 nm and its weight was 600 g" The male was 320 rnm in total length and 300 g in weight" The spawning site ruas observed the next morning and eggs r^rere found on the gravel bottorn of the strean, which confirmed the lithophili-c spawning behaviour of the katre. one thousand fertilized ova $¡ere colrected with the help of a long-handled dip net" The ova were transferred to the Fishery Research station, Trishuli, and incubated at the hatchery" The water temperature at the spawning ground ranged from 20-22"cì the average values of the dissol-ved oxygen content and pH at

08:00 during the observation period (1,s-25 september, 1991-) were 6.98+0.098 mg 1-1 and 6.73+o"113 (! gsz cL), respectivery. ova diameter ova measurements compared between individuals from the river and reservoir, at the same stage of maturity (z-4), show no significant difference in their frequency distributions between habitats" Eggs were taken from the various parts of the ovaries of fish at stages 2, 3 and 4 of maturity" Measurements rc/ere made to the nearest o " ol- nm. These !¡ere grouped in intervals of o.2o rnm and their percentage frequencies are presented in Figure 5:9. 1_59

Figure 5:9. Egg size (¡n¡n) distribution in the ovaries of katle at stages 2 to 4 of rnaturation, combined for river and reservoir fish (Egg size groups: O"2:0"01--0"2; 0"4 =0"2L-O"4¡ 0.6 : O"41,-O"6; 0"8 : 0.61--0"80r" 1"0 : O.8L- 1.0; L.2: l_"01_- L.2Oì I.4 : l"2L-1.4¡ l-.6 : 1-"41-L"6O; l_.8 : : l-.61-l-"80; 2"O l-.81-2.0 nm) " a: stage 2

100

\o 80

oË60 å40 @ tL 20

0 0.8 1 1. Egg diameter mm

b: Stage 3

80 -. 70 o- 60 ðso ã+o 3so t10E20 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 Egg diameter mm

c: Stage 4

25 s20 Ë1s o 3ro t!5E

0 0.6 0.8 1 1.2 1.4 1.6 1.8 Egg diameter mm t-60 At stage 2, which represented immature fish, the rnajority of oocytes v/ere in the size range of o.o5 to 0.l-6 nm (Fig. 5:9a) " As maturation progressed, the oocytes gradually increased in size with the formation of yolk around the nucleus" ^At stage 3, the size of ova ranged from o. j-6 to o.3o j-n mm diameter and two distinct batches of oocytes !¡ere seen

(Fis" 5:eb) " At stage 4, the size of oocytes further increased and varied from o.30 to t-"60 mm in diameter. Three distinct types of oocytes (irnmature, maturing and mature) were present in the ovary. Three peaks v/ere clearly visibre (Figure 5:9c). At stage s I the mature eggs increased in size and their diameter was àl-"60 mm" The second batch shows a peak at O.gO mm and the third batch of eggs shows its peak at o.3o nm (Fig. 5:1-0)" At stage 6, all three batches of ova further increased in size. Data on the diameters of mature eggs of katle of stage 5 from the reservoir and river over four dífferent months (Jury to oetober) v¡ere analysed using two-way analysis of variance. As can be seen in Table 5:6, the location on its own does not appear to have much infruence on the size of the eggs, but the tirne of maturing (rnonth) definitety does. The estimated means of the egg diameter for the different locations and months suggest that the sizes of the eggs maturing in different months are significantry different (Fig. 5:l-1-). The largest eggs were produced in septernber and the smal-lest !ùere produced in october. production of the largest T6L

Figure 5: 1-0. Eqg size (nm) distribution in the mature _ovaries (stage 5) of the katte: a. Reservoir; b" River (Egg size groupsz O.2 : O. O1--O.2¡ O.4 : O"2L-O"4ì 0.6 = 0"41-0.6r. O.B : 0"61_-0"80; l-"0 : 0"81-1-"0; L"Z: 1"01-1_.20; L"4: L"2\- L.4; 1-.6 : 1.41_-l_.60r" l_"8 : 1_.61--J_"g0; Z"O : 1,.8I-2"O¡ 2"2 : 2"OL-2"2; 2"4 : 2.2L-2.4¡ 2"6 = 2"41,-2"6 mm). a: Reservo¡r

200

o 150 .ct E c, 100 tt, E' uJ 50

0 1 1.2 1.4 1.6 1.8 Egg diameter (mm)

b: River

200

¡c, 150 100

ED ED uJ 50

0 1 1.2 1.4 1.6 1.8 Egg diameter (mm) r62

Figure 5: l-l-. Var j-ation of mean egg diameter (with gSZ confj-dence linits) in mature katle from the reservoir and river during JuIy to October. (Location: O = reservoirí L : river) (Months: l- : July; 2 : August; 3 : September; 4 : October) Location Mean 0 L-944 .l ¿ 1.903 1-890 1.920 1-950 1-980 Individual 95% CI Mcnth Mean -+------+------+------+------+ 1 L -825 ( ---x--- ) 2 2-005 ( ---*--- ) 2. 1ô5 ( ---x--- ) 4 1-701 ( ---*--- ) -+------+------+------*+------+ 1-650 1.800 1.950 2-LOO 2-250 (mm) l-6 3

Tabre 5:6. Resurts of anarysis of variance on egg dianeters of katle"

Source DF SS MS Results (52 leve1)

Location 1 0.l-005 o. i-005 1 . 821_ Non-signíficant Month 7 3 "4375 2 " 4792 44.91, Significant fnteraction 3 0.8260 o.2753 4.987 Significant Error 232 1-2.797 0.0552 Totaf 239 21,. L61_ 464 eggs in september probabry indieates that this is the main breeding period of katle"

!'ecundíty

Absorute fecundity of katle in both the river and reservoj-r varied considerably from individual to individual.

rt ranged from 1-1387 eggs (in a specimen of l-60 mm and 53.8 g) to 33,27o eggs (535 mm and 1-zso g) in the reservoi_r

popurati-on, and from 760 (155 mm and 40 g) to 8,951- (395 nlm and 500 g) in the river popuration" These data hrere plotted (Fig. 5:1'2) and the l-ine of best fit determined by the method

of least squares. stopes (b coefficients) of the 1990 and Lgg1, fecundity regression lines for riverine and reservoir popurations were tested for homogeneity and then compared. The b coefficients were not significantly different between years within habitat (p < o"o5) " Therefore, data for two years !¡ere cornbined to provide the following relationship:

: Reservoir: log F -e "9846 + l- " 8848 log L (tz O"77, n : 84) River: l-ogF=-4"30L4 + 3 "2996 log L (rz 0"85, n = 35)

Analysis of variance showed that the slopes k¡ere significantly different between reservoir and river fish (p from the river were ress fecund than the reservoir katre at the smaLrer sj-ze; however, absorute fecundity seemed to increase rnrith size more rapidry in the river fish, and. they l_65

Figure 5.]-2. Retationship between fecundity and fish rength (run) in katle (-e- - reservoir; ". .@... - river) . c, -o 3E c o) o, o g 3,5 b ç, () ¡!o

2.3 2.4 2.5 I aa óaåal laaaaÈ. ad diaE+ taa\ Lvy r\rrv¡ !r=r r!4ü ! L,r ¡¡Ðr r \¡ r ¡¡ a t, 466 Ìdere more fecund than the reservoir f,ish at the higher tot,al length (Fig" 5:1-2). The average relative fecundity in the reservoir popuration was 19"13 + j-"s6 eggs E'1 compared to 22"57 + 1-"4L eggs g-1 for the riverine ¡lopulation" A student, t test showed that the relative fecundities of the reservoir andriverinepopu1ationsIderesignÍficant,lydifferent(p< o"0r-) "

Seasonal varíat,ion in abiotíc factors a " I¡Iater temperature: The average surf ace water temperature in the reservoir was about l_4"c during January and February. rt started to rise from March and remained above

2ooc between May and october (Fig" s: J-3 ) " There are significant seasonal differences in surface wat,er temperature between the river and the reservoir. The average surface water temperature of the river r¡¡as higher than that of the reservoir during March and July and l-ower during November and December

(Fig. 5:13) . b" Day length: The average day length in Kathmandu valley varies from 625 rninutes in December to g3i_ minutes in June. rt remains relativery long between .A,prir and september and relatively short from November to March (Fig. 5:14). c- Annual- precipitation: There are distinct. dry and wet seasons in NepaJ. " usuall-y the monsoon starts in June and lasts until september. Most of the rainfarr occurs during this period reaching a peak in July and August. The riverrs r67

Figure 5: 1-3 . Seasonal- variation in surf ace water temperature ("C) in the Indrasarobar Reservoir and the Tadi River. O 0 (Ð ¿ 5 o.lcd, Ë o o Þct

FMAMJJASOND tulonfhs i_68

Figure 521,4" Length of daylight hours in the study area during the year. l3:55

;:,E 13:26 .g E 12:57 .9, 12:28 õ Ee, l2:@ uJoo øE I l:31 Eo I l:02 (Ð (t) l0:33 o o l0:04 9:3ó JFMAMJJAS Months L69 \,{atershed area receives higher precipit.ation annually than that of the reservoir (Figs " 5: i_5, 5:1_6) ,

Drscussrolt

A signj-f icant departure of the sex ratios from j_: l- was found in the reservoir: females were dominant throughout the study period. The number of males \das higher in the river catches during 1-988 and 1999 but the number of femal-es was slightly higher in the catch of l-990. Higher numbers of males than females have been reported in other species of cyprinids, sampJ-ed mainJ-y in streams (Siddique et ãI., 1_976; Mann, 1-980; and cooper, l-983). These workers suggested that this imbalance \,'las related to a number of factors including differences in age cornposition due to higher rnortality in the males and asynchronous spawning migrations. since the femares had a prolonged breeding season, they may have remained upstream for a longer period than the males" Al-khory (t972) and Et-Absy (L977 ) have reported shoreward migrations of puntius barberinus to safer spawning grounds and that females stayed longer in the spawning areas than males. Thís significantry reduced the proportion of females in the main populatj-ons. simil-arl-y in this study, katle were found t.o have a prolonged breeding season from Äpril to october and most of the rnature femal-es migrated to suitabre breeding grounds, possibly remaining there for longer periods than the males. rt seems 1-7 0

Figure 5: 1-5. Monthly precipitation (run) in the Indrasarobar Reservoir area throughout the period study (1e88-1ee0) " Precipifotion mm 888888899,=l$r\)(/)(f,)ÄÀ L7L

Figure 5:1-6. Monthly precipitation (mm) in the Tadi River area throughout the study period. O €(f muJ uo!+Þlldlca¡d 472 that the higher ratj-o of mal-es to females during the year j-9gg h/as the result of the spawning migration of the femares upstream in the Tadi River beyond the sampling area. This was confirrned by the increased proportion of females during the second half of 1-989 and the year l-990 when the sampling areas I/ùere extended by 2 km upstream in the river. The extrernery low number of mare fish in the reservoir is difficurt to explain. There is no evidence of sex reversal in this speciesr âs is found for some tereosts (Reinboth, 1-970; chant L970) " one of the possible reasons for the lower numbers of mares in the reservoir may have been their preference for living in the riverine environment (in the Kul-ekhani River). They may participate in spawning activities when the mature females migrate upstream in search of suitable breeding grounds. Another reason may have been that mares have

a higher morta]-ity rate so there are fewer ol-der mares. No mal-es larger than 350 nm in length s/ere caught frorn the reservoir throughout the study period" The use of different sarnpling gears may have been a reason for recorded d.ifferences

in the proportion of mares at the two sites. The reservoir was sampJ-ed using multi-panel gill nets and the smalrest fish caught were l-30 mm in totar length" The smalrest males caught in the rj-ver v/ere 80 mm and they were observed at a different stage of maturity. Therefore, it seems possible that males between the sizes of 80 nm and i-30 nm constituted a significant percentage of the katle population in the L73 reservoir and that these &¡ere not caught by the gill nets employed" Ä'nother distinct difference observed between the sexes in this study rdas that the males matured at least one year earlier than the females. Precocious male sexual maturation has likewise been described in other species of fish, inctuding sarmonids (Burgner, L99t; saro, tggL). There arso seems to be a tendency for larger individuals in both habitats to mature earl-ier than smalrer ones, and for river fish to mature earlier than those in the reservoir. The reproductive cycre can be divided into two main phases, gametogenesis and spawning" During gametogenesis, specialized gametes (oocytes and spermatozoa) are formed from simple germ cells (oogonia and spermatogonia). spawning involves a complex sequence of events which is more variabre in duration than garnetogenesis" This involves the liberation of gametes, meiosis resumption, oocyte maturation, owuration and oviposition in females, and sperrniation and sperm rerease in males (craig, agBT). various factors, both intrinsic and. extrinsic, have been shown to regulate gametogenesis and spawning in fish (Bultough, Lg3g; Ang, 1,973-). The intrinsic factor is the internal gonadal rhythn (hormonal), whire the extrinsic factors are environmental conditions which determine the actuar tirne of breeding" Temperature and photoperiod are apparently the most irnportant external factors that regulate breeding in fish while other factors have a secondary effect L74 (Vlaming I L974) " sexual deveropment and spawning in cyprinids are modul-ated both by temperature and photoperiod, although temperature is the predominant infruence in most species (Bye, l-984). The common carp exhibits an interesting evidence of the infruence of t.emperature on its reproductive cycIe. Though in temperate conditions it spas¡ns a single batch per year, spawning may be spread over several days by drawing on portions of a single batch of matured eggs (Horvath, l-985). This repeat spawning within days is quite distinct from fractionaJ- spawnirg, as the carp requires some 3-3"5 months at 2o-22oc between two ovulations. rn temperate crimates any possible second spawning is suppressed untir the foIlowíng year due to l-ow temperature. However, in a tropical climate the comrnon carp is a true fractionar spawner, producing two or even three batches of eggs each year" Reproductive effort may be relativery ]ow, with the female gonads forming around l-o? of body weight at maturity (Horvath, t-986). Although in cyprinids severar hrarm days induce a rapid rise in plasma gonadotropin, this does not inevitably lead to owulation if the environmental conditions are not appropriate. Temperature and photoperiod interact with the endogenous reproductive cycre to ensure that gonads are mature at the appropriate season" The tirning of the endogenous reproduction cycre is synchronj-sed by these environmental stinuli. The external information is transmitted to the brain via the nervous system which in turn regulates the ant.erior pituitary gland. This L75 gland controls gonadal development via the endocrine system

(Mi1ls , I991) " From the inspection of gonadal patterns in this study it appeared that the katle r¡ent into a quj-escent phase in their reproductive cycle between the months of November and February" rn this period both males and females had small gonads and no brooding females srere caught" The gonads started to deverop in March and entered into a reproductive phase from March to October" An atternpt v/as made to relate the effects of several environmentar factors such as day length, temperature and precipitation to the reproductive behaviour of the katle. The average surface water temperature in the reservoir and the river remained low during winter (January, February), started to rise in March, remained higher during the months of April to october and decreased from November, reaching its l-owest level- in January and February. Gonadal devetopmental in the katle seemed to coincide with the rise of temperature in both the river and reservoir. similarry average day length varied from 625 mi-nutes in December to 831 minutes in June" rt remained longer during sunmer and early autumn and shorter during winter. There are distinct dry and wet seasons in Nepal-. usually the monsoon starts in May and lasts untit september. From March to october the periods of ì-onger day length and higher temperature coincided with the initiation of reproductj-ve activities in katle. This is consistent with j.76 suggestions of several e/orkers (pickford and A1'z, t9S7;

Aronson , L957 ; A,bidin, 1-996 ; Hyder , 1-97 O) that high temperature and intense sunlíght are environmental factors that trigger reproductive activity in cyprinids" The role of fl-oodwaters in the spawning of freshwater fish has been studied by many *¡orkers (Hora, LgLs; Alikunhi and Rao, l-951-) " Since the katle has a prolonged spawning season, pre-monsoon to post-monsoon, flooding does not seem to be an essentiar factor in its spawning" stirl, the katle may be taking advantage of floodwater to reach the shallow breeding grounds. similar upward migration of Tor tor during monsoon flood in the river Narmada was been recorded by Desai (1-973). The spawning movements of ripe females in the reservoir and the river suggested that the katle rdere very sel-ective in finding a suitable prace to lay eggs" rt appears that they preferred to lay eggs upstream on a gravel bed free of rnud and algae. Their pre-spaerning migration seems to be associated with the search for a suitable spawning ground with

a freshly inundated gravel bottom. A similar situation &¡as observed in lLirogrex terraesancte, a cyprinid in Lake Kinneret, by Gafny et a7" (1992) " The fish selected the near shore and spawned on algae-free rocky beds when these rdere avaiLable. this resulted in increased egg survival. Ahmad (l-948) reported that katre breeds from Aprir to october with a peak period in August and sepLember røhereas Jhingran (L982) reported its breeding from May to september. L77 In the present study mature katl-e were observed from March to october" However running and spent katre were not recorded ín the reservoir" rt seemed that the majority of mature fish migrated from the reservoir after reaching rnaturity stage 4 and 5" This was further supported by the activities of the mature fernares whose movements were tracked by radio teJ-emetry. The presence of different sizes (batches) of oocytes indicates that the katre is a serj-al spawner. rn several studies of the fecundity of serial- spav¡ners, attempts have been made to estimate batch size and number of bat.ches (Þfacer L974; Mackay and Mann 1969) " Batch size can be defined as the number of oocytes which wilr be released together as a group. the least mature batch comprised the smarlest ova, which rrere transparent and white. The second category contained eggs that were intermediate in size and yeIlow in colour. The most mature batch of ova rúere the largest, being ye]-1ow-orange, translucent and heavily yolked. The presence of several sizes of ova in a mature ovary is an indication of muttipre spawning (Behmer, 1,967; Johnson, r97L) " rt may be assumed that the largest ova are spawned first, the intermediate ova then mature to be spawned, a third batch may then develop, and so on. This sequence of events would probabry continue as long as the temperature, photoperiod and food supply remained adequate and the fish !¡as in a physiorogicarly responsive state. rn serial spav/ners, fecundity would appear to be very frexible, L78 since the process of synchronous oocyte devel_opnent. and oocyte resorption makes it possibre to control the egg number during the current spawning season. More eEgs may therefore be released in a favourable season than in an unfavourabte one. The term favourable night rer-ate, for eNampÌe, to the abundance of food, since there is evidence that. the ratter can

affect fecundity (Bagenal, 1969) " Nikolsky (L969) stated that rnultipre spawning was onry possibre when there was a long períod of adequate food supply for the l-arvae. However, he warned that it wourd be ¡yrong to regard this life history strategy as an adaptation to food suppry alone because it could also be an adaptation to unstabl-e spawning conditions" Burt et al" (1988) have extended Taylor and williams ( l-993 ) optirnar life-history model and suggested that continuous reproduction kras a conceptual standard condition. They believed that nultipre spawning within a season resulted from seasonality constraining reproduction to a particurar time of the year, whereas single spawning resulted from more severe environmental constraints.

They suggested that murtiple spawning within a season was associated with: (1) l-ess seasonar change in the environment; (2) small body sizes; and (3) small-er rerative ovary sizes. Although these three claims probabry have substance for fish in general, they do not seem to be applicable to katle, which is found in seasonal waters and whose body size is relatively large" rn this long-lived low fecundity species perhaps 1l-79 multiple spawning may have developed as an adaptation to spawning under labile conditÍons for egg survival (Nikorsky, L969) and to high recruitment variability. There are several advantages conferred upon fish that are rnultípIe or serial spawners: (1) fncreased fecundity: Just prior to ovulation, oocytes hydrate and increase greatry in size" rf all the oocytes hydrate at the same tirne, the restriction of space within the ovary l-irnits fecundity" However, if smalÌ batches of the eggs hydrate and are spawned at intervals, more eggs can be accommodated in the ovary over time (Mir1er, LgB4; Burt et

ã7" , l-988) " (2) The risk of predation of eggs and larvae is spread over a longer period (Lambert and Ware, 1984) " (3) The impact of larvae on their prey species is spread over tirne" (4) The risk of spawning at a time of unfavourable climatic, hydrographic or feeding conditions is spread out. Dasgupta (1988a) has described katle as a prolific breeder but not very fecund. Low fecundj-ty v/as arso observed in the present study" The relative fecundity and recorded age of katle !/as compared with some other rndian cyprinid.s observed by several workers (Tab1e sz7) " Katle had the lowest nurnber of eggs g-1 body weight among them. rt seems that the nultiple spawning behaviour of the katre with low fecundity is an adaptation to the high mort.atity of juvenires in the hill 1-8 0

Tabl-e 527 " Relative fecundity and recorded age of some cyprinids "

SN" Species R-Fecundity Age Source No Egg g-' (yr) l- Rasbora 630"00 Nagendra et al, L}BJ- daniconius 2. Labeo dero 3g7.I2 6 Bhatanagar, 1964¡ Biswas et a7., L992"

3. Labeo bata 393"04 7 Chetterjii et al_ tLg7g. 4. Labeo caTbasu 277.77 8 Rao & Rao, LTTZ; Gupta & Jhingran, 1-973. 5. Labeo rohita 62 i-o singh & srivastava, r9B2¡ Khan & Siddigue, L973" 6" Labeo A7I 6 Rao, 1974" fímbriatus 7 - catla catTa 232"02 singh & srivastava, ]-g}2. 7 " Cirrhina 21,4 .7 4 7 Hanumantharao, mrigaTa ]-g7L"

B. Cyprinus l_l_O " 80 6 Das, Lg64; Das & carpio Fotedar | 7-96s. 9. Schizothorax 29"04 Jyoti & Malhotra, níger Lg7z" 10. Tor 25"00 17 Tandon & Johal, Putitora 1983 " 1l- " Tor tor 06. i_3 Nautiyal & LaI, l-985

L2 " lleo-Z.issochiTus l_6 " OO Dasgupta, 19BBa hexagonoTepis

1-3 " t. 20.50 l_1 present study l-8 l_ streams due to high monsoon ftooding" The reproductive strategy of a species is a summation of a suite of adaptive traits that enabres individual fish to leave the maximum number of offspring (Millsr L99j_) " Though there have been few conclusive experimental demonstrat,ions of the cost of reproduction (Reznick, 1995), ít, is rikely that the earl-ier and greater the degree to which energy resources are diverted from maj-ntenance of somaÈic growth to reproductive output, the lower will be the parents' survival to future spawning. rt has been argued that this trade-off will be conditioned by the barance between pre-and post- maturity rates of mortality and that selection witt favour lower fecundity and greater longevity with increased variation in spawning success (Mann and Mil1s, Lg7gll " The data collected on â9e, growth and reproduction of the katle reveared that it is a long-Iived, sl-owry growing and nultipry spawning species of row fecundity. Extreme environmental- conditions, such as high frooding in the fast flowing rivers caused by monsoon rain and the substantial annual drawdown in the reservoir, probabry cause high mortarity among juveniles" survíving adults exhibit slow growth, long life and a modest investment of energy in gonadar deveropnent. rt seems reasonable to suggest that, the murt,ipre spawning and l-ow fecundity of the katle is a reproductive strategy, âD adaptation to the unfavourabre hydrographic condiiions of hill streams and fluctuating natural reservoirs. 182

CNÃPTER VT

GE}i¡ERAL SttM}4¡ÀRY Ã3{D DfSCUggECIW'

This study has revealed interest,ing sinilarities and differences between a reservoir and a river po¡ruration of katLe o Neorissochilus hexagonorepis (Mcclelrand), and also 'between katle and other groups of fish. The overalr feeding patterns of katle in the Indrasarobar Reservoir and the Tadi River were found to be basically siurilar. rn both groups, prant matter formed the highest percentage of the totar vorume of the gut contents, folrowed by animar matter and then by detritus and mud. rt was evident from the study that the contribution of prant food increased with the size of the fish in both habitats. Associated with this dietary shift was an increase j-n the relative length of the gut with increasing total length of the fish in both populations (see below). Along with these general sinilarities, some differences $/ere observed in feeding habits between the river and reservoir katre. The gut contents of the river katle were dominated by vascular plant tissue and filamentous algae, while terrestrial grass and pranktonic blue-green argae rdere more common in the diet of the reservoir popuration. Differences hrere also evident in the variety of animar food. rn the reservoir, zooplankton constituted a higher percentage of the total gut contents, and annerids were the most, colrrmon l_8 3 benthic animal-s in the diet" rn the ríveru on the other hand, zooplankton were very scarce ín the diet.o and the ¡lredominant, benthic dietary items krere the nynphs of aquat,ic insects. These differences probably reflect the dífferentíal availabiJ-ity of the respective prey species in the two habitats: zooprankton thrive in the reservoirrs water corumn and annelids are abundant on the reservoir frooru whereas insects favour the frowing water condit,ions of the river bottom to reproduce (yadav, 1989) " The percentage of detritus in the gut contents of the reservo j-r katl-e was considerably higher than in the gut contents of the river katre" There is arso an apparent difference in feeding intensity between popurations. The reservoir population attains its peak consumption in July and maintains quite a high rate until- November. The river katl-e attain their peak intake onry in september. These differences are probably also environmentally induced: the reservoir achieves its peak surface area (conducive to food generation) only in Jury and then maintains a high area until the winter, whereas the river katle's food suuply is diminished by the flushing effect of monsoon floods through July and .A,ugust

(Fig. 5: 1-6," Appendix 3 ) " The average weights of gut contents (in percentage of the body weight) for different J-ength groups in the reservoir are higher than those in the river" Retative gut length was also influenced by habitat: while the length of the gut was similar L84 beÈween the reservoir and river for int,ermediat,e-sized fish (totar length approximatery 150 rnm), the rate of increase ín relative gut length during further Erow-th of Èhe fish çras greater in the reservoir. rt seems apparent that the increase in relative gut length ís related to the observed shift fron carnivorous to herbivorous feeding during the growth of katre (Biswas, 1985). The guts of the smallest katle caught in this study contained 322 to 532 animar matter, while the animal- content, in the larger fish's guts was only 6z Eo l-3å" Herbivorous clprinids in generar have relativery longer guts than carnivorous ones (Das and Moitra, l-956a,b,ct L963; hieatherley and Gil_l , L1BT), presumably because vegetable matter is digested more sIowly. rt is interesting to note that when kat.le are presented with the environmental- opportunity to benefit from increased herbivory (in the reservoir), they can respond by increasing their relative gut length" This capacity may be a major adaptive specialisation in the feeding ecology of katle in the

reservoir " overaì.1, after carefur examination of the feeding behaviour of'katle from the river and reservoir and comparison

of these data with those of previous røorkers, it seems reasonable to suggest that the feeding differences observed between katle in the two systems can be exprained by differing envíronmental conditions and the fishrs adaptability" 185 The growth of katle also showed both sínilarities and differences between the two systems. rt seems to be a feature of katle from both populations that femal_es attain a larger size than maIes" Males, however, mature about a year earlier than females, between the ages of two and three years" This male reproductive precocity is a feature shared with other çtroups of fish, including salmonids (Burgner, L99L; Salo, 1991). Faster growing individuals were observed to mature earl-ier than slow growers. Comparison of specific Arowth rates in various age groups of katle from the reservoir and river shows that the relative growth in length is rapid during the first three or four years in both habitats. All the fish have reached maturity by the age of four years and the growth rate in length declines after rnaturity. rn the reservoir population, the instantaneous rate of growth was 4oZ yr-1 in both females and males between the ages of 1 and 2 years" In the next year the growth rate remained more or less the same in females but dropped to about 2L2 yr-1 in males. The growth rate continued to d.ecrease with increasing age in both sexes" The trend for the instantaneous growth rate in the river popuration to decline with age was similar" The growth rates of 432 yr-1 in females and 33å yr-1 in males between the ages of 1 and 2 decreased in each successive year in both sexes. Estimation of the ultimate size L" and the growth coefficient K of the von Bertalanffy growth moder for each sex 1_8 6 from both habitats revealed that L* is greater for females (73 and 45 cm in the reservoir and river respectivery) than for males (4r and 26 cm), and that K varues are higher for males (0'1-95 yr-r in the reservoir and 0.135 y¡-1 in the river) than for females (0"089 and 0"120 yr-1)" L. is clearly greater for the reservoir kat.re than for the river katle, whire K values are greater in the river popuration than in the reservoir. Comparison of reproductive biology between the reservoj_r and river populations did not reveal any strong differences such as rnight, have been expected on the basis of the observed differences in feeding and growth. one apparent di_fference was in the sex ratio: the reservoir catches $rere dominated by females while males srere more abundant in the ri-ver catches during the whore study period. The use of the different sampling gears may have been a reason for recorded differences in the proportion of males in the two habitats. The reservoir was sampled using murti-paner giIl nets and only a few fish under l-30 mm in total- length were caught. rn the river, sarnpled with a variety of gear, the small-est males caught were 80 nm in total rength and they were observed to be at different stages of rnaturity. Therefore, it, is likely that mal-es between the sizes of go nm and 130 nm constitute a significant percentage of the katle population in the reservoir and that they were not caught by the fishing gear ernployed. L87 The inspection of gonadal cycres revealed that katre in both habitats went into a quiescent phase between the months of November and February" rn this period, both mares and females had smal-J- gonads and no brooding females were caught. The gonads started to develop in March and remained ín their reproductive phase until october" The spawning novements of ripe females in the reservoir and river suggested that katle are very sel-ective in finding a suitable prace to Iay eggs. They apparently prefer to 1ay eggs in fast frowing streams on a gravel bed free of mud and algae" The pre-spawning rnigration in both systems seemed to be associated with the search for a suitable spawning ground with freshly inundated gravel bottoms" The presence of batches of oocytes of different sizes indicated that the katre is a serial spawner. The average relative fecundity hras found to be somewhat lower in the reservoir than in the river (about ag vs. 23 eggs gm-l). The absol-ute fecundity increased with the size of the fish in both populations. At smatler sizes, reservoir fish were more fecund than river fish, while larger fish were sígnifÍcantry more fecund in the river than in the reservoir. The data col-rected on food and feeding, âgê, growth and reproduction revealed that katle is a) a highly plastic omnivorous cyprinid which has evorved to rive successfurly under a variety of conditions, b) a rnultipte spavrner with a pre-spawning nigration and low fecundity, and c) a rong-rived, slowly growing hill stream fish with large urtimate size. rts 1_8 I feeding Íntensity, seasonal growth and reproduct.ive cycle are probably mainly governed by the seasonal variations ín water temperature and length of daylighto and uttimately by abundance of natural food resources. Extreme environmental conditions such as high flood in the fast flowing rivers due to monsoon rain and substantial annual drawdown in the reservoir probably cause high mortality among juveniles, but surviving adults exhibit slow growth, long life and probably modest investment. of energiy in gonadal developmenL" Its omnivorous feeding habits enable this fish to maximize its utilization of available food in the ecosystem. Katle provide a herbivore link with the first trophic level- in the food chain in freshwater rivers and reservoírs. Further, the large ultimate size of katle makes it valuabl_e and attractive for food and sport" Its long spawnÍng period also helps it to continue recruitment during the larger part of the year (April- to October). Considering these characteristics, it is reasonable to suggest that katle has relatively high potential- for development as a food and sport fish in Neparese reservoirs. Although the above-mentioned are positive features, Iow fecundity and slow growth may be two linitations of katre as a species for commercial fisheries" However, fecundity is variable in serj-aI spawners, since the number of eggs produced can be controlled through the processes of synchronous oocyte development and oocyte resorption" Þfore eggs may therefore be 189 released in a favourable environrnent than in an unfavourabl-e one" similarly, the annual length increment of katle is higher in the reservoir than in the river. Therefore, it can be assumed that the grow'bh rate of katle coul-d be further improved by providing an opt,irnal environment. Besides the above (genotlpic or phenotypic) characterístics of katle, certain abiotic factors incruding naturar calamities, man-made barriers and weather conditions play important roles in the survival, growth and propagation of katle in Nepalese rivers and reservoirs. For instance, the extent of water drawdown, which determines the area of the reservoir, was found to be inversely rerated to annual rength increments of katle at different ages. Low feeding intensity of the river katle due to high turbidity during monsoon months (June and July) can be cited as another example of a negative impact of abiotic factors on the tife history of katre. The survival- of katle is also severely hampered by heavy fishing and indiscriminate blasting of winter pools urith explosives when the water level has gone down and the físh are resting at the bottorn. The experience gained with the fndrasarobar Reservoir has yielded important lessons. Katle gros/ to a large size in this l-acustrine environment, feeding well on the reservoirrs frora and fauna. Their success here can be related to their preference for J-arger pools in their naturar stream habitat; in contrast, fish speciarized for the fast frowing parts of l_9 0 streams, such as asra, have not survíved in the reservoír. Howevero the stability of the lacust,rine environmenÈ that favours katl-e/s success is routinely disrupt.ed by the annual_ drawdown of the reservoir, serving its prinary purpose of power generation" As described, drawdown has a negative impact.

on the annual length increment. This probabry represent,s a major obstacle to a viabre katre fishery ín hydroelectric reservoirs" whire the effect of drawdown requires further study, it seems clear that drawdown should be carefully lirnited to minimize negative impact on fish. unfortunatery, in practice, drawdown is governed by the economic consideration of demand for erectricity, and the requirement,s of the fishery have not received equal attention. Even with the adverse effects of these fructuations, horr/ever, the reservoir is presently supporting a commercial fishery that provides needed income to local- residents. This creates yet another problem that this fishery shares with many others around the world, namely overfishing. Excessive fishing pressure appears to be liniting the bulk of the katre stock to low size and age cl-asses at which many of the fish are not yet sexualry mature.

A conclusion that can be drawn is that, whire katte is a successfuÌ fish in the reservoir, governrnent, regulation of both the reservoir,s drawdown and of fishing pressure is definiteJ-y needed to sustain a katle fishery in the future. 1-91-

R@eommendaÈ,åons

Katle is well known as an excellent food and gTame fish in the nountain streams of Nepa1. It has adapted to the fndrasarobar Reservoir and plays an important role in the reservoir fisheries. For rational exploitation of katle in the existing and future reservoirs, the following measures are suggested. l-" Restoration of natural habitat: Natural vegetative cover of stream and reservoir margins needs to be restored to provide suitable feeding and breeding qrounds for katle as well as other indigenous fish fauna. Removal of stones from the river bed and shore shouLd not be alIowed" The spawning grounds of fish have to be IegaIIy and strictly protected"

2" Mitigation of the effects of man-made barriers: Dams, especially those that have been raised in the nid-region of the nigratory route, are obstructions to spawning migrations. Suitable fish passes are required around these barriers for the spawning movements of the fish" Certain minirnum waLer levels nust be established and maintained during the growing season of fish.

3 " Fishing regulations: Age composition of katl-e in both systems revealed that the populations þ¡ere dominaLed by fish L92 of 3 to 4 years, not a1l of which were yet mature" older fish were scarce in both systems" This is an indication of high fishing pressure which might eventualry eradicate the fish in the reservoir and the rivers" Fishing pressure can be reduced by increasing the mesh size of fishing gear (> 7s nm). Fishing should also be prohibited on spa\dninE grounds during the prime breeding season of the fish"

4" The exi-sting Aquatic Life protection .ã,ct of Nepal (t-960) needs to be updated to the present context and irnpremented. This would prohibit blasting and poisoning of fish in rivers and streams, amonq other abuses.

5. Reservoir managiement: The needs of the físhery should be considered in determining how much the reservoir is drawn down during the dry season. Lirnits on drawdown should be established and respected to protect fish populations.

6" Farming of katle: Domestication and artificiar breeding of katle at Trishuli Fisheri-es Research centre, Nepal (p. L. Joshi, personal cornmunication) should be continued to ensure the survivar of this species in the face of increased destruction of their naturar habitat and increased fishing pressure. 1-9 3 In addition to the above listed suggest,ions, the following areas are important for future research on katl-e: a. A pre-impoundment study on the biology of commercially important fish like katle should be carried ouL before the construction of any dam in the future" This will provÍde valuable inforrnation on the existing status of these fish. fnvolvement of a fishery biologist from the early planning phase of any new reservoir is required. b. The effect of drawdown on the growth and production of fish is a very important aspect of the reservoir fishery ç¡hich could not be investigated fully in the present study. This investigation should be attempted in the future" c. Comparisons of mitochondrial DNA of the river and reservoir populations may be helpful in determining whether the apparent differences between the two poputations are genotypic or phenotypic " d. Studies to locate the precise breeding grounds of the reservoir katle will be worthwhile for the management of the reservoir fishery" e" In-depth studies on hatchery managiement, nursingt, rearing and brood maintenance should be carried out" Studies on L94 physico-chemicar requirernents (including water exchange rate, optimum tenperature and food suppry at different st.ages) will be very herpfur in cultivation of katle under controlled conditions " 195

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sunder, s., and c.B. Joshi. rg77. preliminary observations on spawni-ng the .of Tor putitora (Ham.) in a-nii streàm, Jamrnu province during 1969. rndian J. Fish " ziz zs3-zsg. sunder, s., and M.J. Bhagat. lg7g. A note on the food of schizothoprax pJagiostomus (Mccretland) in chenab drainage of Jammu province during Lg73-74. J. rnland Fish. Soc. rndia t-1(1) : l-j_7-11_8. sunderai, B. r-951. Are scales proc. an index to the age and growth of Hirsa? Nat. rnst" sci. rndia 17 i1í, i-e" sr.Jar, D " B. L97 9. some studies on the freshwater crustacean zooplankton from Nepal. M.sc" Thesis, univer"ityoi Waterloo, Ontario, Canada, L41 pp" swar, D.B. 1,992. Effect of impoundment on the indigenous fish popuration in rndrasarobar Reservoir, r¡äp"r . rn: Reservoir f ishery management in Asia: naíted uïs"s" De silva" proceedings of 2nd Asian reservoir fisheries norkshop held in Hangzhou, people's Republiò ãã crrirr., 15-r-9 october r99o. ottawa, oN; canadal rDRC-29r-e, pp" l-11_-118. 2A8 sv¡ar, D"8., and c.H" Fernando " Lg7g" cladocera from pokhara va1ley, Nepat wit.h notes on dÍstríbuÈion. ÏIydrobiologià 6622: l_13 -12g " Tansakul, R., P" sirimontroporn, c. wongwit,, c. lüititha¡nyongr s. Angsupanich, and N" Rittibhonbhun " Lggz. changås í; the fish fauna of Thale Noi-, Thairand, From LgBz to 1989. rn: Reservoir fishery management in Àsia. EdÍted by s.s De Si1va. Proceedings of 2nd .Asian reservoir fishärÍes workshop hel-d in Hangzhou, people's Republic of china, 15-r-9 october 1990. óttawa, oN-, canada, rDRc-29J_e, pp. 141--l_48.

Tandon, K-K., and M"s. Johar" 19g3" study on the age and growth of Tor putitora (Ham. ) as eviãenced by scales. fndian J. Fish. l-: ]-7i,-175" Thakur, N.K" 1-967. studies on the age and growth of I,IugiI cephalus ( Li nn . ) f rom the Mahañadi esf,uarine systãn. Proc. Natn. fnst. Sci. India B 33: t2g_t43. Taylor, P.D., and c.c. lüilliams" 19g3. A geometric uroder for optimal rife history. rn.. population biology, Lecture Notes Biomath No. s2. Edited by H"r. rreedrian and c. Stockbeck. Springer Verlag, Berlin, pp " gL_g7. Terashima, A. 1984. Three nertr species of the Cyprinid Genus schizothorax from Lake nara, North western i,rèpar. Japan. J" Ichthyot . 3r (2) : 1,Zz-1_5. vlaming, v.L.de, r974. Environmental and endocrine control- of teleost reproduction. rn: control of sex in fishes. Edited by c.B. schrek. Virginia polytechnic and state University Blackburh, pp. l-g-g3. von Bertal-anffy, L. 1938" A quantative theory of organic growth. (rnquiries on growth raws rr). Huñan Biol. 10: l_8 l--2 l_ 3 . von oosten , J. 1929. Life history of the lake herring (Leucichthys artedí Le seur) of Lake Huronr âs revealed by its scal-e with cri-ti-que on the scale method. Burl. Bur " Fish " hrash . 44: 265-429 . walburg, c.H. 1976. changes in the fish popuration of Lewis and cÌark Lake, !956-74, and t,heir felation to water management and environment. Res. Rep" 7g, u. s. Fish. Itlild1. Serv. lVashingt.on, D.C. 34 pp. 2]-9 walburg, c"H" 1977. Lake Francis caseu a Missouri River Reservoir: changes in the fish popurat,íon in Lgs4-7s, and suggestions for managernent. rechñicar paper of the u. s. Fish and Wildl. Serv" L2 pp. wal-ford, L.A. 1946. A new. graphic method of describing the growth of animals" Biol" Bulr. Mar. Bior" Lab", woods Hole 90: 1,4I-I47 " !{ard, H.8", and c.c" whippre. 19i-8. Fresh r*ater biology, second Edition. Edit.ed by IÂI.T" Edmonsin (1959). Jõh; t{iley and Sons, New york, London, Sydney fZäa pp. weatherl-ey, 4.H", and H.s. Gill , Lgg7. The biorogy. of fish growth" Academic press. weber, M" and de Beaufort" i-91-6. The fishes of the Australian .Archipelago. Leiden vol. 3 " ldeber, D.D., and c.J. Ridgway " Lg6z. The depositíon of tetracycrine drugs in bones and scales of r-isrr and its possibre use for marking. prog. Fish-cult. 24z L5o-155. weisberg, s. , and R. v. Frie . 1,987. Linear models for the growth of f ish . rn.' Age and growth of f ish. Edited by R.c. summerfelt and G.E. Halr. rowa state universit| Press, pp . 1,27 -L43 . welcomme, R.L. 1985. River fisheries. FAo Fish Tech. pap. 330 p. 2622 whitehouse, R.H. i.gz3. A statisticar study of young fishes from sirvathurai Lagoons, Tuticorin, ttaarai FisÉ. Bul_l_. t7 3 , Rept. No. , pp. 49-l-03 " windell, J.T., and s.H. Bowen. rg7|. Methods for study of fish diets based on anarysis of stomach contents. rn; lrÀtñãã= for the assessment of fish production in fresh waters, 3rd edition. Edited by T" B" Bagener. Brackwell Scientific publications, Oxford, pp. ZLg-226. winters, G.H. .1,979. Healing of wounds and rocation of tags in Atlantic_herring (cJupea herengus herengus) rereased with abdominarl-y inserted magnetic tags. J. Fi;h. Res. Board Can. 34 (1,2) 24OZ-24O4 z " wood, H.s. 1933. Fishing in rndia and in Europe. J. DarjeelÍng Nat. Hist. Soc. 7I: 73_-72 " l{ootton, R.J " ]-992. Fish ecorogy. chapman and Halr, New york 212 pp. 220 Yadav, u"R" 1989. studies on the benthic fauna and their environment in Kul-ekhani Reservoir, ph"D, Thesis, patna University, fndia " 450 pp" 22r

åppendíx å A short, dåseusså@& @a €he t,axonômy of kat,3.e

NomeneLature: valíd name: /{eo-Z.issochiTus hexagonoTepis (McClelland 1839), Rainboth (l-985) NeolissochiTus hexagonolepís, the Nepalese 'katli' or 'katle', has a very confusing taxonomic history from its initial identÍfication in 1839 to the present" The fish was first included in the genus Barbus with four other large- scaled barbel-s by McClelland (1839) " Later Weber and de Beaufort (191-6) placed this fish in the genus LissochiTus, and Oshima (l-91-9) created a nevr genus AerossocheiTus " Recently, Rainboth (l-985) proposed and described the genus NeoTissochiTus. Kat1e has been described under several different species names" McCl-e11and (1839) was the first taxononist to deal with the large-scaled barbels of India and described five species of Barbus.' .B " hexas.tichus , B " progeneius, B. maerocephaTus, B. hexagonoTepis and B " megalepís" The first four species Þ¡ere described from Assam while the last species was obtained in the River Koshi, Bihar (the northern state of fndia). The main characteristics of Barbus hexagonolepis described by McClell-and (l-839) are as follows: Length of the head to that of the body (tot.aI length minus head length) is in the ratio of one to four; there are 222 twenty-seven scales along the lateral line and seven in an oblique line from the ventral fin to the ridge of the back. On the anterior part of the body the exposed surfaces of the scales represent hexagonal outlines" The dorsal fin originates midway between the tip of the snout and the base of the caudal- fin. The rays of the ventral and pectoral fins are small" The fin ray formula is: D"L2: P.16: V.9: 4"7: C"LO/9" The head is small and slightty compressed, the snout smooth and slightly rounded, and the postorbital plates less expanded in this than in any of the other Barbus species. ft has a smooth dorsal spine and large scales. In large-sized individuals, scal-es are blackish grey on the back, head and the base of the fins, while fins and scales on the opercular plates are tipped with yeIIow. After a detailed investigation on a series of specimens of the species from Assam described by McClelland (River Brahamaputra and some tributary streams), Hora (l-940) found that McCIeIIand's descríptions were brief and inadequate and his illustrations rrere inaccurate. Therefore, Hora (1940) revised their taxonomy and placed them in the following order

(Table 1) " Day (t876/78) considered B" hexagonolepis as a valid species and described its characters as fol-Iows: LengÈh of head 5 to 5"5å of the total length, dorsal and abdominal profiles equally and slightly convex, interorbital space 223 rather convex, upper jaÞ¡ Ionger than the loçrer, lower labial fold interrupted, opercle higher than wide, pores on the

Tab1e 1. The identity of McC1el-land's five species and their posÍtion provided by Hora (1940);

McClelland Assamese Hora name l- " Barbus hexastÍches Loburo Barbus (Tor) tor (Han" ) 2" B" Progeníus Jungha Barbus (Tor) progeneÍous McCIelIand 3. B " I'Iacrocephales Burapetea Barhus (Tor) putitora (Han" ) 4" B" hexagonolepis Bokar Barbus (LissoehiTus) hexagonoTepís (McCletland) 5" B" megalepis Barbus (Tor) mosal (Ham. ) cheeks sometimes present, lateral line scales 2g-3i-. He also stated that this species can be distinguished at once from B. hexastíchus (Tor tor) by the interrupted groove behind the lower lip" On the basis of the presence of pores on the snout, Day (7876/78) separated a few young specimens from the Tista River below Darjeeling, India, and placed them in a different species, Barbus dukai" B" dukai has also been recorded from siam (Hora a923) and the rndo-Austrarian Archiperago (t{eber and Beaufort, ]-916) " other authors who have identified katle as 8 " dukai incrude Bouranger (1899) and Annandare (19L8) frorn Burma, and Hora (L923) frorn siam. Duncker (1,904) recorded this katle as B" soroides from sumatra and the penang Malay peninsula. 224 In L925 Nichols descríbed a species under the genus Barhus as B. caldweTTi fron Fukien, China. The fish was characterised by 24 scales al-ong the lat.eral- line and the left side of the snout with only a band of small crowded, warty points above the naxillary. Later in l-928 he included this species in the sub-genus Spinìbarbus Oshima, but Lin (l-933) after a thorough study placed it in the genus LissochíLus" Hora and Misra (1,941-) redescribed the species, found that it hras more allied to L. hexagonolepís, and put .L" caLdweTTi as a synonymy, with a query" l{eber and de Beaufort. (191-6) studied the fish grouped under Barbus and divided them into several new genera" They proposed the genus LissochiTus for B " dukai, and a new species L" dukaí from Sumatra" The nost characterj-stic features of the genus LissochíIus according to Weber and de Beaufort (191-6) are as fol-Iows: 1. The post labial groove, though continuous round the corners of the mouth, is interrupted in the niddle. 2" The lower lip is conspicuously separated from the jaw, which is provided.with a horny covering and 3. The snout is provided with horny tubercles or a series of open pores" A group of Chinese Barbus-Iike forns have also been assigned to the genus LíssochiTus by various authors, and their systematic position has been studied by Herre and Myers (1931), Myers (1931-) and Lin (1933) " The nine identif,ied 225 Chinese species are as fotlows: l-. L" Tabiatus (Regan) 2" L" monticola (Gunther) 3" L" hemispínus (Nichols) 4" L" barbodon (Nichols and Pope) 5. L" kreyenbergii (Regan) 6" L" formosanus (Regan) 7" L" invergatus (Oshirna) 8. L" fasciatus (Steindachner) 9" L" paradoxus (Gunther) The Chinese -Lissochílus species are small in size and the number of scales along the lateral line is generally 40 or more. Most of the species are characterised by the possession of short vertical bars across the body" They are mostly confined to southern China. Other species of Líssochí7us of the hexagonoTepis type are not only large-scaled but also grow to large size and are rnostly confined to the Brahamaputra and Chindwin drainages in India and various rivers in Burma, Siam, the Ma1ay Peninsula and the Malayan .A,rchipelaçto" Hora and Misra (Ig4L) agreed with the statement of Herre and Myers (193L) that a difference of 10 scales in the count along the lateral line is not a valid generic character but suggested that this difference coupled with the geographical position of the two groups merits some sort of distinction" Hora (1940) also proposed to assign them to a separate subgeneric rank. Several species have since been described in the genus 226 LÍssochiJus al-though according to Hora (L94o) their systematíc position is somewhat doubtful. These species are:

L" dukaí (Weber and de Beaufort I L9A6) " L" sumatranus (Weber and de Beafort, I9L6)

L" caLdweTTí (Lin, 1933) ,

L" dukaì (Fow1er, 79341 ,

L. hutchínsoní (Fow1er, 1934) , L" dukai (Suvatti, 1936), L" hutchínsoni (Suvatti, L936), L" sumatranus ( Suvatti 1936 ), L. tweedie (Herre and Myers 1937),

L" dukai (Fow1er, L937) ,

L" dukaí (Fowler, 1938) , L (Herre " hendersoní , 1-940) " The first non-fndian record of LissochiTus hexagonolepis equivalent to Barbus dukai Day was by Boulenger (1898), from

Burma. The lateral line scales in that fish varied from 26 Eo 28" The species was next recorded by Duncker (L904) fron the Malay Peninsul-a lnd from Sumatra as Barbus soroides" The number of lateral line scales varied from 26 to zg and the pre-dorsal scales were 9 in number" weber and de Beaufort (19L6) studied this fish and Day's B" dukai and found them identical" They also described another new species of LíssochiTus (L" sumatranus) from Sumatra, which was based on a singre specirnen of, 148 run in length. -L" sumatranr¡s differs from -L" dukaí by having feiser scares along the laterar rine 227 (24-25 in -L. sumatranus compared to 26-29 in I " d.ukai) " But as Hora (1940) mentioned, the Indian specimen of Barbus hexagonoTepís has the lat.eral Line scales varying in number from 22 to 32" According to Hora and Misra (t94t) no reliance can be placed on small varíations in this character" LissochiTus sumatranus was recorded fron Siarn by Suvatti (1936) " The black colour of both lobes of the caudal fin in the specimens described by Weber and de Beaufort (1916) is similar to that of specimens from siarn. Therefore, according to Hora and Misra (i-941) these specimens and the Indian specimens of -Lissochí7us (L" hexagonolepis) are synonymous. Fow1er (L934) described L. hutchinsoní from Nakon Sritamarat, Siam. His description was based on a 148 mm long fish with 23 lateral line scales and 7 pre-dorsal scales. Fowler stated that this fish hras closely related to L. sumatranus Weber and de Beaufort, but the coloration of the caudal lobes and the dorsal and anal fins differed from L. sumatranus" According to Hora and Misra (1941-) there was no dark blotch on the anal fin as described by Fowler (l_934) " Therefore, they regarded L. hutchinsoni as a synonym of L. hexagonoTepis " Herre and Myers (L937) described L" tweedieÍ from the River Yum, China. Their description was based on four very young specimens of 62 to 92 mm in total length. This species had 26 lateral- line scales, 8 pre-dorsal scales and a broad sharp, horny edge to the lower jaw. .A,ccording t,o Hora and 228 Misra (1-941) these characters were sirnil-ar t.o those of L" hexagonoTepis " In a94O Herre described another species of LissochiTus (L. hendersoni) frorn Ma1aya (Penang Is1and) " His descriptíon was based on 28 specimens ranging from 59 to Z0 nm in length. The l-ateral rine scaÌes \üere 23 and the pre-dorsar scales were 5-6 in number. Hora and Misra (1941) eNanined the para type of this species and found 23-24 scales along the lateral line, and 6-7 pre dorsal scales" They came to the conclusion that this species cannot be separated from the young of L" hexagonolepis" ReaIizíng the great range of variation exhibited by rndian L" hexagonoTepís, they concruded that the Malayan LissochíJus species should be regarded as synonyms of L" hexagonolepis. The list of non-Indian LissochíJ.us and their main characters are given in Table 2. oshima (L9i-9) described a nehr genus .åcrossocheiTus v¡ith a type species Gymnostomus formosonus oshina. The diagnostic characters of AcrossocheiTus are: body elongate, not very deep and the compressed abdomen rounded. Head shorÈ, broad, with several ros¡s of horny tubercles on the sides in front of and below the eyes; these rnay be absent in some examples, and they may be represented by pores when tubercres have falren off. Snout obtusely rounded, slightly overhanging jaw" Mouth rnoderate, horizontal subterminal" Eyes moderate, lateral in positiono not visibl-e from betow ventral surface. Lips thick, continuous round the angJ-e of mouth" Labiar foLd interrupt,ed 229 in the niddle. Lower jaw covered by sharp horny covering. Four barbel-s, a pair each of rostral and maNillary" Caudal fin

Table 2" Non Indian -LissochiTus and their main characters:

Name No of Scales P1ace Source along lateral line

B" dukaí 26-28 Burma Boulengrer, 1898

B" soroides 26-29 MaIaya Duncker, L9O4 L" sumatranus 24-25 Sumatra Weber and de Beaufort, !9L6" L" sumatranus 24-25 Siam Suvatti, L936 L" sumatranus 24-25 Burma Annandale, 1918 L" dukai Siam Hora, L923 L. caLdweTTi 24 China Nichols, L925

L. hitchínsoni 23 Siarn Fowler, 1-934 L" tweedie 26 River Yun Herre and Myers, 1-937

L" hendersoni 23 Malaya Herre, L94O deeply forked with pointed l-obes" Scales large" Lateral line cornplete with 22-32 scales. A scaly appendage is present before each pelvic fin" The Nepalese katli or katle ís reported by Misra (1959) as Acrossoèh"ílus hexagonoTepis. According t,o hin the fish attains 609 nm (2 ft) or more in length and is an important game fish" rn the description he has ment,ioned that the sides 230 of the snouÈ and suborbÍtal region have horny tubercles. The lateral line scales nurnber 22-32 and the pre-dorsal scales, g- 10" Jayararn (1-981) has given the díagnostic characters of AcrossocheiTus oshima and f igured AcrossocheiTus hexagonoTepis after Misra (L962) " Shrestha (1981) has reported AerossocheiTus hexagonolepís from different river systems, lakes and reservoirs of Nepal" The lateral line scales are 28 and the pre-dorsal scales are 10 in number. Recently Rainboth (l-985) comprehensively studied the southern and southeastern Asian species of AcrossocheiTus including katle and created a ne\il genus NeoTíssoehiTus" His description for the nevr genus is as follows: Dorsal fin fV/9 (rarely ÍV/8), with large unbranched and unserrated rays. Pectoral fin í/ L3-L7, the first ray longest." Pelvic fin í/8 (rarely í/7); anal fin íii/S, caudal f in VIf-X, 1,O/9, vi-ix, deeply forked with convex distal margin of each lobe" Body deep anteriorly, trunk and peduncle smoothly tapered from rather broad head to strongly compressed peduncle. Trunk slightly arched pre-dorsally, ventral profile straight or convex. Lateral line scales 20 to 29" pre-dorsal scales large, uncroq¡ded, 6 to 10" Transverse scales 4 or S/4 with pelvic fin on third row below lateral 1ine" Head broad, snout b1unt, with mouth placement varying from oblique and near-terminal, horizontal and inferior" Species with horizontal mouth often with rostral cap 23L overhangÍng on the upper lip. Mouth smoothly rounded. Lower lip with inconplete post-labial groove. Lips thick, intermandibular space usually broader than mandibles" Long maNillary and rostral pairs of barbels always present" Cheeks with numerous tubercles, occasionally a few tubercles inmediately anterior t.o trostralt barbel, but even across the tip of the snout"

GiIl rakers Iong, slender, nedialty directed branches, 2 to 6 rakers on epibranchial and 7 to L2 rakers on hypobranchial- segment. Pharyngeal bones stout, with three robrs of hooked teeth" Grinding'surfaces of each in outer row widest on uppermost teeth, width progressively decreasing along row ventrally" Uppermost teeth in outer row with three or four ridges across face of grinding surface. Living individuals are dark green on dorsal side of head and body and may have a lighter area between the dorsal and the lateral line with a wide bl-uish lateral stripe running frorn eye to the base of caudal fin. The be1ly is silvery white" Fins vary f¡om yellowish to reddish brown, and through varj-ous shades of grey, usually slate-çtrey. Katle is norr¡ included under this new genus and named as

NeolissochiTus hexagonoTepis (McC1elland, 1839) " 232 ObjeeÈíve Synonlnnys 1-839. Barbus hexagonoTepis McClelland, .Asiat. Res" 19 pp. 27O- 336, pI. 4A, Fig-3. 1878" Barbus hexagonolepis Day, Físh. India, p" 564, pl" CXXXVIf, Fig" 4 (pores on snout not shown present in the specimens) " 1-878 " Barbus dukai, Day, Fish. India, P. 564, p1" CXLIII, Fig" 3. 1889 " Barbus hexagonolepis, Day, Fauna Brit" fnd" Fish. 1, p" 305. 1-889 " Barbus dukai, Day, Fauna Brit" Ind" Fish., T, p" 306" 1994" Barbus soroides, Duncker, Milt. Naturhist. Mus" Hamgurg, XXI, p" I78, p1. 1, Fig" 7" (Sumatra and Pahang, Malay Peninsula) " l-898 " Barbus dukai, Boulengèy, Ann. Mag. Nat" Hist., (6) XII, p. 2OL" (S" Shan States, Burma). 1-91-3 " Barbus hexagonoTepis, Chaudhuri, Rec" Ind" Mus", VIII, p" 249 " l-913 " Barbus hexastíchus, Chaudhuri (nec McClelland) , Rec. fnd. Mus., VfIf p. 249" L91,6" LíssochiTus dukaí, !{eber & Beaufort, Fish. Indo-.A,ustra1. Archipel. , III, p" l-68 (Sunatra) . l-91-6 " LÍssochiTus sumatranus, Weber & de Beaufort, fdid., p" t69, Figs" 68-69" ( Sumatra )" 1918 " Barbus dukaí, Annandale, Rec. Ind. Mus" XfV, p" 35, (S- Shan States Burma). L92L" Barbus hexastichus, Hora (nec McClelland) , Rec. Ind" Mus", XXff, p. 186. 1,923. Barbus (LissochiTus) dukaí, Hora, Journ. Nat. Hist" Soc", Sian, VI, p" 155" (Siarn) " 1924" Barbus hexastichus, Hora (nec McC1elland), Rec. Ind" Mus., XXVI, p" 27 " L929" Barbus hexastichus, Prasad and Mukerji, Rec. Ind. Mus., XXXI, p" 2OO, teNt-fig" 7" (Indawgyi Lake, Burma). 233 1934" Lissochí7us hutchinsoni, Fowler, ibid., p. A2O, Fígs. 76, 77 (Siarn). a934. LossochiTus dukai, Fowler, Proc. Acad. Nat," Sci. Philadelphia, LXXXVI, p. L2O" 1935. Barbus hexagonoTepis, Hora and Mukerji, Rec" Ind. Mus. XXXVff, p" 389. 1-936" Barbus hexagonolepis, Hora, Rec. Ind" Mus., XXXVIII, p" 330. 1936 " LíssochiTus dukai, Suvatti, Index Fish" Siam, p" 55. (sian) . 1,936 " LissochiTus hutehinsoni , Suvatti, ibid" o p" 55 " (Sian) . L937 " LíssochiTus tweediei, Herre and Myers, Bull. Raffles, Mus" Singapore, No. 13, p" 6L, pl" V" (Perak, F. M" S"). 1937 " LissochiTus dukaí, Fow1er, Proc" Acad" Nat" Sci. Philadelphia, LXXXIX, p. 188. (Sian) " L937 " Barbus hexagonoTepís, Hora, Rec. Ind. Mus., XXXIX, p" 334 " !937. Barbus (Líssochilus) dukai, Shaw and Shebbeare, Journ. Roy. Asiat, Soc. Bengal, Science, III, p" 37" pl. V, Fig. 6,Èext-fig. 33" 1938 " LíssochíLus dukai, Fovr1er, Fisheries Bull", No" 7, p. 66" (Malaya Peninsula). t94O. LissoehíLus hendersoni, Herre, BuIl" Raffles, Mus" Singapore, No. 16, p" 10, pI" IV" 1959. Acrossocheí7us hexagonolepis, Misra, Rec" Indian Mus" Vol" 57, pp. .L48-3-49"

L985. Neo-ZjssochiTus hexagonoTepis, Rainboth, Beaufortia, VoI " 35" No.3 " 234 Referenees {for Appendåx å onXy} Annandale, N.l-91-8" Fish and fisheries of InIe Lake. Rec. Ind" Mus.XIV.35pp. Boulanger, G. .å,. 1898" List of fishes collect.ed by S{r. E"W. Oates in Southern Shan States and presented by hirn to the British Museurn. Ann. Aag. Hist. 6: XfI, 201- pp"

Day, F " F " 1-8 69 . Remarks on some of the f ishes in the Calcutta Museum. Freshwater fishes of Burna, Part I. Proc " ZooL. Soc. London l-869: 458-560. Day, F.F" l-870" Description of five new species of fishes from Burma. Proc " ZooI. Soc. London LBTOz 99-10r_. Day, F.F. 1"87L" Monograph of Indian Cyprinidae" Jour" Roy. Asiat. Soc" Bengal 4Oz 277-336" Day, F"F" L873. On some new species of fishes of fndia. J. Linn. Soc. London (Zoology) 11"" 524-530 " Duncker,G. L9O4" Die Fische der Malayischen Halbinsel-" Nat. Hist. Mus. Hamburg" XXI. L78 pp. Herre, A.W" i-940. New species of fishes from the Ma1aya Peninsula and Borneo. 8u11. Raffles Mus" Singapore. 1-6: 5-26 " Herre, A.W" and c.S. Myers" 1931" Fishes from southern China and Hainan in 7926 and L927. Lingnan Sci" J. Canton. X: 242-247 " Herre, A.W" and G"S" Myers" 1937" A contribution to ichthyology of the Malaya Peninsula" 8u11. Raffl-es Mus" 1-3: 5-75" Hora, H"L" L923" On the collection of fish from Siam" J. Nat. Hist. Soc. Siam. VI" 155 pp" Hora, S"L" 1940" The game fish of India XI" The mahseers or the large-scaled barbels of India IV" The bokar of the Assamese and katle of the Nepalese, Barbus (LissochíLus) hexagonoTepis McCIelland" J" Bombay Nat. Hist. Soc" XLII: 78-88" Horao S.L. and K"S" Misra" L94L" The game fÍsh of India XXII" The mahseers or large scaled barbels of India" The extra-Indian distribution of the bokar of the Assamese and katli of the Nepalese, Barbus 235 (LíssochiTus) hexagonolepís McCl-el-land. J. Bombay Nat. Hist. Soc" 42; 305-419. Jayaram, K"C. 198L,The freshwater fishes of India, Pakistan, Bangl-adesh, Burma and Sri Lanka" Zoological survey of Indía, Calcutt,a. 475 pp" Jerdon, T"C" 1849. On the freshwater fishes of south India" Madras J" Lit. Sci. l_5: 302-346. Lin, S.Y" 1933. Contribution to the study of Clprinidae of Kwangtung and adjacent provinces" Lingnan Sci. J" Canton" XIIz 2O9-2L5" McClelland, J" l-938" Observations on the six species of Cyprinidae with an outline of new classification of family. Journ" Asiat" Soc" Bengal 7z 94L-948" McClelland, J" l-839. Indian Cyprinidae. Asiat. Soc" Benga1 , L9z 2L7-471," Myers, G" S" 1-931" On the fish described by Koller from Hainan in l-926 and L927 " Lingnan Sci" J" Canton" X: 257 -258 " Misra, K"S" 1959. An aid to the identífication of the colnmon commercial fishes of fndia and Pakistan" Rec. India. Mus" 572 L-32" Myers, G"S" 7947" Suppression of LíssochiTus in favour of AcrossocheiTus for a genus of Asiatic cyprinid fish r¡ith notes on its classifications. Copeia 422 l-0-3 5 " Oshima, M. 1919" Contributions to the study of the freshwater fishes of Formosa".Ann. Carneg" Mus" Berg. L2z L69-328" Rainboth, W.J. l-985. Neolíssochilus, a new genus of south Asian Cyprinid fishes" Beaufortia 35 (3): 25- 35" Shaw, G"8", and E.O" Shebbeare, L937 " The fishes of northern Bengal. J" Roy. Asiat. Soc" Bengal,

Science 3 (1) : L-L37 " Shrestha, J " 1981" Fishes of Nepat" Curriculum Development Centre, Tribhuvan University, Kathmandu, Nepal" Weber, M., and L"F. De Beaufort, 1,916" The fishes of the 3 Indo-Australian Archipelaçto " : i,67 -169 " Ãppendix Z Mean monthly maximum depth of the Indrasarobar Reservoir from June i-991 to December 1989"

Month

Jan 86 84 75.53 96.63 92.63 96 4 l-03 " 00 90 l-0 78 55 Feb 81 31 72"89 94.7 4 90. 63 98 0 0 98.00 84 o4 72 96 Mar 79 47 67.89 92.IL 88.42 86 B 4 93.00 78 1,9 66 22 Apr 68 95 61. 05 89 .47 85.79 86 0 0 86"00 7L L4 59 28 May 47 36 62 " 1,r 80.00 83.95 76 3 2 82"00 63 53 53 38 Jun L9 .47 40 79 54"2L 75.26 84.2L 73 1 6 78.00 60 69 50 84 JuI 41_ . 58 48 95 66 31_ " 80.00 87 "89 94 0 0 67 "OO 65 50 59 58 Aug 58"95 60 00 81" O5 88"95 90"00 96 o 86.00 74 00 72 66 sep 77 "37 74 2L 91. O5 94"74 98"42 10 3 o 0 93"66 84 00 73 94 Oct 87 82 1-0 "63 97 "89 95 "26 99 "75 10 5 0 o 96 "89 89 00 75 97 t\) Nov 88"42 82 63 1-OO 00 L¡J " 96"31_ 100 " 00 10 5 o 0 98"33 84 00 72 25 o\ Dec 88.42 82 1_O l-o0 00 96 " "3I 100 " 00 10 5 0 o 95 "24 82 1_5 7L 50 Appendix 3

Mean rnonthly discharge of the Tadi River in m3 sec-1 (Lg7o-L986) "

Vear Jan Feb Mar Apr May Jun JuI Aug sep Oct Nov Dec

1"970 6"08 4"68 3 95 3"15 4"66 3L 0 l_l_4 " 0 l_61" 0 84"5 47 "9 27 9 1-5" 9 L97L 10" 10 7 "43 6 63 1_l_ " 60 t-3 " 10 90 9 1t_7 " 0 l_40"0 82.7 56.9 27 5 L4"2 L972 9 "43 8.57 7 34 6"70 6"10 20 5 1t_1. O t_18 " O 120.0 45"6 30 7 L4"2 L973 10" 30 6"95 6 78 5 "22 42.20 78 10 90"1 L29 "O L27 "O 65"4 29 3 L3"6 L974 8.75 5.31_ 3 57 3.81- 5. 68 24 90 93.8 163"0 139"0 6l_"6 30 5 L8.8 L975 13.70 t_L. o 5 55 5 "73 6 "79 35 10 120. O 118"0 l_51" 0 s6" I 23 7 L4.5 L976 L0.90 8"43 5 L7 6"16 1,7 "30 46 40 77 "2 113"0 103"0 47 "L 24 7 L2"5 L977 I "49 6"74 4 82 7 "97 9.73 20 60 104"0 151"0 66 "7 32 "3 l-6 7 L0.2 L978 7 "4r 5"57 5 37 5 "77 1_l-"40 59 30 L7t"O 200.0 90 "7 53"8 22 0 L2"5 N) 4 67 28 l_8 (, L979 I " 35 7"32 LL 4 "72 4"00 L4 20 78.O 1_30.0 "L .6 7 14"8 { L980 10 " 50 8"26 7 34 6"10 7 "65 38 30 120"0 t_57 " 0 66"5 27 "5 15 2 9"86 l_98L 7 "78 6"03 4 2L 6"81 9"01 20 80 89 "7 116"0 63 "7 2L"6 14 9 9"87 t982 7 "45 7"LO 5 54 5"49 4"67 1_6 00 7L" O 88"6 57 "L 2L" 4 ls 6 1_0.3 l_983 7 "93 6.15 5 18 5"74 9 .67 11 30 80.8 94"6 57 "L 2L.4 15 6 L0"3 L984 L2"L 8"53 5 51 6"09 1,2 "30 30 90 104"0 Lo3"o 98"1 27.6 L7 L 11"6 l_985 9 "07 7"L8 4 56 4"38 6 "24 2L 40 104"0 L52 "O L42"O 55.6 23 9 13"2 L986 9 "20 6"52 4 04 5 "32 7 "76 40 00 99 "3 83 .0 55.6 23 9 L3"2 238

&ppendix 4

S'ít,t,íng of Èhe von Eer8ala¡¡ffy gnowth moden

Mathematical estimation of qrowth pararneters. .A,s described in Ch" 4, a mathematíca1 regression analysis was used to fit the von Bertalanffy growth curve to the observed growth data for the four separate groups of fish. The results of this analysis are summarised in Tab1es 1 and 2. Table 1 gives values of a, b and L., and their errors" Since ultirnate size I. is obtained from a and b through a nonlinear equation (Eq" 3 in Ch" 4), it is difficult to estimate the errors in I- from the errors in a and b. Therefore, 95 Z confídence intervals for L. have been constructed in a non-standard way. The following rnethod has been used.

Let min I- : [a S"E. (a) ]/{l-tb - S"E. (b) I } râx L. : [a + S"E" (a) ]/{1-[b + S"E. (b) ]] fntuitively, min L" is the smallest value L" can obt.ain r¡hen a and b deviate by 1 standard error" Max L, is defined . anaÌogously" The intervals listed in Table l-0 are of the form

[minfu, maxlú] " 239 Table l-" Results of regression analysis between L(t+i_) and L(r) "

Population Sample size Parameter Esti-mate of I+ (with s " E) (with 95 Z cL; River male 4 a = 4"660 (0"sr_68) Tto = 26"32 b - 0"823 (o"o4o7) [19.03 , 37 "98] River female 5 a = 5"150 (0"3314) ]- = 44"78 b - 0.885 (o . o2o2) [35.64 , 57 "82] Reservoir rnale 4 a = 5"27O (0.e4oe) I-,o = 41"L7 b - 0"872 (o . o642) 122"52, 97 "35J Reservoir female .' a = 5"840 (0" 8636) I,": 73"00 b - 0"920 (0 " 0370) 142"53,155"901

Table 2 shows the values of K and Ès calculated from these values of L. and the regressions of Eq" 4 (ch" 4) "

Tabl-e 2" Results of regression analysis between log"(t--L(t)) and t" PopulatJ-on Parameters Estimate of K Estimate of to (with S. E. 's) (with S"E"'s)

Ri-ver d intercept: 3 " 10 ( 0 . 52 ) 0"1e5(0"04) o"8749 slope : -0.195 (0.040) River ç intercept= 3 "72 (0.004) 0 "12@ " OO1) 0. 681_8 slope: -O"1-2(0"001) Reservoir d intercept 3.63 (0.01-4) 0"135(o"oo5) 0 " 6500 slope -0" 13 (0.005) Reservoir 9 intercept 4"28 (0"008) 0.089(o"ool-) o 1,1,7 4 slope 0.089(0.001-) "

The regression lines, Iog"(f--l1t¡ ¡ on t, for aII four populations were compared by looking at estirnates of their intercepts, and differences between K and to values among the populations vÍere assessed. The results are given in Table 3. It is clear from Tab1es 2 and 3 that the reservoir females appear to grow to a larger final size at a slower rate, and 240 Table 3" Level of significance on the dífferences in intercepts and slopes of regression Iines for von Bertalanffy growth model between seNes and populatíons" (Ns = non- significantand*:P Pair of Parameter S"E. for t statics Conclusion populations difference River d vs I intercept 0"516 1. 199 Ns slope 0"040 L"841 Ns

Res" d vs ç intercept 0. 017 37 985 ¿ " & slope 0.005 7 "989 River d vs intercept 0.517 7"O25 Ns Res. d slope 0"041 L"46L Ns River Ç vs intercept o"o09 56.598 ¿ Res" ç slope 0"002 72 "829 *

I-po and K values for this group are significantly different from the others (p < 0"05). The difference may be attributed to the availability of more food and space in the reservoir" The L" and K values in all other groups did not differ significantly among themselves (p > 0.05)"

Graphical estimation of growth parameters" The parameters of the von Bertalanffy growth curve were also estimated by using a geometrical ÍnÈerpretation of the pattern of growth in length developed by Ford (1933) and Walford (1945). The formula on which the graphic method of Ford and Walford was based assumed that the successive increments added to length yearly decrease in magnitude in geometric progression until a liniting vafue of total- Iength (ultirnate length) is approached" Ford-l{alford plots of lengths at age (t) against, 247 Iengths at age (t, + 1-) for femal-e and nale katle from the reservoir and the river gave straight-line relationships (Fig. A:1-, A:30 Ã,:5 and Ä:7). The lines Þ/ere fitted by the least squares method. The point on the x axis where this line cuts the 45" diagonaì- from the origin yielded I.6" The values of K and to were then estimated by plotting 1og" (L" - L(t) ) against age t (Fig" Az2, Az4, A:6 and A,:8)" This plot yieì-ded a straight line with slope of -K and intercept a on the ordÍnate, equal to (1og I* + Kto), so to : (a 1og fà / K" Thus the various parameters of the von Bertalanffy equation for katle from the reservoir and the river were calcul-ated" The values of Ir, K and to obtai-ned by the graphic method are given in Table 4:9 (Ch, 4) " 242

Figure A:l-. Ford-Walford plot of L(t) against L(t+l-) for male katle from the Indrasarobar Reservoir. E u30()

+. ca) 'E 2s õ -ç. çnC)) Q) J

20 25 30 Length at time t [cm] 243

Figure Az2. Log" (rr - L(t)) plotted against t to determine to and K for male katle from the Indrasarobar Reservoir " =o¡ J qq o) -'- o) o 244

Figure A:3. Ford-Walford plot of L(t) against L(t+l-) for female katle from the Indrasarobar Reservoir" Length at time t+ 1 [cm) 8èE

oHr- l (o J È) -N, :1-.Ò (D oç¡ j(r 245

Figure A:4" Log" (l* - L(t) ) plotted against t to determine to and K for female katle from the Indrasarobar reservoir.

246

Figure A:5. Ford-Wa1ford plot of L(t) against L(t+l-) for male katl-e from the Tadi River" Length at time t +'l (cm) o(¡

O o f CC f Ð ¡=. (¡ (D c) 3 uN) ó 247

Figure A:6. Log" (r. - L(t) ) plotted against t to determine to and K for male katle from the Tadi River" =tlI 2.9 -o) g) o 248

Figure A:7" Ford-l{alford plot of L(t) against L(t+l-) for female katle from the Tadi River. Length at time t+1 [cm) c)(¡ot\) to c,)

f- (D .BB f 0) f\) -. (t 3 CD c)Ò(D 3 249

Figure A:8. Lo9" (I- - L(t) ) plotted against, t to determine to and K f or femal-e katle from the Tadi River. + ct

o) E) J0 250

Appendíx 5 Ef,feet' of varíation of surface area on annua& &eng€,h ånerement Atternpts r¿üere made to fit a regression model t,o explaín the growth of fish as a function of both age and the surface area available during the growing season. Besides ÁT, - a + b log A, the foll_owing models were looked at,:

1_" AL=a+blogX rrhere aL : annual total length increment of the fish, x = age of the fish and a and b are constants. rt rdas evident from Tabres 4:4 to 4:7 that J-ength incremenÈ appeared to decline with age. Therefore, it was assumed that the logarithmic transformation of age wouLd improve the fit. Even then, length increments did not describe the fit, between these two variabres to any great extent. The coefficient of determination did not show much improvernent (Tabte 1). 2" ÁL=a+blog(A/X) Here aL, x, a and b were defined as before, but A : average area of the reservoir. This model irnproved the relationship but seemed inadequate to explain the influence of age and average area of the reservoir on length increments of katle

(Table 1) " 3" AL:a+blogX+clog(A/X)

Here aL, x, A, a and b were defined as before whereas c was an additionar constant to be estirnated. The extra explanatory variable (A/x) added to model- (1) srightly improved the 25r

Table 1- " Summary of the regression analysis t.o assess the katl-e's growth dependence on age and the average area of the fndrasarobar Reservoir"

Model Regression equation t2 P value No"

L Y 68. 0 l-8. L logX 0"43 o. ooo 53

2" Y -23 "5 + l-e. l-5 log (D/x) o "57 0" 000 53 3 Y -34 "6 + 2 . 66J-ogX + 2t.31og (D/X) 0"58 o" 000 53

rerationship but not adequatery to exprain the influence of fish age and average area of the reservoir on length increments of katre. However, when the data were examined at separate ages (Tab]-e 4:1,o), it became crear that the combined data of model 3 hid considerable structure that existed at each age (Tabre 4:10) when considered separately. rn Table 4:10, the age was controlred to see if there rdas any rinear structure in the data" rn fact Table 4:10 demonsLrated a l-inear relationship between the totaL annual length increment and the average area of the reservoir in any given year. However, it r/ì/as difficurt to see any pattern from one age group to the next, and it was arso difficutt to determine what exact,ly was happening at each age. For instance fish at the ages of 7 and 8 displayed a strange t,endency of growth accereration for large values of average area. perhaps this 252 can be attributed to the high mortality of katle before they reach the age of 7 or more. Therefore, the few remainÍng fish night have the opportunity to grow quickly. 253

ÃppendíN 6

VariabiJ-ity of three successive pectoral fin ray age determinati-ons of katl-e from fndrasarobar"

First reader Second reader Third rea Fj.na Fin ray age

6 6 6 6 3 J 3 3 7 7 7 3 4 5 4 4 4 I 2 2 2 2 L 2 2 2 3 J 3 3 5 5 5 5 3 J 3 3 3 3 J 3 5 5 5 5 3 3 3 3 2 2 2 2 4 4 3 : : rejected 6 6 6 6 5 5 5 5 7 7 7 6 6 6 6 5 5 6 5 6 tr 6 6 a 2 2 2 4 4 4 4 6 6 6 6 4 5 4 4 3 J 2 3 4 4 4 4 11_ 11 11 L1 9 Õ 9 o

Note: bold and underlined data indicate assigned fin ray agtes, which lrrere agreed upon by Lwo readers " 254

Appendåx ? Estimated values of log a for length-weight. relationshÍps of the reservoir katle at different sÈages of maturity througnout the year"

Mon Maturity stage Tota weight Sonat rde]-g Y d ç

January 1 "-, January -2"03 -2"04 2 -2"06 -2 "04 -2.04 . on February 1 -2"04 -2"O2 -2"04 -2.O2 February ¿ -2.04 -2"OO -2"52 -2"O2 March 1 -2"OI March .) -2"03 -2.O2 -2"03 -2"02 -2"O5 -2"06 -2"O5 March 2 -2.03 -2"O3 -2"04 -2"04 March 4 -2"OA -2"O2 April 1 -2 .05 -2 "L9 -2"06 -2 "20 April 2 -2"05 -2"03 -2"06 -2"04 April 3 -2. 07 -2"O3 -2"O7 -2"O3 April 4 -2"02 -2.04 -2"O3 -_2 " 06 April 5 -l_.93 -1"95 April- 6 -2.07 -2.l-0 May 1 -2.02 -2"O2 May 2 -2. 06 -2. 06 -2"O7 May J -2. 05 -2.07 May 4 -2.06 -2"08 May 5 -2.05 -2"O7 May 6 -2.00 _r"t, -2"02 - June t_ _2 -2"1o "LL June 2 -2"09 -2"00 -2 "t1- -2.Or June J _2 -2"09 -_2 " 02 "LL -_2 . 04 June /l -2.08 -2 "to June 5 -2.04 -2"08 June 6 -2"04 -2"06 JuIy 1_ -2.07 -! "97 -2. 08 -l_ " 98 July 2 -2. 09 -2"O7 -2"09 -2"08 July J -2.t7 -2"04 -2"18 -2"06 July 4 -2 .1,2 -2"04 -2 "L4 -2"06 JuIy 5 -2.08 -2 " Ol- July 6 -r.99 -2.06 August 1 -2.00 -2 "OL -2"OL 02 August ) .03 -2. -2 -2 " 03 -2"04 -2"03 August 3 -2 .03 -2"OL -2"04 -2"03 August 4 -2"04 -2"O2 -2"06 -2"04 August 5 -2.03 -2"O2 -2.55 -2"04 August 6 -2.04 -2"06 September 1 98 -1"98 -L. -1"98 -l_ " 99 September 2 -2.04 -2"O2 -2.04 -2"03 September J -2.04 -2"01 -2"O5 -2"03 255 Septernber 4 -2"03 -2"04 -2. 05 -2"06 Septernber 5 -2. 03 -2"05 Sept.ember 6 -2.OL -2"O3 October 1 -2"OL '-, -2 " 0l_ October 2 -2. 03 . on -2"O3 lr. ou October 3 -2"03 -2"03 October + -2"04 -_2. OL -2.O5 -2"O3 October 5 -2"06 -2. 08 November 1 -2"03 -2.O3 November 2 -2 .04 -2. 05 -2"03 -2"05 December 1 -2"03 -2.O3 December 2 -2"04 -r.o, -2"04 -r.o, 256 Appendåx I EsÈimated vafues of log a for length-weight relat,ionships of the ríverine katle at different stâges of maturity througrrout the year"

Month Maturity stage Total_ *¡e Soma qht I January t_ -2"OO -1" 9 -2"00 -1.96 January 2 -2"07 -2"00 -2"O7 February 1 -2"00 -l_ " 98 -1"99 -1.99 -2"00 February 2 -2"04 -2"04 March l- rr. -2"04 o, -2 "04 -2"04 March 2 -2 .0O -2.LO -2"00 March 3 -2"10 -2"05 -2"03 -2 "06 -2"04 March + -2"04 -2.05 -2"O5 -2"07 March 5 -2"O2 -2"04 April l_ -2.05 -2.09 -2"O5 -2 ApriI 2 "94 -L.99 -2"O9 -2"00 -2"O9 Àpriì- 3 -1_. 98 -2.07 -2"00 -2"08 April 4 -2.OO -2 "t5 -2 "29 April 5 -2.17 -2"L4 -2 "L6 May 1- -2"09 -2"O5 -2.L2 -2"05 May ¿ -l-.98 -2"08 May 3 -2. 02 -2"05 -2"O3 -2"06 May 4 -2.03 -2"O7 06 May -_2 " -2"O9 5 -2 . 07- -2"O2 June 1 95 -I "99 -l- " -1- " 99 -1"96 June 2 -1.99 -2.05 -1. 99 -2.06 June 3 -1.98 99 June -2"05 -1. -2"06 -L "92 -2.01- -1.94_ -2"03 June 5 _ -2"05 -2. 07 June 6 -2"0s -2"07 July 1_ -2.L0 -2"O5 -2 " Ll, 06 JuIy 2 -2. -2"04 -2"02 -2. 06 -2.02 July 3 -2.08 -2 "Ot -2"O8 JuIy 4 -2"02 -1_.99 -2"06 -2 "Ot July 5 -2"08 -1_.96 -2"03 -2. 00 -2. 05 JuJ-y 6 -2"06 -2"07 August 1 -2. 08 -2"08 -2. 07 August 2 -2.O9 -2"05 -2.04 -2"O5 -2"04 August J -2 . 01- -2"04 -2"O2 August 4 -2"05 -2"03 -2.06 -2"05 -2"08 August 5 -2"02 -2"07 -2"O5 august 6 -2"O9 -2"06 -2"O7 September 1 -2"O9 -2"05 -2"09 Septenber 2 -2"O5 -2.02 -2"01 -2"02 -2"0L September 3 -2"03 -2"06 -2"03 -2"07 September 4 -2"OL -2. 05 -2. 02 -2"06 September 5 -2"Ot -2.05 -2.07 September 6 -2"06 -2. 04 -2 "t3 -2"06 -2 "L5 257

September 7 -2. 02 -2"O2 October l- -2"04 -2"07 -2 "04 08 Oct.ober 2 -2. -2.OL -2"06 -2 "OL Oct,ober 3 -2.O7 -2 " 00 -2"08 -2"O1 09 October 4 -2. -2"07 -2"O7 -2. Ol_ -2"09 October 5 -1_.96 -2"O5 -1"99 -2 "L5 October 6 -2"09 -2 "13 -2 "L2 October 7 -1"88 -1.88 November t_ -2"04 -1"99 -2"04 November 2 -L"99 -1" " 99 -2. 00 -1. 99 -2. O0 December 1 -2"09 -2.05 -2.]-L -2"05 December 2 -2"04 -2"06 -2"04 -2"06 258 agrpendíN I Tota1 and sornatic weight (t 95å cL) of the st,andard reservoir mal-es at different stages of maturity (January -December)

Month Stage No" Total weight Somat,ic weight, q q

January 2 () 98"87 t O"94 98,65 + O "94 February 1 3 66"09 t 2"58 65"74 + 2"59 February 2 6 l_03.73 + L.2L 103"45 + 1"15 March l_ 2 64"55 64.2L March 2 I4 96.36 + 0.61 95 "84 t O. 61 March J 6 1,O1_.26 + t"L2 1,OO"22 t L"L2 April 1- 2 65 .1,4 64.55 Àpril 2 6 99"92 f 1"09 99 "32 t l-. 10 3 April 5 1,OO .92 1 t_ " 31 100"03 + 1.31 April 4 5 97 "75 + L"28 93"45 + 1"18 May 2 4 9l-"28 + 2"61 90"45 + 2"61 June 2 107.00 I 2"58 to6"26 + 2"57 June 3 4 ro2.95 I L"48 l-01" 49 + 1.48 Juì-y 1 2 72.72 72"45 July 2 1_3 90"04 t o.66 89"61 + O"66 July 3 5 97.82 + 1-.35 96"O4 + 1.35 July 4 74 97.96 + 0.65 94"O2 + 0"65 July 5 5 90. 09 t t_. 35 86"95 + 1.35 August 1 /l 66.60 + 1"72 64.28 + I"75 August 2 T2 101.26 + 0"68 .) L00.78 t 0"68 August J 10 105.1_4 J O.76 102"33 + 0"76 August 4 11 L02.23 + O "72 98.40 + O "72 August 5 6 t_02"85 t 1-"11 99"49 + 1"11_ September 1 ) 70.88 70.38 September 2 6 r-02.09 t l_"1-5 1.Ot"44 + 1"L5 Â Septernber J 105. l-3 + L "7 0 101"78 + L"70 September 4 3 99.04 t 2"63 94 "7L + 2,62 October 2 6 97 "54 + O.L7 96"97 + L"67 October 4 4 98.09 t O "L7 93.89 t O"L7 November 2 4 96"I2 t r"67 95"74 + L"67 December 2 + l-0 1,O2"1,2 0"75 101.87 + O "75 259

Appendíx X0

Tota1 and somatic weight (t gSZ CL) of the standard reservoir females at different stages of maturÍty (January - December) "

Month Stage No Tota1 weight Somat,ic weÍght g g

January l_ Õ 65"89 + l_"00 65.59 + 1_"OO January 2 L20 + 11,9"52 J 0"20 119 " 02 0"20 February 1 9 65"29 + 0"88 65 "28 + 0"87 February 2 B9 1,27.97 + O"23 LzL"97 + o.23 March t- 6 68.89 + l-"14 68.57 + L.L4 March 2 73 t20 " 45 J o "25 119.68 + 0"25 March 3 56 + r28 "39 t 0"30 126 " 10 0"30 March 13 l-35.15 t o.67 L29.8L + 0"31 April 1 7 63.47 + 0.99 62 "88 + 0"99 Àpri1 2 75 72L"78 + 0"26 LzL"04 t o.23 1 April J 25 + + II7.21, 0"48 115 " 48 o"48 April A 10 + 130.68 I O.76 L26 " 65 o"76 April 5 4 159.85 t 2.29 150"36 + o "28 April 6 3 + + L16.79 2.67 108 " 88 2"66 May t- 5 68.54 t l-.40 68. L3 + 1" 40 May 2 73 1,I9.17 t 0.26 118.37 + o "26 May 3 10 L21,.69 t 0.81- 120 "24 + 0"81 May 4 5 119. 96 + l_.39 118.30 + 1" 39 May 5 7 I25 .31, t l_ . 05 l-18 " 88 t o. 56 May 6 4 L35.51" J 1"88 130.07 + 1" 91, June t- 5 56"57 t 7.4L 56"30 + l_"41 June 2 70 + 1L1-.64 t O.26 110 " 82 o "26 June 3 + I7 109.70 t 0.61- 108 " 36 o. 61 June 4 T2 + r1,2.62 O "71 :l-o9 "57 + o "7L June 5 7 I1,7 .26 ! L" 0l_ 10.82 + L"02 June 6 5 724 .42 + l_ " 45 118.65 + 1.45 July l_ ö 60"25 + 1""O2 59 "82 + L"O2 JuIy 2 l_00 1l-0.98 t o"25 tto.24 + o"25 July 3 25 89"37 + O"57 87"50 + O"57 July 20 ro2 "82 + 0. 63 99"56 + 0"63 JuIy 5 + 15 rr4.27 o "71 108.43 + O "7L July 6 0 + L39 " 1-7 o "92 l-31.12 + O"92 .August 1 a2 70.90 + 0"68 70.20 + 0"68 August 2 L22 L26"O7 + O.20 124.22 + 0.20 August 3 44 126.94 + O.32 t24"22 + O"32 August 4 2L 722.83 + O"49 118.30 + 0"49 August 5 11 I27.06 + 0"73 t20"64 + 2"O3 August 6 l-0 L24 "1,9 t 0.86 118.23 I 0"85 Sept " 1 11 74.50 + 0.73 74"22 + 0"73 Sept 2 58 I24"98 t O"29 r24"23 + O"29 260

Sept 3 1-6 L23 " 69 t 0.58 121"05 t O"57 Sept 4 13 126 " 47 + 0"64 t2L"23 + 0"64 Sept 5 6 + I29 " 69 l_. 14 L22 "LO t 1" l_4 Sept 6 2 1_33.17 t 9"24 L26"78 + 9"23 October t- 9 69"60 t: 0.83 68"99 t 0.84 October 2 60 1,28 " 24 1 0"27 L27 .56 + O.27 October 3 13 729 .22 J 0"67 125"95 + O"67 October 4 l_0 1_25 "20 t 0"85 L20"44 t 1.3s October 5 l_0 1,L8 " 27 t 0"87 111"9L + O"87 October 6 5 t25 " 8t t l_. 35 L20"44 t 1"35 November l- 5 66"52 t 1" 33 66 "28 t 1.33 November 2 7L l_25. L1 + 0"26 L24"52 t O.26 December 1 6 67 "64 + 1_. 10 67 + 1. 10 December 2 "77 75 L26 " 1,5 + 0.25 125.57 t O"25 26L

AppendÍN XX Total and somatic weight (1 es? cL) of the sÈandard river nales at different sLages of naturity (January -December) " Month Stage No Total- weight (q) Somatic weight (s)

anuary l_ 7 1,4 " 46 t L"o7 L4"40 + r.o7 January 2 9 42 "99 t o.97 42.88 t o.97 February l_ 6 1-5 " 48 + l_"09 15.38 + 1"09 February 2 9 42 "95 t 0"90 42 .47 + 0"90 March l- Õ 14 "34 I 0"93 L2.65 + o"92 March 2 74 38 .1,2 t 0"76 37"85 t 0.76 March 3 7 44 "84 J 1_. 04 43 "77 + 1"04 March 4 7 42 .04 + 1.08 40"4L + 1"08 March 5 4 45.44 t 1-"74 43 "96 + 1"73 April l- 4 1-2 " 69 I r_"88 L2 "64 t 1"88 April 2 10 38.75 t 0"93 38"44 + 0"93 April 3 5 40 "72 t 1-.43 39.76 + L.43 April 4 6 33 " 61 J r_. 51 32 "L2 + l-"50 April 5 4 34.52 + 1"73 33.34 + r"74 May 1 4 t_3.98 t z"LO 13"93 t z"LO May 2 o 39.24 t 0.99 38.82 + 0.99 May J 6 42 + .89 I"22 4l- " 53 + L"23 May 4 5 40.70 t 1.31 38.94 + l-"30 May 5 7 47.29 1 L.t4 45.73 + 1"15 June 1 4 77 "36 + l-"80 17 "28 + 1.89 June 2 7 42.36 I L"03 42"07 + 1"03 June 3 6 42 "91, + 1_. 1,8 41.7 8 t 1"18 June 4 5 46.62 + t.42 44"47 + 1.42 June 5 10 42 .40 t 0.83 40"70 + 0.83 June 6 5 42 "33 t r_"38 40 "84 + 1"38 JuIy l_ 4 13.80 + 1,.69 13"51 t t"67 JuIy 2 9 + 45.85 0.87 45 " 61- + o.87 July 3 4 47 " 41, + t_"85 46"56 + 1-"85 Â July 4 42.O6 t 1_ "73 40 "22 + t"72 July 5 '7 44"75 t 1-"04 43.33 + 1"04 JuIy 6 6 4I"63 + 1_.26 40.40 + L"26 August t_ 3 12 " 85 t 2"59 L2 "75 + 2"58 August 2 9 44.07 I 0"82 43 "54 t o"82 August 3 6 43 "59 t L"46 42 "25 + L"46 .A,ugust 4 4 4L.21 1 I.74 39 "27 + L"74 August 5 5 40.73 t t"46 39"01 + r"46 August 6 3 41 .93 t 2.68 40. 35 + 2"69 September l_ 5 L3.77 t 1"34 13"04 + L"48 September 2 I4 4L.2I t 1.30 40"64 + 1"30 September 3 35.59 + t"L7 33 "92 + L"77 September 4 o 41, " 23 t 0"90 39.36 + 0.90 September 5 t1 42 .58 t 0"97 41"09 + o"97 September 6 9 42.36 + 0.85 4r. " 88 t o.8s September 7 3 45"99 + 2.go 45"74 + 2"90 262

Oct.ober 1_ 5 13"16 + 1_.48 L3.04 + L"48 October 2 6 4L"2L + 1-.30 40"64 t t_"30 October 3 5 39"75 t 1.36 38 "77 + 1" 36 October 4 5 40"92 I I"42 39"7L + L"42 October 5 L 42 .1,2 t 1_ " 63 40.4L + 1"65 Oct.ober 6 2 35"46 + 0"00 33"44 + 0"00 1 November 1- 1,6"07 t t"02 15.99 t L"Oz November 2 t2 48.01_ t 0"74 47.74 + O.74 December t- ô l-3.89 + O.94 L3"82 + O"94 December 2 I4 4L"47 + 0"69 4L.25 + O"69 263

Appendix Lz Total and somatic weight (t es? cL) of the standard length river females at different stages of maturíty (January December)

Month Stage No Total weight g Sonatic weight, g

l- January 5 21, " 44 + 1_"31_ 2L"34 + 1.31 January 2 i_3 76"76 + 0"71_ 76"35 + 0.71_ February 1- 7 22"59 t t_"08 22"45 + 1.08 February 2 L4 82 "L3 t 0"66 8L.44 + 0.66 March I 5 19.53 t 1"38 L9.42 + 1"38 March 2 16 89 " 50 t 0"58 88.95 + 0"58 March J 5 80"06 + 1-"33 78"O9 + 1.33 March 4 4 82 .63 J L.71_ 79 "L4 + L"70 April 1 ö l_9.0r_ + 0"99 18"89 + 1"99 April 2 I7 91_ . 05 1 0"73 89.84 + O.73 April 3 6 92 t L"17 + .) "8r 89.78 L.t7 April 4 89 .87 t 3"07 84"27 + 3"05 May l_ 2 1,7 "04 t 9.38 16"96 + 9"39 May 2 1 94 "27 t 0"99 93"27 + 0"99 May 3 4 85.05 + 1.85 83.07 + 1"85 May 4 3 83.l_0 1 2"70 78"07 + 2"73 June 1_ 7 2t .91, t 1-"00 2L.72 + 0"99 June 2 1_5 90 .63 + 0.66 90.25 + 0"66 June 3 6 93.l-0 t 1-. 09 90.31 + 1.10 June 4 4 83.10 J 2.70 78"07 + 2"73 July L 4 16.83 t L.96 l-6"68 + 1"95 July 2 15 82.58 t 0. 6l_ 8L"72 + O"6t- July J 4 75.36 t I.78 73 "65 + L"78 July 4 5 9l-.05 t 1.39 87,06 + L"42 July 5 4 97.08 t )-"78 89"39 + 1"79 A,ugust 1 4 r_8.21_ t t_.78 18.03 + L"78 August 2 10 79.67 + 0.81_ 78"99 + 0"81 August 3 7 87.98 t 0"99 84"88 + 0.99 Àugust 4 6 84.70 + 1" 1l_ 80"16 + 1"L1 August 5 5 85.59 t 1.37 79"08 + L"37 September l- 6 17 " l_8 t 1-"1-2 L7 "O7 + t"Lz September 2 20 86.34 t o"52 85"69 + O.52 Sepetmber 3 1-0 84.1,4 t 3. l_4 82"6L + 3"14 Sepfember 4 (1 + 87 "95 o"92 85.00 + O "92 September 5 l-3 79 "95 t 0"68 74"88 + 0"68 September 6 7 81_.34 t r_. 00 77 "37 + 1" 00 October L 4 1_9 .29 t r..41_ L9 "29 t 1.41 October 2 9 87.4L t 0"82 83.94 + 0"82 October 3 4 90 .1,4 + t.75 85. 18 + 1"75 October 4 75. 1L t r_"84 68"97 + L"82 October 5 5 85.20 + 1,"40 '16 .40 + I.42 October 6 2 73"02 +00 66.67 + 00 October 7 1 r77 "44 100 113.81 + 00 November t- ö 19 "23 + 0"90 L9"L2 + 0"90 264 November 2 13 90"64 t 0.69 ÙO"ZS + 0.69 December 1_ 5 L7"27 + I"4g L7"L6 t 1_"qg December 2 17 89"02 t O"SB B7,7L + O.S8