Age, Growth and Mortality Studies of Indian Squid, Uroteuthis (Photololigo) Duvauceli (D’ Orbigny) Along Ratnagiri Coast of Maharashtra, India

Indian Journal of Geo-Marine Sciences Vol. 44(1), January 2015, pp. 93-96

Age, growth and mortality studies of Indian squid, Uroteuthis (Photololigo) duvauceli (d’ Orbigny) along Ratnagiri Coast of Maharashtra, India

Pawar Nitin, Nirmale V.H., Metar S.Y., Bhosale, B.P. , Sawant, M.S & Naik, S.D.

College of Fisheries, Ratnagiri-415629, Maharashtra, India

*[E-mail: [email protected] ]

Received 18 November 2013; revised 28 January 2014

The study on the growth and mortality of Indian squid Uroteuthis duvauceli was carried out based on the length frequency data collected during February 2012 to January 2013. Using ELEFAN, the asymptotic length ((L∞)) and growth coefficient (K) were estimated as 376 mm and 0.95 yr-1 respectively. Using the von Bertalanffy’s Growth Formula (VBGF), it is seen that L. duvauceli attain 233, 324 and 355 mm at the end of Ist – IIIrd years respectively. The total, natural and fishing -1 mortalities were 4.5, 1.82 and 2.68 yr respectively. The Lc50 was found to be 107 mm. The exploitation rate (U) and exploitation ratio (E) was calculated 0.53 and 0.54 respectively. The value of E max in the present study is lower than exploitation ratio E of 0.54.This indicates that to maximize the yield per recruit from L. duvauceli the efforts may be reduced from the present E of 0.54 to 0 .5 to sustain the stock. Key words: Indian squid, Uroteuthis duvauceli, growth, mortality, stock assessment

conducted on growth, mortality and stock Introduction assessment of this species. The Indian squid Uroteuthis duvauceli . is the one of the commercial important Material and Methods cephalopod species found along Indian coast. The catch and efforts data was This species is distributed in the Indo-Pacific collected weekly from the commercial catches neritic waters from Mozambique to South from Mirkarwada landing centre (16.98° N, China Sea and Philippine up to Taiwan. It 73.3° E) of Ratnagiri during February 2012 to occurs up to a depth of 120 m or even beyond January 2013. A total of 1059 fish specimen but the most of the stock is found in depths of were measured. The total length (DML) was about 50 m to 60 m 1. The production of measured to the nearest millimeter. The length cephalopods during the year 2012 in India frequency data were grouped into 10 mm class was 1, 90,322 tonnes among which squid U. interval, then raised & pooled month wise 13. duvauceli contributes 92,241 tonnes which is Employing ELEFAN of FiSAT computer more than 48% in cephalopod landings of programme 14,15, the asymptotic length (L ) India. The annual catch of cephalopods by ∞ and growth coefficient (K) was determined. trawlers in Maharashtra state was 15, 658 The total instantaneous mortality (Z) was tonnes forming 11.0% of the total fish calculated by length-converted catch curve landings in the state in 2012. Along the 16,17. Natural mortality coefficient (M) was northwest coast, U. duvauceli with 60% estimated by using Cushing’s method (1968) dominated trawl landings of cephalopods2. In 18. India, cephalopods are principally caught by M= (1/T max – 1) ln (100/1) bottom trawlers operating up to 100m depth (Where T max is maximum age zones. Most of the catch is brought in as by- attained by species) catch from the shrimp and fish trawls The fishing mortality (F) was arrived by employed by the trawlers3. subtracting M from Z. Reports are available on growth and The exploitation rate (U) is calculated as U = mortality studies of Indian squid, U. duvauceli (F/Z) *(1 – e-z) and exploitation ratio (E) on Indian coast by 4,5,6,7,8,9,10 and 11,12 from by F / Z 19. Thailand waters. As no report from Ratnagiri The length frequency data was pooled and by is available for this species, a study was backward extrapolation of catch curve, the 94 INDIAN J. MAR. SCI., VOL. 44, NO. 1, JANUARY 2015

probability of capture for type selection was The value of total mortality (Z) derived. obtained from length converted catch curve is The relative yield/recruit was 4.50 (Fig. 2). The natural mortality coefficient estimated from the relative yield /recruit (M) was estimated by Cushing’s method gave model of 19 & 20 was represented by the estimates of M as 2.10. The annual fishing equation: mortality coefficient (F) was estimated as ( Y/R) = E* UM/K * 1 – 3U + 3U2 - U3 2.40 for U. duvauceli. 1+m 1+2m 1+3m where E = F/Z the exploitation ratio or the fraction of deaths caused by fishing:

m = K/Z U = 1 – Lc/ L the fraction of growth to be completed after entry into the exploited phase, (Y/R)′ is considered a fraction of U and E and the only parameters is M/K. Using different value of E on the X-axis and various sizes at Fig.2- Length converted catch curve for estimation of Z first capture Lc/L∞ ratios on Y-axis, the isovalues of relative yield per recruit were The length at which 50% of the squid became plotted to generate the yield isopleth diagram. vulnerable to the gear was found to 107 mm (Fig. 3). Results

In the present study, the growth parameters L∞ and K were estimated 376 mm and 0.95/year respectively by ELEFAN-I employing FiSAT programme (Fig. 1).

Fig.3- Probability of capture of U. duvauceli

The exploitation rate (U) calculated as 0.53 and exploitation ratio (E) was 0.54 for U. duvauceli Relative yield / Biomass per recruit shows E max at 0.519, E 50 at 0.299 and E 10 at 0.410. The values of Lc/ L∞ and M/K taken for estimation of Y/R and B/R are as 0.290 and Fig.1- Growth curve fitted by ELEFAN method 1.92 respectively (Fig.4)

The to was estimated by VBGF plot was ( - 0.0567) yr. Using the von Bertalanffy’s Growth Formula (VBGF), it is seen that L. duvauceli attain 233, 324 and 355 mm at the end of Ist – IIIrd years respectively. The maximum size recorded during the period of study was 332 mm, at which the estimated age is 2.258 years. The t max was estimated by employing inverse von Bertalanffy‟s growth formula was 3.1578 years taking the largest Fig.4- Relative yield per recruit and relative biomass per squid observed in the catch. recruit of U. duvauceli PAWAR et al.: AGE, GROWTH AND MORTALITY OF INDIAN SQUID, UROTEUTHIS DUVAUCELI 95

Discussion indicated in the present study is almost similar By employing ELEFAN, L∞ and K to that reported by Karnik et al., 8. Thomas and were estimated as 376 mm and 0.95 per year Kizhakudan9 reported the values of Z, M and respectively. In present study the length data F were 3.94, 1.74 and 2.20 respectively. of both males and females have been pooled Karnik et al., 8.reported the values of Z, M and and therefore the present estimates are an F at 4.29, 1.82 and 2.47 respectively. Natural average for both the sexes. Thomas and mortality (M) of 1.82 is more or less same to Kizhakudan9 based on the analysis of length that reported by above workers and is within frequency data, reported the estimates of L∞ the range obtained for this species from India and K to be 303 mm and 0.98 per year (Meiyappan et al., 3). Total mortality respectively from Saurashtra coast. From coefficient (Z) is higher than reported by Mumbai coast, L∞ and K of L. duvauceli were Karnik et al., 8and Thomas and Kizhakudan9 . reported to be 385 mm and 0.85 per year This can be attributed to increased exploitation respectively by Karnik et al.,8. While of the species along the Ratnagiri coast. Chakraborty et al.,7 estimated the values of L∞ and K as 323 mm and 0.449 per year. From The length at first capture was Mangalore coast the L∞ and K of L. duvauceli estimated to be 107 mm. This size is less in have been estimated as 343 mm and 1.43 per relation to the maximum size of 332 mm year by Mohamed & Rao6. From Gulf of reported in the study while it is more than Thailand Supongpan10 reported L∞ and K minimum size at first maturity of 86 mm. value to be 266 mm and 0.86 per year Fishing intensity should be slightly reduced, so respectively. It has been reported that the that size at first capture doesn’t approaches females of squids grow at a faster rate, but size at first maturity. males reach to a larger size (Silas et al.,4, Meiyappan et al.3 , Mohamed et al.,1). In the present study, the exploitation Asymptotic length (L∞) obtained in the rate ( E ) of 0.59 is more or less same to 0.56 (Thomas and Kizhakudan9) and 0.57 as present study is on higher side compared to 8 most obtained by earlier workers except reported by Karnik et al., . Present Karnik et al., 8. Higher K value conforms to exploitation rate shows that the resource is exploited above the optimum level and the most of the earlier reports. In present study, t0 was estimated by employing VBGF plot to be effort has to be reduced for sustaining the 8 resource for long term exploitation. – 0.0567 year. Karnik et al., . estimated t0 for L. duvauceli as -0.0033 years from Mumbai 11 By employing length structure Virtual waters. While Supongpan et al., estimated population Analysis, the maximum fishing the value of t0 for L. duvauceli in Gulf of mortality is observed at length range of 234.5 Thailand was 0. t0 often has a small negative – 254.5 mm, Mohamed and Rao 6 reported value as conformed by the present study. maximum fishing mortality for squids between The present study indicated that L. 85 – 135 mm. In present study, larger length duvauceli attain size of 233, 324, and 355 mm classes are subjected to heavy fishing pressure in comparison to the length classes quoted by dorsal mantle length at the end of I to III year 6 respectively. Maximum size recorded during Mohamed and Rao . This may be attributed to larger cod end mesh sizes of trawlers the period of study was 332 mm at which the exploiting L. duvauceli off Ratnagiri coast. estimated age is 2.3072 years. The tmax value is estimated to be 3.10 years. Thomas and 9 By employing the relative yield / Kizhakudan reported the length at age for L. Biomass per recruit model, the value of duvauceli along the Gujarat coast of India as st rd Exploitation, Emax was estimated at 0.519. 189, 260, 287 mm at the end of I to III year Thomas and Kizhakudan9 reported the value of respectively. He further stated tmax value as 8 E max for L. duvauceli to be 0.44 from 3.06 years. Karnik et al., . reported the length Saurashtra coast. While Karnik et al.,8 at age for L. duvauceli along the Mumbai reported E max of 0.49 for L. duvauceli by waters as 221, 315, 355, and 372 mm at the employing relative yield per recruit analysis end of Ist to IVth year of its life span from Mumbai waters. Value of E max in the respectively. Also the tmaxvalue was estimated present study is lower than exploitation ratio E as 3.53 years. The growth of L. duvauceli 96 INDIAN J. MAR. SCI., VOL. 44, NO. 1, JANUARY 2015

of 0.60 calculated on the basis of ratio of F / Z. 7 Chakraborty, S. K, Deshmukh, V. D, Khan, M. Z, This indicates that to maximize the yield per Vidyasagar, K, and. Raje, S. G., Estimates of growth, mortality, recruitment pattern and recruit from L. duvauceli the efforts may be maximum sustainable yield of important fishery reduced from the present E of 0.60 to 0 .5 to resources of Maharashtra coast. Indian J. Mar sustain the stock. Sci., 26(1997): 53-56. 8 Karnik, N. S, Chakraborthy, S. K, Jaiswar, A. K, Acknowledgement Swamy,R. P, Boomireddy, S, Rajaprasad, R. and Rizvi, A F. Growth and mortality of Indian squid, Authors are thankful to Associate Loligo duvauceli(d’ Orbigny) (Mollusca/Cephalopoda/ Teuthoidea) from Dean, College of Fisheries, Ratnagiri and Mumbai waters, India. Indian J. Mar. Sci., authorities of Dr.B.S.Konkan Krishi 32(2003) : 67-70. Vidyapeeth, Dapoli for providing necessary 9 Thomas Sujitha & Kizhakudan Shobha, Cephalopod facilities for carrying out the research work. fishery and population dynamics of Loligo duvauceli(Orbigny) off Saurashtra region, Gujarat. Acknowledgement Indian J. Fish., 53(2006): 425-430. The authors are grateful to the Associate Dean, 10 Supongpan, M., Assessment of Indian squid College of Fisheries, Ratnagiri for providing (Loligo duvauceli) and meter squid (L. chinensis) necessary help for carrying out this study. in the Gulf of Thailand. Niponsuisan Gakkaaishi. 7(1988),320-323. 11 Supongpan, M., Sinoda, M. and Boongord, K. Catch References analysis of Indian squid Loligo duvauceli by light 1 Mohamed, K. S,, Vidyasagar, K, Sundaram. A. P, luring fishing in the Gulf of Thailand. Niponsuisan Lipton, P., Natarajan, G, Radhakrishnan K. A, Gakkaaishi, 58(1992), 439-444. Balan, K, Kripa, V.and Sathianandan T, V., Stock 12 Sekharan, K. V., On the oil sardine of Calicut area assessment of the Indian squid Loligo duvauceli during the years 1955-56 to 1958-59, Indian J (Orbigny), Indian J. Fish., 44 (1993): 319 -329. Fish., 9(1962), 679-700. 2 Anonymous, Handbook of fisheries statistics, 13 *Bertalanffy, von, L. Urtesuchungen iiber die. Department of animal Husbandry, Dairying and Gesetzlichkeiten des Wachstums, 1. Allgemeine Fisheries, Ministry of Agriculture, Govt. of India, Grundlagen der Theorie, Roux. Arch. (2011):1-91. Entwicklungsmech Org., 131 (1934), 613–653. 3 Meiyappan, M. M, Mohamed, K. S, Vidyasagar, K, 14 Gayanilo, Jr., F. C., Sparre, P., Pauly, D., The Nair, K. P, Ramachandran, N, Lipton, A.P, Rao, FAO-ICLARM Stock assessment tools (FiSAT). G S, Kripa V, FAO Rome Computerised Information Series Joshi, K. K, Abdusamad, E. M, Sarvesan Rand (Fisheries) No..8 (1996)126pp (+ 3 Achary, G. P. K., A review on the cephalopod diskettes),p.198.. resources, biology and stock assessment. in: V.N. 15 Pauly, D., Length-converted catch curves: a Pillai and N.G. Menon (Eds.) Marine Fisheries powerful tool for fisheries research in the tropics Research and Management, Central Marine (Part I). ICLARM Fishbyte, 1(1983): 9-13. Fisheries Research Institute, Cochin. (2000): 546- 16 Pauly, D., Length-converted catch curves: a 562. powerful tool for fisheries research in the tropics 4 Silas, E. G, Meyyapan, M. M, Sarvesan, R, (Part II). ICLARM Fishbyte, 2 (1984):17-19. Prafahakaran, K. Nair, Srinath, M. and Rao, K. S., 17 Cushing, D. H., Fisheries biology ; A study of Stock Assessment of Squid* and cuttlefish at population dynamics, Univ, Wisconsin press, selected centre. Bulletin of Central Marine Fisheries Madison, USA, (1968),p.200. Research Institute, 37(1985):11-79. 18 Beverton, R. J. H. & Holt, S. J., On the dynamics of 5 Kuber, Vidyasagar D., A study on cephalopod of exploited fish populations. Fish. Invest. Minist. Bombay waters, Ph.D. thesis, University of Agric. Fish. Food G.B. (2 Sea Fish) 19(1957), 533. Bombay, India, 1987. 19 Beverton, R. J. H. & Holt, S. J, Manual of methods 6 Mohamed, K. S. & Rao, G. S., Seasonal growth, of the fish stock assessment Part II Tables of stock recruitment relationship and predictive yield yield function. FAO Fisheries Technical Paper No. of the Indian squid Loligo duvauceli exploited off 38(4) 1966 . Version 1, 67(1962), 679-700. Karnataka coast. Indian J. Fish., 44 (1997) : 319- 329.