Indian Journal of Geo Marine Sciences Vol.46 (11),November 2017, pp. 2367-2371

Age, Growth and Mortality characteristics of lentjan (Lacepede, 1802) exploited off Thoothukudi coast, Tamil Nadu, India

M. Vasantharajan1, P.Jawahar2, S. Santhoshkumar2 & P.Ramyalakshmi3

1Directorate of Research, Tamil Nadu Fisheries University, Nagapattinam 611 001, Tamil Nadu, India 2Department of Fisheries Biology and Resource Management, Tamil Nadu Fisheries University, Nagapattinam 611 001, Tamil Nadu, India 3 Department of Aquaculture, Fisheries College and Research Institute, Tamil Nadu Fisheries University, Nagapattinam 611 001, Tamil Nadu, India.

[E- mail: [email protected]]

Received 17 July 2015 ; revised 17 November 2016

Study on maximum sustainable yield along Thoothukudi coast indicated that L.lentjan is underexploited. The L∞, K and t0 value of L.lentjan were 78.8 cm, 0.37 year-1 and -0.68 year respectively. The K value of L.lentjan was relatively higher inferring slow growth rate of this tropical demersal fish . Total instantaneous mortality (Z) of L.lentjan was 1.28 year-1 and the estimated Fishing mortality was 0.73. Recruitment of L.lentjan was recorded in throughout year with two peaks in July – August, 2011and April, 2012.

[Keywords : Lethrinus lentjan, Age, Growth, Mortality ]

Introduction In India, the good perch grounds were L.nebulosus (Starry emperor bream), L. harak found in northeast coasts from the depth of 60 -70 (Yellow banded emperor bream), L.elongatus (Long m and located in the range between 18° to 20° N face pig face bream) and Lethrinella miniatus (long and 84° to 87° E, as recorded1. Perches contribute nosed emperor)5. The family fishes about 5.1% of the total marine fish catch of Tamil such as L.harak, L. lentjan, L. mahsena, L. Nadu state. Among that Thoothukudi district microdon, L. miniatus, L. nebulosus, L. ornatus, L. contributes around 11.08% of total marine fish variegates and Gymnocranius griseus are recorded catch of the state2. The L. Lentjan has couple of as coral reef fishes in the Gulf of Mannar6. The spawning peaks from December to February and Lethrinid fishes are not included in the IUCN red June to August. The L. lentjan has fast growth in list. Though in depth studies were made on the the first year and with the increase in age a decrease stock assessment of the various species of lethrinid in the rate of growth was also observed3. During the fishes by different authors throughout the Indian month of mid-June, the large sized juveniles of waters elsewhere, detailed studies on the stock Lethrinids ranging from 30 to 40 mm of total length assessment and management of lethrinid fishes in were found in sea grass beds4. It included Thoothukudi coast were not done so far. Hence, the L.atkinsoni, L. harak, L. obsoletus, L. genivittatus present investigation was undertaken. and L. ornatus. The lethrinid juveniles preferred the sea grass-replenished reefs only and not the sea Materials and Methods grass-free reefs. In India, the available species of The present study was carried out for a family Lethrinidae (Pig face breams) are period of 12 months from July 2011 to June 2012.

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The abundance of lethrinid fish species in the Thoothukudi coast triggered this study on its fishery management aspects. Major lethrinid species available along Thoothukudi coast were Lethrinus lentjan, L.nebulosus, L.ornatus, L.elongatus, L.microdon, L.mahsena, L.harak, L.ramak. L.conchyliatus, L.rubiroperculatus, Gymnocranius robinsonii and G.griseus. A total of 5760 specimens of L.lentjan were collected during the study period Fig.1. Length frequency distibution and seasonal occurrence of to estimate the stock assessment parameters. Lethrinus lentjan (July 2011 – June 2012)

Age and growth studies The minimum size recorded was 12 cm weighing approximately 10 g, while maximum size Length frequency data of L.lentjan were recorded was 75 cm (3300 g) during the months of October every week for the period from July 2011 to June and December. The length group ranged from 14.5 2012. About 120 specimens were collected during cm to 75 cm L.lentjan which constituted the major every sampling and the total length and the weight lethrinid catch in trawl net fishery. of each specimen were measured and recorded. Age and growth were assessed using the FiSAT Age and growth computer software7. The L∞ and K values were analysed by non-parametric scoring of VBGF fit Progression of modes of various length using ELEFAN-I. The length frequency data were groups of L.lentjan were obtained using subjected to model progression technique by Bhattacharya’s method and linking of the means are splitting the modes using Bhattacharya’s analysis represented in Fig. 2 . followed by linking of the means. The seasonality of growth was confirmed using Appeldoorn’s method in FiSAT software. The ‘ϕ ' ’ an index of growth performance was also estimated using Pauly and Munro’s formula8.

ϕ ' = ln K+2 ln L∞ where, K - curvature parameter L∞ - asymptotic length Mortality parameters Fig.2. Progression of modes of various cohorts of Lethrinus lentjan The total mortality rate (Z) was estimated by length converted catch curve method using FiSAT. The The growth curve of L.lentjan is given in Fig. 3. natural mortality (M) was estimated by Pauly’s equation (1980) considering the mean annual habitat temperature, L∞ (asymptotic length) and K (curvature parameter) of L.lentjan. The co-efficient of fishing mortality (F) was derived using the relationship Z = F + M.

Results and Discussion The analysis of catch composition on Lethrinid fishery revealed that L.lentjan was available throughout the year at Thoothukudi coast.

The length composition and length frequency data collected are presented in Fig. 1. Fig.3. Growth curve of Lethrinus lentjan VASANTHARAJAN et al.: AGE, GROWTH AND MORTALITY CHARACTERISTICS OF LETHRINUS LENTJAN 2369

The maximum life span was found to be 11 assessed by using the FiSAT software with 5760 years for L.lentjan. The Von Bertalanffy’s Growth specimens. From the result, it is evident that L. Function plot of L.lentjan is represented in Fig.4. lentjan is a long lived species.

The estimated growth parameters of L∞, K, to for L. lentjan in the current work were 78.8 cm, 0.37 and - 0.68 respectively. The results of L∞, K, to of L. lentjan from the Mauritius coast were estimated as 78.26, 0.235, - 0.6111. Similar studies such as L∞, K, to made from the Persian Gulf and Oman Sea for L. lentjan is 67.2cm, 0.16 and - 1.161 respectively which is lower than that recorded in the present study12.

Fig.4. Von Bertalanffy’s Growth function plot of Lethrinus lentjan The length base index of growth performance (ϕ') of 7.74 was found to be in L. The estimated growth parameters of lentjan. The factor explaining the relationship L.lentjan are shown in Table 1. between natural mortality coefficient and physiological factor ‘M/K’ was also recorded in L. Table .1. Growth parameters of Lethrinus lentjan of lentjan. These value found in L. lentjan is 1.48. This Thoothukudi coast is due to the fast metabolic rate in L. lentjan as observed now. Hamsa et al., (1994) The estimated L∞ Species K M/K t ϕ ‘K’ value of L. lentjan as 0.4172 in the Gulf of (cm) 0 Mannar from Kilakarai13. and 0.03994 in the Gulf 14 Lethrinus 78.8 0.37 1.48 -0.68 7.74 of Mannar from Thoothukudi . The present lentjan estimated ‘K’ values also do not differ much from these studies. Thus, it is evident that L. lentjan is a The Asymptotic length (L∞) of L.lentjan slow growing fish. was found to be 78.8 cm. The growth co-efficient (K) of L.lentjan is 0.37 respectively. The estimated Mortality parameters ‘t ’ value for L.lentjan it was -0.68. The length base o The mortality parameters and exploitation index of growth performance (ϕ '– phi prime) of ratio of L. lentjan are shown in Table 2. L.lentjan was 7.74. Table.2. Mortality parameters and exploitation ratio of The factors explaining the relationship Lethrinus lentjan of Thoothukudi coast between the natural mortality coefficient and physical factor (M/K) were 1.15 for L. lentjan. The generalized von Bertalanffy’s growth equation for Natural Fishing Total Exploitation L. lentjan is given below : Species mortality mortality instantaneous ratio (M) (F) mortality (Z) (E = F/Z) Generalized VBGF equation for L. lentjan Lethrinus 0.55 0.73 1.28 0.57 L (t) = 78.8* {1-exp - 0.37 (t - 0.68)} lentjan

In the present study, the life span of L. lentjan was estimated at 11 years. 9Earlier studies The estimated total instantaneous mortality (Z) and indicated the similar results of 14 years of life span natural mortality (M) of L. lentjan was found to be in L. lentjan by sectioning the scale patterns. In case 1.28 and 0.55 respectively. The fishing mortality of otolith sectioned study it showed the oldest age co-efficient (F) of L. lentjan were 0.73. The of L. lentjan as 27 years. Marriott et al10 also estimate exploitation ratio of L. lentjan was 0.57. recorded the average life span of L. lentjan as 8-15 The estimated ‘Z’ values of L. lentjan by length years. In this study, the life span of L. lentjan was converted catch curve method were 1.28 (Fig.5).

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be increased to achieve the Maximum Sustainable Yield from this region.

Acknowledgement This article is part of M.F.Sc., thesis submitted to the Tamil Nadu Veterinary and Sciences University, Madhavaram, Chennai – 51. The Authors are thankful to the Dean, FC&RI, Thoothukudi for supporting this study.

References 1. Mathew, G., Gopakumar, G., Lazaru, S., Chakraborthy, S. K., Kaladharan, P., Firoz khan, M., Jayasankar, P., and Venugopal, K.M., Perch resources of the shelf waters in the Fig.5. Length based catch curve of Lethrinus lentjan EEZ of India. in : Proceedings of the Second Workshop on Scientific Results of FROV Sagar Sampada, (1996) pp. In the present study, fishing mortality of L. 387– 397. lentjan was found to be higher when compared to 2. Durai.,V., Neethiselvan, N., Chrisolite, B., and Sundaramoorthy, B., Long line selectivity and fishing the natural mortality. A direct relationship was pressure on the fishery of Lethrinus elongatus off observed between ‘M’ and ‘K’ for both the above Thoothukudi coast. Tamilnadu Journal of Veterinary and species as observed15-16 in both fin fishes and Animal Sciences, (2011) 7: 137-143 shrimps. The estimated values of ‘M’ (0.53) and ‘Z’ 3. Toor, H.S., Biology and fishery of the Pig-face bream, (0.74) for L. lentjan from Mauritius coast11. Lethrinus lentjan Lacepede. III. Age and Growth. Indian journal Fisheries. (1964) 11: 597-535 Compared to this result, the ‘M’ value of the 4. Nakamura, Y., Shibuno, T., Lecchini, D., and Watanabe, present study is very similar and the ‘Z’ value was Y., Habitat selection by emperor fish larvae, Aquatic higher. Earlier results of M and Z for Lutjanus larvae, (2009) 6: 61 – 65 synagris is 0.527 and 1.65 respectively from Puerto 5. Mathew G., Status of Exploited marine fishery resources of 17 18 India, Central Marine Fisheries Research Institute, Cochin, Rico waters . Motlagh et al recorded the Vol:13 (2003)102 – 109. mortality parameters ‘Z’ (1.13), ‘M’ (0.57) and ‘F’ 6. Varghese, M., Manisseri, M.K., Ramamurthy, N., Geetha, P (0.56) in Persian waters and these are not much M., Thomas, V.J., and Gandhi, A., Coral reef fishes of different from the present investigation. Hence it is Gulf of Mannar, S.E of India, Fishing Chime,. (2011) clear that the mortality observed in this study in 31: 38 – 40. 7. Gayanilo, F.C., Sparre, P., and Pauly, D., FAO-ICLARAM fishing was higher than the mortality occurring Stock Assessment Tools. in: User’s guide.FAO naturally. computerized information series. (1996), 8: pp 126. 8. Pauly, D., and Munro, J.L., Once more on the comparison Conclusion of growth in fish and invertebrates. ICLARM: International Among the major perches L.lentjan form Center for Living Aquatic Resources Management, Fishbyte, (1984) 2:1 p. 21. good fishery in Thoothukudi region throughout 9. Ebisawa A., and Ozawa T., Life-history of traits of eight year. The recruit pattern found two peaks in July – Lethrinus species from two local populations in waters off August, and April. Small sized fishes were the Ryukyu Islands, The Japanese Society of Fisheries represented considerably in the catches during the Science, Japan, (2009) Vol. 75: pp.553 – 566. months of November, December and January. The 10. Marriott, R.J., Adams, D.J., Jarvis, N.D.C., Moran, M.J., Newman, S.J., and Craine, M., Age-based demographic highest estimated total catch and the average assessment of fished stocks of Lethrinus nebulosus in the catch per unit effort (CPUE) were observed in the Gascoyne Bioregion of Western Australia, Fisheries month of October and December. The growth Management and Ecology.,(2010) 18:21 – 15. coefficient reveals shows that it is a slow growing 11. Rathacharen, S., Venkatasami, A., and Degambur, D., Growth parameters and mortality rates of Epinephelus species. The weight gain in relation to total length fasciatus, Lethrinus nebulosus, Siganus sutor, Naso seems it has isometric growth pattern. The life span unicornis and Mugil cephalus from the coastal areas of of this species is about 11years evident that long mauritius as estimated from analyses of length frequencies, living species. The present study revealed that, the Albion Fisheries Res. Centre 1999, pp.217 – 228. stock was under exploited in Thoothukudi coast. 12. Motlagh, S.A.T., Vahabnezhad, A., Seyfabadi, S.J., Shojaei, M.G., and Hakimelahi, M., Growth, mortality and The present level of effort for this species may spawning season of the spangled emperor (Lethrinus VASANTHARAJAN et al.: AGE, GROWTH AND MORTALITY CHARACTERISTICS OF LETHRINUS LENTJAN 2371

nebulosus Forsskal, 1775) in coastal waters of Hormozgan 16. Sundaramoorthi B., Studies on the stock assessment of Province in the Persian Gulf and Oman Sea, Iranian penaeid shrimps (Family: Penaeidae) of Thoothukudi Coast. Journal of Fisheries Science., (2010) 9:1 161 – 172. in : Ph.D. Thesis, Tamilnadu Veterinary and Animal 13. Hamsa K M S A and Kasim H M, The perch fishery by Sciences University, 2001. traditional traps at Kilakarai (Gulf of Mannar) and some 17. Acosta A., and Appeldoorn R.S., Estimation of growth, aspects of biology of Lethrinus nebulosus (Forskal), mortality and yield per recruit for Lutjanus synagris Bull. Cent. Mar. Res. Inst. Vol:47 (1994) 98 – 105. (Linnaeus) in Puerto Rico, Bulletin of marine science., 14. Kasim, H.M., Hamsa, K.M.S.A., and Bennet, P.S., Present (1992) 50:2 282 – 291. status of perch fishery resources in India and its prospects, 18. Motlagh, S.A.T., Seyfabadi, J., Vahabnezhad, A., Shojaei, in : National Symposium on Research and Development in M.G., and Hakimelahi, M., Some Reproduction Marine Fisheries, (1989) Vol:44, 226 – 237. Characteristics and Weight - Length Relationships of the 15. Beverton R.J.H., and Holt S.J., A review of the life spans Spangled emperor, Lethrinus nebulosus (Lethrinidae) of the and morality rates of fish in nature and their relationship to South Coastal of Iran (Persian Gulf and Oman Sea), Turkish growth and physiological characteristics, in: CIBA Journal of Fisheries and Aquatic Sciences., (2010) 10: pp. Foundation Colleqequia Agency. (1959) Vol. 5: pp.142- 221 – 227. 180.