Dynamics of some bio indices (carapace width [CW] and body weight [W] relationship, relative condition factor [Kn]) of mud crab Scylla serrata (Forsskål, 1775), collected from the Hooghly-Matlah Estuary of West Bengal, were studied for a period of one year. A total of 325 specimens were collected (CW 44 – 120 mm, W 20 – 210 g) and studied. The CW and W relationship was found as W = 0.0006 CW2.665 for male and W = 0.001 CW2.561 for female. The b value was found relatively higher in male indicating better growth rate compared to females. Moreover, the growth pattern was allometric. The monthly mean Kn was 0.968 to 1.058 for males and 0.962 to 1.054 for females that significant varied (P &lt; 0.05) among sampling months

Bhakta, Dibakar

Das, Sudhir Kumar

Khan, Mohinor Alam

Journal of Fisheries (University of Rajshahi)

  Journal of Fisheries Volume 6 Issue 3 Pages 650–653 December 2018 Peer Reviewed | Open Access | Online First eISSN 2311-3111 pISSN 2311-729X  Short Communication DOI: 10.17017/jfish.v6i3.2018.301   BdFISH Publication | journal.bdfish.org | © Creative Commons BY-NC-SA 4.0 License 650   Dynamics of bioindices in mud crab Scylla serrata (Forsskål, 1775) occurring in Hooghly-Matlah Estuary of West Bengal, India Mohinor Alam Khan1  Sudhir Kumar Das1  Dibakar Bhakta1, 2 1  Department of Fishery Resource Management, Faculty of Fishery Sciences, WBUAFS, Chakgaria, Kolkata- 700 094, West Bengal, India. 2  ICAR-Central Inland Fisheries Research Institute, Regional Centre, B-12, Hans Society, Harney Road, Vadodara 390 022, Gujarat, India.  Correspondence  Dr Sudhir Kumar Das; Department of Fishery Resource Management, Faculty of Fishery Sciences, WBUAFS, Chakgaria, Kolkata- 700 094, West Bengal, India.  dassudhirkumar1@gmail.com   Manuscript history Received 17 November 2017 | Revised 3 April 2018 | Accepted 28 October 2018 | Published online 28 November 2018 Citation  Khan MA, Das SK and Bhakta D (2018) Dynamics of bio-indices in mud crab Scylla serrata (Forsskål, 1775) occurring in Hooghly-Matlah Estuary of West Bengal, India. Journal of Fisheries 6(3): 650–653. DOI: 10.17017/jfish.v6i3.2018.301 Abstract Dynamics of some bio indices (carapace width [CW] and body weight [W] relationship, relative condition factor [Kn]) of mud crab Scylla serrata (Forsskål, 1775), collected from the Hooghly-Matlah Estuary of West Bengal, were studied for a period of one year. A total of 325 specimens were collected (CW 44 – 120 mm, W 20 – 210 g) and studied. The CW and W relationship was found as W = 0.0006 CW2.665 for male and W = 0.001 CW2.561 for female. The b value was found relatively higher in male indicating better growth rate compared to females. Moreover, the growth pattern was allometric. The monthly mean Kn was 0.968 to 1.058 for males and 0.962 to 1.054 for females that significant varied (P < 0.05) among sampling months. Keywords: Scylla serrata; mud crab; biotic index; relative condition factor; Hooghly-Matlah Estuary  1 | INTRODUCTION The mud crab Scylla serrata (Forsskål, 1775) is one of the largest Portunids under order Decapoda and is widely distributed throughout the coastal Indo-Pacific region (Barnes et al. 2002). The species forms a highly potential fishery of Hooghly-Matlah estuarine system due to its well-known export trade, delicacy, medicinal value and local consumer preference. The length-weight relation-ship (LWR) is a prerequisite to know the population struc-ture and implements management measures of respec-tive species. It is also useful in estimating and comparing the population status and general wellbeing of aquatic species with high commercial value (Mohapatra et al. 2010). In crabs, the study of carapace width and body weight relationship is widely used to know the growth patterns during their developmental stages (e.g. Prasad et al. 1989, Khan and Alam 1991, Poovachiranon 1991, Knuckey 1996, Nandi et al. 1996, Sukumaran and Neelakantan 1997). However, very limited studies were done on this issue from the Hooghly-Matlah estuarine system. So, the pre-sent work was conducted to find out dynamics of bioin-dices of mud crab which will be a useful reference for biological management of fisheries, especially in India and adjacent countries.  Bioindices of mud crab Scylla serrata J Fish 6(3): 650–653, Dec 2018; Khan et al.  BdFISH Publication | journal.bdfish.org | © Creative Commons BY-NC-SA 4.0 License  651  2 | METHODOLOGY The mud crab S. serrata  is the largest crab species found in near shore and brackish water habitats and formed lucrative fishery at Hooghly-Matlah estuarine system. The present work on carapace width and body weight rela-tionship was conducted for a period of 12 months from September 2007 to August 2008. The samples were col-lected from Sagar Island, Bokkhali and Kakdwip landing sites of Hooghly-Matlah Estuary. The collected specimen was caught by fishing lines, locally known as ‘haarsuti’ or ‘doan’, ‘gultasuti’ or ‘thupasuti’, ‘chhankanjal’, ‘kancha’, ‘ganjia’ and ‘kanpi’. During the period of study, a total of 325 specimens, 181 male and 144 female individuals, were procured and examined with size ranged from 44 to 120 mm carapace width and 20 to 210 g of body weight. The carapace width (CW) was measured with a standard ruler (to the nearest mm) and body weight (W) was measured by a mono-pan balance (to the nearest g).  Le Cren (1951) proposed a nonlinear equation in the form of W = aLb, which explains the relationship between length (L) and weight (W). A student ‘t’ test was em-ployed to test the variation among ‘b’ values. The relative condition factor (Kn) was calculated by using the formula Kn = W○ / Ŵ, where W○ is the observed weight and Ŵ is the calculated weight. Kn value was observed for male and female separately in different months. Significant difference among mean values of different biological pa-rameters was tested employing by a Student’s ‘t’ test and analysis of variance (ANOVA) technique (Snedecor and Cochran 1967). Data were checked to meet the assump-tions for a parametric test and necessary transformation was made where needed. 3 | RESULTS AND DISCUSSION It was observed that there was a high positive significant correlation between CW and W of mud crab (r = 0.98 for male, r = 0.97 for female). The nonlinear equation was found as W = 0.0006 CW2.665 for male and W = 0.001 CW2.561 for female crabs. It bears similarity with earlier works where CW and W relationships of mud crab S.  ser-rata were W = 0.0423 CW2.726 (male) and W = 0.3357 CW2.6265 (female), with male exhibiting more growth rate compared to female in Queensland (Lee 1992). A signifi-cantly high growth rate of male mud crabs than female was reported (W = 0.0423 CW3.726 for male and W = 0.3357 CW2.7285 for female) in the Andaman sea (Poovachiranon et al. 1991). The growth was found allometric for both the male (t = 9.265, df = 180, P < 0.05) and female (t = 7.845, df = 143, P < 0.05) crabs and b values of male were comparatively higher than female that indicates a relatively better growth rate in male. Mohapatra et al. (2010) reported b value of 3.21 – 3.22 for male and 2.75 – 2.92 for female S. serrata and 3.01 – 3.11 (for male) and 2.72 – 2.89 (for female) of S. tranquebarica, similar to present findings. However, the results obtained in this study differ from Gayathre et al. (2016) who reported isometric growth pattern in S. serrata with pooled b value of 2.915 from Pulicat Lake of Tamil Nadu. In another study b values of 2.240 to 3.549 in S. serrata was reported from the coastal waters of Western Seram, Mluku, Indonesia (Siahainenia et al. 2016). Higher b values in male compared to female S. serrata were also reported from the Sunderbans man-grove ecosystem and other areas of Bangladesh (Khan and Alam 1991; Zafar et al. 2006) and mangrove ecosys-tem in the Andaman Sea (Poovachiranon et al. 1991). Higher b values of two marine Portunids were also re-ported (3.10 for males and 2.96 for females of adult Por-tunus sanguinolentus; 3.62 for males and 3.25 for females of P. pelagicus) from Karnataka Coast (Sukumaran and Neelakantan 1997). It was reported that length-weight relationship can vary among same population depending on the life stages (Ricker 1975). Chakrabarti (1981) men-tioned relationships between CW and W can be inflenced by food habits, maturity and spawning of S. serrata.  Relative condition factor (Kn) is an indicator of physiologi-cal state and general well-being of fishes. It is influenced by maturity, spawning, environmental conditions and availability of food (Brown 1957). The monthly average Kn value for the male crab was ranged from 0.975 (Decem-ber) to 1.058 (April) and for female it varied between 0.962 (February) and 1.054 (May) (Figure 1). The Kn values varied significantly (F = 2.8463, df = 11.11, P < 0.05) among months. However, Kn did not vary significantly between the sexes (P > 0.05). The Kn values ranged from 1.41 to 1.53 (male) and 1.0 to 1.04 (female) S. serrata of Sundarbans mangrove ecosystem Bangladesh (Ali et al. 2004). Mohapatra et al. (2010) reported Kn values of S. serrata of Chilika Lagoon and it varied from 0.83±0.12 to 1.21±0.16 (male) and 0.84±0.15 to 1.13±0.24 (female). A mean condition factor of 1.02 to 1.04 was reported in S. serrata in the coastal waters of Western Seram, Maluku, Indonesia (Siahainenia et al. 2016). 4 | CONCLUSION The carapace width and body weight relationship was found to be allometric for both males and females of mud crab. Relative condition factors indicate that the species  Bioindices of mud crab Scylla serrata J Fish 6(3): 650–653, Dec 2018; Khan et al.  BdFISH Publication | journal.bdfish.org | © Creative Commons BY-NC-SA 4.0 License  652  exhibits healthy and robust conditions in the in the study area and males shows a better condition than females. The present findings will be useful for proper assessment and management of the mud crab fishery in the Hooghly-Matlah estuarine system.   FIGURE 1 Monthly variation of relative condition factor of males and female of mud crab Scylla serrata in the Hooghly-Matlah Estuary ACKNOWLEDGEMENTS The authors are thankful to the Dean of Faculty and Head of the Department of Fisheries Resource Management, Faculty of Fishery Sciences, WBUAFS, Kolkata, West Ben-gal for providing the necessary facilities to conduct the research works and their encouragement. We are also thankful to the reviewers for their valuable comments. REFERENCES Ali MY, Kamal D, Hossain SMM, Azam MA, Sabbir W, Murshida A, Ahmed B and Azam K (2004) Biological studies of the mud crab, Scylla serrata (Forskal) of the Sundarbans mangrove ecosystem in Khulna region of Bangladesh. Pakistan Journal of Biological Sciences 7(11): 1981–1987. Barnes DKA, Dulvy NK, Priestley SH, Darwall WRT, Choisel V and Whittington M (2002) Fishery characteristics and abundance estimates of the mangrove crab Scylla ser-rata in southern Tanzania and northern Moçambique. African Journal of Marine Science 24: 19–25. Brown MR (1957) Experimental studies on growth. In: Brown ME (ed) The physiology of fishes, Volume 1. Academic Press, New York. pp. 361–400. Chakrabarti KA (1981) growth study of the mud crab Scylla serrata (Forskal), in the Sundarbans. Indian Journal of Forestry 4(2): 102–106. Gayathre VL, Felix S and Durairaja R (2016) Carapace width-weight relationship of mud crab Scylla serrata (Forskal, 1975) collected from Pulicat Lake, Tamil Nadu, India. International Journal of Applied Sciences 5(1): 29–33. Khan MG and Alam MF (1991) The mud crab (Scylla serrata) fishery and its bioeconomics in Bangladesh. In: Angell C (ed) The mud crab: report of the seminar on the mud crab culture and trade held at Surat Thani, Thailand. November 5–8, 1991, Bay of Bengal Programme, pp. 29–40. Knuckey JA (1996) Maturity in the male mud crabs, Scylla serrata and the use of mating scars as a functional indi-cator. Journal of Crustacean Biology 16(3): 487-495. Le Cren ED (1951) The length-weight relationship and sea-sonal cycle in gonad weight and condition in the perch (Perca flaviatilis). Journal of Animal Ecology 20: 201–219. Lee C (1992) A brief overview of the ecology and fisheries of the mud crab Scylla serrata in Queensland. In: Angell AC (Ed) The mud crab Bay of Bengal Programme, Madras, India. pp. 65–70. Mohapatra A, Mohanty RK, Mohanty SK and Dey SK (2010) Carapace width and weight relationships, condition factor, relative condition factor and gonado-somatic index (GSI) of mud crabs (Scylla spp.) from Chilika La-goon, India. Indian Journal of Marine Sciences 39(1): 120–127. Nandi NC, Dev Roy MK and Pal S (1996) Biometrical studies on the mud crab Scylla serrata (Forskal) from Sundarban, West Bengal. Seafood Export Journal 27: 17–22. Poovachiranon S (1991) Biological studies of the mudcrab Scylla serrata (Forskal) of the mangrove ecosystems in the Andaman Sea. The Mud Crab. A report on the sem-inar convened in Surat Thani, Thailand. 57 pp. Prasad PN, Reeby J, Kusuma N and Neelakantan B (1989) Width-weight and length-weight relationships in three Potunid crab species. Uttar Pradesh Journal of Zoology 9(1): 116–120. Ricker WE (1975) Computation and interpretation of biologi-cal statistics of the populations. Bulletin of the Fisheries Research Board of Canada 191: 203–233. Siahainenia L, Natan Y, Khouw AS and Pattikawa JA (2016) Size distribution, growth pattern and condition factor of mangrove crab Scylla serrata in the coastal waters of Western Seram, Maluku, Indonesia. International Jour-nal of Fisheries and Aquatic Studies 4(2): 291–296. Snedecor CW and Cochron WG (1967) Statistical Methods. Oxford and   IBH Publishing Company, New Delhi, India. 35 pp. Sukumaran KK and Neelakantan B (1997) Length-weight rela-tionship in two marine Portunid crabs, Portunus san-quinolentus (Herbst) and Portunus pelagicus (Linnaeus) from the Karnataka coast. Indian Journal of Marine Sci- Bioindices of mud crab Scylla serrata J Fish 6(3): 650–653, Dec 2018; Khan et al.  BdFISH Publication | journal.bdfish.org | © Creative Commons BY-NC-SA 4.0 License  653  ences  26: 39–42. Zafar M, Nurul Amin SM and Rehman MM (2006) Population dynamics of mud crab (Scylla serrata) in the southern coastal region of Bangladesh. Asian Fisheries Science 19: 43–50.  CONTRIBUTION OF THE AUTHORS MAK primary data collection; DB data analysis and manuscript preparation; SKD research supervision    Sudhir Kumar Das  https://orcid.org/0000-0003-2229-2887 Dibakar Bhakta  https://orcid.org/0000-0002-3871-3028 

Dynamics of bioindices in mud crab Scylla serrata (Forsskål, 1775) occurring in Hooghly-Matlah Estuary of West Bengal, India

https://journal.bdfish.org/index.php/fisheries/article/download/JFish_301/9

Dynamics of bioindices in mud crab Scylla serrata (Forsskål, 1775) occurring in Hooghly-Matlah Estuary of West Bengal, India

Abstract

Similar works

Full text

Available Versions

Journal of Fisheries (University of Rajshahi)