Body Weight, Carapace Length and Width Relationship and Condition Factor of the Mud Crab Scylla serrata (Forskal) in Mangrove Ecosystem

Sarvabhowma Chakravarty Myla,Rama Chandra Ganesh Paturi,Vijaya Bharathi Tirumani

doi:10.15835/nsb9310127

Sarvabhowma Chakravarty Myla, Rama Chandra Ganesh Paturi + Show 1 more

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https://doi.org/10.15835/nsb9310127

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Abstract

The relationship of length-weight and width-weight of the carapace and the relative condition factor of mud crab Scylla serrata from Coringa Wildlife Sanctuary (Andhra Pradesh, India) was the subject of present study. Significant difference in both males and females was observed between carapace length-weight, carapace width-weight with a linear relationship. The regression values of both the sexes were found to be statistically significant. The regression equations calculated for length-weight were W= 0.00000178 L 3.1139 (r= 0.95) for males, W= 0.00000520 L 2.8056 (r=0.94) for females and for sexes combined it was W = 0.0000297 L 2.9891(r= 0.94). In case of carapace width-weight relationship of males, females and sexes combined the regression equations were W= 0.00000121 CW 3.0426 (r= 0.92), W= 0.00000178 CW 2.775 (r=0.93) and W = 0.00000204 CW 2.9210(r= 0.92) respectively. The male crabs showed positive allometric growth whereas female had negative allometric growth. Analysis of covariance confirmed remarkable difference between males and females in the growth pattern. The mean relative condition factor (Kn values) of both males and females and of the pooled sexes ranged from 0.680 (April) to 1.029 (November). A gradual raise in Kn values was observed from small- to big- sized crabs in both the sexes. Peak values were observed in 12.0-13.9 cm size group in November.

Highlights

Mud crab, Scylla serrata (Forskal) is the only species of the family Portunidae inhabiting the mangroves of the tropical latitudes Indo-Pacific (Hill, 1975; Overton et al, 1997) and subtropical environments of China and Japan (Sakai, 1976; Dai and Yang, 1991), having tolerance to a wide range of environmental variations
According to Mohapatra (2008) the carapace width-weight relationship, condition factor and relative condition factors in mud crabs are important for biological studies like catch data, yield recruit, model analysis and so on
Crab samples were collected every month from the main landing center Pedavalasala village (16° 46’ 45.93”N; 82° 15’ 47.05” E) where all the crab catches in Coringa mangroves were brought and pooled

Summary

Introduction

Scylla serrata (Forskal) is the only species of the family Portunidae inhabiting the mangroves of the tropical latitudes Indo-Pacific (Hill, 1975; Overton et al, 1997) and subtropical environments of China and Japan (Sakai, 1976; Dai and Yang, 1991), having tolerance to a wide range of environmental variations. It ranks first among crabs because of its large size, high meat quality, delicate taste (Rattanachote and Dangwatanakul, 1992). Individual variation in length-weight relationship has been considered as the general condition of the organism to analyze the condition factor or k-factor or prepondral index (Le Cren, 1951)

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