Length–weight relationship of Charybdis callianassaHerbst, 1789 (Decapoda: Brachyura) in relation to sex and carapace length along the Mumbai coastal water, India

Background: The present study was performed to determine carapace length–body weight relationship of Charybdis callianassa.In fisheries biology, length–weight relationships are important as they allow for the calculation, by creating a mathematical equation between the two, of the total weight of the fish in a particular group in fish. Such information is helpful for fishery scientists to research the dynamics of development and populations and for public agencies that can maintain and preserve these resources sustainably. Results: A study on the carapace length–body weight relationship of Charybdis callianassa(Herbst, 1789) was made on the northwest coast of India for the first time. The study was based on experimental trawl fishing conducted fortnightly from August 2019 to March 2020.A total of 479 specimens, including 262 males and 217 females from fishing trawler, were examined for their carapace length and total weight. The carapace length ranged from 2.69 to 3.54 cm, and the total weight from 5.26 to 7.36 g. This analysis revealed that the crabs exhibited negative allometric development, as shown by average exponents 'b' = 2.71 for pooled data with high coefficient (r) = 0.91 and r²= 0.83. Conclusions: The carapace length–body weight relationship of Charybdis callianassain relation to sex and carapace was studied in the Mumbai coastal water, India. We found major differences in the average “r²” values of species reported for males (0.89), females (0.79) and pooled data (0.83). Such kind of study is essential for fisheries biology to comprehend the differences in circumstances in small and large specimens that vary with environmental conditions and seasons.