Length–weight relationships of three species of pelagic sharks from southeastern Arabian Sea

Abstract

Length–weightrelationships (LWRs) of three species of pelagic sharks belonging to the family Carcharhinidae viz., the silky shark Carcharhinus falciformis and the graceful shark C. amblyrhynchoides and Alopidae viz, the pelagic thresher Alopias pelagicus, were estimated based on 525 samples collected from the longline and gillnet fishery of southeastern Arabian Sea from January 2016 to November 2018. Two major fish landing centres of Kerala, southwest coast of India were selected for sampling; Cochin (Lat. 09∘56′327′′N, Long. 76∘15′764′′E) and Munambam (Lat. 10∘10′965′′N, Long. 76∘10′258′′E). The estimated allometric coefficient b value ranged from 2.687 (A. pelagicus, N = 122) to 3.11 (C. falciformis, N = 295). Coefficient of determination scores ranged from 0.901 (A. pelagicus) to 0.984 (C. amblyrhynchoides, N = 108), indicating robustness of the samples analysed. Maximum total length presented for C. amblyrhynchoides in this study was a new record. The study reports first estimates of length–weight relationships for three important species of pelagic sharks which contribute to most of the shark catches in the region, and the generated parameters will be useful for the assessment of stocks and sustainable management of pelagic sharks in southeastern Arabian Sea.