Length-Weight Relationships of Ten Small Pelagic Fishes along the Coastal Waters of Karnataka, Southeastern Arabian Sea, India

Information on the length and body weight of fish is the foremost requirement for regulation of catch and estimation of biomass as they are the pre-requisites for conservation and management of fish. Length-weight relationships were estimated for ten major marine small pelagic fish species landed along Karnataka coast, southeastern Arabian Sea. Specimens were collected on a weekly basis from various gears such as purse seines, ring seines, trawl nets and gillnets landed at two major fishing harbors (Mangalore and Malpe) located along the Karnataka coast from January 2018 to December 2019. The estimated allometric coefficient b ranged between 2.513 and 3.205, falling within the expected range (2.5-3.5). The LWRs were highly significant (P<0.001; r²≥0.90) for all the species and ranged from 0.90 to 0.99. The analysis divulged isometric growth (b=3) for Sardinella albella (female), Sardinella fimbriata (female), Sardinella gibbosa (male and pooled) Decapterus macrosoma (pooled) and Stolephorus commersonii (pooled).  However, Sardinella albella (male and pooled), Sardinella gibbosa (female), Escualosa thoracata (pooled), Decapterus tabl (pooled), Stolephorus waitei (pooled) showed positive allometeric growth (b>3) while Sardinella fimbriata (male and pooled), Seriolina nigrofasciata (male, female and pooled) and Encrasicholina devisi (pooled) showed negative allometric growth (b<3).  The present study reported a new maximum size for Sardinella fimbriata, Escualosa thoracata, Encrasicholina devisi, and Stolephorus waitei. In addition, this study would contribute to providing the first estimate of LWRs of Decapterus tabl from Indian waters. The basic biological information provided in this study in the form of length-weight estimates for 10 commercially important small pelagic fish species from the southeastern Arabian Sea filling important knowledge gaps in population studies and stock assessment and further assists in sustainable management and conservation of fisheries.