Length-weight Relationship of Fish Species Captured as Bycatch Along the Northeastern Coast of Brazil

Abstract Length-weight relationships (LWRs) are widely used in fisheries biology to describe growth patterns, estimate biomass, and provide essential information for stock assessment and fisheries management. This study estimated the LWR parameters of fish species captured as bycatch in shrimp trawl fisheries along the coast of Sergipe, northeastern Brazil. Samples were collected monthly from January to December 2020 from vessels operating bottom trawl nets targeting penaeid shrimp. Total length and body weight were recorded for each specimen, and LWRs were estimated using the equation W = aL^b. A total of 1,204 individuals belonging to eight species were analyzed. The estimated allometric coefficient (b) ranged from 2.1086 in Larimus breviceps to 3.3482 in Citharichthys spilopterus . Three species exhibited negative allometric growth ( Odontognathus mucronatus , Larimus breviceps , and Prionotus punctatus ), whereas five species showed positive allometric growth ( Paralonchurus brasiliensis , Pellona harroweri , Syacium papillosum , Citharichthys spilopterus , and Stellifer rastrifer ). Coefficients of determination (R²) ranged from 0.66 to 0.97, indicating a good fit of the regression models. This study provides the first record of the length-weight relationship for Syacium papillosum from the coast of Sergipe. The results contribute valuable biological information on bycatch species and may support future biomass estimations, stock assessments, and sustainable management strategies for demersal fish resources in northeastern Brazil.