Length-weight relationship of the bony fish community inhabiting the southwest Atlantic coast, with emphasis on commercially important species

Knowledge of the parameters of the fish length-weight relationship model (LWR), $Weight=a\ast Lengh{t}^b$, provides essential information for understanding biology and population assessments, enabling the development of conservation measures and fisheries management. This study estimated LWR parameters and described the growth type of 46 bony fish species (from 28 families and 43 genera) caught by bottom trawl in the fishery assessment surveys carried out by the National Institute of Fisheries Research and Development between 1981 and 2022 on the southwest Atlantic coast between 34° and 42°S, <50 m depth. The LWR parameters (a and b) were estimated by fitting linear regression models to the total length and weight data after log transformation. Growth type was assessed by statistically comparing the parameter b with a value of 3 (isometric growth), and considering a negative or positive allometric growth when b < 3 or b > 3, respectively. Model fit was statistically significant for all species (R² = 0.83–0.99). Half of the species evaluated exhibited negative allometric growth, 35 % positive allometric, and 15 % isometric growth. Among the 24 commercially important species, nearly half showed positive allometric growth. Thus, most of these bony fishes from the southwest Atlantic coast appear to fail the cube law of isometric growth. This study publishes for the first time information on this important biological trait for 42 species along the assessed region, four of which had no data available worldwide, and updates the available information for a further four species, improving knowledge for future biological and ecological assessments of their populations.