Calculating growth parameters of Genidens barbus (Siluriformes, Ariidae) using length composition and age data

The marine catfish Genidens barbus was once one of the most important estuarine fishery resources in the Patos Lagoon (southern Brazil), which had the largest population known for the species. However, clear signs of overfishing have been observed since the 1980s. Growth parameters for this population were estimated by combining length frequency data for juveniles and selected published data on annuli reading from adult otoliths. This methodology yielded a more realistic set of parameters using both the specialized and generalized von Bertalanffy growth model. The species growth can be described as: L-t = 118.6[1 - e(-0.043(t+1.505))] or L-t = 104.6[1 -e(-0.137D(t+4.013))](1/D) with the surface factor D = 0.542. The growth performance index phi' was estimated as 2.78 for the special (classical) model. Stock rebuilding is expected to be slow, as the species is slow-growing, has a low natural mortality rate, and mouthbreeds a small amount of large eggs.