Estructura de tallas, crecimiento y tasa de explotación de Potamorhina altamazonica (Characiformes: Curimatidae) en el río Ucayali (Perú)

The llambina Potamorhina altamazonica is one of the most important resources for the commercial fishery in the Ucayali region. In this context, we conducted this study to determine the size structure, growth parameters, and exploitation rate of the llambina in the Ucayali River (Ucayali region). We analyzed samples taken from commercial fishing catches in Pucallpa, which concentrates the largest fishing fleet in the region. Our results are based on specimens sampled between January 2008 and December 2012. We determined that the average catch size of llambina was lower in the Ucayali region compared to that of Loreto evidencing a higher fishing pressure in Ucayali. The estimated growth parameters for combined sexes were L_∞ = 31.45 cm and K = 0.37 year^-1. The von Bertalanffy function satisfactorily described the growth in length determined by the electronic analysis of length frequency and allowed us to observe that the species grows rapidly during the first year and it reaches the theoretical longevity at 8,1 years. The estimated total mortality rate (Z) was relatively high (1.69 year^-1) while the exploitation rate considering the natural mortality coefficient (M = 0.90 year^-1) and the fishing mortality rate (F = 0.79 year^-1) was estimated at 0.47 year^-1, which indicates that the resource is almost at the optimal level of exploitation (E = 0.5).