Study of the mortality of Paralonchurus brasiliensis [Teleostei, Sciaenidae], in fishery ground of the shrimp Xiphopenaeus kroyeri

Abstract

The mortality rates are described for Paralonchurus brasiliensis, caught in inshore areas of northern part of São Paulo State coast, Brazil, at the fishery area of the shrimp Xiphopenaeus kroyeri. The growth of P. brasiliensis was described by the von Bertalanffy equation, with the parameters k = 0.274 year^-1 and L∞=26.3 centimeters. These parameters have been got according to Harding method that involves plotting the length distributions on cumulative probability paper and identifying the points of inflexion and using them in Beverton plots. The instantaneous rate of total mortality (Z) was estimated in 0.460 year^-1, and the instantaneous rate of natural mortality (M) was 0.405 year^-1. With the values of Z and M, the instantaneous rate of fishery mortality (F) could be estimated in 0.055 year^-1. Because the low value for fishery mortality, total mortality was similar to natural mortality. The annual mortality was A = 36.9%, and the survival rate was S = 63.1%. There is not a catch effort for P. brasiliensis, but it has been caught with shrimps in trawls.