Biologia alimentar e reprodutiva do peixe-cachorro (Oligosarcus Jenynsii Günther, 1864) na região do alto rio Uruguai - Brasil

Abstract

The aim of this study was to analyze feeding habit and reproductive aspects of Oligosarcus jenynsiiof the upper Uruguay river. A total of 246 specimens of O. jenynsiiwere captured: 127 were females, 78 were males and the sex of 41 specimens could not be identified. Total length and weight ranged from 35 to 310mm and 0.3 to 330g, respectively. Highest average replection index values were observed during autumn (1.9% ±1.4). The species was carnivorous with a tendency to piscivory. The sex ratio was 1.6 female: 1 male. According to variations of average gonadosomatic index, the frequency distribution of maturity stages, and the relative distribution of oocyte diameter, O. jenynsiipresents a multiple spawning, breeding from winter to spring. Size at maturity was estimated as 164mm for both males and females. The absolute fecundity average was 20,727.