Reproductive biology of Pachyurus bonariensis (Perciformes, Sciaenidae) before the daming of the Taquarembo stream in southern Brazil

This work describes aspects of the reproductive biology of Pachyurus bonariensis (Steindachner, 1879) through the analysis of 278 specimens collected from July 2006 to July 2007. The estimated reproductive period lasted from October 2006 to February 2007 and showed a positive correlation with photoperiod and water conductivity. The oocyte development was synchronous in more than two groups, characterizing the species as multiple spawner. Mean absolute fecundity was 39,313 oocytes and relative fecundity was 0.43 oocysts per milligram of total weight. The length of the first specimen mature was set at 112.6 mm for females and males 110.7 mm and sex ratio of the population as a whole did not differ significantly from 1:1.