Reproductive strategies of two Curimatidae species in a Mogi Guaçu impoundment, upper Paraná river basin, São Paulo, Brazil

Abstract

Considering that reproduction studies are fundamental to understand the life cycle of organisms, this study aimed to investigate the reproductive strategies of saguirus Cyphocharax nagelii and Steindachnerina insculpta in a dam of Mogi Guaçu River, (SP). Specimens were collected between August 2005 and July 2006 using gillnets with mesh sizes ranging from 1.5 to 5.0 cm between adjacent knots. Reproductive dynamics, body condition, reproductive period, spawning type and fecundity were analyzed in both species. The body condition reflected the reproductive dynamics, and differed significantly between the wet and dry seasons. During the dry season, the feeding activity and the accumulation of fat in the visceral cavity were higher. The reproductive period of both species covered the months between August and February, with peaks in October and December, and the distribution of the diameters of oocytes allowed to classify them as total spawners. The fecundity increased with weight and length, reaching 28,800 and 27,906 oocytes per female for C. nagelii and S. insculpta, respectively, whereas the amplitude of oocyte diameters varied between 50-1025 μm for the former and 75-975 μm for the later species. Taking into account that species with different reproductive strategies also respond differently to environmental impacts, our findings provide important information to subsidize management plans for these curimatid species. © 2012 Sociedade Brasileira de Ictiologia.