Condition Factor and gonadal cycle of females of Pimelodus maculatus (Osteichthyes, Pimelodidae) in Piracicaba River (SP, Brazil)

Abstract

This study aims to describe the seasonal variation of the Condition Factor of Pimelodus maculatus in Piracicaba River (SP, Brazil), and to test whether the seasonal cycle of ovarian development exerts a significant influence on the condition variation of the species. From the data of 241 individuals (161 females), the Allometric Condition Factor by including and excluding the ovarian weight, the frequency of occurrence of the gonadal maturity stages and the Gonadosomatic Index of the females were calculated. The results indicate that spawn occurs in the Piracicaba River during the summer and that the lowest condition indices appear during the autumn, as a possible effect of the energetic reserves mobilization during the reproductive activity. Besides that, it was observed that the seasonal cycle of gonadal development does not exert a significant influence over the body condition variation of Pimelodus maculatus.