Dinâmica reprodutiva da piranha branca Serrasalmus calmoni (Steindachner,1908) (Characiformes: Serrasalmidae) no primeiro mosaico de unidades de conservação do Brasil, na Amazônia Oriental

Abstract

The white piranha, Serrasalmus calmoni (Steindachner, 1908), is a species of the Serrasalmidae family, widely distributed in the Amazon Basin. Understanding its reproductive biology is essential to support sustainable management and conservation strategies. This study analyzed the reproductive dynamics of the species in the Tucuruí Lake Mosaic, Eastern Amazon, considering aspects such as sex ratio, size at first sexual maturation, reproductive period, and spawning areas. Sampling was conducted between December 2017 and January 2019 using gillnets with different mesh sizes. In the laboratory, biometric data were recorded, and macroscopic and histological analyses of the gonads were performed. The sex ratio was calculated monthly and by length class. The size at first maturation was estimated using the graphical extrapolation method and the Galton’s ogive. The reproductive period was determined based on the monthly variation of gonadal maturation stages and the Gonadosomatic Index (GSI). The spatialization of spawning areas was carried out using georeferenced collection data and analysis in Geographic Information Systems (GIS). Macroscopic analysis of the gonads allowed the identification of five gonadal maturation stages. Histological analysis revealed four phases of oocyte and spermatogenic development. The sex ratio (females:males) was 1: 0,77, with no statistically significant differences between the analyzed months. The size at first maturation was estimated at 14.22 cm for females and 14.19 cm for the combined sexes. The reproductive period coincided with the rainy season, with a reproductive peak observed in March. The temporal variation in gonadal maturation stages, in accordance with histological analyses, suggests that the species has batch spawning. The spawning areas were identified in the Alcobaça Sustainable Development Reserve (RDS) and above the Wildlife Preservation Zone (ZPVS), near the margins, with the presence of submerged vegetation. Therefore, S. calmoni exhibits a reproductive cycle synchronized with the hydrological variations of Tucuruí Lake, with evidence of batch spawning and a size at first maturation compatible with other species of the genus. The identification of spawning areas reinforces the importance of protected regions for the reproductive success of the species.