Reproductive dynamics, age and growth of Astyanax aff. fasciatus in a Neotropical basin

Population dynamics provide crucial information for management and conservation. This study analysed the spatial and temporal patterns in reproductive biology, age and growth of Astyanax aff. fasciatus from a Neotropical river. Although located in a priority area for conservation, this river is affected by human activities in the surrounding landscapes. Water and environmental parameters were subjected to principal component analysis (PCA) to characterise the different sampling sites. Length-frequency distributions, gonad development and body indices were used to evaluate maturity and spawning, and to calibrate the von Bertalanffy model to determine the age and growth of A. aff. fasciatus. Reproductive behaviour of the species was not homogeneous along the river, due to geomorphology and human activities in the surrounding areas, with some sites becoming unavailable for breeding. The PCA highlighted the geomorphological, human (first axis) and temporal (second axis) trends influencing the environmental features along the river. Females predominated throughout the basin, and spawning took place from September to June in distinct areas of the river. The species matures at an age of 1-1.5 years, and so tends to be a fast-growing species, with a life span close to 3.5 years. Fish population dynamics should be monitored to support conservation and management, both for the fish species and the aquatic environments.