Dinâmica da migração e reprodução dos peixes na Região da Foz do Rio Abaeté, Alto São Francisco

Abstract

The increasing quest for economic development has increased the demand for greater amounts of electricity. Besides its necessary, the physical barrier imposed by the dams of hydroelectric power plants, promotes serious changes in the watercourses. Blocking the free access for breeding and/or feeding represents a significant threat for migratory fish populations. Knowing the migratory fish area of movements is critical to the restoration and conservation policies of the species and can also function as a conservation strategy for all the fish fauna of the region. Therefore, the aim of this study was to evaluate the distribution and the reproductive behavior of migratory species of the upper São Francisco River, under the influence of the hydroelectric plant in Três Marias and a significant tributary, the Abaeté River. For the both rivers it was evaluated which physicochemical variables most influence the migratory fish distribution, spawning area preference, gonadal maturation stages, size and movement patterns. The hydroacoustic was the main tool of this study; however ichthyoplankton and cast nets were used to supplement information. The higher preference of fish reproductive activity, significant catches of ichthyoplankton, maintenance of physicochemical characteristics closer to original, high density of large fish and direction of migratory fish for its course, reinforces the importance of the Abaeté River for the Upper São Francisco River fish species conservation.