Ichthyofauna composition in marginal environments and tributaries from the middle and lower São Francisco River

Abstract

The middle and lower stretches of the São Francisco River are the most affected by the construction of hydroelectric dams, with over 550 km dammed. Despite of impact of dams on fish composition and distribution, the ichthyofauna of theses stretches is the least known of the entire river basin. The present study aimed at characterizing the fish assemblages of nine marginal lakes, three temporary ponds and 12 streams and rivers, located between
the municipalities of Barra (BA) and Belém do São Francisco (PE), during the rainy and dry periods, between September 2006 and September 2009. Sixty-one species distributed among Characiformes (39 species), Siluriformes (8), Perciformes (7), Cyprinodontiformes (3); Gymnotiformes (2); Clupeiformes  and Synbranchiformes (1 each) were identified. Fish assemblages were composed of small-sized fish, 76% of them with SL < 100 mm, and the remaining with SL between 100 and 180 mm. Despite the importance of flooded environments for rheophilic fish, only 12 migratory species were recorded. The ichthyofauna of the environments studied is predominantly composed of small-sized and resident invertivores, invertivores and omnivores occurred in all
tributaries, whereas most herbivores were recorded in ponds.