This study aimed to verify the alterations on the fish assemblage due the installation of the Small Hydroelectrical Power-Station Salto Forqueta in the course of the Forqueta River. The study area is located in the Taquari River basin, between the municipalities of Putinga (left margin of the river) and São José do Herval (right margin of the river). The study encompassed four phases: Phase I - from dec/2000 to feb/2002 (before damming), Phase II - from dec/2002 to jan/2004 (first year following damming), Phase III - from may/2004 to apr/2005 (second year following damming) and Phase IV - from may/2005 to jul/2006 (third year following damming). The samples were taken using fishing nets with diverse mashes. It was registered 28 species during Phase I, 21 species during Phase II, 19 species during Phase III and 18 species during Phase IV. The abundance rates, during the four phases, varied among the following species: Astyanax spp., Hemiancistrus punctulatus Cardoso & Malabarba, 1999, Steindachnerina biornata (Pearson, 1924), Oligosarcus jenynsii (Günther, 1864) and Geophagus brasiliensis (Quoy & Gaimard, 1824). It was verified a range of alterations in the local fish assemblage, nevertheless, these alterations were not statistically significant.
Ichthyofauna; Reservoir; Taquari Valley; Hydroelectrical Power-Station
