A comunidade de peixes dos reservatórios dos trechos médio e baixo rio Tietê, com ênfase nas espécies Plagioscion squamosissimus e Geophagus surinamensis.

Abstract

From sixties, the fish species introduction has been being a constant event in the reservoir system located on middle and low Tietê River - SP, which resulted the success introduction of Plagiosicon squamosissimus and Cichla cf. ocellaris in all these reservoirs. According to this context, the present work objectified characterize the fish community, with focus on the introduction analysis of Geophagus surinamensis, a not-native specie, and its probable progressive occupation in the system, like that already had occurred with Plagioscion squamosissimus. The results showed the occurrence of Geophagus surinamensis is confirmed in these reservoir system, indicating that its fast occupation in the Três Irmãos reservoir is made possible by the free connection that Pereira Barreto provides between Três Irmãos reservoir and Ilha Solteira reservoir, on the Paraná River. This way, it is evident the great possibility that the Geophagus surinamensis comes to be disperse for the whole reservoir system of middle and low Tietê River, like that already had occurred for the Plagioscion squamosissimus. Then, it is important to consider the Geophagus surinamensis in management programs for the Três Irmãos reservoir, so as to control and to reduce its density and of avoiding its effective spread for the others reservoirs of Tietê River.