Efeitos de empreendimentos hidroelétricos instalados e previstos sobre as rotas pontenciais de migração de peixes para o Pantanal

Abstract

The ichthyofauna is of fundamental importance in the provision of a balanced environment, besides the economic importance for the country, the migratory processes of these populations have a direct influence on their maintenance. Natural factors such as slope of the talvegue can interfere as much as artificial barriers on the migratory routes of fish. According to data from the National Electricity Agency (ANEEL), the number of hydroelectric plants operating in the Hydrographic Region of Paraguay (BHP), considering the ones with a reservoir, amount to around 36, and more 104 are planned, and of these, 101 are SHPs. Differentiating anthropic impacts of natural barriers on the migratory fish route is essential to estimate the real impact of hydroelectric dams. Thus, the objective of this study was to estimate the losses of migratory fish routes imposed by existing and planned hydroelectric plants, considering the natural barriers that already restricted migration. The study was developed in a Geographic Information System (GIS) environment, where routines were identified for the identification of potential natural barriers, based on the slope of the talvegue, and considering the diagnosis and prognosis of the loss of migratory routes. The limitations of scale and accuracy of the database, among other factors, led to the consideration of different criteria, slopes of 15, 20 and 30% as potential natural barriers. For the purposes of diagnosis and prognosis, only barriers with a slope greater than or equal to 30%, which characterize waterfalls and cliffs, were considered. As a result, it is pointed out that basins such as Cuiabá, northeast of the RHP, have approximately 30% of the rivers without connection to the Pantanal biome, due exclusively to hydroelectric dams. And in the prognosis, indicates that, if all hydroelectric dams are built, the region will have 75% of the rivers disconnected from the Pantanal. The implementation of these hydroelectric dams should be studied and discussed in light of the benefits and impacts generated, especially in relation to the RHP, which is home to one of the planet's largest wetland plains, the Pantanal.