Review of fisheries resource use and status in the Madeira River basin (Brazil, Bolivia and Peru) before the hydroelectric dam’s completion

The Madeira River, which drains one of the major tributary river basins of the upper Amazon, contributes to small-scale fisheries in Peru, Bolivia, and Brazil. This paper provides a base-line of fisheries resources and their status in six sub-basins of the Madeira River: upper Madre de Dios River basin (Peru), Beni and Mamoré River basins (Bolivia), Iténez or Guaporé River basin (Bolivia and Brazil), middle Madeira, and (two sections of the) lower Madeira River (Brazil). Data were collected between 2009 and 2011, before the completion of two hydroelectric dams in the Brazilian portion of the basin. Biophysical, social, and biological indicators were used to characterize the fisheries. The results show an overall small-scale multispecies fisheries pattern but with notorious differences between the Madeira sub-basins. The Beni and Mamoré sub-basin shows the largest flooded area, with associated higher total fisheries yields. Trophic level of the catch, diversity, and mean weight of fish caught were shown to be very sensitive to exploitation level, river water type (white or clear water), flooded area, and the introduction of Arapaima gigas in Bolivia. The Bolivian fisheries are characterized by less exploited stocks, whereas stocks in Peru and Brazil show signs of intensive exploitation, resulting in fisheries of smaller bodied, lower trophic-level species. Landing data in the upper basin show a predominant reliance on migrating fish resources, which might be vulnerable to the construction of dams. These data serve as a baseline to evaluate anthropogenic impacts on the Madeira River basin fisheries in the future.

KEYWORDS: Amazon, freshwater ecosystem, trophic level, diversity, fish catch