Fish farming as the main driver of fish introductions in Neotropical reservoirs

Several human activities may result in or facilitate species introductions. In aquatic environments, species introductions are often associated with the construction of dams. In this study, we use reservoirs of the Neotropical region as a model to determine the main causes of fish species introductions. We compiled information on non-native fish species present in reservoir ichthyofauna surveys in the past 14 years and classified these species based on their probable reason for introduction (vector). Fish farming activities introduced approximately 7.6-fold more species in reservoirs than the other vectors identified. The matrix of the number of fish species per vectors explained the greatest proportion of the composition of non-native assemblages, whereas the geographic distance and age of the reservoir explained few of these variations. The non-native ichthyofauna composition varied among Neotropical basins and can be explained by the different sets of species introduced by the companies managing the reservoirs. Although power companies have banned stocking with non-natives, fish farming in the Neotropical region continues to use non-native species, and these species are occupying water bodies, especially reservoirs.