Introduction of fishes in Brazilian continental ecosystems: Review, comments and suggestions for actions against the almost invisible enemy

Abstract

The introduction of species is a major threat to the conservation of biodiversity, being the main precursor of a prominent global biotic homogenization. In the case of perception, control or eradication, aquatic species are among the most problematic. In this sense, fish introductions become serious threats because these organisms are very widespread, mobile and of difficult perception and/or detection by the society. In the early stages of introduction, they may be considered “invisible” (e.g. less exposed than the majority of the introduced organisms, especially terrestrial organisms). Thus, it is common fact that introductions of this group of organisms are perceived only when they are already in advanced stages of the invasion process and the damage is irreversible. A species of fish can be considered non-native, even at the level of basins or sub-basins. This makes the perception or detection of introduced fish even more complex in Brazil, due to its continental dimensions and rich continental aquatic environments. Often, the cultural aspects and time of release contribute to the “invisibility” of the problem. Even fish coming from other continents, such as carp, tilapia and trout are incorporated in the country for so long that they are considered “native”. Even in the scientific field the theme is under-explored in Brazil, but information about problems that may arise from biological invasions is building up. Indeed, not all introductions have catastrophic consequences, but many do. However, we can understand older impacts and detect new ones in the near future if we want to do so. In view of the exposed, and given the magnitude of the problem, and disproportion in the search for answers and impacts, a review of the theme with suggestions for actions is presented.

Key words: introduction of species, threats, non-native species, biological invasions, biodiversity, aquatic ecosystems.