Introduction of Exotic Species and Transplantation of Native Species across River Basins in Venezuela

The intentional introduction of biological organisms from their native environments into new areas is expanding, partially to satisfy an increased need for protein for human consumption. These alien species introductions, often promoted aggressively by international interests, have the potential to cause significant and increasing adverse impacts on native species and ecosystems, and on national economies. They may also pose risks to human health. Although these invasions have been of interest to ecologists for a long time, the attention that the effects of introduced species draws today is of unprecedented proportions. Understanding how introduced species influence natural communities is one of the most important challenges linking ecology and conservation today. In Venezuela, the introduction of exotic species dates back to the 1930s, when several species of trout (including Oncorhynchus mykiss) were introduced into Andean streams. To date, 10 species of fishes and 4 species of shrimps have been introduced. More recently, frogs and algae have joined the list of exotic cultured species. Extensive culture of native species is also common. Several authors have called attention to the various effects that aquaculture of alien species may have on the environment, especially when the cultured organisms are genetically altered. Another less-publicized mode of exotic introduction has been taking place in several countries: the transportation of native species across river basins. Although our knowledge of how that activity may affect ecosystems is very limited, these transplantations, which are often conducted without regard for biotic or biogeographic criteria, rivals the introduction of exotics in its potential danger, especially in countries where there is little knowledge of the autochthonous fauna. Establishing regulatory controls, providing incentives for research on the aquaculture of indigenous species, and creating awareness about the particular biotic situation of each country could increase fish supplies, rural employment, and income while preserving the biological integrity of the environment.