Wels Catfish - Ecology

Ecology

There are concerns about the ecological impact of introducing the Wels catfish to non-native regions. These concerns take into account the situation in Lake Victoria in Africa, where Nile perch (available in stores as Lake Victoria perch) were introduced and rapidly caused the extinction of numerous indigenous species. This severely impacted the entire lake, destroying much of the original ecosystem. The introduction of foreign species is almost always a burden on the affected ecosystem. Following the introduction of Wels catfish are fishes whose number is in clear and rapid decline. Since its introduction in the Mequinenza Reservoir in 1974, it has spread to other parts of the Ebro basin, including Ebro and its tributaries, especially the Segre River. Some endemic species of Iberian barbels, genus Barbus in the Cyprinidae, were once abundant especially in the Ebro river but due to competition from and predation by Wels catfish have since disappeared in the middle channel Ebro. The ecology of the river has also changed, as there is now a major growth in aquatic vegetation such as seaweed and algae. Barbel species from mountain stream tributaries of the Ebro that Wels catfish have not colonized are not affected.