Relative Impacts of Non-native Aquatic Predators on Native Fishes of the Verde River, Arizona
September 2000 to September 2004
Laura Leslie, Cristina Velez
Currently little is known about which introduced fishes have the most impact on the native fishes inhabiting the Verde and many other Arizona river systems. We estimated which introduced fish species and size classes have the most impact on native Arizona fishes in the Verde River by habitat and time of year. Bioenergetics techniques were used on stomach content data to estimate feeding rates of various introduced predators. This was combined with introduced fish population estimates to estimate total impact of the common introduced fishes of the Verde. This information could be used (1) to focus control efforts on those species, size classes, habitats, and times of year where most of the impacts are occurring for cost-savings and increased effectiveness of native-fish recovery efforts and (2) reduce impacts to those introduced sportfishes which many contribute to valuable fisheries, but may have little impact on natives. The two graduate students on this project finished their MS theses in 2003 and early 2004 and are now writing reports and publications.