Habitat Suitability Criteria for Non-Native Fishes in Intermediate-Sized Arizona Rivers
Nonnative fishes were stocked into Arizona streams, starting over 100 years ago, and are currently found in most streams of the state. Commonly, species introduced to Arizona are able to outcompete or predate on native Arizona stream fishes, and fish communities are entirely dominated by nonnatives. However, in some areas, nonnatives have not been able to outcompete native fishes, and both live together. Knowledge of the habitat used by selected nonnative fishes in Arizona streams is important for predicting where they might persist and how habitat might be managed to reduce their numbers or discourage their establishment when desired. We sampled four Arizona streams containing a variety of habitats and documented habitat used by nonnative fishes. Furthermore, we developed habitat suitability curves for the seven nonnative aquatic species based on this use. Nonnative species were generally selecting similar habitats to that of their native range. Depth, temperature, velocity, and substrate all showed significant relationships, but results varied by species. Native species management and augmentation programs in these Arizona streams have typically relied on stocking of native species, fish barriers to impede the spread of nonnatives, and chemical and mechanical control to eliminate pest species. Understanding nonnative species populations and habitat use provides managers with additional information that can help them to better structure habitat in stream systems to benefit native species over nonnative species. Field work and data analysis on this project was completed in the fall, 2018. A thesis was completed on this work in December 2018, and results being prepared for publication.