Successful Restoration Of A Native Fish Assemblage In The Blue River, Arizona

Translocation is one of the most commonly proposed management actions for securing and recovering native fish species. However, the success of native fish translocations has varied widely due to several limiting factors, including the presence of nonnative fishes. The Blue River Native Fish Restoration Project involved construction of a fish passage barrier, removal of nonnative fish, translocation of three native fish species (Spikedace Meda fulgida, Loach Minnow Rhinichthys cobitis, and Roundtail Chub Gila robusta), and monitoring to determine the success of these actions. After construction of a physical fish passage barrier, the three focal species were stocked several times upstream of the barrier. Nonnative fish were removed annually using multiple gear types, including spearfishing, backpack electrofishing, and trapping. Monitoring data demonstrated a significant shift in the fish assemblage from one with a substantial component of nonnative fishes to one that was exclusively native fishes. Persistence, reproduction, increased abundance, and dispersal were documented for all three focal species within the study area, meeting criteria for establishment success. All nonnative fishes, including the primary targets of removal efforts-Channel Catfish Ictalurus punctatus and Green Sunfish Lepomis cyanellus-were successfully suppressed, if not eradicated entirely, during the study period. Our results illustrate the importance of long-term monitoring to track and successfully achieve native fish recovery goals. In addition, our results demonstrate that nonnative fish can be mechanically removed from warmwater streams if initial abundance is low, distribution is restricted, and fish passage barriers are in place. Results from this study may be informative for managers hoping to improve the conservation status of warmwater stream fishes through creation of a fish passage barrier, nonnative species removal, and native fish translocation efforts.