Translocation of Humpback Chub into Tributary Streams of the Colorado River: Implications for Conservation of Large-River Fishes

Abstract

The Humpback Chub Gila cypha, a large-bodied, endangered cyprinid endemic to the Colorado River basin, is in decline throughout most of its range due largely to anthropogenic factors. Translocation of Humpback Chub into tributaries of the Colorado River is one conservation activity that may contribute to the expansion of the species’ current range and eventually provide population redundancy. We evaluated growth, survival, and dispersal following translocation of approximately 900 Humpback Chub over a period of 3 years (2009, 2010, and 2011) into Shinumo Creek, a tributary stream of the Colorado River within Grand Canyon National Park. Growth and condition of Humpback Chub in Shinumo Creek were consistent among year-classes and equaled or surpassed growth estimates from both the main-stem Colorado River and the Little Colorado River, where the largest (and most stable) Humpback Chub aggregation remains. Based on passive integrated tag recoveries, 53% ( = 483/902) of translocated Humpback Chub dispersed from Shinumo Creek into the main-stem Colorado River as of January 2013, 35% leaving within 25 d following translocation. Annual apparent survival estimates within Shinumo Creek ranged from 0.22 to 0.41, but were strongly influenced by emigration. Results indicate that Shinumo Creek provides favorable conditions for growth and survival of translocated Humpback Chub and could support a new population if reproduction and recruitment occur in the future. Adaptation of translocation strategies of Humpback Chub into tributary streams ultimately may refine the role translocation plays in recovery of the species.

ACKNOWLEDGMENTS

Funding for this project was provided by the U.S. National Park Service through the Great Rivers Cooperative Ecosystems Study Unit (task agreement H6000080300), the U.S. Bureau of Reclamation, U.S. Geological Survey, and Natural Resources Preservation Program). We thank numerous biologists, technicians, volunteers, and others who helped with field collections, logistics, and all other aspects of the project. We particularly thank Larkin Powell, Joanna Whittier, and Daniel Whiting for help with analysis and discussions about the study. The Missouri Cooperative Fish and Wildlife Research Unit is jointly sponsored by the Missouri Department of Conservation, the University of Missouri, the U.S. Fish and Wildlife Service, the U.S. Geological Survey, and the Wildlife Management Institute. The use of trade names or products does not constitute an endorsement by the U.S. Government, the U.S. Geological Survey or other sponsoring or participating agencies. This research was permitted under NPS Scientific Research and Collecting Permit GRCA-2010-SCI-0010, study GRCA-00543.