Cover design by Eric Schrepel, Technical and Web Data Specialist Cover photos of Caspian tern and California sea lion by Tony Grover, northern pikeminnow courtesy of Steve Williams (Pacific States Marine Fisheries Commission), and northern pike by Ralph Behrens, www.flickr.com/photos/rbehre/27413420361 Independent Scientific Advisory Board for the Northwest Power and Conservation Council, Columbia River Basin Indian Tribes, and National Marine Fisheries Service 851 SW 6th Avenue, Suite 1100 Portland, Oregon 97204 Kurt D. Fausch, Ph.D., (ISAB Vice-chair) Professor Emeritus of Fisheries and Aquatic Sciences, Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, Colorado Stanley Gregory, Ph.D., Professor Emeritus, Department of Fisheries and Wildlife, Oregon State University, Corvallis, Oregon William Jaeger, Ph.D., Professor of Applied Economics, Oregon State University, Corvallis, Oregon Cynthia Jones, Ph.D., Eminent Scholar and Professor of Ocean, Earth, and Atmospheric Sciences; Director of the Center for Quantitative Fisheries Ecology; and A.D. and Annye L. Morgan Professor of Sciences, Old Dominion University, Virginia Alec G. Maule, Ph.D., (ISAB Chair) Fisheries Consultant and former head of the Ecology and Environmental Physiology Section, United States Geological Survey, Columbia River Research Laboratory Peter Moyle, Ph.D., Distinguished Professor Emeritus, Department of Wildlife, Fish and Conservation Biology and associate director of the Center for Watershed Sciences, University of California, Davis Katherine W. Myers, Ph.D., Research Scientist (Retired), Aquatic and Fishery Sciences, University of Washington, Seattle Thomas P. Quinn, Ph.D., Professor, School of Aquatic and Fishery Sciences, University of Washington, Seattle Steve Schroder, Ph.D., Fisheries Consultant and Fisheries Research Scientist (Retired), Washington Department of Fish and Wildlife, Olympia, Washington Carl J. Schwarz, Ph.D., Professor of Statistics and Actuarial Science at Simon Fraser University, Burnaby, British Columbia, Canada Thomas Turner, Ph.D., Professor of Biology and Associate Dean for Research at the University of New Mexico, Albuquerque, New Mexico ISAB Ad Hoc Member James N. Sanchirico, Ph.D., Professor, Department of Environmental Science and Policy, University of California, Davis ISAB Ex Officios and Manager Michael Ford, Ph.D., Director of the Conservation Biology Program, Northwest Fisheries Science Center, Seattle, Washington Nancy Leonard, Ph.D., Program Performance Manager, Northwest Power and Conservation Council, Portland, Oregon Zach Penney, Ph.D., Fisheries Science Manager, Columbia River Inter-Tribal Fish Commission, Portland, Oregon Erik Merrill, J.D., Independent Science Manager, Northwest Power and Conservation Council, Portland, Oregon A Review of Predation Impacts and Management Effectiveness for the Columbia River Basin (ISAB Predation Management Report) Acknowledgments ............................................................................................................................................... vi Executive Summary ............................................................................................................................................... 1 I. Introduction ....................................................................................................................................................... 6 II. Review Process ............................................................................................................................................... 10 A. Sources of information ............................................................................................................................... 10 B. Key past ISAB findings, assumptions, and observations ............................................................................. 12 III. Summary Answers to Council Questions ....................................................................................................... 15 IV. Impacts of predators and effectiveness of predator control ........................................................................ 24 A. Ecosystem perspectives .............................................................................................................................. 24 Food Webs .................................................................................................................................................. 26 Relative Vulnerability of Salmonids to Different Predators ........................................................................ 28 Background ............................................................................................................................................. 28 Methodological considerations .............................................................................................................. 29 Temporal and spatial considerations ...................................................................................................... 29 Considerations related to the reporting of predation ............................................................................ 29 Relative vulnerability of salmonids to predators: “straw dog” tables .................................................... 30 Multiple Species and Complex Interactions................................................................................................ 33 Landscape Context ...................................................................................................................................... 34 Dam Infrastructure ..................................................................................................................................... 35 Flow Modification ....................................................................................................................................... 36 Temperature and Water Quality ................................................................................................................ 36 Riverine Habitat .......................................................................................................................................... 37 Hatchery Releases ....................................................................................................................................... 38 Estuarine Habitat ........................................................................................................................................ 38 Future Concerns .......................................................................................................................................... 39 B. Socioeconomic considerations for control of northern pike and other invasive species ........................... 41 i Social dimensions of harvest incentives to control invasive species .......................................................... 41 Management goals and objectives ............................................................................................................. 42 Incentive approaches .................................................................................................................................. 42 Outreach ..................................................................................................................................................... 43 C. Piscivorous fish ........................................................................................................................................... 44 Native Northern Pikeminnow ..................................................................................................................... 44 Northern Pikeminnow Management Program ....................................................................................... 46 Program results and effectiveness.......................................................................................................... 48 Invasive Northern Pike ................................................................................................................................ 53 Distribution and biology ......................................................................................................................... 53 Risk of invasion downstream .................................................................................................................. 54 Successful eradication of pike ................................................................................................................. 56 Efforts to suppress pike where they cannot be eradicated .................................................................... 57 Conclusions: Lake Roosevelt northern pike suppression ........................................................................ 58 Ecological impacts of northern pike ....................................................................................................... 59 Conclusions: ecological impacts ............................................................................................................. 60 Genetic methods for detection and potential control of invasive northern pike in the Columbia Basin ................................................................................................................................................................ 61 Monitoring and early detection of pike via eDNA .............................................................................. 61 Genetic study of