Northwest Fisheries Science Center

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Document Type: Chapter or Section
Center: NWFSC
Document ID: 6485
Type of Book: Technical
Section or Chapter Title: Appendix C: NOAA Fisheries report: Caspian tern predation on juvenile salmonid outmigrants in the Columbia River estuary
Book Title: Caspian tern management to reduce predation of juvenile salmonids in the Columbia River estuary
Author: T. P. Good, K. Barnas, D. M. Marsh, Michelle M. McClure, Brad A. Ryan, Benjamin P. Sandford, Edmundo Casillas
Publication Year: 2005
Publisher: Report of the U.S. Fish and Wildlife Service, U.S. Army Corps of Engineers, and U.S. National Marine Fisheries Service. Portland, Oregon
Volume: Appendix
Pages: C1-C32
Abstract:

•   Relatively new human–constructed islands in the Columbia River estuary have provided breeding habitat for Caspian terns, where they have been able to successfully exploit juvenile salmonids as a food resource.

•   The effect of Caspian tern predation varies between years, varies among salmonid species, is greatest on steelhead, and is lowest on wild yearling Chinook.

•   Caspian tern predation on juvenile salmonids reduces salmon population growth rate and thus recovery; however, removing all tern predation will not, by itself, lead to full recovery of any listed salmon and steelhead stock.

•   The effect of Caspian tern predation on recovery may be comparable to fish passage improvements at Columbia River dams and harvest reductions for some Evolutionarily Significant Units.

•   Relocating Caspian terns to habitat closer to the mouth of the Columbia River significantly reduced predation impact on juvenile salmon.

•   Additional PIT tag data needs to be collected and evaluated to validate initial predation rates at East Sand Island.

Notes: Full text available from U.S. Fish and Wildlife Service Migratory Birds and Habitats Program: www.fws.gov/pacific/migratorybirds/nepa.html
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