2009 Field Report: Evaluation of Pinniped Predation on Adult Salmonids and Other Fish in the Bonneville Dam Tailrace

Since 2002, we have used surface observations to evaluate the seasonal presence, abundance, and predation activities of pinnipeds, including California sea lions (Zalophus californianus), Steller sea lions (Eumetopias jubatus), and Pacific harbor seals (Phoca vitulina richardsi) in the Bonneville Dam tailrace (Stansell, 2004; Tackley, et al., 2008a; Tackley et al., 2008b). This monitoring program is part of an ongoing effort to understand and appropriately manage pinniped predation on threatened and endangered and non-listed salmonids, including Columbia River spring Chinook salmon (Oncorhynchus tshawytscha) and steelhead trout (O. mykiss) in the tailrace of the dam. The U.S. Army Corps of Engineers (USACE) and partnering agencies have utilized a variety of deterrents and barriers to prevent predation in or around fishways and to deter predation on salmonids and other fish in the tailrace. This report is intended as a summary of monitoring and deterrence efforts implemented by, or coordinated with, the USACE. Agency partners included the Oregon Department of Fish and Wildlife (ODFW), the Washington Department of Fish and Wildlife (WDFW), the Columbia River Inter-Tribal Fish Commission (CRITFC), the National Marine Fisheries Service (NMFS), the U.S. Department of Agriculture (USDA) Wildlife Services, and Portland State University (PSU). 2009 NMFS (National Marine Fisheries Service) Submitted Public Domain 1862