2011 Field Report: Evaluation of Pinniped Predation on Adult Salmonids and Other Fish in the Bonneville Dam Tailrace, 2011

The U.S. Army Corps of Engineers (USACE) has used surface observations since 2002 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., 2008; Stansell, et al., 2010). This monitoring program is part of an ongoing effort to understand and manage pinniped predation on salmonids, particularly Endangered Species Act (ESA) listed Columbia River wild spring Chinook salmon (Oncorhynchus tshawytscha) and steelhead trout (O. mykiss) in the tailrace of the dam. The USACE and partnering agencies have utilized a variety of deterrents and barriers to prevent predation in and around fishways and to deter predation on salmonids and other fish in the tailrace. 2011 NMFS (National Marine Fisheries Service) Submitted Public Domain 1861