2015 Field Report: Evaluation of Pinniped Predation on Adult Salmonids and Other Fish in the Bonneville Dam Tailrace, 2015

Sea lions have been in conflict with the Columbia River salmon fishery for decades. Before passage of the Marine Mammal Protection Act in 1972, the states of Oregon and Washington paid a bounty for pinnipeds and employed full time seal hunters to clear them out of the river (Pearson and Verts 1970). California sea lions (Zalophus californianus) were first noted returning to the dam’s tailrace during the 1980’s (Stansell 2004) and one or two California sea lions (CSL) were seen consuming adult salmonids periodically from the 1980’s through 2000. In 2001, up to six CSL were observed in the tailrace at one time and in 2002 at least 30 CSL were feeding in the tailrace consuming 1,000 adult salmonids (Stansell 2004). The next year showed sharp increases in the number of CSL present and predation of adult salmonids more than doubled. In addition to increasing abundance of CSL in 2003, the first Steller sea lions (Eumetopias jubatus) were also observed in the tailrace. 2016 NMFS (National Marine Fisheries Service) Submitted Public Domain 1861