Willamette Falls Pinniped Monitoring Project, 2017

In 1972, the Marine Mammal Protection Act (MMPA) provided protection for all marine mammals in U.S. waters, ending centuries of exploitation for many species. As one result, the U.S. stock of California sea lions (Zalophus californianus) has increased steadily to the point that it is now likely within its optimum sustainable population range, thus meeting the conservation objective of the MMPA. Over this same period many salmon and steelhead (Onchorynchus spp.) populations in the Pacific Northwest experienced significant declines in abundance and were subsequently listed as threatened or endangered under the Endangered Species Act (ESA). These declines were initially and primarily the result of multiple factors unrelated to predation by pinnipeds but in areas where salmonid abundance is low and California sea lion numbers are now high, increased predation levels can result in serious negative impacts to the survival and recovery of individual salmonid populations. 2017 NMFS (National Marine Fisheries Service) Submitted Public Domain 1861