Impact of seals and sea lions on salmon recovery

Populations of harbor seals, Steller sea lions, and California sea lions – known formally as ‘pinnipeds’ – have increased substantially in the coastal waters of Washington State following implementation of the US Marine Mammal Protection Act in 1972. At the same time, many populations of Pacific salmon, several of which are federally listed under the US Endangered Species Act, have declined in abundance or have failed to recover from low abundance. Pinnipeds hunt both juvenile and adult Pacific salmon and have been implicated in the lack of recovery of salmon populations in Washington State. The Washington Department of Fish and Wildlife asked the Washington State Academy of Sciences to examine the scientific basis for whether pinniped predation has impeded the recovery of salmon populations in Washington State’s Salish Sea and outer coastal waters. The committee conducted a critical review of the existing literature and engaged scientists, tribal representatives, and other stakeholders through workshops. The resulting report includes an assessment of scientific and technical aspects of potential management actions. The report concluded that seals and sea lions are likely impeding salmon recovery in the Pacific Northwest, but the full impacts of predation on salmon may not be fully understood without lethal intervention.