Sea lions and salmon

The people of the Columbia River basin have supported and invested in salmon recovery efforts for decades having developed subbasin plans to restore habitat, improve dam passage survival, reform hatchery programs, and reshape fisheries to improve the status of salmon. Coincidently, pinnipeds responding to protection under the MMPA are enjoying 5 to 6% annual population growth rates. This has lead to increased pinniped-fisheries conflict between the mouth of the Columbia River to Bonneville Dam located approximately 150 miles upriver.

Studies of scat samples collected in coastal waters and the Columbia River estuary indicate that salmon comprise 10 to 30 percent of the animals’ diet. Additional studies show the percentage of salmon and steelhead in sea lions' diet increases as they move upriver. Each year since 2004, California sea lions have consumed 3,000 to 3,500 salmon and steelhead immediately below Bonneville Dam, according to an ongoing study by the U.S. Army Corps of Engineers.

A number of California sea lions have learned to exploit an artificial situation at Bonneville Dam to disproportionately impact depressed salmon runs. In the last five years, over a hundred sea lions have learned to prey on spring runs of threatened and endangered adult salmon as they attempt to pass through the dam's fish ladders. Many sea lions have been documented returning year after year. Over the past four years, an average of nearly 3,000 salmon per year has been consumed in the tailrace of the dam alone. Significant sea lion predation on endangered spring Chinook salmon at Bonneville Dam is rising, evidenced by the number of salmonids eaten by sea lions nearly tripled from the first to second week in April this year. Increased predation and drastically low spring Chinook salmon runs make this a serious management issue. The states of Washington and Oregon along with the Columbia River Inter-Tribal Fish Commission have implemented hazing activities to disperse sea lions below the dam.

The states of Washington, Oregon, and Idaho have filed a section 120 application under the MMPA with NOAA to develop a long-term solution to problem sea lions. In the mean time, the three states and the treaty tribes have united efforts to create a pinniped task force to disperse problem sea lions until a long-term solution is developed under the MMPA. The Marine Mammal Protection Act Section 120 Pinniped-Fishery Interaction Task Force Report from NOAA is available here.

The links to the left include a photo gallery of injured or destroyed salmon and a video of salmon hazing efforts below Bonneville.

Download a fact sheet for detailed information.