Columbia River Sea Lions
Columbia Basin residents 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. A number of California sea lions have learned to exploit an artificial situation at Bonneville Dam to disproportionately impact depressed salmon runs.
An endangered diet
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.
In the last decade, 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. During that time, an average of over 3,745 salmon per year has been consumed in the tailrace of the dam. Sea lion predation on endangered spring chinook salmon at Bonneville Dam is rising. In 2014 California sea lions consumed 4,746 salmonids immediately below Bonneville Dam. This number skyrocketed in 2015, doubling to over 7,000 salmonids being consumed by May 15. (Click graph at right to see details on how this problem has grown over the past decade.) Minimum predation estimates are based on daytime feeding observations. Actual consumption numbers are estimated at 20% of the returning run. 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. CRITFC has secured funding under the Columbia Basin Fish Accords that will support hazing and abundance and predation estimation efforts until 2018.
Finding a solution
A coalition of tribal, federal & state representatives, NGO’s, and independent scientists participate in the Pinniped Fishery Interaction Task Force. It evaluated the situation in 2007, 2010, and 2011. Each time the task force recommended removal. NOAA approved the states’ application for removal authority. The proposed Endangered Salmon and Fisheries Predation Prevention Act would change the Marine Mammal Protection Act to allow tribal members to kill sea lions and harbor seals.