Columbia River Sea Lion Management

California sea lion below Bonneville Dam       Evaluation of sea lion predation An assessment by the U.S. Army Corps of Engineers of sea lion predation below Bonneville Dam and efforts to address it from 2009-10. Learn More >>

Restoring balance between predators and salmon

Columbia River salmon and steelhead face a serious threat from California sea lions that prey on fish waiting to move up the fish ladders at Bonneville Dam in early spring. Each year since 2002, sea lions have consumed thousands of migrating fish, many from threatened and endangered runs protected under the federal Endangered Species Act (ESA).

The federal Marine Mammal Protection Act recognizes that predation by a growing sea lion population can jeopardize salmon and steelhead stocks at risk of extinction.  For the past five years, wildlife managers from Washington and Oregon have worked with federal and tribal partners to chase sea lions away from the area immediately below Bonneville Dam. But these efforts, alone, have not proven effective in curbing salmon predation by a robust population of California sea lions.

In March 2008, fish and wildlife agencies in Washington, Oregon and Idaho received federal authorization to remove California sea lions that have been observed preying on salmon and steelhead below Bonneville Dam. That authorization allows wildlife managers to use lethal measures to remove those sea lions, although the states’ first priority has been to relocate them to zoos and aquariums.

Through 2010, wildlife managers removed a total of 40 California sea lions that met the federal criteria for removal below the dam.  While it is too early to assess the effectiveness of those efforts, fewer California sea lions were observed below Bonneville Dam in 2009-10 than at any time since 2002.