Under MMPA Section 120, NOAA Fisheries has authorized the lethal removal of sea lions in the Columbia River basin to reduce predation on salmon and steelhead listed under the ESA.
The U.S. population of California sea lions on the west coast has grown from fewer than 75,000 to an estimated 257,000 animals over the last 30 years. The abundance of California sea lions in the Columbia River basin alone has increased from less than 500 to around 4,000 animals in the past decade. A small number of these animals have moved upriver to places such as Bonneville Dam and Willamette Falls. The presence of animals accustomed to frequenting these areas likely contributes to even more animals traveling upriver. We have observed that animals are generally arriving earlier and remaining longer at these upriver sites.
The Steller sea lion population has also been increasing in the basin, particularly in the past 2 to 4 years. The Eastern stock of Steller sea lions reached a minimum population estimate of over 75,000 in 2015. Both species are having a negative impact on salmon, steelhead, eulachon, lamprey, and sturgeon populations.
Steller sea lions were first documented at Bonneville Dam in 2003 with three animals present. In 2018, a minimum of 66 animals were observed at the dam during a single day. While pinniped abundance tends to be highest during the spring, their residency during the fall and winter months has increased. Steller sea lions are now present for 11 months per year at Bonneville Dam.
Over the same period that sea lion abundance has increased, many salmon and steelhead populations in the Pacific Northwest have significantly declined and been listed under the Endangered Species Act. In the Columbia River basin, thirteen stocks are currently listed as threatened or endangered. These declines were initially and primarily a result of multiple factors unrelated to predation by pinnipeds, but a growing body of evidence suggests the rise in abundance of pinniped populations on the U.S. west coast is having a significant impact on the survival of many salmon and steelhead populations, both in the ocean and in freshwater. In areas where salmonid abundance is low, even a modest unmanaged increase in predation by pinnipeds can result in serious negative impacts to the recovery of individual salmonid populations.
There has been an unprecedented effort to recover salmon and steelhead in the Columbia basin by NOAA Fisheries, Pacific Northwest states, and Columbia Basin tribes, along with many other agencies and organizations. Actions have been implemented in every watershed to restore habitat and improve dam passage survival. Hatchery programs have been re-tooled to assist production in wild populations. Fisheries have been closed, reduced, or reshaped to limit fishery-related mortality of listed stocks and focus on selectively harvesting healthy stocks. These efforts equate to hundreds of millions of dollars invested annually and billions over the past decades. These efforts, however, are put at risk by the increasing impact of sea lions. Both California sea lions and Steller sea lions have been observed in other tributaries that contain salmon and steelhead. Based on patterns previously observed at other sites in the region, there is concern that sea lions in these rivers will follow a similar pattern.
Past efforts to non-lethally deter sea lions at the Ballard Locks, Bonneville Dam, Willamette Falls, and other locations have been unsuccessful. Meaningful actions to reduce the risk of extinction of ESA-listed salmonids must include appropriately addressing California sea lion and Steller sea lion predation.
Our experience has shown when there are lengthy delays in implementing lethal removal, more animals become accustomed to an area, resulting in further negative impacts to fish populations. To more effectively manage California sea lion and Steller sea lion predation, we propose to reduce the existing habituated population, then manage proactively by not allowing new animals to habituate within a specified geographic scope, consistent with the intent of the recent amendments to the Marine Mammal Protection Act MMPA, specifically subsection 120(f).
Sea Lion Removals Annual Summary
MMPA Section 120(f) Actions & Documents
Under MMPA Section 120, NOAA Fisheries has authorized the states of Washington, Oregon, and Idaho to lethally remove individually identifiable, predatory California Sea Lions in the vicinity of Bonneville Dam that are having a negative impact on the recovery of salmon and steelhead listed under the Endangered Species Act.
Bonneville Dam Actions & Documents
Under MMPA Section 120, NOAA Fisheries has authorized the state of Oregon to lethally remove individually identifiable, predatory California Sea Lions in the vicinity of Willamette Falls that are having a significant negative impact on salmonids listed under the Endangered Species Act.
Willamette Falls Actions & Documents
North Pacific right whale. Credit: Brenda K. Rone
Southern Resident killer whales encountered during NOAA's PODs (Pacific Orcinus Distribution Survey) in October 2021 near the west end of the Strait of Juan de Fuca. Credit: NOAA Fisheries
