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. 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. The federal authorization allows wildlife managers to use lethal measures to remove sea lions that meet specific criteria, although the states’ first priority has been to relocate them to zoos and aquariums.
Removal of problem sea lions continues to be the most effective means of protecting fish from their predation. While exclusion gates keep sea lions out of the fishways, other non-lethal deterrents (pyrotechnics and rubber buckshot) fired at them have only a temporary effect. For several years the Oregon Department of Fish & Wildlife and Washington Department of Fish & Wildlife have staffed a branding and removal program for problem California sea lions.
From 2008 to 2016 a total of 166 California sea lions were removed from the Columbia River: 15 were placed in permanent captivity, 7 died in accidents incidental to trapping, and the remainder were chemically euthanized.
Learn more about why California sea lions are being removed from the Columbia River (pdf)
Summaries of sea lion trapping
Section 120 Authority to remove sea lions
In March 2012, NOAA Marine Fisheries issued a letter authorizing (pdf) the states to remove specific California sea lions eating threatened salmon and steelhead in the Columbia River. That authorization expired in June 2016 but was renewed for another five years until June 30, 2021. The authorization allows the states to remove up to 93 California sea lions a year; these animals must meet the following criteria:
- Must be individually identifiable through natural or applied features (usually a brand)
- Have been observed eating salmonids in the Bonneville Dam area between Jan. 1 and May 31 of any year
- Have been observed on a total of any five days (consecutive days, days within a single season, or days over multiple years) between Jan. 1 and May 31
- Have been subjected to but not responded to non-lethal hazing
Visit the NOAA Marine Fisheries Website for more information about the Section 120 application and authorization.
Pinniped Branding on the West Coast (pdf)
California sea lion predation on Upper Willamette River salmon and steelhead stocks has been identified as a growing biological concern. The number of listed salmon and steelhead being taken by California sea lions below Willamette Falls is significant and is one of many factors having a negative impact on salmon and steelhead populations in the basin.
Hazing and monitoring programs
ODFW conducted non-lethal hazing of sea lions in 2010, 2011 and 2013 in an attempt to deter sea lions from foraging near the fish ladder entrances at Willamette Falls. After hazing proved to be unsuccessful, ODFW began a rigorous monitoring program, tracking sea lion abundance and predation in order to document the extent of the problem. The results of these monitoring efforts can be found in these reports: 2014, 2015 and 2016.
Beginning the week of Jan. 9, 2017 ODFW will begin sea lion predation monitoring at Willamette Falls and will continue through May. This marks the fourth year of monitoring sea lion-related predation on Endangered Species Act (ESA)-listed salmonids, sturgeon and lamprey in the Willamette River.
2017 sea lion trapping below Willamette Falls
Monitoring efforts in 2017 will include trapping sea lions in order to brand unmarked individuals and to potentially relocate sea lions back to the ocean. Beginning in January, a trap will be located at SportCraft Landing Moorages in Oregon City, a place where sea lions currently rest. Depending on sea lion use, the trap could eventually be moved to the downstream entrance of the non-operational locks area managed by the U.S Army Corps of Engineers. Trapping may occur year-round any time sea lions are on the trap. The trap will be monitored electronically by cameras and the doors on the trap will be locked open when not in use.