SALEM, Ore.— For the third straight year, crews from the Oregon Department of Fish and Wildlife and the Washington Department of Fish and Wildlife will begin non-lethal hazing actions on the Columbia River to deter sea lions from feeding on white sturgeon.
Hazing with acoustic and percussive devices, flares, and rubber bullets is scheduled to begin in mid-December from Bonneville Dam downstream approximately six miles to Navigation Marker 85, according to wildlife managers in both states.
Those methods have generally been effective in deterring predation by Steller sea lions, which account for most sturgeon lost to predation below the dam, said Charlie Corrarino, ODFW Conservation and Recovery Program manager.
“White sturgeon do not reach maturity until they are 12 to 20 years old, and Steller sea lions tend to target the larger and older sturgeon,” Corrarino said. “We need to protect these fish because they are broodstock for future generations of sturgeon.”
Steller sea lions ate more than 350 white sturgeon near Bonneville Dam last winter, but took only 19 after hazing began in March, according to the U.S. Army Corps of Engineers. Fifty-five of the sturgeon taken last year were over five feet long, some carrying millions of eggs.
“We plan to start hazing a few weeks earlier this year,” said Sandra Jonker, WDFW region wildlife manager, noting that Steller sea lions have been observed near Bonneville Dam since early October.
Hazing by boat-based crews from ODFW and WDFW is scheduled at least four days per week during daylight hours in the area from Bonneville Dam six miles downstream to Navigation Marker 85. USDA Wildlife Services, under contract with the U.S. Army Corps of Engineers, will also begin hazing sea lions from the face of the dam on a similar schedule.
While Steller sea lions have generally responded to non-lethal hazing, that has not been the case with California sea lions, which prey primarily on salmon and steelhead below the dam, Jonker said. Despite hazing efforts, observations by the Corps of Engineers indicate that both the number the number of California sea lions and their rate of predation on salmon and steelhead have increased in recent years, she said.
Separate from their hazing efforts, fishery managers from Washington, Oregon and Idaho are seeking federal approval to use lethal means to remove individual California sea lions below Bonneville Dam that prey on chinook salmon and steelhead listed for protection under the federal Endangered Species Act (ESA).
The states’ application, submitted last year under Section 120 of the Marine Mammal Protection Act, would not apply to Steller sea lions, which are themselves listed as threatened under the ESA.
Last month, an 18-member task force appointed to review the states’ application recommended that NOAA-Fisheries approve the states’ request, concluding that predation by California sea lions has a “significant negative impact” on ESA-listed salmon and steelhead stocks in the Columbia River and Snake River basins.
NOAA-Fisheries is expected to conduct an environmental assessment on the states’ application, and expects to make a final decision on the states’ request by next March, at the start of the spring salmon migration past Bonneville Dam.