The Oregon Department of Fish and Wildlife says its latest attempt to discourage savvy sea lions from feasting on native fish at Willamette Falls has proven to be an exercise in futility.
The agency reports more than 25 California sea lions and Steller sea lions continue to prey on salmon, steelhead, sturgeon and lamprey at the falls between West Linn and Oregon City.
The state spent five weeks in February and March relocating 10 California sea lions to a beach south of Newport, only to see the animals return within four to six days. One of the sea lions was even captured and relocated to the coast twice, but swam back both times.
Shaun Clements, senior policy adviser with the Department of Fish and Wildlife, said the problem is becoming increasingly dire as Upper Willamette Basin steelhead are pushed to the brink of extinction. This year’s run stands at 1,338 steelhead — slightly higher than 2017, but far below historic steelhead returns that often topped 10,000 fish.
Biologists estimate that California sea lions ate at least 18 percent of returning adult steelhead prior to March. The Department of Fish and Wildlife applied in October to kill sea lions from Willamette Falls under the Marine Mammal Protection Act in order to protect threatened salmon and steelhead. Clements said they are still awaiting a final decision from the National Marine Fisheries Service.
“It’s our responsibility and mandate from the people of Oregon to ensure these fish runs continue,” Clements said. “So it’s incredibly frustrating to us that federal laws prevent us from taking the only steps effective at protecting these fish from predation.”
To be clear, Clements said predation is not the only thing harming fish in the Willamette Basin. Drought and operations at 13 federal dams have also had a sharp impact on the species’ survival. But unless wildlife managers are able to cull sea lions, Clements said all other actions to protect fish will not matter in the long run.
For example, the U.S. Army Corps of Engineers intends to build a 300-foot-tall water temperature control tower and floating screen at Detroit Dam on the North Santiam River to improve fish survival. The project is estimated to cost between $100 million and $250 million, and could require draining Detroit Lake for up to two years, leaving farmers without critical irrigation supplies.
All that work would be for naught if sea lions are left to eat the fish to extinction, Clements said.
“Clearly our experience on the Willamette River this year demonstrated the futility of relocating sea lions as a way of stopping them from driving our native fish runs to extinction,” Clements said.
Since President Richard Nixon signed the Marine Mammal Protection Act in 1972, Clements said the population of California sea lions has grown from around 70,000 to 300,000, and the Steller sea lion population has also increased from roughly 30,000 to 70,000.
With the population increase has come more sea lions to prey on freshwater fish runs in the Pacific Northwest. It started in the late 1980s at Ballard Locks in Seattle, Clements said, and by the 2000s sea lions had arrived at Willamette Falls.
Steelhead aren’t the only fish species at risk, Clements said.
“We also know that predation on white sturgeon has increased dramatically this year, and that sea lions are preying on salmon, steelhead and sturgeon in other rivers like the Sandy and Clackamas,” he said.
Clements said changes are needed to the law that would allow wildlife managers to be more proactive when it comes to dealing with sea lions. He said the Department of Fish and Wildlife is working with Oregon’s congressional delegation on a possible solution.
In the meantime, the agency has decided to shift its focus to controlling sea lions at Bonneville Dam on the Columbia River, where they already have authorization to kill sea lions. The state does plan to leave its sea lion traps at Willamette Falls while continuing to monitor predation, but simply does not have enough staff to cover both locations.