A sea lion is relocated from Willamette Falls to the Oregon coast in the back of a pickup truck. Courtesy of Oregon Department of Fish and Wildlife

Oregon wildlife managers are trapping sea lions at Willamette Falls and trucking them out to the coast in an effort to protect a very fragile run of steelhead.

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Biologists estimate the sea lions at Willamette Falls are eating at least a quarter of the winter steelhead run. At that rate, they say, there's about a 90 percent chance at least one population of the fish will go extinct.

Bryan Wright, a biologist with the Oregon Department of Fish and Wildlife, said the state is waiting for federal approval to kill sea lions at Willamette Falls. In the meantime, they're moving as many sea lions as they can to the coast.

"Everyone knows it's not a long-term fix," he said. "It's barely a short-term fix. ... But right now, it’s the only tool we have, and it does save about three steelhead per day according to our estimates.”

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So far, they’ve moved three sea lions to the beach near Newport. That's given the marine mammals the chance to demonstrate that they can swim back in a matter of days.

One sea lion swam the 230 miles in less than four days – a rate of about 3 miles an hour.

Wright said that supports the state's argument that lethal removal will be necessary to protect the dwindling wild winter steelhead run, which reached a low of around 500 fish last year.

"It would be great if we could just take them to the coast and they could stay there, but that’s not what we've found," Wright said. "I wish it were that simple."

This California sea lion was the first one captured on the lower Willamette River by the Oregon Department of Fish and Wildlife to protect imperiled wild steelhead. It was transported to South Beach in Newport. Courtesy of Oregon Department of Fish and Wildlife

The states of Oregon and Washington have been lethally removing sea lions from below Bonneville Dam on the Columbia River since 2008. One of the sea lions on the lethal removal list turned up in the Willamette Falls trap last week and was euthanized on Thursday.

According to ODFW, other sea lions with a documented record of killing salmon and steelhead near Bonneville Dam may also be killed if they are captured in the Willamette Falls trap.

A decision on additional lethal removals at Willamette Falls isn't expected until the end of this year.