A federal judge on Wednesday refused to stop Oregon and Washington from trapping and killing California sea lions at Bonneville Dam this spring to keep them from gobbling endangered salmon.

The Humane Society of the United States filed a lawsuit against the plan and asked for a preliminary court injunction to stop it.

Humane Society attorneys argued that culling sea lions won’t significantly benefit threatened salmon and steelhead runs. Shooting the animals would harm Columbia River kayakers and others who have relationships with individual sea lions, they said

But U.S. District Judge Michael Mosman rejected the injunction request. The judge agreed that it appears somewhat arbitrary to crack down on sea lions when fishing kills more salmon listed under the Endangered Species Act. But initial evidence indicates that sea lions do “very serious” harm to endangered and threatened salmon, Mosman ruled.

“It’s a rather remarkable thing to say that (destroying) an individual animal will cause irreparable harm,” Mosman said early in the hearing. He later called the Humane Society’s evidence of damage “far less weighty” than the government’s.

State officials said they could begin trapping sea lions as early as Tuesday, targeting animals that have been seen eating federally protected fish at the dam.

The plan authorizes capturing and killing up to 85 sea lions a year for five years. But the states’ goal is to capture 30 this year, with first priority given to relocating the animals to captive environments such as Sea World and the St. Louis Zoo.

About 20 slots have been found so far, said Guy Norman, director of the Washington Department of Fish and Wildlife’s Vancouver office. Only about four weeks remain in the spring chinook’s journey upriver to Bonneville, Norman said.

“Our No. 1 step is to relocate as many sea lions as we can,” he said. “Whether we will get to lethal means this year is unknown.”

Anglers and biologists have grown increasingly frustrated with sea lions that feast on salmon gathering to climb Bonneville’s fish ladders. Last year, crews counted sea lions eating more than 4 percent of the salmon run, although biologists suspect they probably ate more.

Sea lion numbers have surged from about 1,000 animals in the 1930s to about 238,000 now along the West Coast. Fishery managers say it doesn’t make sense to let sea lions eat salmon while the Northwest restricts fishing and spends billions to try to help the fish recover.

Humane Society officials said the killing of sea lions at Bonneville Dam would be the first government-led killing since at least 1994, when Congress beefed up protection of marine mammals.

Other sea lions probably will take the place of the captured sea lions, they argued. Getting rid of 30 sea lions would save about 2,100 endangered or threatened fish, far fewer than fishing takes.

A decisive hearing on the lawsuit will be held as early as mid-May — when sea lion trapping probably will be finished for the year.

Sharon Young, a Humane Society field director, said the government should back off in the meantime. “We’re hoping they will not start shooting while the court is still hearing arguments.”

I have recieved permission to use this news article from Scott Learn at scottlearn@news.oregonian.com