Federal fisheries managers are giving the go-ahead today for Oregon and Washington officials to trap and, if necessary, kill sea lions that wolf down thousands of salmon at Bonneville Dam every year.

The Associated Press received a copy of the order late Monday. It limits lethal removal to sea lions deemed to have a significant effect on federally protected salmon and steelhead stocks. They must have been seen eating such fish between Jan. 1 and May 31 of any year.

The order says sea lions captured in traps must be held for at least 48 hours to allow a search for a home in captivity before they are euthanized. It identifies about 60 sea lions "authorized for immediate removal."

The voracious California sea lions have become a hot-button issue on the Columbia as they consume the same fish the federal government is spending billions of dollars to save.

Some of the sea lions have become especially brazen, snatching fish from frustrated fishermen and nearly upsetting boats.

State officials, anticipating the federal authorization, said Monday that they are preparing to move ahead with control measures that will step up the pressure on the sea lions. The states have tried hazing the sea lions with noisemakers, with mixed success.

The states, with support from Idaho, applied to the National Marine Fisheries Service in 2006 for permission to kill sea lions that go after salmon.

The National Marine Fisheries Service earlier this year proposed to let state officials trap or shoot as many as 85 sea lions a year, or as many as necessary so they eat no more than 1 percent of salmon passing through Bonneville Dam.

Under the proposal, state officials must only target specific offending sea lions, after first trying to scare them off. State officials expect to remove far fewer than 85 sea lions a year, said Guy Norman, regional director at the Washington Department of Fish and Wildlife.

He also said the states have identified zoos, aquariums and marine parks where sea lions trapped in the river may be moved to captivity instead of killing them. He said the states would prefer to relocate the animals to such facilities if at all possible.

"If we could find more homes to relocate them to, that's our number one option," Norman said.

The proposal underwent environmental and public review, attracting more than 3,500 comments, said Garth Griffin, a marine biologist with the fisheries service in Portland. The biggest segment of comments were largely form letters opposing killing of sea lions, with the second biggest group from people -- many of them fishermen -- saying sea lion control is long overdue, he said.

Most anticipated federal approval of lethal sea lion control in the formal decision due today.

"We have a pretty strong sense that it will be a granting of the application for lethal take," said Charles Hudson, a spokesman for the Columbia River Inter-Tribal Fish Commission.

He said the approach to controlling the sea lions is reasonable because it would turn to lethal measures only after other options have been exhausted.

"We have no doubt it will have an immediate benefit to the ability of salmon to migrate safely," he said.

Salmon and sea lions are protected species. But California sea lion numbers are booming, while many Northwest salmon species are struggling. The sea lion population, about 1,000 animals in the 1930s, now numbers about 238,000 along the West Coast. Biologists think the animals have maxed out available breeding sites and habitat.

The number that could be killed under the initial federal proposal is about one one-hundredth of the number that biologists estimate could be removed without undermining the overall population.

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

Close to a third of the salmon eaten by the sea lions were from stocks listed under the Endangered Species Act, the fisheries service said. That's undercutting fish runs battered by dams across their migration routes and by deteriorating habitat.

Hudson said state and tribal biologists estimate sea lions may consume 13 percent to 17 percent of spring chinook salmon passing through the dam.

However, Sharon Young of the Humane Society of the United States said agencies should look to cut back fishing before looking at sea lions as a scapegoat for the struggles of salmon.

"If you're really concerned about the fish, then you don't let more of them get taken," she said.

Michael Milstein: 503-294-7689; michaelmilstein@news.oregonian.com