PORTLAND, Oregon (Reuters) - Washington and Oregon can start killing sea lions that feed on migrating salmon to help preserve dwindling U.S. Pacific Northwest salmon populations, a federal agency said on Tuesday.

A sea lion feeds its pup in Golfo Nuevo, off the beach of the Argentina's Patagonian village of Puerto Piramides, March 18, 2008. REUTERS/Enrique Marcarian

The National Marine Fisheries Service granted permission to the states to target as many as 85 sea lions a year near the Bonneville Dam on the Columbia River. Oregon’s Department of Fish and Wildlife said removal will start after April 1.

Salmon-gobbling pinnipeds have been a problem in West Coast waters for over a decade and at Bonneville Dam for about five years. About 100 California sea lions make the 150-mile (240-km) trip upriver to feast on spawning salmon channeling into the dam’s fish ladders, according to Oregon.

Authorities have tried to deter the sea lions by installing physical barriers and driving them off with rubber bullets, firecrackers and other noise-makers with little success.

Only sea lions seen gobbling salmon during between January 1 and May 31 can be killed, according to the order. Before sea lions are killed, they must be trapped and held for 48 hours while fisheries managers try to find them a home at a zoo or aquarium.

There is a provision, however, that allows sea lions to be shot in the water if the animals are not easily captured. The decision raised the ire of one animal protection group.

“This is a waste of money, time and lives and diverts attention from the real problems the fish face,” Sharon Young, marine issues field director for The Humane Society of the United States said. The HSUS supports “non-lethal harassment” of sea lions at Bonneville Dam.

The decision comes just in time for the peak of the spring salmon run in April and May. Washington, Oregon and Idaho were required to ask permission because the sea lions are protected under the Marine Mammal Protection Act.

A male sea lion, which can reach 1,000 pounds (454 kg), consumes about 30 pounds (13.6 kg) or five to seven fish a day. The National Marine Fisheries Service estimates that the sea lions ate nearly 4,000 salmon last year, which accounted for about 5 percent of the spring salmon run.

About one-third of the salmon eaten are endangered, according to the National Oceanic and Atmospheric Administration.

State and federal governments have spent billions trying to protect the once abundant fish and fishery managers have also proposed a virtual shutdown of salmon fishing this year in California and Oregon coastal waters.