The National Marine Fisheries Service authorised Oregon and Washington state officials to first attempt to catch the sea lions that arrive at the base of the Bonneville Dam on the Columbia River and hold them 48 hours to see whether an aquarium, zoo or similar facility will take them. Otherwise, they could be euthanised, along with those that avoid trapping.

About 60 of the California sea lions, identified by branding, scars or other markings, were deemed the worst offenders and qualify for 'immediate removal.'

One, branded C404, became something of a celebrity because of his ability to work his way into the fish ladders of the dam, and even into the window where upriver-bound salmon are counted to determine the size of later runs. Many sea lions have been coming to the dams for years.

Fidelia Andy, chairwoman of the Columbia Intertribal Fish Commission, said the order 'was the right decision at the right time' and asked for 'the public's patience and support while management activities proceed.' The ruling followed three meetings of a task force comprising commercial and sport fishermen, treaty tribes and animal rights interests.

But Mr John Balzar, spokesman for the Humane Society of the United States, said the idea that sea lions must be killed to save salmon was 'entirely bogus.'

He said fishermen catch three times as many salmon as the sea lions eat, and Oregon and Washington have proposed higher fishing quotas. Federal estimates are that hydroelectric dams in the Columbia system kill nearly 60 per cent of juvenile salmon headed downriver, he said.

The plan to shoot sea lions, he said, coincides with estimates that this year's spring chinook run will be one of the biggest in decades.

Marine Mammals Protection Act
Sea lions are protected under the 1972 Marine Mammals Protection Act. An amendment permits the killing of sea lions if Columbia River states get federal permission. Oregon and Washington asked for the permission in 2006, and Idaho offered its support.

Such permission has been granted only once before - in the 1990s for sea lions in the Ballard Locks in Puget Sound in Washington, where five animals were identified as offenders that drastically diminished a steelhead run that has yet to recover.

Three were taken in by an aquatic park before they were killed. The fate of the two others has not been made public.

Sea lion populations have soared since they and other marine mammals were covered under the 1972 act. They numbered about 1,000 in the 1930s, when they were hunted and used, among other purposes, for dog food. They are thought to number about 240,000 today.

Ms Sharon Young with the Humane Society of the United States said on Tuesday the group is studying the documents to decide whether to challenge the order in court.

The order applies to sea lions observed eating salmon or steelhead below the dam between Jan 1 and May 31. The authorisation is valid until June 30, 2012, and can be extended for five years. It can be revoked by the National Marine Fisheries Service on 72 hours notice. -- AP