Sea Shepherd activists are monitoring California sea lions on the Columbia River, where on Sunday in Astoria, Ore., they photographed a state branding operation that triggered bursts of flames on the hides of some animals.

“It was horrific to watch,” said Ashley Lenton, a campaign leader for the Friday Harbor-based group that has launched international campaigns to save whales and other marine mammals.

In the Pacific Northwest, the group opposes the killing of sea lions lion to reduce predation on threatened and endangered salmon.

Last year, 10 sea lions were euthanized, and those removals are scheduled to resume this spring.

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“We believe these animals are being scapegoated,’’ said Lenton.

The branding process photographed Sunday has been conducted by the Oregon Department of Fish and Wildlife since 1997, and has marked some 1,400 sea lions.

The brands helps biologists monitor the movements and feeding habits of sea lions both in the Columbia River and along the West Coast, according to Jessica Sall, a spokeswoman for the department.

In recent years, the brands also have helped to identify sea lions that repeatedly feed on salmon and steelhead on the Columbia below Bonneville Dam, where wild runs are protected under the federal Endangered Species Act.

Lenton said that the Sunday branding process appeared to be extremely painful to the animals.

Sea Shepherd photos showed flames and smoke coming from the hides of sea lions while being branded.

Sall said the branding operations do sometimes trigger flashes of flame as hair is burned away.

But she said branding does not cause the sea lions great pain because their skin is far tougher and thicker than that of humans, and has fewer nerve endings.

“It was a routine operation that went as planned,” Sall said.

Material from The Associated Press is included in this report.Hal Bernton: 206-464-2581 or