PORTLAND, Ore. -- Thr trapping of sea lions near Bonneville Dam will continue, despite the death of one of seven trapped sea lions, a Fish and Wildlife spokesman told KGW Wednesday.

One of seven sea lions trapped at Bonneville Dam on the Columbia River and sent to the Point Defiance Zoo and Aquarium in Tacoma, Wash. died while undergoing medical inspection before transfer to a Sea World park, the Humane Society of the United States said Tuesday.

The society, which is mounting a federal appeals court challenge to federal authorization to kill or capture some of the animals, demanded a moratorium on the captures until a full investigation can be held.

But Oregon Department of Fish and Wildlife spokesman Rick Hargrave told KGW Wednesday "we are moving forward with the trap and transfer."

The trapping had been scheduled to resume on Thursday morning and it will go forward as planned, Hargrave said.

As for the sea lion's death, Hargrave said the department's marine mammal specialist, Robin Brown, said such deaths are neither common nor unusual among marine mammals. He said plans are to continue trapping on Mondays and Thursdays.

Sharon Young, who directs the marine mammal program for the national society, said the sea lion, branded as B198, died after being anesthetized so blood samples and other biological work could be done to make sure it was healthy.

"It went under anesthesia and never came back," Hargrave said.

Oregon and Washington fish and wildlife authorities began trapping the animals at the dam on Thursday after the 9th U.S. Circuit Court of Appeals said federally authorized captures could proceed but said no animals could be killed pending the outcome of a hearing the court has scheduled for May 8.

 Background: Sea lion controversy

At the request of Oregon and Washington the National Marine Fisheries Service authorized the killing or capture of up to 85 sea lions a year for five years at the base of the dam, where they feed on salmon headed upriver to spawn, but recommended that the total number be closer to 30 and that emphasis be placed on live trapping.

State wildlife officials say they have confirmed commitments for homes for 19 or 20 of the animals.

Those sent to Tacoma were branded or otherwise identifiable as being among about 60 animals known to be problems and targeted for immediate removal.

Several others, including some threatened Steller sea lions, have been caught at the dam but were not on the "wanted" list and were released on the spot or taken to the mouth of the river near Astoria and freed.

The sea lions are not endangered or threatened but are protected under the 1972 Marine Mammals Protection Act.

An amendment to the act allows selected animals to be captured or killed under some circumstances if states request it, which Oregon and Washington did in 2006.

The Humane Society contends the NMFS has not proved the required "significant negative impact" from sea lions on the salmon runs.

It seeks an injunction barring trapping or killing for this year until the case can get through the courts.

The government contends the animals do major damage to fish runs that are supported at heavy public cost. They are backed by Columbia River Indian tribes and commercial and sport fishing interests.