AP

Police and investigators from Oregon Fish and Wildlife investigate the death of sealions held in this cage at the Bonneville Dam on the Columbia River between Washington and Oregon, east of Portland.

PORTLAND, Ore. - The six sea lions found dead in traps near Bonneville Dam apparently were not shot to death, federal officials said Wednesday, leaving open the questions of how the animals died or whether humans killed them.

NOAA fisheries spokesman Brian Gorman in Seattle said Wednesday that preliminary results of a necropsy found no evidence of recent gunshot wounds but found numerous shallow puncture wounds in one animal consistent with sea lion bite marks.

He says the department still is trying to determine how the animals died and how the doors to the traps in which they were found had been closed.

Because the first examination of the carcasses turned up no slugs, investigators had believed the animals were shot at close range with high-powered rifles, the bullets passing through the flesh.

On Tuesday, Gorman said, X-rays found metal fragments in soft tissue near the neck of two animals.

A metal slug was found in the blubber of one animal.

But, he said, neither the fragments nor the slug appear to be fatal and may have been from old wounds, he said.

The sea lions included two endangered Steller sea lions and one California sea lion pup.

On Tuesday the Humane Society of the United States, which is suing to block the authorized killing or removal of up to 85 animals a year for five years, agreed with the federal government and the states of Oregon and Washington to continue a ban on killing and stop permanent removal until next year, in part to allow more efforts to go toward investigating what was thought to be shootings of the animals over the weekend.

The agreement allowed the governments to continue removing animals and branding them for identification if they return them to their natural habitat.

Trapped sea lions identified as troublemakers at the dam where they gather each spring to eat migrating salmon were being sent to aquariums such as Sea World.

Arguments were to have been heard before a panel of the 9th U.S. Circuit Court of Appeals on Thursday.

Under the agreement a hearing on the sea lions would be expedited but killing or permanent removal could not take place until then, probably early next year.