Wildlife officials said that the bodies of the sea lions were discovered at noon Sunday on two floating traps just below Bonneville Dam.

“In each of the two traps were three dead sea lions,” Brian Gorman, regional spokesman for the National Marine Fisheries Service, said. “There was one Stellar sea lion and two California sea lions in each trap.”

The sea lions appear to have been shot during the night by someone on the Washington side of the river, Gorman said.

“There was a great deal of blood in both traps,” he said by phone from Seattle. “The state patrols from Oregon and Washington are on the scene now, and they are treating the traps as a crime scene.”

Four traps were installed near Bonneville Dam in an attempt to protect endangered salmon.

The trapping program has been placed on hold until the investigation is finished.

The six dead sea lions had not been confined within the two traps, said Oregon wildlife official Rick Hargrave. The gates on all four traps were in the open position, and the six sea lions had clambered — or “hauled up” — onto the floating platforms.

Both species are federally protected. Washington and Oregon have been authorized to trap California sea lions, then relocate the most serious predators. More than 60 of the California sea lions have been branded as frequent offenders eligible for removal.

Wildlife agencies follow strict procedures for trapping the animals.

“We have trapping and transfer on Mondays and Thursdays,” Hargrave said by phone. “The traps have gates that are open all the time, until a marine mammal biologist checks the trap. If the animal is branded, we are authorized to transfer it.”

Only then is the gate closed and the animal trapped inside the cage.

Hargrave said the traps were placed in a restricted zone.

Most of the time, the sea lions have been treating the floating cages as a handy place to hang out.

“I’ve seen as many as nine sea lions on a trap at a time,” said Hargrave, spokesman for the Oregon Department of Fish and Wildlife.

On Sunday, the gates were closed to prevent other sea lions from becoming easy targets.

The investigation will include necropsies for all six animals. As far as evidence from witnesses or videotape surveillance goes, “There is none I’m aware of in either case,” Hargrave said.

Tom Vogt can be contacted at 360-735-4558 or at tom.vogt@columbian.com.