North Bonneville, Washington --- Washington and Oregon wildlife managers have suspended efforts to capture and relocate California sea lions from the Columbia River until further notice, after six animals were discovered dead on trapping platforms Sunday near Bonneville Dam.

The carcasses of four California sea lions and two Steller seas lions were found at mid-day Sunday in floating traps. Although the animals appear to have been shot, necropsies are being performed to confirm the cause of death. Necropsy results are not immediately available.

NOAA-Fisheries, the federal agency that manages migratory marine mammals, is investigating the deaths, with assistance from the Washington Department of Fish and Wildlife (WDFW), the Oregon Department of Fish and Wildlife (ODFW), state police and the U.S. Army Corps of Engineers, operators of Bonneville Dam.

Both California and Steller sea lions are protected under the federal Marine Mammal Protection Act. Steller sea lions, which are not subject to removal, are also federally protected under the Endangered Species Act. Killing an animal federally listed as endangered is a crime punishable by a fine of up to $100,000 and a year in jail.

“In light of yesterday’s incident, the states are focusing their efforts on assisting the investigation and have suspended capture operations at Bonneville Dam until further notice,” said Guy Norman, regional director of the Washington Department of Fish and Wildlife’s southwest Washington region.

Over the past two weeks, Washington and Oregon wildlife managers have captured seven California sea lions for relocation to zoological facilities. One of those animals died last week when it failed to resume breathing after being sedated for a health examination. The other six sea lions have been flown to SeaWorld facilities in Orlando, Fla., and San Antonio, Tex.

California sea lions are part of a robust West Coast population that since 2001 has taken an increasing toll on federally protected salmon and steelhead below the Bonneville Dam.

Despite three years of efforts to deter them through hazing, sea lions last year consumed more than 4 percent of the returning spring chinook salmon run in just the area visible to observers on the dam. In recent weeks, more 50 sea lions were observed feeding on salmon and steelhead immediately below the dam.

In March, NOAA-Fisheries granted Washington, Oregon and Idaho the authority to remove up to 85 sea lions annually from the river to stem salmon predation. The states began relocating sea lions to approved zoological facilities in late April. The removal authorization has been challenged in federal court by the Humane Society of the United States and several private citizens.