Image caption Fishermen regard sea lions as pests because they prey on salmon

Eight sea lions have been found shot dead in the US state of Washington in the past few weeks, wildlife officials have told a local TV station.

The bodies of seven sea lions with bullet wounds were recently found on the Nisqually River, KING-TV reports.

An eighth sea lion was found dead in West Seattle on 23 January. The Seal Sitters conservation group said it, too, had been shot.

Fishermen regard sea lions as pests because they prey on salmon.

The Seal Sitters say the eighth dead animal was a California sea lion, a mature male. The species is protected under the US Marine Mammal Protection Act.

"Evidence of a 'penetrating' wound, suspected to be that of a bullet, was found deep in the tissue and tracked back to the entrance wound," the Seal Sitters said on their blog.

The sea lion's remains were analysed by a biologist from the Washington Department of fish and wildlife.

The examination also revealed a wound from a shark bite and the sea lion's intestines were twisted, the Seal Sitters said.

One of the animals found on the Nisqually River was a Steller sea lion, protected under the Endangered Species Act.

Both the state Department of Fish and Wildlife and the National Oceanic and Atmospheric Administration (NOAA) are investigating the deaths, KING-TV reports.

"California sea lions are sometimes viewed as a nuisance by commercial fishermen and there are records of stranded sea lions with gunshot wounds and other human-caused injuries," the NOAA says on its website.