A dead 700-pound California sea lion riddled with at least 12 gunshot wounds was found near Harbor Island last week.

Seal Sitters, a volunteer group that monitors marine wildlife along West Seattle's shores and the Duwamish Waterway, reported the carcass on Friday, Sept. 18, near the mouth of the Duwamish River.

The group called in SR3 SeaLife Response, Rehabilitation and Research for its medical expertise and mobile X-ray equipment.

Casey McLean, SR3's executive director and veterinary nurse, told KIRO Newsradio the animal had been shot at least a dozen times. SR3's field X-ray could not cover the entire body, so the true count may be higher.

"This was probably the most amount of projectiles I have seen on one body in my career," McLean said.

SR3 determined the gunshots killed the animal. The sea lion was a healthy adult with a substantial blubber layer. No full necropsy was performed because of the cost and difficulty of moving a body that size.

Who fired the shots, where exactly the shooting happened and the motive all remain unknown. McLean said the animal likely did not travel far after being shot. No law enforcement agency has publicly confirmed an investigation.

The shooting happened along public, working waterways in an area where SR3 said gunshot strandings of marine mammals have been documented during this season over the years. The organization has also examined sea lions that survived shootings and carried projectiles in their bodies for years.

McLean said the violence stems from misinformation about sea lions' impact on salmon fisheries. SR3 said killing the animals will not recover salmon populations.

California sea lions are federally protected under the Marine Mammal Protection Act (MMPA). The law makes it illegal to harass, hunt, capture or kill any marine mammal without a permit.

Violators face civil penalties up to $36,498, up to one year in prison plus criminal fines, and forfeiture of any vessel involved with penalties up to $25,000, according to NOAA Fisheries.

The case echoes a recent federal prosecution in San Diego. Tyler Muehl, 18, pleaded guilty in August to violating the MMPA after video showed him kicking a sea lion at La Jolla Cove, CBS News reported. He faces up to a year in prison and a $100,000 fine at sentencing on Tuesday, Oct. 20.

SR3 is part of NOAA's West Coast Marine Mammal Stranding Network. Anyone who encounters a dead, injured or stranded marine mammal can call the West Coast Region Stranding Hotline at 1-866-767-6114. To report suspected violations, call NOAA's Enforcement Hotline at 1-800-853-1964.