(CNN)Since September, 13 dead California sea lions have washed up in Puget Sound near Seattle, a conservation group says. Eight of the sea lions were shot, and the rest died from other wounds, most likely also caused by humans.
Dead sea lions with gunshot wounds are washing up in Puget Sound
The Seal Sitters Marine Mammal Stranding Network, a volunteer organization that responds to calls for stranded animals, said all the sea lions died from acute trauma -- including one found last week that had its head sliced off.
It's not uncommon for sea lions to get shot -- most often by fishermen who believe the animals are reducing salmon populations and harming their livelihood. But the current spate of sea lion shootings is much higher than usual for the months of September through November, the Seal Sitters group says.
And the organization said this is just the beginning. High season for shooting sea lions is typically in the winter months, during fish runs.
"According to those who live and work along the Elliott Bay and Duwamish waterfront, shots are being heard even more frequently this year," said Robin Lindsey of Seal Sitters in an online post. "Animals searching for food to survive and fishermen searching out fish for consumption or livelihood are on an annual, never-ending collision course."
Even though California sea lions live mostly in the waters off central Mexico and California, it's not uncommon to spot them inside Puget Sound. They travel north to feed on the salmon that have returned to spawn.
Sea lions are protected under the Marine Mammal Protection Act, and harming one can result in a fine of up to $28,520 and a year in prison.
"We are concerned about a number of recent reports of marine mammal deaths caused by gunshots in the greater Seattle area," said Greg Busch, an assistant director of the National Oceanic and Atmospheric Administration's National Marine Fisheries Service's Office of Law Enforcement. "All marine mammals are protected by the Marine Mammal Protection Act and OLE investigates all reported unlawful takes of sea lions."
But catching and prosecuting offenders can be difficult. Since 1998 more than 700 California sea lions have been found shot or stabbed in the United States, according to NOAA Fisheries -- but only a handful of fishermen were charged.
Seattle's chapter of the Sea Shepherd Conservation Society, a marine conservation group, is hoping this time will be different. They're offering a $10,000 reward to anyone with tips that lead to the arrest and conviction of those responsible for the killings and a $2,000 reward to anyone with video e