Fisheries and Oceans spokesman Paul Cottrell said Friday the carcass was found nearly a week ago on Tyee Spit, on the east coast of Vancouver Island.
Cottrell said evidence suggests the sea lion's head was removed after the animal had been killed by several gunshot wounds to the shoulder.
He said there's no obvious motive but that such incidents have occurred in the past.
"It used to be a very common site to find shot seals and sea lions," Cottrell said. "There was quite a competition in the past between fishers and seals and sea lions."
He said that's one of the reasons for creation of the B.C. Marine Mammal Response Network, a coast-wide organization to examines deaths of marine mammals.
Sometimes the mammals are beached after being caught in a net or killed by whales that don't end up eating them, Cottrell said.
He said members are now relying on possible witnesses to come forward to identify a suspect the recent shooting case. (CKAY, The Canadian Press)