A sea lion that was found in distress on Vancouver's Spanish Banks last week had been shot multiple times in the face, the Vancouver Aquarium revealed Friday.

The adult California sea lion was underweight and lethargic when he was reported to the aquarium's Marine Mammal Rescue Centre on May 5.

A team was dispatched to collect the animal, who was in such poor shape he wasn't responding to the activity surrounding him on the busy beach.

It took days of therapy and medication before the aquarium's veterinary team, led by Dr. Martin Haulena, was able to perform a full exam under general aesthetic on Tuesday.

"He's been shot and has two bullets, probably .22 caliber bullets, in his head," Haulena said. "One of the bullets shattered his lower-left canine. We removed the shards out, that got rid of the immediate pain, but the rest of the tooth will have to come out."

The shooting also blinded the sea lion in one eye, and possibly hit his optic nerve.

It's unclear who shot the sea lion or why, but Haulena said the wounds weren't new, and the animal likely spent weeks in distress before being rescued.

"This is an animal that's been suffering very severely,” Haulena said. “It’s absolutely devastating.”

The Department of Fisheries and Oceans confirmed it has launched an investigation into what happened to the sea lion, which, because his rescue coincided with Cinco de Mayo, has been named Senor Cinco.

Marine mammals such as sea lions and otters can be a nuisance for fisherman, but shooting them is illegal. The Independent Fish Harvesters' Association is adamant they have other ways of dealing with prey, including by distracting them with another vessel.

It's too early to know whether the sea lion will be released back into the wild or need long-term care, a decision that, in all rescues, is made by the DFO.

In 2013, a sea otter was rescued after being shot in the face near Tofino. The otter, which staff named Walter, was also left blinded, and lived his final years at the Vancouver Aquarium.

The Marine Mammal Rescue Centre, which saves everything from seals to false killer whales, has taken 174 animal patients in for treatment over the last year.

With files from CTV Vancouver's Penny Daflos