A false killer whale that was cared for at the Vancouver Aquarium for years after being found stranded on a beach near Tofino has died.

Staff noticed a change in Chester's behaviour Wednesday and placed the animal in intensive care. Unfortunately, despite veterinarians' best efforts, Chester died early Friday morning.

"It is devastating to have to announce his passing," the aquarium said in a news release. "His health was compromised when he stranded on the beach and he continued to be a health-challenged animal."

The cause of death hasn't been determined, but the aquarium staff expects to learn more in a port-mortem examination.

Chester was named after Chesterman Beach, where he was discovered in distress back in July 2014. The roughly one-month-old false killer whale was in extremely poor condition, with cuts and wounds over his body, when the aquarium's Marine Mammal Rescue Centre brought him in for treatment.

He went on to become the first false killer whale calf to survive stranding in Canada.

According to the aquarium, Chester was kept in captivity – a decision that falls on Fisheries and Oceans Canada – because he was so young when he was brought in.

"Chester’s lack of life skills would have put him at a disadvantage in the wild — he did not know how to forage on his own or protect himself from predators and other possible dangers," the aquarium said.

The loss of Chester is the latest in an unfortunate string of deaths at the facility, which has faced anger and protests from parts of the public over its cetacean programs.

Daisy the harbour porpoise died in June, nine years after being rescued, and the aquarium's two beluga whales, Qila and Aurora, died in late 2016.

The Vancouver Park Board has since voted to ban the import or display of any new whales, dolphins and porpoises at the popular Stanley Park attraction – a decision the aquarium is challenging in court.

False killer whales are actually dolphins, and the aquarium said Chester had all the personality associated with the playful creatures: he was "affectionate, cheeky, and full of fun."

According to staff, his rescue and subsequent years in captivity helped build understanding about his little-known species.

"Chester’s rehabilitation and care provided invaluable learning opportunities for veterinarians, scientists and students around the world. He contributed to a greater body of knowledge by participating in valuable research, such as vocalization and echolocation studies and assessment of his lung function via respirometry," the aquarium said.

"Just as important, Chester enchanted and educated millions of Vancouver Aquarium visitors about his unusual species and their life in the wild. He will be missed by all."