Chester the false killer whale has died, officials with the Vancouver Aquarium confirmed Friday.
Aquarium officials said Chester appeared fine earlier in the week, but his behaviour changed on Wednesday afternoon, and despite around the clock care he passed away early Friday morning.
The cause of death has not yet been determined, and the aquarium said a post-mortem exam is planned for Friday.
However, in a news release, the institution said Chester’s health had been compromised since his rescue three years ago.
Chester was found in distress on a beach near Tofino in 2014, and was taken to the Vancouver Aquarium’s Marine Mammal Rescue Centre for care.
Officials said that at the time, it was estimated the lone calf would have a 10 per cent chance of survival.
He has lived permanently at the aquarium’s main facility since 2015.
WATCH: Checking in with Chester the false killer whale
In a statement, Vancouver Aquarium head veterinarian Dr. Martin Haulena said Chester’s death may be connected to complications from his stranding.
“We know that stranded animals, possibly because of injuries sustained during stranding, do have incidences of renal failure later on. That is something we’ll be looking at during the necropsy,” he said.
False killer whales, also known as Pseudorca crassidens are not actually whales but are actually the fourth-largest member of the dolphin family.
Chester was one of the few remaining cetaceans at the Vancouver Aquarium.
In 2016, the last two beluga whales living at the facility, Qila and her mother Aurora, died. An investigation later found their deaths were due to an unknown toxin.
And in June, Daisy the harbour porpoise — another rescue animal — also passed away.
WATCH: Chester the false killer whale meets Helen the Pacific white-sided dolphin
Helen, a Pacific white-sided dolphin, is now the last cetacean currently living at the Aquarium — though the facility owns several belugas on breeding loan to U.S. facilities.
The issue of cetaceans in captivity at the Vancouver Aquarium has been a hot-button issue in recent years.
In May, the Vancouver Park Board approved a new bylaw banning the Vancouver Aquarium from bringing any new cetaceans to its Stanley Park facility.
Vigil for Chester
Meanwhile, a group of animal-rights activists is already organizing a vigil for Chester.
David Isbister with VanAquaFacts says they want to honour the animal and try to extend their liberation that they achieved through death to the ones living.
“So it’s important for us to come here because this a lot of the time is the only time this voice from the animals is open to being heard,” said Isbister.
The vigil will be held at the aquarium Saturday evening.
~With files from Michelle Morton