Three months after the Vancouver Aquarium's resident beluga whales died suddenly, the facility announced its plans to phase out its beluga display by 2029.

Head veterinarian Martin Haulena made the announcement at a joint news conference with president John Nightingale on Monday afternoon at the Marine Science Centre.

Nightingale said the exhibit will be closed in the next 12 years, but in the meantime the aquarium plans to bring back belugas with some changes to the program. He said the habitat will be expanded, but will change its focus to research and will no longer allow captive breeding.

Officials said between three and five whales will be brought back to the new exhibit, after being behaviourally matched. The whales that will be brought in are owned by the aquarium but currently on loan to other institutions.

The new display is expected to be open by the spring of 2019.

The public display will be closed by 2029, but the aquarium will continue to be a home for some whales that cannot be released into the wild.

"We think that lots of things are going to change in the world in that timeframe," Nightingale said.

"What was important to us was to carry on with our mission. And the way we saw that five years ago was different today, and I'm sure five years from now it'll be different again."

Haulena also announced there is still no definitive cause of death for Qila and Aurora, the belugas that died in November, despite spending $100,000 on testing. The tests suggest they died of "toxic etiology," but Haulena said no toxins or pathogenic organisms have been identified through their testing.

There was no evidence of infections or issues with the whales metabolism, according to autopsy results.

Staff said the toxins they believe killed the whales may have been planted intentionally by humans, and that the Vancouver police will be involved in an ongoing investigation.

But shortly after the aquarium press conference, the VPD spokesperson said no formal investigation has been requested.

"At this time, we are not aware of any evidence to suggest that the unfortunate deaths of the Beluga whales at the Vancouver Aquarium were as a result of a criminal act," said Const. Jason Doucette.

Doucette added that the VPD Mounted Unit had touched base with staff "to ensure all of the necessary steps were taking place, in the event that at a later time, foul play was suspected."

No other cetaceans will be kept in the belugas' habitat until further precautions are taken by the aquarium.

While it is no longer home to any whales, the aquarium currently houses dolphins, porpoises and a false killer whale.

The aquarium published details of its "new commitments to research" on its blog following the news conference. Staff touted the importance of education and research, saying the research team has "set a new course" for the future of its conservation program.

The new program will study cetaceans like belugas in a "significantly expanded beluga habitat to accommodate the unique lifestyle of belugas and the needs or researchers who will be studying these animals up close."

"The expanded habitat will also support Vancouver Aquarium’s role as the only Marine Mammal Rescue Centre facility in Canada, which includes a team of first responders whose role is to take on emergency rescues for stranded, sick or injured marine mammals along Canada’s coastlines," the aquarium said in a statement.

Researchers will be using their findings to better understand the rapid decline of belugas in the wild. When the conservation program phases out at the end of 2029, staff will shift focus "further afield with the intention of applying its scientific knowledge to saving this iconic Canadian species."

But a report released by two animal rights groups in December questioned how significantly the Vancouver Aquarium's whale and dolphin research contributes to conservation efforts.

Aquarium staff and others frequently cite that contribution as justification for keeping cetaceans in captivity, but after evaluating some of the facility's many peer-reviewed studies, the Vancouver Humane Society and Toronto-based Zoocheck suggest the merits are "debatable."

Last month the Vancouver Park Board delayed a decision about a possible plebiscite regarding whale and dolphin captivity, saying the report would be presented to the board in February. The motion suggests a referendum on cetaceans in captivity on Vancouver's civic ballot in 2018, and a halt on introducing any more whales and dolphins at the aquarium until after the results of the vote.

The idea was put forward by park board commissioner Sarah Kirby-Yung following the deaths of Qila and Aurora. The mother-daughter duo died in November, likely due to a virus or toxin.

With files from CTV Vancouver's Sarah MacDonald