In the wild, beluga whales - who are highly social and like to dive a thousand feet or more to eat their meals - can live to be 50 years old. Belugas in captivity tend to die before reaching 30.
In the wild, however, beluga whales face different kinds of threats to their well-being and survival. Because they tend to gather along coasts, pollution and offshore oil drilling put the animals at risk.
Aurora was captured in the wild and arrived at the Vancouver Aquarium in 1990. She gave birth to three calves while in captivity, all of whom died before her. Qila survived longest, whereas Tuvaq died at age 3 and Nala at age 1.
Qila had a calf in 2008, who died just three years later.
"No matter how you feel personally about marine mammals in captivity, I defy anybody to contradict me on the reason that we have them," Barrett-Lennard said. "We have them to serve as animals ambassadors - to inculcate a stewardship ethic and a care about these animals in the wild."
But Rose believes the recent deaths should shape the future of the aquarium.
"The Vancouver Aquarium should reconsider its plans to expand its cetacean enclosures and instead phase out the exhibition of these species," she said. "It should follow the example of the National Aquarium in Baltimore, which is planning to build a natural sanctuary and retire its eight bottlenose dolphins. The 21st century is no place for captive cetaceans."
To learn what you can do to help beluga whales, click here.