The Vancouver Aquarium's legal challenge to keep cetaceans in captivity hopes to prove that the Vancouver Park Board does not have the legal power to enact a ban and that a bylaw amendment made some whales homeless.

The case, in B.C. Supreme Court, began Monday, with about a dozen protesters watching from the gallery.

Before the proceedings started, protesters placed cardboard tombstones outside the courthouse that bore the names of cetaceans that had previously died at the aquarium.

David Isbister helped place the protest signs but said he does support the conservation work done by the aquarium.

"We think they can still do the sporadic good they do without needlessly killing cetaceans," he said.

DAISY HARBOUR PORPOISE VANCOUVER AQUARIUM

Daisy the harbour porpoise was only a month old when she was rescued by the aquarium's Marine Mammal Rescue service on August 26, 2008. She died in June, 2017. (Vancouver Aquarium)

On Monday, the court heard how the aquarium has already spent $45 million on a previously approved expansion of the facility, located in Stanley Park which includes plans to update the cetacean display.

The aquarium also plans to argue that the Vancouver Park Board doesn't have the legal power to enact the ban, and that the language in the bylaw amendment is vague and the move will cost the aquarium financially.

It will look to prove that the bylaw amendment, which was passed in May, resulted in the loss of a long-term home for rescued and "non-releasable " cetaceans, hampering conservation efforts.

"The Vancouver Aquarium's rescue program is the only one of its kind in Canada with the facilities, accreditation and expertise to provide ongoing care for sick and stranded whales, dolphins and porpoises that Fisheries and Oceans Canada deems to be unfit for release following rescue and rehabilitation," the aquarium said in a statement when it filed its challenge in June.

In 2016, Qila — the first beluga whale conceived and born in captivity in a Canadian aquarium — died at 21 years old after becoming ill.

A week later Qila's mother, 30-year-old Aurora died after displaying the same symptoms, which the aquarium said were caused by an unknown toxin.

Earlier this year a harbour porpoise named Daisy died. The aquarium said preliminary necropsy results showed she had pulmonary disease.

Two animal rights groups, Animal Justice and Zoocheck, were both granted the right to intervene in the Vancouver Aquarium's case against the Park Board over its ban on displaying whales and dolphins.

The Park Board is not commenting on the matter while it is before the courts.