VANCOUVER -- New restrictions adopted by Vancouver's park board mean only threatened species of whales and dolphins will soon be bred at the city's aquarium.

The unanimous vote Thursday saw park-board members amend a bylaw that will prohibit the breeding of all other captive cetaceans at the facility.

Elected members also decided to form a committee of animal-welfare experts to provide public oversight and ensure the well-being of all cetaceans owned by the Vancouver Aquarium.

The contentious issue drew more than 130 people to speak at several recent park board public hearings, and four former Vancouver mayors signed letters in support of the aquarium's cetacean program.

Park Board chair Aaron Jasper says the issue is complex and he thinks the board struck a balance between supporting the aquarium's good work and continuing the discussion of the ethics of keeping the animals in captivity.

The aquarium houses rescued animals that cannot be returned to the ocean or animals that were born in captivity, and among its current residents are two Pacific white-sided dolphins, two harbour porpoises and two belugas.