Vancouver Aquarium will be allowed to keep whales and dolphins in captivity, but must not breed them or otherwise promote reproduction amongst captive mammals, following a ruling by the Vancouver Park Board.

The contentious decision is unlikely to completely satisfy either side of the argument, with animal rights protesters arguing that cetaceans in captivity should be banned altogether, while the aquarium has said continued captivity programmes are essential for research into the animals.

Aquariums have been under immense pressure in recent months following the release of the documentary Blackfish, which recounts the 2010 killing of trainer Dawn Brancheau by an Orca at SeaWorld Orlando. In the documentary it is claimed that by being kept in captivity for entertainment, the whale was driven to madness.

Vancouver Aquarium already operates under a mandate to handle only animals saved from captivity elsewhere, or otherwise unable to be returned to captivity. The new breeding rules were passed by a unanimous decision from the Park Board, which is made up of seven elected commissioners with jurisdiction over a raft of leisure facilities and visitor attractions in Vancouver.

“There were a lot of intelligent, thoughtful, passionate presentations and we had a lot of information to digest,” said board chair Aaron Jasper in a statement. “I think we struck a balance between supporting the good work of the Aquarium and continuing the discussion of the ethics of keeping cetaceans in captivity.”

The decision, while only affecting the Vancouver area, is seen as key for setting a precedent as many in the industry feel it will have a ripple effect with further rulings expected to be put in place across the US and Canada as a result.

The ruling does pose a quandary, in that the aquarium must review the status of its animals with an eye on removing them from public exhibitions. The problem is the aquarium covers expenses for its world-renowned rehabilitation programme, in part, through visitors paying to see the animals.

The most notable future ruling on aquariums in the US is in the state of California. The proposed new legislation could spell trouble for SeaWorld attractions, which would no longer be able to hold orca shows in the state. The ruling is currently being delayed for additional study.