The debate on whether or not cetaceans should be kept in captivity continues to rage on, as more than 100 countries signed a pledge to consider banning the capture of wild dolphins and whales for display, while a landmark ruling on breeding rules in Vancouver has collapsed.

A resolution, signed by 120 countries at the triennial meeting of the UN Convention on the Conservation of Migratory Species of Wild Animals, isn’t a legally binding document, though it commits signatories to consider drafting laws banning the capture of whales and dolphins for commercial display.

SeaWorld – which has been in the eye of the animal rights storm following the release of the documentary Blackfish – no longer captures cetaceans from the wild for shows, but a spokesman said SeaWorld would oppose the resolution if no provision was made for rescuing and rehabilitating beached animals, conserving critically endangered species, and recognising the "significant educational and scientific benefits of marine mammal displays".

Meanwhile a landmark ruling by the Vancouver Park Board – allowing whales and dolphins to be kept in captivity but prohibiting breeding or otherwise promoting reproduction among captive mammals – has collapsed as the board tried to push the ruling through at the last minute.

Vancouver Aquarium took the body to court in July, contesting that, short of sterilisation, the ruling was an “impossible task and would be psychologically damaging to the highly social animals”, while the incoming NPA commissioners have already promised to kill the proposal to ban cetacean breeding.

At the outgoing board's final meeting before a new board takes over next year, outgoing commissioner Sarah Blyth tried to push through a vote on the ban, but NPA commissioner Melissa de Genova, who has since been elected to Vancouver city council, questioned the timing of Blyth's motion, which ultimately failed. While good news for the aquarium, a motion was passed to review its policy of cetaceans in captivity in 2015, so changes to its policy could be made during the course of the next year.