BARCELONA, Spain (AP) — Animal rights activists in Barcelona are celebrating a victory after the Spanish city ordered its municipal zoo to restrict the breeding of captive animals unless their young are destined to be reintroduced into the wild.

Barcelona's town council voted on May 3 to modify the zoo's bylaws to include a rule to eventually halt breeding programs unless there is a plan to release the offspring into nature at some point.

Activist Leonardo Anselmi, who coordinates ZOO XXI, the animal rights group that successfully pushed for the new mandate, said the group wanted to stop zoo breeding programs "that do not respond to an environmental strategy."

But some zookeepers are worried that reproduction restrictions could do more harm than good, and held a strike early this month to voice their concern.