Animal rights activists have welcomed a ruling by the California Coastal Commission, banning SeaWorld from breeding orcas in captivity at its San Diego park.

The agency, which regulates major construction projects along the coast of the Golden State, approved SeaWorld’s plan to double the size of its orca habitat at a hearing on Thursday.

The company intends to spend $100m (£65m) to expand its orca facility, but the commission’s decision came with several conditions. SeaWorld cannot add any new whales from the wild to its San Diego tanks, and none of the 11 orcas currently at the park will be allowed to breed there.

More than 600 people attended the hearing in Long Beach, with hours of testimony from SeaWorld supporters and opponents, including the actress-turned-animal rights activist Pamela Anderson.

SeaWorld said it was disappointed with the ruling. “Breeding is a natural, fundamental and important part of an animal’s life and depriving a social animal of the right to reproduce is inhumane,” the park said. John Reilly, the president of SeaWorld San Diego, said before the ruling: “A ban on breeding would sentence these animals to a slow extinction in our care.”

The park’s critics hailed theruling. People for the Ethical Treatment of Animals said: “The commission’s action ensures that no more orcas will be condemned to a nonlife of loneliness, deprivation and misery.” The breeding ban will not apply to the 13 other whales at SeaWorld attractions in San Antonio and Orlando.