SeaWorld said on Thursday that it would immediately cease breeding killer whales, bowing to mounting criticism by animal rights activists, regulators and lawmakers over the treatment of marine mammals in captivity.

SeaWorld announced in November that it would phase out its San Diego killer whale performance this year, but it went further on Thursday, declaring that the orcas in its care would be the last generation of killer whales at its theme parks.

“We need to respond to the attitudinal change that we helped to create,” Joel Manby, the president and chief executive of SeaWorld Parks and Entertainment, wrote in an op-ed article in The Los Angeles Times announcing the decision.

The company has 29 orcas: 11 in San Diego; seven in Orlando, Fla.; five in San Antonio; and six in Loro Parque, on Tenerife, the largest of the Canary Islands. It does not plan to release the killer whales into the ocean, arguing that they would not be able to survive in the wild.