Kalia, the 9-year-old orca at SeaWorld in San Diego, is pregnant and set to give birth in December. (SeaWorld San Diego/Associated Press)

A killer whale, or orca, at SeaWorld is expecting a calf, the San Diego theme park said Tuesday. The news wasn’t welcomed by animal rights activists trying to outlaw the breeding of captive orcas and put an end to whale shows.

The baby, due in December, would be the sixth at SeaWorld’s California park, spokesman Dave Koontz said. It would be the first calf for Kalia, who is 91 / 2.

Animal rights activists expressed anger at the announcement, saying Kalia is too young to be a mother.

“SeaWorld routinely breeds its females too young,” said Naomi Rose, an orca biologist who supports a bill in the California legislature that would ban the breeding program and the shows. “In the wild, killer whale females don’t have their first calf until they are around 12 to 14 years of age.”

SeaWorld has been criticized recently after the release of the documentary “Blackfish,” which tells the story of an orca that killed a trainer in 2010 at the company’s park in Orlando, Florida. The movie quotes former SeaWorld trainers who say that orcas don’t thrive in captivity and can become dangerous.

SeaWorld has responded angrily to the film, saying its claim that orcas do not fare well under its care is false.

Koontz said the breeding program enriches the lives of the whales “by allowing them to experience, interact with and help raise another member of their pod.”

The company also pointed to the research it does on marine mammals and its rescue efforts for injured whales.

— Reuters