A trainer pinned to the bottom of a show pool Wednesday by Kasatka, considered the matriarch of SeaWorld's whales, was still in the hospital as park officials tried to figure out why Kasatka did what she did.

Ken Peters, who has worked at Shamu Stadium for 12 years, is "doing well" but remains hospitalized at University of California, San Diego Medical Center, where he is being treated for a broken left foot, said Dave Koontz, SeaWorld San Diego's communications director.

The "Believe" killer whale show continued Friday, and Kasatka was allowed to participate, but no decision has been made on when trainers will again be allowed to perform with the whales in the water, Koontz said.

In an incident Wednesday afternoon that made headlines worldwide, Kasatka was supposed to shoot out of the water upright so Peters could dive off her nose.

Instead, the whale grabbed his foot and dived to the bottom of the 36-foot tank. She surfaced about 30 seconds later, but ignored other trainers' signals to come to the side of the pool and dived a second time with the trainer, keeping him under water for about a minute as spectators watched with growing concern and some recorded the drama with cameras.

Koontz said that senior trainers from SeaWorld's sister parks in Florida and Texas are working with their colleagues in San Diego to try to determine why Kasatka turned on her trainer.

Kasatka tried to bite a trainer during a 1999 show, but he was unhurt. She tried to bite another trainer in 1993, according to SeaWorld officials.

Meanwhile, an animal rights activist condemned SeaWorld for keeping wild animals in captivity, describing the practice as cruel.

"Orcas are incredibly intelligent and self aware animals," said Bryan Pease with the Animal Protection and Rescue League.

"Keeping them in a tiny aquarium tank is sort of like forcing a human to spend its entire life in a phone booth," he said.

Pease said SeaWorld and other similar facilities should stop breeding animals in captivity.

"Just because they are born and raised in captivity doesn't mean it is any better for them," he said. "We do not think that these animals should ever be kept in captivity -- that includes orcas, dolphins and sea lions."