— Tilikum, the male killer whale that fatally injured trainer Dawn Brancheau in front of a stunned audience at SeaWorld in Orlando on Wednesday, was a breeding "stud" often housed in isolation.
Experts believe he did not kill for food, but may have been acting out due to stress and raging hormones.
While some reports have been portraying Tilikum as a particularly aggressive orca, a nearly identical incident involving another killer whale male named Ky occurred in July 2004 at the San Antonio SeaWorld.
Trainer Steve Aibel, like Brancheau, was pulled underwater by the whale, which also attempted to bite, but Aibel walked away uninjured. He later blamed Ky's "adolescent hormones" for the episode.
Marine biologist Nancy Blake told Discovery News that Tilikum could have acted out for similar reasons.
"He was used a lot [by SeaWorld] for mating, and could have even been enacting a mating behavior during the incident," explained Blake, a leading expert on killer whales who runs California's Monterey Bay Whale Watch.
According to GREMM, a Quebec-based marine mammal research and education group, intense competition may take place between male whales before mating. Males and females may also challenge each other, with females sometimes changing their diving behavior during the process.
Captured near Iceland in November 1983, Tilikum "was housed in small tanks from the beginning," said Blake. SeaWorld Orlando acquired the whale in January 1992, and put him in a breeding program shortly thereafter.
Over the years, Tilikum has sired at least 17 calves, 10 of which are still alive, making him the most successful orca father in captivity. He is also the only captive killer whale grandfather.
His captivity, frequent breeding and the fact that Tilikum was caught in the wild could all have contributed to Wednesday’s fatality, Blake believes.
"It is my understanding that he is often kept by himself," she said. "That is not natural. Males in the wild generally live with their mothers and other family members. Such social contact is critical to their development."
She said he may even have "lashed out" at Brancheau due to "stress and boredom."
Richard Ellis, a marine conservationist at the American Museum of Natural History, agrees that the whale "was not trying to eat the trainer," but believes the marine mammal's actions were "premeditated" and intentional.
"He decided to do this as opposed to keep swimming around in circles," Ellis said in a televised interview with the Associated Press. Ellis would not speculate, though, on what the whale actually intended.
Captive killer whales are fed 140 to 240 pounds of food, mostly fish, per day, according to the Orlando Sentinel. It is therefore unlikely that the whale would have suddenly viewed the trainer as prey, especially as hunting is a learned and repetitive behavior, Blake said.
Killer whales in the wild also do not target humans as prey. In fact, "there are no documented cases of killer whales attacking a human in the wild," according to an American Cetacean Society fact sheet. An ACS spokeswoman also told Discovery News that the society does not believe killer whales should be kept in captivity.
The whale's fate remains uncertain, but both Blake and Ellis believe it will not be killed, due to public outcry. They additionally think such whales will become more popular attractions because of the incident and the perceived danger aspect.
Hinting at changes to come, however, Dan Brown, SeaWorld Orlando's general manager, promised in a public address that "all of our standard operating procedures will come under review."