According to a veteran whale trainer, interviewed by CNN today, whales become "neurotic" when in captivity. I agree with this opinion, as they are ferocious creatures that are essentially being confined.
Tillikum, the whale responsible for the death of SeaWorld trainer, Dawn
It was reported he shook
However,
Biologists: Killer whales 'neurotic' in captivity
February 25, 2010 9:25 p.m. EST - ...Spectators who had attended the whale show before Brancheau was killed reported that the whales were not behaving -- "they weren't following instructions," Lori Miller, SeaWorld visitor, said.
This suggests that the whales had something going on socially among themselves, Ventre said. "It's probably reasonable to suspect that something going on amongst the whales themselves may have triggered the frustration," he said.
Ventre speculated that there may be more restrictions placed on who can work with the whale, but it's unclear whether much can be done -- someone still has to feed Tilikum 300 pounds of fish a day, administer medication and perform other daily tasks with the animal. Tilikum is also part of an artificial insemination program, which means someone has to roll him over and extract sperm from him.
"This is one of the inherent risks of working with animals like orcas or elephants, or walruses or even California sea lions," he said. "This kind of stuff happens."
http://www.cnn.com