A former employee from Sea Land (A corporation that was similar to Sea World) stated in the film Black Fish:

"When you know the animal and have a relationship with it. You know, that he's not killing, because he's a savage. He's not killing, because he's crazy or because he doesn't know what he's doing. He's killing, because he's frustrated and has aggravation. And when he's... He has no outlet for it."
Killer Whales are affected mentally, people who attend Sea World shows or any show similar to that believe that when a killer whale attacks, they are attacking for no reason. Even an employee realized that these species suffer when held captive for so long.