Orcas are one of the most social, family-oriented creatures on this planet. One of the reason whalers are so successful is because whale pods stay together--a whale won't leave an injured family member. If only all humans were so compassionate. Orcas have gotten a lot of criticism in light of the recent death of a SeaWorld trainer by Tilikum, the park's largest orca whale. Apparently Tilikum "has been valuable property for the resort through the years, both as a stud who has fathered 13 calves and as a performer who delights audiences with outsized splashes." (http://articles.orlandosentinel.com/2010-02-25/news/os-shamu-kills-trainer-tilikum-20100225_1_killer-whale-orca-network-curator-of-animal-behavior)
He was often kept away from the other orcas in an isolated tank--the complete opposite of how he would live in his natural environment. Furthermore, the fact that he has been used extensively as a breeding device also plays into his apparent aggression--thank you, testosterone.
I understand that sea animals in venues such as SeaWorld are good educational tools. But obviously they are not domesticated and can be unpredictable. I cannot see how anyone can put blame on Tilikum. I feel sure he was not trying to kill his trainer, and he most certainly wasn't acting out of spite--that is a uniquely human trait; we've got the bragging rights to spite.
Animals attack when their instincts tell them to do so. Either they feel afraid, threatened, or desperate. I don't know what exactly happened that day at SeaWorld to make this whale's emotions change and his instincts tell him to react in the way that he did, and I doubt anyone knows other than Tilikum. But something happened that wasn't quite right. Either the whales and other aquatic animals can continue to be captured and trapped in artificial environments and more humans' lives can be put in mortal danger, or we can leave the whales in the ocean to be with their families and live naturally. Which option sounds better?