A female trainer;Dawn Brancheau,was killed this week by a captive killer whale which dragged her into its tank at the Sea World center in Orlando,Florida.

So why do they attack people in captivity when they don't in the wild?

The answer seems to be captivity-related stress.It's not hard to understand.Killer whales are wild animals.They are strong.They are unpredictable.They are very intelligent,with their own complex communications system.They are very social - in the wild,they live in closely cooperating social groups with maybe 10 to 20 members.
If you take one out of the sea and stick it in a concrete swimming pool for the rest of its life,do you think that will have a bening effect on the animal's personality?What, thanks far all the fish?When you consider the thousands of miles of open ocean though which wild killer whales freely roam - they are dolphins,after all,the biggest members of the dolphin family - ending up in Sea World is the orca equivalent of you or me being imprisoned by a lunatic in a cupboard under the stairs.
many zoos have now recognised that close confinement of big mammals - sticking lions and tigers in cages,and elephants in concrete houses - is entirely wrong and counter-productive.In the 1970s,London Zoo,for example,held a polar bear in a concrete pit which used to pace up and down continually all day long in what was clearly mad despair.

Orcas in captivity by country -USA-23,Japan-8,France-4,Spain-4,Canada-2,Argentina-1.

(The Independent,Friday 26 February 2010)