Here's some info on Cetacean releasing, the most famous case being Keiko the Killer whale that starred in the "Free Willy" films.
It's clear that some releases require substantial funds to make sure the animal is habituated Ok, funds that might be better spent preventing the capture of them for use as entertainment in the first place. It seems that animals that have lived in captivity most of their lives don't allways want to lose human company.
http://csiwhalesalive.org/csi95301.html http://www.savethewhales.org/captivity.html www.rockisland.com/~orcasurv/releases.htm