Way back in the depths of time there was a moderately successful children’s movie called Free Willy, which detailed a boy’s attempts to free a killer whale from an amusement park.

‘Willy’ was actually Keiko, a whale from an amusement park in Mexico. After the film, amid much publicity, Keiko was returned to the wild. The Keiko Project website states: “After a wonderful journey in freedom, Keiko passed away in Norway on December 12, 2003 at age 27.”

“The most important question is did we do the right thing? I am certain we did,” wrote Jean-Michel Cousteau in 2003 on the website of the Ocean Futures Society, which was heavily involved in returning Keiko to the wild.

Now, in 2009, a peer-reviewed paper on ‘Free Keiko’ has been published. This again raises the question: was release really the best option?

As Malene Simon and colleagues write in Marine Mammal Science, previous successful reintroductions to the wild have been of animals held in sea pens (unlike Keiko) and for short periods of time (unlike Keiko).

“In retrospect, Keiko was indeed a poor candidate for release, due to the early age of his capture, long history of captivity, prolonged lack of contact with conspecifics, and strong bonds with humans,” they write.

After his release Keiko often initiated interactions with humans, the authors note. He never really dived like wild whales did. He seems not to have socially integrated with wild whales and it is possible he didn’t feed at all without human help.

“A release program can be considered a success when the released animal is able to feed, maintain health and stress levels comparable to his wild conspecifics, show normal predator avoidance behaviour, and ultimately reproduce (unless unable for other reasons, such as reproductive senescence),” write the authors of this new paper.

“Under these criteria, Keiko’s release to the wild was not successful, since though physically unrestricted and free to leave, he kept returning to his caretakers for food and company.”

At the end of the day, while it might have been appealing for humans to free Keiko, it may not have been good for the whale.