Group hopes anti-slavery laws will free the whales

A Kiwi scientist is behind attempts to free orcas from American marine parks by citing ancient anti-slavery laws.

Dr Ingrid Visser is one of five people filing a lawsuit seeking to apply a constitutional right from 1865 to free five orcas from the slavery of performing at marine parks.

The five orcas or killer whales are at two Sea World parks in the United States and have all been in captivity for about 20 years or more.

Tutukaka-based marine scientist Visser with two other orca experts, two former Sea World orca trainers and People for the Ethical Treatment of Animals (Peta) wanted to apply the United States constitution's 13th Amendment, which prohibits slavery.

Visser said Peta contacted her to be part of the suit.

She hoped the law suit would go ahead, and if it did she would go to the US for it.

"In a perfect world we would get these animals out of there and have them retired."

Visser has been researching orcas since 1992 and said now was the time to do this because scientific research revealed the intelligence of orcas, their culture, social structures and the distances they swam.

She said animals in the wild swam large distances regularly, something captive orcas clearly couldn't do.

There was also evidence of negative effects of living in captivity. Visser said their lifespans were shortened and they behaved abnormally.

She said in the wild the average orca lifespan was more than 50 years, whereas in captivity the average was less than nine years.