Some marine mammals at SeaWorld can actually live longer than their counterparts in the wild, according to a new study analyzing five decades of data.

The park has been the subject of censure after "Blackfish," a documentary that condemned the practice of keeping orcas in captivity, was released last year.

Officials at the park credit newer training and medical methods that let the staff perform necessary evaluations on the animals without causing them distress, the Associated Press reported. SeaWorld is the biggest holder of marine mammals in the U.S.

''We do a lot of self-critiquing of who is doing what, how,'' said Todd Robeck, vice president of reproductive research at SeaWorld Entertainment, Inc., as quoted by the AP. ''How are you handling food? How are you handling your moms and calves? What is the medical care?''

While staff may have had to drain pools of water and restrain animals decades ago, SeaWorld mammals today are taught through training sessions and treats to give samples of breath, urine and blood when needed. The samples can then be evaluated at SeaWorld's on-site laboratory.

The recent analysis revealed that orcas born in captivity at SeaWorld have an average life expectancy of 46 years, while the average life expectancy for killer whales in captivity at U.S. parks is more than 27 years. Killer whale survival rates are about the same in captivity compared with in the wild.

When it comes to bottlenose dolphins and California sea lions, survival rates are greater for the animals in captivity than in the wild.

Despite the numbers, animal rights activists contend that marine mammals have a lower quality of life in captivity.

''SeaWorld continues to exploit these complex and very socially interactive animals,'" said Bryan Wilson, a coordinator for the Animal Rights Foundation of Florida, as quoted by the AP.   

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