Ventre and his co-author, another former SeaWorld trainer named John Jett, pored over data from 201 captive orca whales, 66 who were born in captivity and 135 who were caught from the wild. The data starts in 1961, when orcas were first put in captivity in the U.S., and draws from records from the Marine Mammal Inventory Report, a database run by the National Oceanic and Atmospheric Administration that catalogues all the marine mammals held in the country. They calculated the annual survival rate (ASR) for captive whales, almost half of whom were held in tanks in the U.S.
Globally, 63 percent of the whales who died in captivity before 2014 had been in captivity for fewer than six years, according to the paper. The researchers point out that these deaths occur despite the fact that the animals are free from predators and other environmental stressors. Only eight of those whales made it past their 30th year in captivity.