SeaWorld has announced that it is ending orca captivity at its parks.

The operator has been under immense pressure from animal rights groups ever since the release of Blackfish, which catalogues alleged mistreatment of killer whales and the death of three people as a result. Now SeaWorld says its ending its orca breeding programme effective immediately, with its current generation of whales the last it will house.

"When we opened our doors more than 50 years ago, killer whales were feared and even hunted. Now, they are among the most beloved marine mammals on the planet thanks, in part, to SeaWorld," said a statement from the operator.

"The killer whales in our care will be the last at SeaWorld. We haven't taken a whale from the wild in nearly 40 years. Now, we're going further and will end our orca breeding programs as of today. With the skills and dedication of our entire SeaWorld team, we will protect and care for these whales -- here at our parks – for the rest of their lives where guests will continue to view and be inspired by them."

Additionally, SeaWorld has announced that its "more natural" orca show planned for its park in San Diego in 2017 will now be rolled out to it parks in San Antonio and Orlando in 2019.

The SeaWorld statement added that The Humane Society of the United States (HSUS) has supported the move, agreeing a new partnership with SeaWorld to protect ocean and marine mammals.

"While these decisions were not easy to make and represent a shift in our business, they do not change our core values and purpose: to protect animals in the wild and inspire our guests to join us in this critical mission," said the statement.

SeaWorld has been on the offensive in an effort to rebrand itself after a tough few years. In November, CEO Joel Manby said the company was rebuilding itself from the ground up, with an enhanced focus on conservation and creating meaningful experiences for guests.

SeaWorld’s most recent financial results painted a positive picture for the company, with attendances and revenues at its attractions during 2015 almost the same as the previous year, indicating numbers are stabilising after being in decline.