BLACKFISH is a documentary about Tilikum the killer whale from SeaWorld, and in general how dangerous it can be keeping these animals in captivity. Because of the movie (as well as SeaWorld's poor handling of the criticism), Pixar is apparently changing the ending of one of their movie that involves a sea park: FINDING DORY.
An employee for Pixar has told the New York Times that the new ending will still have a marine park, however now the sea creatures brought to the marine park in the film will have the option to leave. So does that mean the SeaWorld-like business in the film is more like a hotel, where fish and mammals can come and go as they please?
This change probably isn't necessary, and when FINDING DORY is released in two years I highly doubt many people will even think about BLACKFISH when they go to see the new Pixar film. I really don't think that a lot of people would have complained if Pixar didn't change things, but Pixar is probably trying to avoid the bad publicity surrounding marine parks just in case we are still talking about SeaWorld in a couple of years from now.
FINDING DORY swims into theaters on November 15th, 2015.