in 2013, cowperthwaite directed her second documentary "blackfish", which premiered at the 2013 sundance film festival, before she found a larger audience among television via her distribution partner cnn. "blackfish" is one of cowperthwaite's controversial documentaries as it tells the story of tilikum, a killer whale at the sea world theme park in orlando, florida who killed its trainer, dawn brancheau. the film created the new movement called "the blackfish effect" that stems from the documentary. by investigating the treatment of orcas in captivity through news and archival footage, interviewing former trainers and marine mammal experts, and questioning the ethics of captivity cowperthwiate created her film. in 2016, seaworld announced it would stop breeding orcas and put an end to all killer whale performances by 2019, which was largely attributed to cowperthwaite's documentary. the film however received a number of criticisms from trainers involved in the project, believing information was willfully withheld to support the thesis of the story. claims of interviewees of substandard quality were voiced by bridgette pirtle, herself a former trainer.