As a brief summary, Blackfish explores the horrific death of one of its trainers, Dawn Brancheau, in 2010. She was killed by Tilikum, the orca who had been involved in previous "accidents" with trainers, drowning one and almost certainly killing a human intruder. The film also explores the circumstances surrounding the capture and captive maintenance of orcas (also known as "killer whales," as they are highly predatory in the wild -- but are actually the largest dolphins -- not technically whales, though related to whales). "Blackfish" is another term for the species.
SeaWorld Says: Stock Footage, capture, and captivity:
SeaWorld has claimed, "Blackfish employs false and emotionally manipulative sequences concerning the collection and separation of killer whales: Through stock footage and video mismatched to the narrative, the film implies that the SeaWorld collects killer whales from the wild and separates mothers and calves. NEITHER IS TRUE." (Emphasis theirs).
SeaWorld has, to date, refused open debate with the producers of Blackfish (or those involved with another movie about cetacean abuse, The Cove). But, one thing they might do is show film of capture that is contemporary or recent. It is extremely difficult to obtain any film of orca capture, simply because the process of wild capture is brutal by nature and cannot help but separate animals, who otherwise live in a communal structure, from their cohorts. Thus, the people who capture cetaceans (whales, dolphins, and porpoises) do not want us to see the practice.