KEEPING orcas under environmental and social conditions that capsize virtually every natural principle influencing their lives in the wild is an exemplar of human awfulness.

Gabriela Cowperthwaite’s documentary, motivated by the death of whale trainer Dawn Brancheau when the orca Tilikum reacted to a break from his routine, offers as balanced a view as possible of the worldwide “industry” that entraps these free-spirited animals to entertain humans for money.

“As possible” highlights the film’s major omission. Zoos impose a huge moral obligation of care on their proprietors. The proprietors of Seaworld refused to be interviewed.

The film delivers a succinct and persuasive mix of archive footage, rostrum shots of press pages and interviews with “trainers”, spectators, officials of occupational safety agencies and cetacean biologists. And its quick course in Orca Biology And Lifestyle 101 can give us grief and heartbreak.

The populist name for Orcinus orca is killer whale. The film reminds us that there is no record of an orca attacking a human in the wild. They kill to eat. When captivity becomes intolerable, they go feral, as the film shows.

What enables humans to persuade animals to step outside their normal behavioural boundaries is food. When Tilikum performed his closing routine, he’d already received all the fish in Dawn’s bucket. The combination of isolation, break in routine and denial of expected reward was enough.

At Dendy