Caught in a sting by Oscar-winning film-makers, a top California fish restaurant has shut its doors after being exposed selling illegal whale meat at $85 (£57) a plate.

The Hump, a sushi restaurant near Santa Monica airport, was the subject of a secret camera operation by producers of The Cove, a movie chronicling environmentalists' battles with Japanese dolphin hunters, which won best documentary at this year's Academy awards.

The restaurant was selling a meal billed as omakase, a Japanese term for chef's choice. Posing as diners last month, while in town for the Oscars, the film-makers discreetly recorded a waitress describing slices of exotic pink flesh on their plates as kujira, meaning whale.

Facing a fine of up to $20,000 and a possible year's imprisonment, the owners of the restaurant shut up shop yesterday, describing closure as "a self-imposed punishment on top of the fine that will be meted out in court".

The Hump pledged a "substantial contribution" to charities aimed at preserving the endangered whale population, adding: "The Hump apologises to our loyal customers, the community of Santa Monica and the public at large for our actions."