The award of an Oscar to a documentary against dolphin hunting has dealt Japan a public relations blow just as it faces growing pressure on other aspects of its exploitation of maritime resources.

In recent weeks, Tokyo has been confronted with an Australian ultimatum over its annual whale hunt in Antarctic waters and is risking increasing isolation over its opposition to a ban on the trade in Atlantic bluefin tuna.

The Academy Award won by the sometimes grisly documentary The Cove on Sunday seems certain to focus public attention on its makers’ call for an end to the slaughter of dolphins in a cove in the south-western Japanese town of Taiji.

The award has already raised the profile of the documentary in Japan, where it has only been shown twice and had drawn little media attention.

Taiji authorities were quick to denounce the film – which portrays the town’s annual dolphin catch as a barbaric slaughter of highly intelligent mammals whose mercury-poisoned meat is a threat to humans.

“Each place in this country and elsewhere has its own dietary habits, and it is important to be mutually respectful of differences in food culture rooted in longstanding regional traditions,” the Taiji mayor and head of the municipal fishermen’s association said in identical statements. They also challenged the scientific accuracy of the documentary, a fast-paced drama that draws on Hollywood heist movies to show an “elite” activist team’s successful efforts to film the killing over the objections of local fishermen.

Japanese officials have long accused western opponents of maintaining double standards by condemning Tokyo’s support for whale and dolphin hunts while backing industrial-scale livestock farming and the slaughter for meat of large land animals such as pigs and kangaroos.

Western criticism has had limited impact in Japan, even though few Japanese now regularly eat whale meat. “In the past whales and dolphins were an important part of the diet and I don’t think that’s necessarily a bad thing,” said Tamami Hashimoto, a guide who takes tourists on swimming trips with dolphins off Japan’s Mikura Island. “It isn’t something that should be condemned on emotional grounds alone.”

However, participants in The Cove have said they are hopeful their film will spark greater debate and media attention. The film could also help to harden international attitudes toward Japan’s maritime industries.

Kevin Rudd, Australia’s prime minister, last month threatened to launch action against Japan before November at the International Court of Justice over its Antarctic whale hunt, which is conducted under an exception for scientific research within the international moratorium on commercial whaling.

In a separate dispute, Tokyo has angered marine conservationists by warning it will “opt out” of its obligation to stop importing Atlantic bluefin tuna if members of the United Nations Convention on International Trade in Endangered Species vote this month to add the fish to the treaty’s list of most-protected species. The US and European Commission have recently backed a ban on the international trade in bluefin tuna aimed at protecting the fish from extinction, although Japanese officials have suggested such a danger is exaggerated. Bluefin are prized for sushi and sashimi, and the Japanese consume as much as 90 per cent of the bluefin caught during the May-June Mediterranean fishing season.

Japan blames shrinking stocks on poor management by the International Commission for the Conservation of Atlantic Tuna, a regional body that has been criticised by environmentalists. For years ICCAT has set annual catch quotas at levels far higher than its scientists deem sustainable.