Australian has announced new measures to protect stocks of southern bluefin tuna, whose numbers are being threatened by the rising global popularity of sushi food.

Environment Minister Tony Burke said the fish would be listed as "conservation-dependent", meaning it would be covered by new management plans to stop over-fishing.

"While ongoing improvement in management measures are helping to stabilise the population, the breeding population is still considered to be less than eight per-cent of unfished levels," he said.

Burke denied the move would restrict fishing, but Southern Bluefin Tuna Association chief executive Brian Jeffriess condemned the decision.

"It really shows an appalling lack of judgment frankly, you know what the minister has is some scientific advice from his own personal scientific committee," said Jeffriess.

Australia is a member of the Commission for the Conservation of Southern Bluefin Tuna, a grouping including Japan, New Zealand, Indonesia and South Korea which aims to reduce the global catch by 20 percent over the 2010 and 2011 seasons.

Southern bluefin tuna can grow to more than two metres (six and a half feet) in length and weigh up to 200 kilos (440 pounds). It is mainly used in the Japanese sashimi market, where a single fish can fetch more than 100,000 US dollars.

The tuna can live for up to 40 years and its only known breeding area is in the Indian Ocean, southeast of Java, Indonesia. Greenpeace says its numbers have shrunk by 95 percent since the 1950s.