Populations of important commercial species such as bluefin tuna, of which Japan consumes more than half, are already critically depleted, the WWF said in a statement.

"Atlantic bluefin, used for high-end sushi and sashimi, is massively overfished and the spawning stock of Southern bluefin in the Indian Ocean is down about 90 percent," it added.

The world's five major tuna management groups -- regional clusters of governments known as Regional Fisheries Management Organisations -- are meeting this week in Kobe, western Japan, to discuss problems facing the industry. Some 300 officials from 77 countries and regions are slated to take part.

"The tuna stocks have been overfished across the oceans, and we have to handle this problem with a global point of view," Japanese Fisheries Agency Director General Toshiro Shirasu said at the opening of the meeting.

WWF officials called the gathering an important first step but said regulators needed to set quotas based on scientific data and combat illegal fishing.

"For the first time, there's a general agreement by the governments that something significant has to be done," said Alistair Graham, High Seas Advisor for WWF International.

"One of the key decisions they have to make is to stop ignoring scientific data and to put in place catch limits."

With fishing a touchy political topic in many nations, governments have tended to shy away from imposing restrictions on the industry.

ILLEGAL OVERFISHING

The Kobe meeting is not expected to set catch limits, since those are decided at regional gatherings, but Graham said one outcome could be a decision by governments to use data on stocks and depletion for their fisheries policy.

The meeting may also call for greater coordination among the regional management organisations and including tighter documentation of catches to prevent overfishing.

"Many governments are routinely ignoring scientific advice, failing to implement the available conservation and management measures, turning a blind eye to illegal fishing, and not prosecuting those who flout rules," said Simon Cripps, director of WWF's global marine programme.

Japan was rocked in November by news that global quotas for Atlantic bluefin tuna will be cut by nearly 8 percent next year.

Japan's quota for southern bluefin was halved the month before for the next five years as punishment for years of overfishing.