RECIFE, Brazil (Reuters) - Fishing nations agreed on Sunday to cut by about a third the quota for Atlantic bluefin tuna, a giant fish prized by sushi lovers, numbers of which have been decimated by commercial catches.

A man looks at dead bluefin tuna heads dumped by Greenpeace activists in front of the Agriculture Ministry in Paris to protest the continued mismanagement of the Eastern Atlantic and Mediterranean bluefin tuna fishery that is leading to the commercial extinction of the species, in this November 17, 2008 file photo. REUTERS/Charles Platiau/Files

The move was denounced as inadequate by environmental groups who had called on the International Commission for the Conservation of Atlantic Tunas (ICCAT) to agree to a zero quota and list the fish as an endangered species.

ICCAT, an intergovernmental body of 48 nations that environmentalists say has consistently failed to protect bluefin, said the annual quota for bluefin next year would be 13,500 tonnes, down from 19,950 tonnes.

“I think it’s quite an achievement and in full conformity with the scientific advice,” ICCAT chairman Fabio Hazin told Reuters after a week-long meeting in Recife, northeastern Brazil.

He said the cut and further measures agreed upon on Sunday -- including a cut in the tuna-fishing season to one month and a recovery plan -- gave a 60 percent probability that the bluefin stock would recover in 15 years.

ICCAT’s scientists said last month bluefin catches must drop to below 15,000 tonnes a year to stabilize their numbers and start a recovery that would one day allow sustainable catches of around 50,000 tonnes a year.

Environmental groups said a quota of 8,000 tonnes was needed to give a 50 percent chance of a revival in stocks.

“It’s too little, too late,” said Susan Lieberman, director of international policy for the Washington-based Pew Environment Group. “It is a decrease and that’s nice, but it’s not going to recover the species.”

Fishing nations in the European Union including Spain, Italy, France, Cyprus, Greece and Malta have consistently opposed sharper quota cuts.

TRADE BAN EYED

ICCAT also agreed to ban fisherman from taking big-eye thresher sharks, one of several shark species endangered by overfishing. Fisherman had previously been allowed to take the sharks if they came up dead in nets, but under the new rule will not be able to use them at all, said Matt Rand, head of the Pew Environment Group’s shark conservation campaign.

The porbeagle and thresher sharks are fished for their fins, which are prized in Asia as an ingredient for soup and they struggle to recover their numbers because they breed so slowly.

Atlantic bluefin commands huge prices in Asia, particularly in Japan where a single fish can fetch up to $100,000. The warm-blooded fish can reach weights of over 1,300 pounds (600 kilograms) -- heavier than an average horse.

ICCAT’s scientists this year found Atlantic bluefin tuna stocks are at less than 15 percent of their historic size before large-scale commercial fishing started.

Environmental groups now aim to have bluefin added to the Convention on International Trade in Endangered Species (CITES) next year, which would result in a ban on international trade.

“A ban on international trade in Atlantic bluefin tuna is now the only remaining chance to save the iconic fish from extinction,” said Francois Provost, international oceans campaigner for Greenpeace.