Annual catches of Atlantic bluefin tuna will rise slightly from next year, environmental groups said Monday at a meeting of countries that hunt the much-prized but threatened species.

In 2013 and 2014, catches will rise to 13,500 tonnes annually for fish taken in the Mediterranean and east Atlantic, compared with 12,900 tonnes today, a move that is in line with advice by marine biologists, said Susan Sainz-Trapaga of conservation group WWF.

"A new assessment of the stock will take place in 2014," she said.

"We are satisfied with this decision," she added. "After a positive sign for bluefin tuna, it was important today to respect the scientific recommendations and to continue efforts to properly manage this fishery."

The new quotas were set by the 48-member International Commission for the Conservation of Atlantic Tunas (ICCAT) at the end of a week-long meeting in Morocco's port of Agadir.

The new catch limits were set in a context of conflicting news about a species listed by conservationists as endangered.

In 2006, ICCAT agreed to a 32,000-tonne annual catch maximum but two years later set progressively tougher limits as evidence mounted of a threat to stocks.

But last month, ICCAT scientists said they had found the first evidence of a bluefin revival, a finding that spurred hopes in some countries of an easing on catch constraints.

The current annual quota is 12,900 tonnes for the Mediterranean and east Atlantic and 1,750 tonnes for the west Atlantic -- the goal being to encourage a complete population recovery by the end of the decade.

The catch total for the west Atlantic has been maintained for a period of one year, sources in Agadir said.

"It is encouraging that ICCAT listened to the recommendations of its own scientists and agreed to keep catch limits for bluefin tuna within their advice," said Susan Lieberman, director of international policy at the Pew Environment Group.

"This decision will give this depleted species a fighting chance to continue on the path to recovery after decades of overfishing and mismanagement," said Lieberman.

"Although we are disappointed that the quota has only been set for one year in the western Atlantic and two years in the eastern Atlantic, we are hopeful that governments will expand their efforts to stop the illegal fishing and fraud in parts of this fishery."

The Atlantic bluefin tuna is on the endangered list of the International Union for the Conservation of Nature (IUCN).

Five of the world's eight tuna species are classified by the IUCN as threatened or near-threatened, a situation driven mainly by demand for sushi in Japan.

ICCAT is tasked with the conservation of 30 fish species in the Atlantic and Mediterranean.

Its members include Britain, Canada, China, Russia, the United States, several Mediterranean countries, the European Union and Japan, which single-handedly consumes over 75 percent of all the bluefin tuna caught, according to the WWF.

The Atlantic bluefin can live up to 40 years and grow to more than four metres (13 feet) long.

The fish spawn just once a year and do not reach reproductive maturity until they are eight to 12 years old, making them more vulnerable to overfishing than smaller species which spawn more frequently.

Stocks are estimated to have halved over four decades in some areas, with catches in the 1990s exceeding 60,000 tonnes per year.

In a separate decision, ICCAT agreed to launch a process for re-crafting its mandate to boost protection for sharks, Pew said.

If successful, ICCAT's new convention will explicitly include sharks, which at present are considered "bycatch", or an accidental catch which does not require detailed oversight.

"This action sets the stage for improved international shark fishing in the Atlantic, which is causing serious depletion of many shark species," said Lieberman.