The annual catch of bluefin tuna in the Mediterranean Sea and eastern Atlantic Ocean is to be cut by one fifth in an attempt to conserve dwindling stocks.
Bluefin tuna is a delicacy prized in Japan's sushi restaurants
The 42-nation International Commission for the Conservation of Atlantic Tunas (Iccat) agreed the quota cut at a meeting in Dubrovnik, Croatia.
Iccat also agreed measures to combat illegal hunting of the giant fish.
Conservation groups criticised the scale of the cuts as "weak, scandalous and inadequate".
Scientific advice prepared for the Iccat meeting concluded that catches in the eastern Atlantic and Mediterranean were about three times above sustainable levels.
Pressure from organisations such as WWF and Greenpeace had led some European and north African nations to back quota cuts and measures to combat illegal fishing.
A WWF study found that one in every three bluefin landed in the Mediterranean was caught illegally.
The Iccat deal will see:
- catches fall from 32,000 tonnes now to 25,500 tonnes in 2010
- an increase in the permitted minimum size of fish caught from 10kg to 30kg
- extensions of closed seasons
- control, licensing and inspection schemes aimed at enforcing regulations
- a limit of a single bluefin for recreational fishing trips
"The decisive measures agreed by Iccat represent a realistic chance for the gradual recovery of bluefin tuna and, also importantly, for the sustainability of the fisheries, the fleets and the coastal communities involved," said EU Fisheries Commissioner Joe Borg.
But conservation groups lambasted the "weak" quota cuts.
The Atlantic bluefin tuna is a bulky marine predator
"Today's decision will go down in history as destroying the credibility of Iccat as a regional fisheries management organisation," said Dr Sergi Tudela, Head of Fisheries at WWF Mediterranean.
"This is a collapse plan, not a recovery plan - and a mockery of the work of scientists."
WWF said EU governments had traded long-term conservation for short-term commercial interests.
The Iccat decision follows reductions made earlier in the year in Japan, which agreed unilaterally to cut its own catch of southern bluefin tuna by 50%.
The two sets of restrictions are expected to raise prices still further in Japan.