The International Commission for the Conservation of Atlantic Tunas, meeting for the past week in Genoa, Italy, said the annual catch limit for the western population of the lucrative species will rise from 1,750 tonnes to 2,000 tonnes next year and stay at that level in 2016.
Katie Schleit of the Ecology Action Centre in Halifax said the 15-per-cent increase, supported by the Canadian government, could hinder recovery of the big, fast fish.
"It seems like a really short-sighted decision given where the population level is," she said in an interview from Genoa. "As far as the western population is concerned, we still have a long way to recovery."
Scientists monitoring bluefin tuna in the western Atlantic since the 1970s say overfishing reduced the population to one-fifth of its size by the late 1990s, when strict conservation measures were introduced.
Since then, the population has grown to about half its size in the '70s, with a recent study for the commission confirming that a recovery is underway.
American fisheries scientist Clay Porch, who led the commission's western stock assessment, has described the findings as the most optimistic seen in years.
"However, there is a lot of scientific uncertainty around that estimate, and the true numbers may be lower," he said in online post for the National Oceanic and Atmospheric Administration. "So there's reason to be optimistic, but there’s also reason to be very cautious regarding the question of catch limits."
Schleit says that's why conservationists had wanted the limit to remain frozen.
"We're still at 55 per cent of 1970s levels, and the '70s were already at a time when the stock was depleted," said Schleit, adding that the mixing of the populations from the western and eastern Atlantic has contributed to a higher degree of uncertainty.
"This is all the more reason to keep the quota where it is."
Canada, Japan and United States, which conduct most of the bluefin fishing in the western Atlantic, tabled the 15 per cent proposal at the conclusion of the commission's week-long meeting.
Faith Scattolon, head of the Canadian government's delegation, said federal officials were guided by scientific advice contained in the commission's study.
"We're very happy that the plan is reflective of the scientific advice," Scattolon said, adding that the study recommended keeping the limit below 2,250 tonnes.
However, Schleit said the commission's study goes on to say that raising the limit closer to 2,250 tonnes would result in only a 50 per cent chance that the population would be at or above current levels by 2019.
"We feel that a risk with the chance of a coin toss on an endangered population is much too high," Schleit said in an email.
Scattolon said there are always uncertainties associated with stock assessments and she agreed that the mixing of bluefin populations was a major issue that requires more study.
The new limits mean Canada's 600 licensed bluefin tuna fishermen will see their allotment increase by 70 tonnes to a total of 452 tonnes for the next two years, Scattolon said.
That will likely translate into $2 million in additional income for the fishermen, who live in Quebec, the island of Newfoundland, Nova Scotia, New Brunswick and Prince Edward Island.
About 45 per cent of the quota is for Nova Scotians, and another 30 per cent goes to the fleet in P.E.I. The remaining 25 per cent is split between the other three provinces, with Newfoundland and Labrador taking the largest chunk at about 13 per cent.
Adult bluefin tuna, which weigh about 250 kilograms on average, are prized for their tender flesh, especially for sushi and sashimi dishes. Earlier this year, a 230 kilogram fish was auctioned off at US$70,000 at Tokyo's Tsukiji market.
The western population is about one-tenth the size of the eastern population, which spawns in the Mediterranean Sea. The catch-limit for that population was raised by about 20 per cent a year from 13,400 tonnes for the next three years.