Bluefin tuna swim too far - at their peril

On both sides of the North Atlantic, few denizens of the deep command more respect - and none fetches higher prices dockside - than the mighty bluefin tuna. Its meat graces sushi and sashimi platters in restaurants from Tokyo to New York.

For some 20 years, Atlantic bluefin have been hauled out of the sea at unsustainable rates, marine scientists say, despite international attempts to limit the catch by establishing separate fishing quotas for the eastern and western Atlantic.

Now, fresh research on bluefin migration suggests that unless governments change their view of bluefin stocks and begin to treat them as one population, overfishing - particularly on the European side of the Atlantic - could torpedo the North Atlantic bluefin.

For five years, a team led by Stanford University marine biologist Barbara Block used a set of high-tech tags to monitor bluefin movements. The study, which shed light on a number of tuna traits, confirmed that populations in the western and eastern Atlantic mixed to a much larger degree than previously believed.

This observation, other researchers say, undercuts a key premise behind the current conservation scheme and raises the prospect that continued overfishing in the eastern Atlantic could offset any gains from the tight quotas that exist for the western Atlantic.

Maintaining bluefin stocks at a level that allows for the maximum sustainable catch "will require increased cooperation among all nations fishing for bluefin," says Dr. Block, whose team reports its results in today's edition of the journal Science.

Her team's work, along with recent studies headed by New England Aquarium staff scientist Molly Lutcavage, are expected to add kerosene to a smoldering transatlantic debate over the adequacy and fairness of current bluefin quotas.

In November, the Madrid-based International Commission for the Conservation of Atlantic Tuna (ICCAT), which established the current quota regime, meets to review its conservation approach. In addition, next month the commission's scientific advisory panel is scheduled to hold an unusual midyear meeting to weigh the impact of recent studies on estimates of bluefin-tuna stocks in the North Atlantic.

The concern over bluefin is part of growing worries worldwide about humanity's impact on fisheries - vital sources of food for a burgeoning population. "Some 60 percent of the world's fish stocks are overfished or fully utilized," says Rolland Schmitten, former director of the US National Marine Fisheries Service and now head of its habitat-conservation office. He adds that in a majority of cases for the remaining 40 percent, governments lack enough information to determine the status of the populations.

For its part, North Atlantic bluefin tuna have been prized as a source of food for millenniums. Their biggest draw for fishermen today, however, is their street value. Last January, for example, a 444-pound bluefin fetched $175,000 at a seafood auction in Tokyo's famed fish market.

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