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Bluefin tuna at 'risk of collapse' without drastic action

By Martin Leggett - 07 Jul 2011 18:0:1 GMT
Bluefin tuna at 'risk of collapse' without drastic action

The economics of supply and demand don't work in favor of endangered species, it would seem.

A new report into the conservation status of tuna and billfish shows that the most endangered fish are the most high-valued - and the only way to prevent a total collapse is to close those fisheries down.

The study is being published in Science today, and comes ahead of the third joint meeting of the Tuna Regional Fisheries Management Organizations, being held in California next week.

Tuna, which belong to the scombrid family of fishes - also including mackerel and bonitos - are some of the top predatory fish in the oceans, together with billfish such as swordfish and marlin. But many species of both groups are teetering on the edge of catastrophe, because of overfishing - driven in part by rising prices for ever scarcer fish.

This report is the first to assess the extinction risks of all 61 scombrid and billfish species, using the criteria for the Red List of Threatened Species. It is part of an effort by the IUCN to get 20,000 marine species assessed for inclusion on the Red List. This list helps conservationists worldwide to plan their work, telling them which species are most at risk of vanishing; but marine creatures have often been left out of assessments in the past.

According to this new study, 5 of 8 tuna species are so threatened as to make it onto the list - plus three billfish species, the Blue, White and Striped Marlin. But it is the Bluefin tuna which is closest to the edge of the precipice, according to Dr Kent Carpenter, from the International Union for Conservation of Nature (IUCN), and one of the paper's authors.

'All three bluefin tuna species are susceptible to collapse under continued excessive fishing pressure. The Southern Bluefin has already essentially crashed, with little hope of recovery. If no changes are made to current fishing practices, the western Atlantic Bluefin stocks are at risk of collapse as they are showing little sign that the population is rebuilding following a significant reduction in the 1970s.'

Part of the problem is that these large predators grow and reproduce slowly. Recovery is therefore a long-term game of patience and forbearance. Whilst temporary fisheries closure is seen as the best hope for Southern and Atlantic Bluefin tuna, in practice this could simply cause a greater loss, as illegal fishing takes over. So the IUCN sees closure as part of program with a wider, longer reach.

'Temporarily shutting down tuna fisheries would only be a part of a much needed recovery program. In order to prevent illegal fishing, strong deterrents need to be implemented,' said Jean-Christophe Vie, Deputy Director, at the IUCN. 'This new study shows that there is an urgent need for effective management. Scientific findings should not be discarded in order to maintain short-term profit. Marine life and jobs for future generations are both at stake.'

Top Image: Japanese fishing ship crew cleaning Bluefin tunas © anemone