By Richard Black
Environment correspondent, BBC News website
Bluefin tuna may just be the coolest fish on the planet.
They are big - in fact huge, the biggest weighing more than 800kg and attaining 3m in length.
Most amazingly, they have evolved to be warm-blooded, allowing them to hunt from the tropics to near-polar seas, while maintaining the capacity to accelerate as fast as the sports cars that emulate their streamlined shapes.
Unfortunately for them, they are also delicious to eat, an icon of Japanese cuisine in particular, their crimson flesh a centrepiece of sushi plates across the nation.
It looks as though they may be about to gain a new iconic stature, as the fish we hunted to the very door of global extinction.
"There's a problem in the fishery, for sure," admits Rafael Centenera, general assistant director of the Spanish fisheries ministry.
"[The fishermen] usually catch fish of more than 140kg as an average; and in the last five to 10 years they have seen a reduction in the average size, and that means you are catching more of the spawning stock."
Many of Spain's tuna boats operate in the Mediterranean Sea, where the larger proportion of Atlantic bluefin spawn. They are joined by vessels from France, Italy, Turkey, Algeria, Morocco, Libya - in fact, from just about every country with a Mediterranean coastline, and some further afield.
They fish according to annual quotas set by the International Commission for the Conservation of Atlantic Tuna (Iccat).
A year ago, the bureaucrats who represent Iccat's 42 member governments finally gave in to warnings from scientists about the parlous state of Atlantic bluefin, and agreed a "multi-annual recovery plan".
Quotas were lowered, the fishing season curtailed. Mechanisms were established to track fish from the sea to the plate, and to curb illegal, unreported and unregulated (IUU) fishing, which according to Iccat's scientists had been adding as much as 50% each year to the amount extracted legally from the seas.
Tracking fish has become much more difficult by the recently developed practice of tuna "ranching", or farming, in which the fish are kept for many months swimming in giant pens towed slowly by ships, fed on fishmeal, gaining fat.
Seafood plays a key role in the culture and cuisine of Spain
Iccat's assistant executive secretary Victor Restrepo admits that the situation remains parlous.
"The outlook is very negative right now, and it's only fair to imagine that if these controls don't work, things are going to stay the same or get worse.
"[One possibility is that] the catches will go down as the stock goes down, and there could be commercial extinction at least for a large part of the fleet."
Catch all solution
Conservation groups have an unkind nickname for Iccat - the International Commission to Catch All Tuna.
In truth, it can only do what its member governments instruct and allow it to. It has no powers to enforce, no sanctions with which to punish; these remain the preserve of national governments, and the European Union.
Although its scientists recommended quota cuts for the Mediterranean of about 50%, governments whittled that down towards 20%. Scientists recommended that the fishery close at the beginning of June; bureaucrats opted for the end of June.
"The problem is that the fishery is taking place when you can fish the fishes," says Rafael Centenera, who has represented Spain at Iccat meetings.
"If you close in the month of June, you are closing the fishery. That means all the people living on that, and that's a lot of people, are going to go home with no compensation at all.
"For sure we are friends of fish; but still more, we are the friends of fishermen."
Environmental groups believe that even the modest restrictions that were passed are being undermined.
Greenpeace has noted transhipments of tuna in apparent violation of the new regime. Transhipments make it much harder to track tuna and so make sure that illegally caught fish are not entering the market.
They also photographed light aircraft flying above the purse-seine fleet, spotting schools of tuna, something that the new regulations ban.
Criticism also comes from Japan. "Iccat adopted the so-called rebuilding plan; but a more important part was full compliance," says Masanori Miyahara, a senior official with Japan's Fisheries Agency and its Iccat delegate.
"But if you see the situation this year, for example, some fishing fleets operated even after the closure of the fishing season at the end of June. So we are very concerned."
Meanwhile the European Commission has launched infringement proceedings against seven EU states over apparent breaches of the new management plan.
It is difficult from the outside to comprehend the mentality that would exploit a fishery to collapse in the face of warning after warning.
Even from a commercial point of view, it appears to make no sense.
Iccat scientists believe that if catches were halved now, the stock would rebound, allowing fleets to catch almost as much as they have ever done, and do so sustainably, ensuring an income for the foreseeable future.
According to Sebastian Losada, oceans campaigner at Greenpeace in Madrid, there is a simple problem; the industry needs profits today, not tomorrow.
"The root of the problem is that we have too much capacity in the region," he says.
Greenpeace filmed spotter planes with tuna fleets
"We have a number of fishing vessels that are able to catch double the quota - they are not only able to do it, they need to do it to be profitable."
The EU provides money for putting vessels out of commission. But what appears to have happened in the murky Mediterranean is that some owners have taken the money and spent it on newer and bigger vessels, meanwhile redeploying the old boats to countries such as Libya where fresh quota is available.
Faced with the need to catch more and catch it quickly, Greenpeace believes, owners and skippers will bend the rules as far as they can.
The job of stopping them falls mainly to national authorities. But when this is a competitive business, is there not a chance that authorities will turn a blind eye to the transgressions of vessels from their own country, in the belief that other countries' regulators are doing exactly the same thing?
And turning a blind eye may be encouraged in certain quarters. There is a tale, which may or may not be apocryphal, of a European Union fisheries official on an inspection trip in a southern EU nation finding a note in his hotel room listing the names and addresses of his immediate family, together with a one-way air ticket out of town.
Short of a horse's head on the pillow, no hint could have been less subtle.
Total extinction for a fish species is relatively uncommon, given their mobility. But once numbers have fallen, ecological factors can take over that mean the stock is highly unlikely ever to rebuild.
It appears to have happened on the Grand Banks near Newfoundland, where cod fishing was banned in 1992.
There are still cod there; but their numbers do not appear to be increasing. Boris Worm from Dalhousie University in nearby Nova Scotia believes the ecosystem has moved into a new, probably stable, state.
"Other species have increased in abundance, species that usually were preyed upon by cod," he says.
"Things like herring or capelin or sand lance, for example, are now thought to prey heavily on the larvae and eggs of cod; so the prey now is the predator, and that may diminish the ability of cod to recover."
Could the bluefin tuna become ecologically trapped at a vanishingly low population level?
The story of its demise typifies ocean fisheries "management". Measures that independent scientists recommend are watered down by politicians keener on keeping a share of the diminishing stock than allowing the stock to rebuild; scarcity brings a high market price, keeping fishing profitable.
And it is all someone else's fault. The Japanese blame the EU, the Spanish blame the French, the French blame the Italians, the Italians blame the Libyans and the European Commission, and everyone blames Iccat which governments give no power to in the first place.
When even Iccat officials believe commercial extinction is possible for this Lamborghini of the oceans, I for one am not betting against it.
The Atlantic bluefin is among the issues covered in the current edition of One Planet on BBC World Service