When Oceana photographer and MarViva Med diver Keith Ellenbogen first dove with bluefin tuna in the Mediterranean, he felt reverberations in his chest when the powerful fish darted by. Despite their strength, however, the fish were juvenile-sized, smaller than Ellenbogen himself.
Ellenbogen was documenting bluefin tuna in vast fattening cages, the last stop before heading to market. These fish would never get the chance to reach maturity, roaming the Atlantic and eventually returning to the Mediterranean to spawn. Instead, like three-quarters of all bluefin caught in the Mediterranean, the fish were most likely headed for Japan. Once there, they can sell for $80 a pound or more.
The Atlantic bluefin tuna is one of the world's most coveted and threatened seafood species. Since the mid-1990s, tuna populations have spiraled downward, and scientists warn that an immediate moratorium on fishing is the only way to avoid an irreversible collapse. In June, the European Union closed the bluefin tuna season for most ships two weeks early, but that's only a stopgap measure in the race to save these unusual creatures.
Conservationists often refer to the bluefin tuna as the tiger of the sea, but in truth a mature bluefin outweighs, outgrows and outpaces even the heftiest wild cat. Bluefin can weigh up to 1,400 pounds and measure 15 feet long, and can sustain bursts of speed up to 60 miles per hour in pursuit of prey. Warmblooded, they migrate across oceans, and females produce up to 30 million eggs each spawning season.
Bluefin tuna have fascinated and fed humans for millennia. The first evidence of bluefin fishing in the Mediterranean dates to the 7th millennium B.C.E. when the Phoenicians established fisheries using hand lines and primitive seine nets. Aristotle studied tuna in his "History of Animals," written in 350 B.C.E., and contended that the enormous fish gorged for two years before bursting from overeating. Four hundred years later, Pliny the Elder recommended eating tuna to treat ulcers, suggesting the neck, belly and throat as the finest pieces that must be eaten fresh even though "they cause severe fits of flatulence."
But it wasn't until the late 20th century that that tuna became a global business. Sushi and sashimi exploded in popularity in Japan and around the world, and consumers touted the fatty flesh of the bluefin as the most prized meat.
Purse seiners, which close drawstring nets around schooling fish, became larger and more sophisticated, and fattening cages dotted the seas starting in 1996. These cages, which can measure 50 meters across, may represent the biggest threat to bluefin survival.
Tuna, often juvenile, are captured and dumped in the cages - or "ranches" - for months to fatten up, with all the associated problems of aquaculture: disease, waste and overfishing of the smaller fish used to feed the bluefin.
Fishing for giant bluefin has become hugely profitable: In the 1960s, bluefin sold in the United States for seven cents a pound. This season, the first bluefin sold in Chinese Taipei netted $105 a pound.
Despite this booming business, there is little understanding of how tuna populations work. Several bluefin fisheries have cropped up in the Atlantic, only to collapse within a few years. The North Sea fishery collapsed in 1963, and a Brazilian fishery appeared in the early '60s only to vanish by 1967. No one knows why.
Current catch quotas set by the International Commission for the Conservation of Atlantic Tunas (ICCAT) are nearly impossible to enforce, as fewer than 5 percent of catches have been sampled independently in the last decade. Some conservationists estimate that the fishing industry took 50,000 metric tons of bluefin from the Mediterranean by mid-June of this year - and the quota was set at 28,500 metric tons.
In two and a half months aboard MarViva Med this summer, Ellenbogen photographed undersized bluefin tuna circling in cages as well as dangling on the ends of fishing lines. He saw so many purse seiners clustering around schools of tuna that the horizon appeared nearly urban. What Ellenbogen didn't see was evidence of abundant marine wildlife of any kind. "When we went diving, we saw nothing constantly," he said.
The ICCAT has set a declining quota for Atlantic bluefin over the next few years as part of a 15-year recovery plan, reducing the total allowable catch to 25,500 metric tons in 2010. Scientists argue that it's not enough - that bluefin need a generational breather to prevent total collapse. In the meantime, the data gathered by Ellenbogen and the rest of Oceana's crew aboard the MarViva Med indicates that the quotas that are in place are not effectively enforced and are ignored by the tuna fleet.
"The laws continue to be disregarded and mocked. Hundreds of vessels continue fishing, the fattening farms continue receiving catches and the companies that supposedly should have concluded their activities continue obtaining profits while pushing the fishery to the limits of collapse," said Xavier Pastor, Vice President of Oceana Europe. "The bluefin tuna fishery around critical spawning areas must be urgently and completely closed until the stocks can recover, and the implementation of this decision must be effectively monitored."