About 10 years ago, hundreds of sushi bars popped up in New York, Paris, London and other large Western cities. Once reserved as a Japanese culinary tradition, the habit of eating raw fish has spread to the Western world, and not always for the best, experts say.
Westerners' appetite for sushi, maki and sashimi has threatened the survival of bluefin tuna, which are caught in the Mediterranean Sea and the Atlantic Ocean, and one of the finest species for the Japanese specialty. Organizations and governments have now tried to find ways to keep the species alive.
"We have indications of a stock decline," says Mireille Thom, the spokeswoman on fisheries for the European Commission. "Fishing efforts have become too important."
According to the World Wildlife Fund, which defends threatened species, catches around Spain's Balearic Islands have declined by 15 percent, and only around 2,300 tons of bluefin tuna have been caught this year by the French and Spanish fleets, compared with 14,700 tons in 1995.
"The situation is unsustainable," says Sergi Tudela, head of fisheries at the World Wildlife Fund's Mediterranean program. "We are near collapse of the bluefin tuna species in the Mediterranean and the Atlantic."
As a result, some restaurants now find it hard to get their hands on bluefin tuna.
Wasanka Samaradiwakara, the manager of Koto, a sushi restaurant in London, says that "sometimes, we won't find bluefin tuna." When he does find some, the high price he's forced to pay is passed on to the customer -- £3.50, or $6.60, per tuna sashimi.
The restaurant manager says he now reserves bluefin tuna for "special occasions," and mostly uses yellowfin tuna, which he imports from Sri Lanka. It costs him seven times less than bluefin tuna.
Bluefin tuna "is an expensive product, because the demand is high," says Thom. "The sushi market brings in a lot of money."
To keep up with demand, the World Wildlife Fund says some players in the industry do not hesitate to break the law. The organization says illegal fishing is threatening the survival of the species.
"Real catches are 50,000 tons per year in the Mediterranean, compared with the quota, which is 32,000 tons per year," said Tudela. "It is very clear that there is an illegal amount of tuna being caught."
The World Wildlife Fund says the existing rules to protect the fish are not sufficient.
"The quotas are not the solution. [They] have never been applied," said Tudela.
The European Commission admits that, because of new fishing methods, it has become harder to enforce the quotas.
"Some countries have set cages to fatten tunas," said Thom. "This is not necessarily a bad thing in itself, but there are suspicions that it encouraged overfishing."
Ten years ago, all catches were exported directly to be sold on the market. Now some of the fish are kept in cages, which makes it harder to control the amount of fish that is caught.
The World Wildlife Fund has pushed for a ban on fishing during the spawning season, which takes places between May and July. It also requests that some countries reduce their fishing fleets -- again, a matter on which the organization accuses some of the players of breaking the law.
According to a report the World Wildlife Fund released in July 2006, some French companies registered boats in Libya so they could increase their fleet capacities without being noticed.
The report said that "Ten vessels were exported to Libya, where they continue exploiting the same bluefin tuna stock under effective French control, skirting management measures and adding to the pressure on the stocks."