Bluefin tuna, captured and fattened in pens, is prized in Japan for use in sushi and sashimi, and a 200 kilogram (440 pound) specimen can fetch up to 80,000 dollars, the conservation group says.

The lucrative market has doubled in the last two years to 21,000 tonnes as new farms are proliferating along Mediterranean shores, notably around Sicily and off Murcia, Spain, as well as Malta, Croatia, France, Tunisia and Algeria.

The tiny island of Farvignana off Sicily is known for its Mediterranean caviar and preserved products from bluefin tuna.

WWF says Japanese imports have risen by a factor of 21 over the past three years to 4,300 tonnes.

The spike in tuna farming threatens to destroy the already overfished wild tuna in the Mediterranean, WWF warned, noting that the practice is not subject to controls by the General Fisheries Commission for the Mediterranean or the International Commission for the Conservation of Atlantic Tunas.

Permits are easily obtained and tuna farmers are eligible for European Union subsidies, WWF said.

TERRA.WIRE