Soaring demand for sushi and shashimi in Japan has resulted in fisherman recruiting helicopters to help them spot schools of Mediterranean tuna that can be fattened up and then exported, Greenpeace said yesterday.

According to the environmental group, the innovative fishing technique involves either a helicopter or a small plane which locates the fish and traps them in cages with the help of a fishing boat. The trapped fish are then towed to fish farms, where they are fattened before being sold to Asian markets, mainly Japan.

A survey prepared by Greenpeace said that some 44,000 tons of tuna are taken from the Mediterranean per year while the EU-imposed limit is 32,000 tons.

Estimates indicate that the fish trade is pushing toward extinction the red tuna, whose populations have been reduced by 80 percent in the last 20 years.