Sushi is in danger of falling victim of high oil prices after fishing industry groups warned that a third of the world's long-line tuna fleet - the ships that catch high-grade tuna used in the Japanese dish - could remain in dock this year as soaring fuel costs make fishing unprofitable.

The business is already in decline due to dwindling fish stocks. Japan Tuna, an industry group, said the cost of heavy fuel for long-range tuna ships had doubled over the past year to Y120,000 ($1,137, €733, £576) a kilolitre.