The £1m tuna

Demand for sushi is still depleting stocks

A bluefin tuna sold for more than £1m at a Tokyo auction yesterday. The record – nearly three times the previous high set last year – came as environmentalists warned that stocks of the majestic, speedy fish are being depleted worldwide as demand for sushi rises.

In the year's first auction at Tokyo's sprawling Tsukiji fish market, the 222kg tuna caught off north-eastern Japan sold for Y155m, said Ryoji Yagi, a market official. The fish's tender pink and red meat is prized for sushi and sashimi. The best slices of fatty bluefin – called o-toro – can sell for Y2,000 (£15) per piece at upmarket Tokyo sushi bars.

The Japanese eat 80 per cent of the bluefin tuna caught worldwide, and much of the global catch is shipped to Japan for consumption. The winning bidder, Kiyoshi Kimura, president of Kiyomura Co, which operates the Sushi-Zanmai restaurant chain, said "the price was a bit high" but that he wanted to "encourage Japan", according to Kyodo News agency. He was planning to serve the fish to customers yesterday.

Mr Kimura also set the previous record of Y56.4m at last year's New Year's auction, which tends to attract high bids as a celebratory way to kick off the new year – or get some publicity. The high prices do not necessarily reflect exceptionally high fish quality. The price works out at Y700,000 per kilogram, or £2,242 per pound.

Stocks of all three bluefin species – the Pacific, Southern and Atlantic – have fallen over the past 15 years because of overfishing. Tomorrow, an intergovernmental group is to release data on Pacific Bluefin stocks which environmentalists believe are likely to show an alarming decline. "Everything we're hearing is that there's no good news for the Pacific Bluefin," said Amanda Nickson, director of the Washington-based Pew Environmental Group's global tuna conservation campaign. "We're seeing a very high-value fish continue to be overfished."

The population of another species, the Southern Bluefin, which swims in the southern Pacific, has plunged by more than 90 per cent over the past 40 years. Stocks of bluefin caught in the Atlantic and Mediterranean fell by 60 per cent between 1997 and 2007 owing to rampant, often illegal, overfishing and lax quotas. Although there has been some improvement in recent years, experts say the outlook for the species is still fragile.

In November, the 48 member nations of the International Commission for the Conservation of Atlantic Tunas voted to maintain strict catch limits on the species, although some countries argued for higher limits. The quota will be allowed to rise slightly from 12,900 metric tons a year to 13,500. Quotas were as high as 32,000 tons in 2006.

A recent catch limit on the Pacific Bluefin has been imposed only in the eastern part of the Pacific near the US and Mexico, but not by the intergovernmental group that oversees the western Pacific, Ms Nickson said. "Effort limits", which restrict the number of vessels and days of fishing, are not effective, she added, and fishermen are also targeting juvenile populations and spawning grounds. "This poor species is being hit from every angle," she said.