TOKYO » It is the king of sushi, one of the most expensive fish in the world — and dwindling so rapidly that some fear it could vanish from restaurant menus within a generation.

Yet there is little alarm in Japan, the country that consumes about 80 percent of the world’s bluefin tuna. Japanese fisheries experts blame cozy ties between regulators and fishermen and a complacent media for failing to raise public awareness.

"Nobody really knows the bad state bluefin tuna is in," veteran sushi chef Kazuo Nagayama said from his sushi bar in Tokyo’s Shimbashi district. "It’s obvious we need to set quotas."

Catching bluefin tuna, called "hon-maguro" here, is a lucrative business. A single full-grown specimen can sell for 2 million yen, or $22,000, at Tokyo’s sprawling Tsukiji fish market. Japanese fishermen are vying with Korean, Taiwanese and Mexican counterparts for a piece of a $900 million-a-year wholesale market.

Fish dealers at Tsukiji market say the number of bluefin sold at early morning auctions has fallen during the past 10 to 15 years, but most are confident the supply will never run out. Sushi bars and supermarkets still readily sell the fish, which is considered a special treat. There’s no government campaign to encourage people to rein in their appetites for the iconic Japanese food.

"I have seen some reports on TV about their numbers falling, but I really haven’t thought about cutting back on eating hon-maguro," said Sumire Baba, a Tokyo homemaker. "I guess I’m optimistic they’ll recover."

A scientific assessment released in January found that Pacific bluefin spawning stocks — a key measure of adults that can reproduce — have fallen by about three-quarters during the past 15 years to match historic lows last seen in the early 1980s. It estimated that the species has dwindled to just 3.6 percent of its original population and that more than 90 percent of fish caught were juveniles between the ages of 0 and 3, before they reach reproductive maturity.

The report, compiled by the International Scientific Committee for Tuna and Tuna-like Species in the Northern Pacific and based on data through 2010, received only scant coverage in the Japanese press.

Yomiuri Shimbun, Japan’s largest newspaper, ran a brief story that ignored the drop in numbers and focused on a projection offered by the report’s authors that Pacific stocks could triple by 2030 if current "effort limits" were fully enforced — coverage that a senior Fisheries Agency official blasted as "misleading."

NEWS REPORTS earlier this year about the record 155.4 million yen ($1.76 million) auction sale of a Pacific bluefin at Tsukiji market focused mostly on the exorbitant price and the buyer — the owner of a sushi chain — with little context about the species’ falling numbers.

The drop follows similar plunges in the other two bluefin species, the Atlantic and the southern, which are now protected by catch quotas that experts say need to be applied to their Pacific cousins as well.

Without stricter caps "there is a high likelihood that Pacific bluefin will become less available to Japanese consumers," said Masayuki Komatsu, a former senior Fisheries Agency official. Japan faces two choices, he said: immediately impose catch quotas or "stop eating the bluefin to protect it."

BUT MASANORI Miyahara, deputy director-general of the Japan Fisheries Agency, said that in the past five or six years, "our policy has changed. Now we are in the driver’s seat."

But conservation groups say the recent measures are full of loopholes and not well enforced.

While Japanese consumers are sensitive about food safety and quality, awareness about resource management is still not prevalent. Major retailer Aeon Co. has a lineup of 50 products with a special blue label from the Marine Stewardship Council, which certifies sustainable marine foods. However, MSC-labeled products account for only 3 percent of Aeon’s total fish sales.

"Eating fish is a fundamental part of Japanese culture," said Kozo Ishii, program director for MSC in Japan. "That fish is readily available is taken for granted."