This segment was originally broadcast on Jan. 13, 2008. It was updated on Sept. 4, 2008.
Sushi is becoming so popular these days, you can find it in grocery stores all over America. But it's distinctly Japanese, and the Japanese have turned sushi into a multibillion-dollar international business.
Sushi wouldn't be sushi without tuna, particularly bluefin tuna. It is so revered in Japan that they call it the" king of sushi."
But as correspondent Bob Simon reported last January, the bluefin is in deep trouble.
Fresh bluefin tuna arrives in style at Tokyo's Narita airport every day, from all over the world. They are carefully packed in crates and unloaded onto palettes often less than 24 hours after being caught.
It's delivered on ice, in custom-made wooden boxes called "coffins," to the Tokyo fish market, which is called Tsukiji. It's the place where the world's top sushi chefs get their fish.
More fish flow through Tsukiji than any other market on earth. More money, too: $4 billion a year. In today's global economy, fishermen from around the world watch the prices set at Tsukiji, which enables them to figure out what their catch is worth.
Harvard anthropology professor Ted Bestor understands the movement of money and tuna. He's been studying Japanese sushi culture for the last 20 years. "This place is the nerve center of a global fishing industry," he explains.
"Sort of like a Wall Street of fish," Simon remarks.
"Yeah. It is. It is," Bestor agrees. "There's no futures market, no derivatives. But other than that, it's like the Wall Street of fish."
At four o'clock every morning, six days a week, the buyers arrive at the market's fresh tuna hall to check out what's on offer.
How do buyers tell what's good and not so good?
"Well, if you look over you can see them rolling the tuna over on their side, looking in the belly. They're looking for the fat content. They're looking for the color of the meat. They're x-raying the fish and then you'll see that they'll take a little piece and they'll rub it between their thumb and forefingers. And that's to get a sense of the oil content," Bestor explains.
"So these guys must be the toughest customers in the world," Simon remarks.
"Absolutely," Bestor agrees. "They know their fish inside and out."
Bestor says the buyers also know the market inside out and are prepared to pay the highest price in the world.
The average price of a single bluefin tuna is anywhere between $2,000 and $20,000. It all depends on the size, the season, and their fat content - the fattier, the better.
Tsunenori Ida is one of the most respected buyers in the market. His family has been bidding on top quality bluefin for seven generations.
He's well versed in the auctioneers' lingo and he knows the signals. Within seconds, Ida has bid for and bought the most expensive tuna at today's auction, a 450 pounder for $8,500.
Ida is the master of the house of Hicho, a wholesaler supplying Tokyo's most exclusive sushi restaurants. He wields his blades like a latter day samurai.
Like everything in Japan, cutting apart the tuna is a ceremony. The fresh bluefin is massaged and stroked as befitting a king. The masters even have what they call "Maguro No Kaiwa," conversations with the tuna. Ida appeals to the fish to make him proud and give him their best.
The demand for the freshest bluefin tuna from the world's most exclusive restaurants is insatiable. So how is this global yen for bluefin satisfied? Well, globally, from the coast of Japan, the Gulf of Maine, Mexico or the Mediterranean.