The rarest tuna of all - Japan's farmed Kindai

Editor's Note: This story is part of an occasional series on issues surrounding our food supply.

These days, sit down at a sushi bar for a plate of unctuous, glistening toro, and along with it will come a heap of guilt and grief.

Toro, the Kobe beef of fish, is the extremely pricey, highly coveted, fattiest part of a bluefin tuna. The species is so prized for its lush belly meat that in the past century, it has been severely overfished. Of equal concern, it also contains among the highest mercury levels of any seafood.

But now a farm-raised bluefin called Kindai - the first ever raised in captivity from the egg - offers what some consider a promising new alternative. Produced by a Japanese university fisheries laboratory, Kindai is being touted as a more healthful and more eco-friendly option. However, marine scientists say whether it proves a true panacea remains to be seen.

You won't find Kindai in your local supermarket or Asian seafood store. Because supplies are severely limited, the only way to experience its silky, rich, clean taste is at one of a handful of Bay Area restaurants, including the French Laundry in Yountville, the Dining Room at the Ritz-Carlton in San Francisco, Sebo in San Francisco, Hana in Rohnert Park and Manresa in Los Gatos.

Each week, one shipment of Kindai, generally three 130- to 200-pound fish, is flown from Japan to the United States. One fish goes to New York, and the other two to the Bay Area.

IMP Foods Inc. of Hayward, a specialty seafood wholesaler that supplies many Northern California sushi bars, as well as high-end restaurants in the Bay Area and a few in Chicago, is one of only three distributors of Kindai in the United States.

Tuna for the future

"It's not just a fish. The story behind the fish is very important, too," said Glenn Sakata, IMP branch manager, who has been importing Kindai since February. "It is the hope of the future. At this point, it's the only hope."

The hefty fish arrives overnight at IMP Foods, cocooned in Bubble Wrap inside a thick foam container. Only IMP's best fillet person is allowed to cut this fish, whose exquisite fatty flesh ranges in color from sirloin-steak red to the milky pink of the toro.

IMP won't say how much it pays for each Kindai, only that the price is comparable or sometimes even higher than wild bluefin, which, depending on the season, can fetch five to six figures at auction.

After the fish is cut, each section is labeled with a handwritten piece of paper indicating its weight and which restaurant it will go to. The more fat a piece has, the more expensive it is. Top restaurants are willing to pay a dear sum for this exclusive fish - $40 to $70 a pound wholesale. And every last bit of it will be sold.

Charlie Trotter's in Chicago purchases the toro, as does chef Laurent Gras, formerly of San Francisco's Fifth Floor, who is just opening his L20 restaurant in Chicago. Manresa puts dibs on the head; Sebo often buys the collar, which it serves salt-grilled for as much as $25 a portion.

"The flavor is incredible, and it slices unbelievably well. It's not sticky like other farm-raised tuna," says Ron Siegel, chef of the Dining Room at the Ritz-Carlton, who features Kindai sashimi as part of a $110 tasting menu, and Kindai-geoduck tartare with cayenne emulsion as a $25 appetizer.

The Kindai that arrived at IMP one recent Thursday was about 5 feet long, and 130 pounds. It took 3 1/2 years for it to reach this size - and 32 years for it to become a reality at all.

That's how long Kinki University Fisheries Laboratory in Wakayama struggled to find a way to culture bluefin, not an easy task because the aggressive fish bruises easily and is prone to cannibalism.

The laboratory finally succeeded in raising the fish from eggs in pens in the Pacific waters. The first Kindai (the name is a contraction of the university's name in Japanese) were sold to a hungry Japanese public in 2004.

It remains a precarious operation. Only 1.5 percent of the egg population survives to adulthood, according to Mika Higurashi, project leader at IMP for the Kindai.

Fish in peril

There are other bluefin farms around the world. But they differ in that they catch young bluefin in the wild, herd them into pens, then fatten them up until they are large enough to slaughter.

In the wild, Pacific bluefin, the largest of tunas, can weigh as much as 1,000 pounds and take 14 years to become fully grown. Over the years, our insatiable appetite for bluefin, found in Pacific, Atlantic and Mediterranean waters, has had catastrophic effects.

Since the 1970s, the Atlantic population of wild bluefin alone has declined by nearly 90 percent, according to the Monterey Bay Aquarium's Seafood Watch program. In the past, environmental organizations have called for a five-year moratorium on fishing, but to no avail because bluefin is just too valuable.

"With one fish going for $130,000 at auction, it doesn't give a lot of hope to serious conservation measures," said Tim Fitzgerald, a marine scientist with the Environmental Defense Fund in New York.

Chef David Kinch was so concerned with the plight of bluefin that he stopped serving it at Manresa six months ago. But when he heard about the possible merits of Kindai, he started featuring it on his chef's tasting menu in February in a trio of sashimi, tartare and seared cheeks called "fromage de tete," or headcheese. He favors the stronger tasting flesh from the head. And when he's scraped the skull clean, it gets buried in the compost pile to nourish the biodynamic garden that provides the restaurant's vegetables.

"l love wild bluefin toro, but I finally just had to back off from it," Kinch said. "With Kindai, nobody has ever raised it from the embryonic stage until now, which could lead to true sustainability."

But will it?

A major issue with any farmed fish is how much feed is required. Kindai takes about 26 pounds of feed to produce 1 pound of the brand-name farmed bluefin, said Higurashi. Kindai is fed squid, blue mackerel and sand eel, all considered sustainable species. But marine scientist Fitzgerald worries that intensive bluefin farming may result in the depletion of these wild seafood populations.

Mercury concerns

Scientists also remain concerned about mercury levels in bluefin. Because mercury has the potential to damage developing nervous systems, young children and women of child-bearing age have been advised by the U.S. Food and Drug Administration and the U.S. Environmental Protection Agency to avoid certain seafood with high levels of the toxic metal.

Wild bluefin have been found to have a mercury concentration of 1 part per million or greater, according to recent samplings. That is the level at which the FDA can legally remove a product from sale. In comparison, Kindai have a mercury concentration of 0.6 parts per million, according to Higurashi. That is lower, but not nearly as moderate as other recommended seafood such as wild salmon, tilapia, catfish and sardines.

"There's the argument that if you farm it, you'll take pressure off wild stocks. But that's playing roulette," said Corey Peet, aquaculture research manager for the Monterey Bay Aquarium.

"What's really the question is just how much tuna we should be eating in the first place. When it comes to bluefin, people should just say no."