Peter's Clam Bar in Island Park serves turkey sushi for...

Peter's Clam Bar in Island Park serves turkey sushi for Thanksgiving week. Credit: Peter's Clam Bar

Jiro Ono, 89, widely considered the world's greatest sushi chef, has some dire news for aficionados of raw fish: The delicacy's best days may be behind us.

"The future is so bad," the owner of the three Michelin star-rated restaurant Sukiyabashi Jiro, who was the subject of the 2011 documentary "Jiro Dreams of Sushi," told CQ in December. "Even now I can't get the ingredients that I really want. I have a negative view of the future. It is getting harder to find fish of a decent quality." The reason is overfishing, particularly of the endangered bluefin tuna, a sushi staple. With 90 percent of the world's fisheries deemed either maxed out or overexploited, we may be, as one conservationist put it, in the era of "peak wild fish."

Whether the ocean apocalypse that Ono foresees comes to pass will depend on conservation efforts and international accords with spotty records of preventing overfishing. Yet fish aren't about to disappear from stores or restaurant menus. There just may be fewer wild fish hunted and hauled out of the seas. Farmed fish will pick up the slack.

As the oceanographer Jacques Cousteau said: "We must plant the sea and herd its animals using the sea as farmers instead of hunter. That is what civilization is all about - farming replacing hunting." By some measures, this transformation is well under way: almost as much fish is produced via aquaculture as is caught at sea, according to a recent report by the UN's Food and Agriculture Organization. For certain species of fish and seafood, almost all that is consumed is farm-raised. For example, about 90 percent of all shrimp eaten in the U.S. is farmed, as is almost all European sea bass, some times sold in the U.S. as branzino.

Perhaps salmon best sums up the promise, and drawbacks, of aquaculture. Once a luxury, it is almost as ubiquitous on restaurant menus and in supermarkets as steak or chicken, and 70 percent of the production comes from farms in Canada, Norway, Britain and the United States.

The economic case for salmon farming is undeniable. The fish is more efficient at converting feed into protein than cattle. It takes anywhere from 1.5 to three pounds of feed to produce a pound of salmon, whereas as much as a dozen pounds of feed is required to yield a pound of beef.

But the environmental case for salmon farming is more complicated and intensive production poses problems. Salmon are predators that require a diet made up largely of other fish, such as sardines, anchovies or herring, which are ground up and made into pellets that are fed to salmon in netted pens floating in coastal waters. These forage species also make up the largest share of the wild fish caught every year. Catch rates have been in decline, however, and there are doubts about whether today's harvests are sustainable. Research into feed that relies less on other fish and more on cereals and potatoes might help ease the demand for forage fish.

And, for the moment, large-scale farming at sea suffers from many of the flaws of industrial farming on land (without, perhaps, the ethical qualms that attend raising warm-blooded animals in often-inhumane conditions for human food).

Fish farms pack thousands or even millions of animals in close quarters, conditions that favor the transmission of infections from bacteria and parasites. Just like animals on terrestrial farms, fish in aquaculture pens often must be treated with antibiotics and parasiticides. And though they may be less obtrusive than industrial farms on land, fish farms are also a source of pollution from animal waste and unconsumed food falls to the sea bottom and decomposes.

Some in the industry hold out hope that genetically modified salmon that grow twice as fast as wild salmon may offer a way forward. The Food and Drug Administration has yet to approve commercial production of GM salmon amid objections by environmental groups and members of Congress. Some supermarket chains, under pressure from consumer groups, have vowed not to sell the modified fish even if it is cleared for production.

Even if aquaculture offers answers, Jiro Ono is right about one thing: none of this will help with the depletion of prized wild species such as bluefin tuna, whose stocks have been depleted by more than 96 percent in some parts of the world. They have become so rare that they can fetch astronomical prices: last year a 500-pound tuna sold for almost $1.8 million at a Tokyo seafood auction.

Sushi devotees shouldn't despair just yet. Researchers keep trying to farm bluefins from egg to maturity, though doing so poses challenges: As juveniles, bluefins have a larval stage and feed on other fish larvae and microscopic sea creatures that consume algae. When they are older, they must be fed other fish. A Japanese company earlier this year said it succeeded in developing feed that bluefins will consume, but whether the process can be scaled up is unknown.

Let's hope that farm-raised tuna becomes commercially viable and that conservation efforts allow stocks to replenish. If not, there's the risk that the last wild bluefin tuna will be caught, sliced up and served up as toro, the most desirable of sushi ingredients. If that happens, sushi as we know it will never the same.

James Greiff is an editor for Bloomberg View.


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