Customers sometimes call Jeremy Sewall into the dining room and ask him to explain himself.
The chef-owner of Island Creek Oyster Bar in Boston offers daily fish specials, and when they include bluefin tuna, his ethics are called into question.
The big meaty fish, whose fatty, marbled belly, called toro, is the crown jewel of many high-end sushi and sashimi meals, once swarmed the North Atlantic in massive schools, but since the 1970s the population has been depleted dramatically. Bluefin is now on nearly everyone’s seafood watch list.
Still, the fish’s prized position in the culinary world and its financial value — big specimens fetch $100,000 or more at Tokyo’s Tsukiji market — make it hard to ignore.
“Whether it’s fishermen or chefs or watch groups, everyone’s talking about it,” Sewall said.
Despite some disagreement about exactly how sparse the population is, chefs are exploring ways to meet demand for bluefin within their own ethical comfort zones. For some that means patronizing vendors that use only specific fishing or farming methods. For others it means using different products to replicate the texture and richness diners expect from bluefin.
Sewall only serves bluefin that is caught locally on small vessels helmed by people he knows.
“I believe it’s important that we really manage worldwide how much of this fish is being harvested,” he said. “But if I buy and sell a local product from a local fisherman [who caught it responsibly and] in season, ... I’m helping the local economy.
“I’m equally responsible to support the fishermen as I am the fish,” he added.
He tends to prepare the fish simply — crudos or tartares as appetizers that he sells for around $15, or grilled as an entrée with a warm tomato salad or local beans or squash for $30 to $34.
“Nothing too heavy,” Sewall said. “The fish is so good, you really want it to be the star.”
Despite the complaints of some diners, Sewall said he has no trouble selling the fish.
To meet growing demand, companies in Japan, Mexico, the Mediterranean and elsewhere have started farming bluefin, a method that is not without its own controversies.
Critics call some of these operations “ranches” rather than farms, as they round up young bluefin and then fatten them up for sale. Even operations that breed the fish face criticism because of the large amount of other fish that have to be fed to the tuna.
Proponents say that both the farmed and the ranched fish eat less fish than migratory wild tuna because they move less, and the farms take pressure off of the wild tuna population.
Troy Guard of TAG restaurant in Denver serves ranched bluefin, which he regards as sustainable.
Each week he buys one weighing in at around 50 pounds.
“We usually get it on Fridays and we run it until it runs out — usually on Saturday,” he said.
He either sears or grills a six-ounce portion and serves it with seasonal sides for around $29.
“We don’t really make money, but we’re not losing money,” he said. “It’s something that I want to give to my guests, and the cooks love getting it. They love breaking it down.”
He sells the belly as sushi or sashimi appetizers. He also scrapes the carcass after the four loins are removed and uses the leftovers as tartare or sushi rolls.
He sells the two collars separately for around $25.
Chefs say although good toro is a unique culinary experience, many other portions of the bluefin have substitutes.
“I have switched to using albacore tuna,” said Andy Arndt of Aquariva in Portland, Ore. He poaches it with fennel and makes a salad with shaved fennel, olives, lemon zest and aïoli and serves it on country wheat bread.
“I’ve also started doing halibut or scallops from Alaska that can give the same mouthfeel when used in a raw application,” Arndt said.
Michael Leviton, chef-owner of Area Four in Cambridge, Mass., and of Lumière in Newton, Mass., recently was named chair of conservation group Chefs Collaborative. He has taken bluefin off his menus, but he said the issue’s not black and white.
“Yes, clearly, it’s overfished … and we really ought to minimize its harvest,” he said.
But at this time of year, bluefin is sometimes caught as bycatch on boats targeting swordfish.
“It seems to me an awful waste to throw that back,” he said.
Contact Bret Thorn at [email protected] .