The popularity of tuna is growing as more people from Boston to Beijing learn the pleasures of succulent raw fish. But the heavy fishing of wild tuna to meet this demand is rapidly shrinking the global supply.

Now a Hawaii company wants to build the world’s first commercial bigeye tuna farm so the masses may savor sashimi without further reducing tuna populations.
“All indications are we’re on a rapid race to deplete the ocean of our food resources,” said Bill Spencer, chief executive of Hawaii Oceanic Technology Inc. “It’s sort of obvious — well, jeez, we’ve got to do something about this.”
If successful, the startup could blaze the way toward the environmentally sound farming of one of the world’s most in-demand sushi ingredients. But the potential challenges are significant, highlighting the difficulty of relying on farmed fish.
Hawaii Oceanic aims to build a 12-pen farm just under 3 miles off the west coast of the Big Island in two years. The farm would produce 6,000 tons of bigeye a year when fully operational, serving Hawaii, the mainland, Japan and other parts of Asia. In 2007, fishermen caught 224,921 tons of wild bigeye in the Pacific.
Bigeye is called ahi in Hawaii, where it’s commonly grilled or lightly marinated in soy sauce and eaten raw. It’s also used in canned tuna.
Bigeye is the second most coveted tuna after bluefin. But bluefin has been so heavily hunted for its soft, buttery meat that the species’ population in the Atlantic and Mediterranean has plummeted more than 80 percent in 30 years.
Now, bigeye is becoming the favorite catch, said Mark Stevens, a senior program officer at the World Wildlife Fund. In the Eastern Pacific, humans are capturing bigeye faster than the species can reproduce and replace what we eat. The situation is almost that bad in the Western Pacific, he said.
“The fishing industry has turned to bigeye because it’s the closest meat when it comes to quality,” Stevens said. “Pressure has switched to bigeye, not just in the Pacific but everywhere.”
Aquaculture has great appeal amid overfishing, but environmentalists and scientists note its dangers: Fish farms can pollute the ocean, hurt fish lower on the food chain and lead to problems when farm-raised fish escape into the wild.
At some farms, tightly packed fish cages have become breeding grounds for disease. Fish waste, uneaten feed and antibiotics fed to sickly herds have collected under pens, suffocating marine life on the sea floor.
Spencer says his farm will avoid these pitfalls because his pens will be in waters 1,300 feet deep where strong currents will sweep away waste.
The dozen pens — each with a diameter of about 56 yards or more than half a football field — would be spread out over 250 acres of ocean. Spencer says each fish would have plenty of room, preventing disease.
Hawaii Oceanic plans to artificially hatch bigeye at a University of Hawaii lab in Hilo. After the fry grow, the company would take the fish to the pens, where they will be harvested when they reach 100 pounds.
Groups in Australia and Japan are starting bluefin farms, but techniques to spawn and raise tuna fry are young and it’s still a new field. Currently, most tuna farms are actually ranches where fishermen bring wild-caught juvenile bluefin for fattening before harvest.
Peter Bridson, aquaculture manager at the Monterey Bay Aquarium in California is concerned about how much fish Hawaii Oceanic would need to feed its bigeye.
Tuna is a carnivorous fish, high on the marine food chain, and they must eat large volumes of sardines and other smaller fish to grow. Maintaining a tuna farm may add to the pressures on wild stocks of other fish.
Hawaii Oceanic plans to feed its bigeye fish meal. But fish meal itself is made from ground-up wild fish, and has the potential to pressure wild fish stocks.
“You kind of have to come back to the whole debate on whether these fish are the right thing for us humans to be eating,” said Bridson. “There are lots of other things which have a lower impact in terms of how they are farmed.”
Spencer says Hawaii Oceanic eventually wants to replace fish meal with a feed made out of soy, algae, or maybe even fish oil recycled from his bigeye. But he expects he’ll have to use fish meal at the beginning.
“We’re concerned about the environmental impact of what we’re doing,” Spencer said. “Our whole goal is to do this in an environmentally responsible manner.”
Richard Langan, director of the Atlantic Marine Aquaculture Center at the University of New Hampshire, declined to speak specifically about Hawaii Oceanic because he may become a consultant to the project.
Speaking generally, however, he said aquaculture ventures are worth a try, especially considering wild-caught fish aren’t meeting demand, and because the industry is researching ways to make alternative feeds.
“Let’s get out there and do it and see,” Langan said.
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On the Net:
Hawaii Oceanic Technology: www.hioceanictech.com/