A mission to assure supplies of a prized food
Japan delicately attempts to find a way to breed tuna on industrial scale
BY YURIKO NAGANO
Keiichi Mushiake slowly pushes back the red velvet curtains of a brand new viewing hallway in a fisheries research lab near Nagasaki, to reveal, behind a plate glass window, a dimly lit round pool. Sleek, dark, shadowy objects are darting in circles around the emerald green waters.
‘‘Those are Pacific bluefin tuna,’’ Mr. Mushiake said.
There are 48 fish in the pool, averaging 110 centimeters, or 3.6 feet, in length and 18 kilograms, or 40 pounds, in weight. A similar pool nearby holds an additional 41.
Security is tight at the tuna aquaculture research center, opened in 2011 at the Seikai National Fisheries Research Institute here. Access to the tank area is strictly limited. Signs inside and outside the viewing hall forbid photography. ‘‘We’re trying to protect our technology,’’ said Mr. Mushiake, the institute’s director.
The center is part of an intensive effort to develop bluefin tuna farming on an industrial scale—an effort which pits sushi-loving Japan in fierce competition with South Korea, Australia and Spain. The research center’s two pools, measuring about 20 meters, or 65 feet, across, and six meters, or 20 feet, deep, are the first in the world built on land for the specific purpose of harvesting fertilized Pacific bluefin tuna eggs. Built with 2.1 billion yen, or $21.2 million, provided by the Japanese Fisheries Agency, the pools started operating in May, with an estimated annual operating budget of \70million to \100 million, Mr. Mushiake said. ‘‘We’re trying to keep kuro-maguro available’’ while reducing and ultimately phasing out the catch of wild fish, said Mr Mushiake, using the Japanese name for Pacific bluefin. Of all the types of tuna, Pacific bluefin is the most prized in Japan. According to government figures, Japanese consume 70 percent of the world’s annual Pacific bluefin tuna catch, or about 21,000 tons last year, mostly as sushi or sashimi. The global value of the market is unclear, but the average price of a whole wild bluefin tuna is $40 to $50 per kilogram, while the price for farmed fish ranges from $12 to $30 per kilo, according to a 2007 report by the U.N. Food and Agriculture Organization. The price depends on the quality of the fish, the way it is caught and the season it is caught — winter being best — said Shigeru Miyashita, director of the fisheries laboratory at the Wakayama campus of Kinki University, who likened it to another favored Japanese delicacy, high-quality Kobe beef. With global environmental protection treaties such as the Convention on International Trade in Endangered Species leaning toward listing Pacific bluefin tuna as an endangered species, finding a better way to farm the fish has become of national importance. The farming of Pacific bluefin is not new. Japan has 140 established farms, including 60 in the Nagasaki area alone, growing the fish from age three months to adulthood. The scale of production, however, has always been limited by the supply of fingerlings. Pacific bluefin are highly sensitive to their environment: Getting them to spawn in a completely artificial environment has never been achieved —and when they do spawn the loss rate of fertilized eggs is extremely high. This is the problem that the Nagasaki research center, and a sister facility on Amami-Oshima Island in Kagoshima Prefecture — which has been working on Pacific bluefin research since 1995— are trying to solve. The challenges aremultiple and complex. For starters, the fish are sensitive to harsh weather. ‘‘In years where there are many typhoons, we’ve seen cases where farmed kuro-maguro do not spawn,’’ Mr. Mushiake said.
In addition, the skin of Pacific bluefin is delicate and human contact can be fatal, he said; the farmed fish are susceptible to viral diseases such as iridoviruses, which can damage their spleen; at an early stage of their development they are prone to devour any food in reach, including one another; and if they are disturbed by external factors, such as loud noises, they have a tendency to go into a potentially fatal hyperactive ‘‘speed burst,’’ in which they may swim into the pool walls and break their own necks. The challenges are reflected in the history of the fish in Mr. Mushiake’s Nagasaki pools, the survivors—so far—of a batch of two-year-olds brought in from the Amami-Oshima Island facility. Originally numbering 200, the Amami-Oshima fish died by dozens en route to Nagasaki—many at the start, when researchers tried to catch them for the journey. Just 127 arrived alive. Since May, almost 40 more have died, leaving only 89.
What happens next remains uncertain. ‘‘We first need to gauge if the fish will successfully lay eggs,’’ Mr. Mushiake said. Still, if all goes well, he said, the surviving fish in the tank should start reproducing by around June 2015. At that point, the numbers game gets interesting. A large female Pacific bluefin produces tens of millions of eggs but on average, even in a protected farm environment, only 0.2 percent to 0.3 percent of fertilized eggs will survive the first three months to grow into 30-centimeter fish; and fewer than 0.1 percent will survive to full adulthood. If hightechnology methods can significantly raise the survival rate, the commercial consequences will be considerable. Mr.Mushiake and his team—six marine biologists, including himself, in Nagasaki and another six on Amami-Oshima Island—are trying to do just that. By strictly controlling the pool environment, they hope to maximize egg production and survival. The pool water is kept in a constant temperature range, between amaximumof 30 degrees Celsius, or 86 degrees Fahrenheit, in summer and a minimum of 13 degrees Celsius, or 55 degrees Fahrenheit, in winter. Daytime lighting follows the rhythm of sunrise and sunset in the outside world. At night, light-emitting diode, or LED, lights above the tanks are set to provide twice the light intensity of natural moonlight. The tanks have been designed with built-in egg-collecting stations. ‘‘Viable eggs should float to the surface and naturally glide to the depositories,’’ Mr. Mushiake said. Once collected, the fertilized eggs will be transferred to Amami-Oshima for hatching and early growth. The project also aims to develop improved strains of fish, using classic breeding techniques, rather than genetic modification, to produce fast-maturing, disease-free fish with high survival rates. The goal is to develop a method capable of producing as many as 100,000 three-month-old fish a year to stock the nation’s fish farms, Mr. Mushiake said.