Major trading companies are making serious efforts to farm bluefin tuna, as the farming projects have been increasingly important for securing stable supplies of the fish.
At an international conference in Fukuoka to discuss restrictions on fishing of Pacific bluefin tuna, Japan, the United States and other countries concerned reached an agreement Thursday to halve catches of immature Pacific bluefin tuna beginning in 2015.
In early August, a crane plucked two bluefin tuna from a 40-meter-wide farming pen in the Takashima district of Matsuura, Nagasaki Prefecture. The city faces the Genkainada sea in the northern part of the prefecture. The two fish were processed on a fishing boat and transported to a nearby port.
Sojitz Corp., a major trading company, established a subsidiary, Sojitz Tuna Farm Takashima Co., in the city in 2008. The subsidiary is in charge of farming tuna fish.
With its subsidiary, Sojitz began a tuna farming project that raises young fish weighing about 500 grams, called "yokowa," into larger stock.
The sea off the Takashima district is known as a productive area for robust farmed bluefin tuna.
Koji Hayashi, president of the subsidiary, said proudly, "We are providing farmed tuna that consumers can feel safe and secure about."
In this fiscal year, the company has set a goal for shipments of about 400 tons. According to Sojitz Kyushu Corp., another regional subsidiary based in Fukuoka, tuna farmed there have been exported to China, Thailand and other Southeast Asian countries. The company is also considering exports to the Middle East.
In the Goto Islands in the western part of Nagasaki Prefecture, Toyota Tsusho Corp. is conducting a joint project with Kinki University, which succeeded in farming of bluefin tuna to completion for the first time in the world.
In the complete tuna farming cycle, eggs are obtained from mature farmed fish, hatched and raised into mature fish, which then produce eggs of their own.
Kinki University achieved the complete cycle in 2002. Since 2010, the university and Toyota Tsusho have been conducting a joint project in the city of Goto in the prefecture. In the project, young fish are bred until they grow to yokowa size and are then shipped to fish farmers.
Makoto Takahashi, chief of the farming division of Tuna Dream Goto, a subsidiary of Toyota Tsusho, said: "We are making efforts to improve conditions in our farming facilities. For example, we also farm oysters to clean the water."
In this project, artificially hatched young fish are shipped from Kinki University's facility in Wakayama Prefecture to the city of Goto, but the percentage of young fish that die in transport is high.
In July, Toyota Tsusho announced it will build a facility in Goto to artificially hatch fertilized eggs, to begin joint production of young fish. Toyota Tsusho President Jun Karube expressed his enthusiasm, saying, "We'll succeed even if it takes us 10 years."
Toyo Reizo Co., a major tuna trading firm and a group company of Mitsubishi Corp., has been reinforcing tie-ups with local governments in places with tuna farming facilities, including the Goto city government.
Starting this year, the company provided eggs of farmed tuna to other entities, such as a company jointly established by the public and private sectors in Nagasaki, where the eggs are hatched. Young fish from the artificially hatched eggs are raised by Toyo Rezio.
According to estimates by the central government, about 30,000 tons of bluefin tuna were supplied in Japan in 2012. Farmed fish accounted for about 10,000 tons, or about 30 per cent.
An official of a major trading company said, "Compared with natural tuna, farmed tuna with stable qualities have supported the baseline the supply."
The quantity of completely farmed tuna is still about 100 tons. If the method becomes widely used, people in the fisheries industry expect it to boost the stable supply of bluefin tuna.