A fish farm (PANA)

Increasing Fat Content
In most cases, fish farms that cultivate tuna first catch the fish in the ocean. They then raise the fish for several months in a way that increases the amount of tasty fat in their meat. Fatty tuna meat is called toro and is a favorite and expensive delicacy in sushi restaurants. About 20% of wild tuna consists of toro. Modern fish farming, however, can raise this ratio to as high as 95%.

Yet the bluefin tuna required a much more thorough cultivation process. The fish were 100% farmed, meaning that the eggs came from parents that had also been artificially bred. The bluefin were then farmed from hatching to adulthood. It took three decades of work to produce the first successfully 100% farmed bluefin tuna in the world.

The meat of two of the bluefin was sold in an Osaka department store for use as sashimi. Priced lower than the same meat from naturally raised bluefin, the meat sold out within a day. "It has high fat content, which gives it a sweet flavor," commented a department store representative.

Fully 90% of the farmed bluefin tuna consists of the highly coveted toro. The credit for this extraordinarily high ratio belongs to the Fisheries Laboratory of Kinki University. At the lab's experimental ponds in Kushimoto City, Wakayama Prefecture, approximately 900 such tuna are already awaiting shipment.

These fish are the result of a long and costly process, which has raised a conundrum over the pricing of the meat. Setting the price below that of wild bluefin tuna is hard because of the costs involved in production. It has therefore been decided that the prices should be in line with those for imported farmed tuna.

According to a laboratory official, the facility needs to have at least 2,000 fish constantly in production to bring the operation into the black. Achieving that will require raising huge numbers of fry, as only around 5% of the fry survive in the ponds. The ponds' current crop of 900 fish, for instance, are the survivors of nearly 20,000 fry. It is no surprise, then, that the lab's next objective is to raise the fry's survival rate to around 50%.

Farming Safe Flounder

In a related development, a major supermarket chain has announced plans to take part in the cultivation of flounder. The plan is to ship more than 40,000 of the fish raised in ponds located on land in Mie Prefecture, starting in February. Flounder has been raised in land-based ponds before, but this plan is different in that food safety is the top priority, particularly regarding the use of antibiotics.

Fish farming usually entails the use of antibiotics, but the supermarket plans to eliminate them completely from its farming process. It plans to achieve this by using artificial seawater, which is made from underground water mixed with rock salt, rather than relying on water from the sea. Minute particles, such as waste and leftover food, will be removed using microorganisms so that the water can be reused. It's an expensive arrangement, costing about ¥500 ($4.70 at ¥105 to the dollar) more per kilo of fish meat than conventional fish farming. The project's success depends on how much extra consumers will be willing to pay for the assurance that their fish is free of antibiotics.

Fish-farming technology is also being developed for other highly sought-after types of fish and shellfish, including spiny lobster, eel, red sea bream, and scallops. It is a business that appears to have a bright future.

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Copyright (c) 2005 Web Japan. Edited by Japan Echo Inc. based on domestic Japanese news sources. Articles presented here are offered for reference purposes and do not necessarily represent the policy or views of the Japanese Government.