Profile
Maruha Nichiro AQUA
Maruha Nichiro AQUA Co., Ltd. is a member of the Maruha Nichiro Group and engages in the aquaculture of greater amberjack and yellowtail. Maruha Nichiro’s Sakurajima Office manages Japan’s largest aquaculture operation for the farming of greater amberjack and yellowtail in the calm waters of Kinko Bay, between the Satsuma and Osumi peninsulas.
Problem
Maruha Nichiro AQUA was facing worsening yields due to parasitic skin flukes and was overly burdened by the costs and labor involved in dealing with the issue
Damage caused by parasitic skin flukes is an issue for greater amberjack farms that is becoming more serious by the year. Itching causes parasitized amberjack to rub their bodies against the wire meshes, resulting in wounds on their bodies that increase the risk of disease. The stress of the parasites also slows their growth rate. Accordingly, regular chemical baths are necessary to remove the parasites during the summer, the time when the skin flukes are most prolific. Once a week, the operator covers the insides of the fish cages with sheets and adds chemicals to the water that eliminates the parasites.
It is also necessary to keep the wire meshes of the fish cages clean at all times to control skin fluke parasitization. At Maruha Nichiro AQUA, these tasks were very labor intensive and the costs of chemicals and wire mesh cleaning were high.
Nitto Seimo’s Proposal
Instead of relying on chemicals, combat the skin flukes by introducing copper alloy fish cages that stay cleaner, longer
Nitto Seimo proposed switching to a copper alloy fish cages with antifouling properties to combat the skin flukes without relying on chemicals. The copper alloy naturally prevents organisms from adhering to the nets, keeping fish cages hygienic without the need for frequent cleaning.
Maruha Nichiro AQUA initially had concerns about the durability and effectiveness of the copper alloy meshes, but became interested after hearing about the successes of overseas aquaculture companies from Nitto Seimo. After two years of demonstration experiments to investigate their concerns, they made the decision to go ahead with full-scale introduction.
Current Status
An instant reduction in the labor and costs that needed to be invested in combatting skin flukes, improved profit margins
Since their introduction of copper alloy fish cages, skin fluke parasitism has been drastically reduced, and chemical baths, which used to be performed about 10 times a year for each cage, have been reduced to zero. In addition, net cleaning, previously conducted about 20 times a year per net, is now conducted only once or twice annually. Further, the replacement of 80 of 8x8m fish cages with 12 of 20x20m copper alloy fish cages has also reduced the labor involved.
According to Mr. Yamamoto, director of the Sakurajima Office, “Although the cost of introducing the copper alloy fish cages was more expensive than our existing nets, we were able to reduce costs other than the wire meshes through improvements in operations and breeding numbers. Also, the fact that the copper alloy wire meshes can be recycled is in line with our company’s environmentally conscious policies.” Maruha Nichiro AQUA is currently working to further reduce the manpower and labor they require, and to increase quality even more.
