JAPAN - Offshore aquaculture, or open ocean aquaculture, is a type of farming where fish farms are moved some distance offshore. Although it's still only a small fraction of global aquaculture, hopes are high that it will play an increasingly important role in meeting the demand for seafood as the world population continues to grow. Meanwhile in Japan, one company has announced plans to build the country's first large-scale offshore aqua-farming system.
Based on high expectations for the development of aquaculture, offshore farming has been receiving considerable attention. Good water qualities in the open sea, for example oxygen conditions, less pollution and less eutrophication, are seen as big advantages, while other reasons to move offshore include environmental aspects such as the dispersal of both dissolved and particulate waste products.
In October 2016, Japanese engineering company Nippon Steel & Sumikin Engineering Co. Ltd., which designs and installs offshore platforms for oil and gas development projects, announced a plan to build the world's first large-scale offshore aquaculture system with Yumigahama Suisan, a subsidiary of Nippon Suisan, or Nissui.
Using a prototype system, verification tests are due to be carried out between December 2016 and May 2017 at the Yumigahama Suisan Coho salmon farm off Sakaiminato City in Tottori prefecture, western Japan.
The test period coincides with the farming season for coho salmon at Miho Bay, around 3km off the coast of Sakaiminato. Hopes are high that if the tests are successful and the system implemented, it could play a key role in the further development of Japan's aquaculture.
The prototype features a platform on which stands a steel tower that's 18 metres tall with two tanks attached. The tanks, which store food, became ready in July this year. Fish pens extend 150 metres from the tower.
The tower also contains blowers, which are connected to an undersea piping system at the bottom of the ocean that stretches from around 150 to 400 metres and sends out food by air pressure using compressed air. The pipes are linked to automatic feeders that serve five circular fish pens, each 25 metres in diameter.
Computers and tablets can be used to operate everything from land, and depending on the size of the fish, the tanks can also store food that will last from three to seven days.
The system will also be able to determine the appetite levels of the fish using artificial food with built-in sensors that are attached to the fish pens.
Developed by Nissui's Central Research Laboratory, when the fish bite the artificial food, the sensors will pick up data every 0.1 second and transmit the information to farmers on land. Depending on how often the fish bite, it will also be possible for the farmers to ensure zero waste and better quality fish by adjusting the amount of feed according to the fish's hunger levels.
During the test period, the following areas will be checked: equipment to store large amounts of feed at sea, technology to transfer fishmeal from storage tanks to fish and technology that can remotely manage the feeding of fish in offshore tanks.
An ultra-large floating fish pen that can be lowered to a depth of 20m will also be tested. Depending on the results, Nippon Steel & Sumikin Engineering plans to pitch the system to the fisheries industry and receive its first orders sometime next fiscal year.
Nissui's Central Research Laboratory intends to further enhance the stable supply of farmed fish, beginning with Ikejime Sakaiminato salmon that's incubated, bred and processed at Yumigahama Suisan.
The new offshore farming system will offer several advantages. For example, it will be able to withstand waves of up to 7m high and tidal speeds of up to 2 knots. Thanks to larger fish pens, it will also be possible to increase production by over 10 times and up to 25 times, even if farming density is restricted, while farming in offshore locations with strong currents will offer more environmental protection from waste such as uneaten fish meal.
The global consumption of seafood is growing, and aquaculture supports most of the increased demand. Inland areas for aquatic farming are still limited in Japan so offshore aquaculture is seen as a key step in the industry's development. Hopes are also high that the system could be exported as part of new projects involving engineering or construction.