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RAS in a box

A Japanese firm is building compact units to bring fresh seafood closer to cities.

August 28, 2023  By Bonnie Waycott

An early prototype rendering of an ARK system in the middle of Tokyo’s Shibuya Square. (Photo: ARK INC.)

For the past three years, land-based recirculating aquaculture systems (RAS) have been drawing attention in Japan, with companies keen to establish new ways of meeting demand in the seafood-loving island nation.

Salmon farmer Proximar Seafood is making final preparations to produce Atlantic salmon at the foot of Mount Fuji, while land-based shrimp farming may be key to Japan’s shrimp supply.

Kansai Electric Power (KEPCO) has been farming Pacific whiteleg shrimp since March 2022 using a system called the Indoor Shrimp Production System (ISPS). This was jointly developed by aquaculture engineering firm International Mariculture Technology Engineering Inc. (IMTE) and the Japan International Research Center for Agricultural Sciences (JIRCAS).


Offshore farms have long been viewed as a potential game changer for fish production. But although they are growing rapidly around the world, they are threaded with huge challenges and can potentially come at the detriment of the environment. Add to this other challenges like stricter regulations and a shortage of ideal locations, and the expansion of offshore farming has become more difficult.

In contrast, RAS farms have various advantages – they treat and re-use water, typically use bio-filtration to reduce ammonia toxicity and can be sited closer to urban consumption areas, making it possible to lower transportation costs and distribute fresh produce. But there are also challenges. RAS farms consume vast amounts of energy, require costly indoor spaces and have continuous and substantial operational requirements. Furthermore, their investment costs are high.

With this in mind, some have been rethinking whether RAS farms could become smaller and more accessible, not just to big companies with significant capital but also to ordinary people.

Cutting edge of small RAS
The coastal region of Shonnan near Tokyo is home to one innovative start-up that may have a solution. CSO and co-founder of ARK Inc., Yosuke Kurihara, has been pioneering a smart, sustainable land-based seafood farm in the area since establishing his company in 2020. His solution is a closed circulation system that supports off-the-grid aquaculture with solar power generation and a solar hot water supply. But most importantly, it helps clients cultivate aquaculture anywhere.

A closer look of vannamei shrimp raised in an ARK unit (Photo: ARK INC.)

“One major issue with RAS is that it’s a very centralized system,” said Kurihara. “If it’s not done on a large-scale, it doesn’t make a profit, so those who can get involved tend to be individuals or companies with a lot of capital who can invest at once. Of course, this is indispensable, especially in future when we will have to feed a population of nearly nine billion, but I wondered whether there was a way to farm fish or shrimp in various locations using a smaller system. This is what we are focusing on at ARK – small distributed closed recirculating aquaculture systems that are able to farm a variety of different species and in which anyone can get involved.”

ARK’s units are about 10 square metres and cleverly designed to fit in a parking spot. They can grow fish, shrimp or seaweed in any location, and come with a tank that can contain around 7.3 tons of water. The units have everything that a species needs to survive. Sensors are in place to measure water supply and quality, while an Internet connection allows farmers to see what is happening inside their units in real-time.

An automated feeding system makes it possible to feed fixed amounts at certain times, while parameters such as water temperature, oxygen levels and nitrate can be measured regularly. There are also cameras installed underwater so that everything happening in the tanks can be seen with the naked eye, while farmers can download data from their units using an app and receive notifications accordingly.

Thanks to solar power generation, which removes the need to heat the water and run up high energy costs, the units also save a considerable amount of energy, said Kurihara. They can also run without any external energy supply for 24 hours with lithium ion batteries.

Letting the ocean rest
Kurihara is optimistic that one day his units will bring fresh seafood to cities, the countryside and to communities, if ARK Inc. can create an industry in which the units can generate a significant amount of produce.

ARK-V1 at Ryukyu University (Photo: ARK INC.)

In the long term, he believes that land-based aquaculture will develop further in Japan and that new innovations like his will be key to an area of aquaculture that needs further investment and development to meet demand and become more sustainable.

Japanese consumers are also aware of issues such as the rising cost of seafood, declining numbers of fish that are making certain species unavailable and how the ocean is changing, he said. This has led to strong interest and demand in the country for ways to procure seafood without relying too heavily on fishing vessels or the ocean itself.

Kurihara believes that land-based aquaculture will play a significant role in ensuring that seafood-conscious consumers like the Japanese can continue to enjoy fish, shellfish and more.

It’s also a way of letting the ocean “rest,” and guaranteeing that future generations will be able to reap its benefits, said Kurihara.

“Through our units, we are aiming to give the ocean a break, or let it rest,” he said. “Land-based aquaculture is one way to slowly reduce activities at sea. It’s impossible to say please stop fishing from tomorrow or please stop offshore farming but we can, at least, ease the pressure on the ocean by introducing more land-based activities. This will help to ensure that the bounties of the ocean survive in future and are enjoyed by the next generation. Our units can also help others, such as fishermen who are suffering from decreased catches and a resulting lower income, by providing them with an opportunity to try land-based aquaculture. We receive many enquiries every year and the vast majority are from people who want to try farming fish or shellfish on land. We hear from former fishermen, restaurant owners and fisheries cooperatives.”

RAS for recovery and resilience
On a cold Friday afternoon, life for millions changed in a few minutes when northeastern Japan was struck by one of the most powerful earthquakes in recorded history on March 11, 2011. The damage from the earthquake and resulting tsunami, as well as from the accident at the Fukushima Daiichi nuclear power plant soon afterwards, forced hundreds of thousands to evacuate their homes.

ARK Inc. marine biologist, Joris Jeursen and Yosuke Kurihara, co-founder & chief science officer (Photo: ARK INC.)

Twelve years on, and the region looks very different, with the combined efforts of professional reconstruction teams, local residents and support from the international community making a huge impact towards returning life to normal.

Kurihara’s RAS units have been involved in this reconstruction thanks to a partnership between ARK Inc. and JR (Japan Rail) East Japan. Through the partnership, work is underway in Namie station, Fukushima prefecture, to rear shrimp and sell them under the name Namie Shrimp.

Although reconstruction in the area is over, Fukushima prefecture continues to live with the aftermath of the nuclear accident and the impact on its reputation, which is delaying economic recovery and impacting tourism. Together with ARK Inc., JR East Japan has been investigating ways to revitalize Fukushima’s economy and rebuild the prefecture by using rail infrastructure to create a base for food production and distribution.

“Seafood is an important product in Fukushima but local fishermen are still suffering, not only because of the nuclear accident but also because of the upcoming release of treated water into the Pacific,” said Kurihara. 

“Together with JR East Japan, we felt that land-based aquaculture could help the area rebuild by offering a new seafood product that is farmed away from the ocean in a controlled environment and is unique to Namie. If it can also provide employment to fishermen who have lost work because of the reputation of their seafood, that’s a huge source of support. Our units can be installed very easily but their production volume is still low, so we hope that the number of users increases over time and we can install more. We are delighted that land-based aquaculture can take root in Fukushima in this way, and we want our units to be a way of gaining a new income, creating an industry, and in more simple terms just helping.”

Looking forward, Kurihara summed up the importance and need for collaboration and the sharing of knowledge in the RAS sector.

“Further improving our RAS units will depend on the extent to which we can work with those in other regions,” he said. “There is a lot of RAS-related knowledge in Europe, for example, a lot of large-scale projects, expertise, research and technical innovations, and working with academia, research organizations and companies is something that we are very keen to do in future. Collaboration and sharing experiences are critical. I am also optimistic about the focus and value of RAS in Japan and around the world, and I believe that there is room for our work to grow.” 

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