Recirculating land-based aquaculture (RAS)
Recirculating Aquaculture Systems (RAS) is a method of land-based aquaculture. Fish species produced in RAS include salmon, sturgeon, tiger pufferfish, and shrimp.
In recent years, salmon farms have been attracting attention due to the ease of controlling the breeding environment, the ease of stable supply, the relatively small amount of wastewater, and the small impact on the surrounding environment. In 2022, the world's largest trout salmon RAS (annual production of 9,000 tons) will be established.*1In Japan, Norway's Proximar Seafoods is building one of the largest land-based salmon farms in the country at the foot of Mount Fuji, with shipments scheduled to begin in 2023 (planned annual production of 6,300 tons).*2.
Because RAS requires equipment to control various aspects of the rearing environment, such as water temperature and water flow (see the diagram below), IoT and AI are increasingly being used to monitor the condition of the fish and changes in the environment, helping to optimize the rearing environment (smart aquaculture).
From "The Fundamentals and Issues of Circulating Land-Based Aquaculture" (Provided by Hiroyuki Yoshino, Hakodate Regional Industry Promotion Foundation)
There are many benefits to recirculating land-based aquaculture.
・By controlling the rearing environment, such as water temperature, growth is promoted, feed efficiency is improved, and stable production is possible.*3
・ Wastewater can be utilized (e.g. aquaponics)*3
・Since it can be produced without using natural water, there is no invasion of pathogens and the occurrence of infectious diseases can be prevented, so antibiotics are not used.
・The production history of fish and shellfish raised at aquaculture farms can be recorded (traceability).
In addition to the above, the work is less strenuous because it is done on land, and there is no risk of predation.*4No fishing rights are required, so the barriers to entry are low*4This is also cited as an advantage.
On the other hand, there are also disadvantages and points to note.
・High running costs, including capital investment and electricity bills*5
・There is a risk of total destruction if equipment breaks down due to a disaster, etc.*5
・If the number of entrants increases, there is a risk that thorough management of environmental conservation will become difficult.
In addition, there are only a limited number of fish species that can be farmed, and some are difficult to fully farm.*6, and mechanisms to ensure safety (certification, inspection, etc.) are not fully in place.*7There are also disadvantages such as:
There are several points to be aware of in terms of sustainability when it comes to land-based recirculating aquaculture. For example, the impact on the surrounding ecosystem must be considered when selecting a site for building aquaculture facilities. The amount of water pollutants contained in wastewater is several times greater than that contained in the seafood produced. One solution to reduce the release of substances into the natural environment is to use these substances as fertilizer and practice aquaponics, which grows crops and seaweed. Furthermore, the electrical energy used to regulate the temperature and power the equipment in aquaculture facilities accounts for approximately 4%*7 of the total cost, and considering the CO2 generated during production, the use of renewable energy is necessary.
*1 Firm foundations laid for world's biggest trout RAS (Fishfarmingexpert, 2022/8/29)
*2 Norwegian company to farm Atlantic salmon in Shizuoka using land-based recirculating system, 24 tons by 6300 (Minato Shimbun, 2021/2/9 issue)
*3 About land-based aquaculture (Japan Aquatec Co., Ltd.)
*4 What are the advantages, disadvantages and challenges of land-based aquaculture? (FISH-NETA! ~ Fish Neta, July 2023, 7)
*5 What is land-based aquaculture? A summary of land-based aquaculture technology venture companies (Social Good Catalyst)
*6 Land-based salmon farming: current status and challenges (Salmon Life, June 2023, 6)
*7 The basics of land-based aquaculture! Explaining methods, equipment, and costs (Matsui Corporation, July 2021, 7)
Supervisor: Associate Professor Masato Endo, Department of Marine Biological Resources, Tokyo University of Marine Science and Technology
