The RAS 4.0 project, led by the Norwegian Food Research Institute Nofima, is designed to optimize recycling aquaculture systems to improve the welfare and productivity of Atlantic salmon. Here, Jelena Kolarevic, project manager and senior researcher at Nofima, explains more.

Jelena Kolarevic, senior researcher at Nofima

Aquaculture has undoubted potential to contribute to increasing the supply of protein to a growing world population. Recently, this is the fastest growing and most efficient way to produce protein for human consumption. Over the last 20 years, global aquaculture production has tripled from 34 to 112 million metric tons of live weight, and demand for aquaculture products is growing. Norwegian seafood production and exports have also increased in recent years. Today, Norway is the second largest exporter of seafood with 3.1 million metric tonnes of seafood worth € 12.1 billion exported in 2021. Atlantic salmon is the most valuable and leading seafood export, accounting for almost 68% of total exports last year.

However, the sustainability of Atlantic salmon production and its performance in aquaculture has been monitored over the last few decades due to its potential contribution to the reduction of wild fish stocks worldwide. Namely, Atlantic salmon is a carnivorous species that requires the use of fish oil and fishmeal in its diet to manage its efficiency and well-being, which comes mainly from anchovies, herring and krill. These species have been strongly targeted by fishing due to the high demand for fishmeal and oil.

To meet the growing demand for sustainably produced food, efforts have been made to replace fishery products in salmon feed with alternative sources of protein, including plant proteins, microbial ingredients, algae and insects. This was done in parallel with extensive research on the effectiveness of feed and fish nutrition. As a result, the amount of fish oil and fishmeal in salmon diets has been reduced from 90% in the 1990s to 25% now.

Innovations in Norwegian aquaculture

Another challenge for sustainability for the Norwegian salmon industry in recent years is the management of pathogens and parasites during production. As of 2017, reported Atlantic salmon mortality is between 14.7-16.1% of total production, representing 54 million individuals in 2021. The control of salmon lice is the Achilles’ heel, which hinders desired production targets, increases operating costs, affects fish welfare and reduces profits for the salmon aquaculture industry.

Attempts have been made to limit the use of chemicals in the treatment of this parasite in order to prevent its acquired resistance and to reduce environmental pollution. Instead, large investments have been made in developing new technologies for degreasing fish or preventing contact between salmon and sea lice. Innovative new production technologies, such as aphid skirts for sea cages or floating semi-enclosed sea retention systems, have been developed and tested as methods to prevent lice infestation. Recycling aquaculture systems (RAS) have been used over the last decade as an effective solution for increased biosecurity and control of parasites and pathogens. At the same time, RAS provides probably a greener way to produce salmon.

In Norway, the use of RAS is due to the lack of fresh water, which would increase production in the salmon hatchery before the marine cage phase. However, problems with salmon lice, escapees and increased mortality have led to a change in regulations that have allowed long-term salmon production on land in fresh, salt and sea water. Currently, a number of salmon producers in Norway produce more fish on land in the RAS, followed by a shorter phase of seawater production. In this way, production at sea can be reduced to only seven months, and thus the need to use chemicals and other methods to control lice. However, RAS is the most expensive way to produce salmon in Norway, which is viable due to the ever-increasing operating costs of production in marine cells.

fish welfare
© 1 iStock / slowmotiongli-122

What are recycling aquaculture systems (RAS)?

RAS are terrestrial production systems that allow the reduced use of new fresh water by purifying and reusing process water from fish tanks. It is common for over 90% of RAS water to be reused, while small amounts of new water added daily are treated to varying degrees to prevent parasites such as lice and potential pathogens from entering. Extensive wastewater treatment from RAS facilities allows the collection of unused nutrients and their revaluation, creating value and reducing potential environmental pollution. RAS production can be placed close to the market, reducing the environmental footprint of transport and logistics, which is another reason why this technology is perceived as more environmentally sustainable. However, it is important to note that the high energy demand for RAS’s work undermines its potential for sustainability.

As part of RAS treatment, uneaten food and fish droppings are removed mechanically, while biological filtration is used to remove potentially toxic metabolites produced by fish, such as ammonia and nitrite. Gas exchange processes are necessary to enrich the water with oxygen and to remove carbon dioxide, providing fish with the necessary conditions for optimal growth.

It is often said that RAS provides fully controlled production conditions that can be tailored to the needs of farm animals. This can be done to control the temperature, oxygen and pH of the systems, along with water flows, water velocity and the addition of new water. However, fully automated control of key water quality parameters, such as ammonia, carbon dioxide, turbidity, then nutrition management and energy consumption, is still lacking.

At present, these key water quality parameters are measured manually as spot measurements, which serve as a basis for decision-making during daily operations. Fish are fed on the basis of calculated biomass in the systems, which can often lead to overfeeding and detonation of water quality or malnutrition, which leads to reduced welfare of the fish produced. Several water treatment processes are designed for maximum production capacity and cannot be optimized to reduce energy consumption when biomass is lower.

The main barriers to reaching the desired level of automation are the lack of reliable sensors to measure these key parameters and the lack of models describing the dynamic relationships between them. All these elements interact through complex biological / chemical / physical mechanisms that are not fully understood. Therefore, it is not enough to control or optimize one parameter at a time – to achieve this level of control in RAS requires a holistic model of the whole system.

RAS 4.0

In 2021, the Norwegian Research Council funded a four-year research project known as RAS 4.0 to provide biologically controlled automation with rapid response to RAS production conditions. This will be achieved through the integration of new sensor technology, data integration and intelligent algorithms for optimal control of the basic parameters of water quality, nutrition management and energy use. The main innovation will lead to the creation of new control loops within the RAS, focusing on the three aspects of focus: ozonation control, ammonia control, power control and control of energy consumption in daily work. By the end of the project, we hope to integrate new feedback loops into the work of RAS and to validate their work with the help of digital twin RAS and empirical testing.

RAS 4.0 is a collaboration between Nofima, project owner, NORCE research partners, UiT – Norway’s Arctic University and industry partners, technology providers Searis, CreateView, Pure Salmon Kaldnes, OxyGuard and Norwegian salmon producer Lerøy Seafood group.

The project draws on the experience of established technologies and know-how of industry partners in sensors, data standards and integration. Together with leading research partners in RAS technology, fish physiology, behavior, welfare, machine learning, data analysis, smart cameras and computer vision, we are working to develop smart digital approaches to connect and optimize some of the physical, digital and the biological aspects of the system.

The goal of RAS 4.0 is guided by the hypothesis that the optimization and control of production conditions based on biological engines in RAS will lead to improved welfare and productivity of Atlantic salmon. Intelligent feeding of fish according to the actual biomass and appetite will ensure optimal growth of fish and will minimize waste of feed. Intelligent water quality control will ensure stable environmental conditions during production, minimizing the potential for unforeseen episodes that can lead to reduced fish welfare and mortality. This will allow producers to use energy sources efficiently in accordance with production needs. These improvements will increase the environmental and economic sustainability of RAS production and reduce operational and investment risks.

Informative results

The RAS 4.0 project will create extremely valuable knowledge that can be used by aquaculture and industry providers working to maximize the sustainability of these operations. The technology providers in this project offer commercial products for fish monitoring or aquaculture operations and RAS or are suppliers of RAS. This project will catalyze their existing efforts to digitize and automate RAS and integrate their products in the best possible way into existing RAS operations.

For Atlantic salmon producers, optimal fish growth and welfare performance and efficient production are prerequisites for sustainable production. Automation is the next logical step in the development of RAS, which will allow them to maximize existing experience and learn from it. The ability to predict events during production based on data analysis is another aspect that is high on the wish list of manufacturers. Realizing the potential of the RAS will reduce the pressure to increase production at sea and provide increased investment in this important environmentally sustainable solution for fish production.

Jelena Kolarevic
Senior Research Associate

Please note that this article will also appear in the tenth edition of ours quarterly publication

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Recirculating aquaculture systems: Improving Atlantic salmon performance

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