by Mette Cristine Schou Frandsen, communications adviser for OxyGuard International, Denmark


Early maturation, disastrous events that kill entire stocks, off-flavors, construction flaws and red figures on the bottom line: the media is full of stories like this. Critiques say that land-based Recirculating Aquaculture Systems (RAS) are dead.

In the early days of the wind turbines, experts considered the venture a failure. They stated that there was no future for wind power. The same was the case for refrigerators, smartphones and space travels. They were wrong. We only know this because someone did not listen and kept developing, improving and believing in their innovation.

It takes time to introduce entirely new technology and methodology. There will be bumps along the way, and it is expectable – and acceptable. Today, frontline companies are paving the way, taking the risk and they dare to make the mistakes others will learn from and thereby grow.

We have been looking through the list of failed RAS companies and we have evaluated disastrous events, re-calculated flows and loads and extrapolated technological development that can support RAS.

Our conclusion? There is a bright, promising future for land-based RAS – as long as we are willing for them to accept that it takes time to develop and implement such complex innovation in their sector.

Main challenges one-by-one

We have done a short walk-through of the main challenges and possible solutions faced by land-based RAS below.

• Mass die-offs

We can read about these unfortunate and dramatic events once a year in the media, that are always followed by plummeting stocks and blooms of negative articles on the future for RAS.

A major part of these events are caused by hydrogen sulphide (H2S) formed under anaerobic conditions in the biofilters and/or pipe system where sludge can be accumulated and released to the production water during cleaning or reinforced water flow.

H2S formation is often associated with drops in nitrate concentrations (Nitrate keeps hydrogen sulphide in check following this reaction: 5H2S + 8NO3- -> 5SO42- + 4N2 + 4H2O + 2H+).

How to prevent it? It is easy to minimise the risk considerably.

First, we should build these facilities in units with separated water flow ensuring that for example, that H2S released from the filters does not affect the entire stock.

Second, the maintenance protocols must be kept within a strict frame of operational procedures. As much as possible should be automated digitally to prevent human errors.

In the end, mass die-offs are a management problem - not caused by bad management, but by lack of both practical and theoretical experience in the sector and by immature management protocols. RAS units are highly technological and complex production facilities possibly too complex to run without modern digitalisation tools and automation of procedures.

We strongly believe the mass die-offs will become history only, in a very short timespan.

• Off-flavour caused by Geosmin and MIBs

As the technology matures, so does our knowledge on water quality and the water matrix development over a production period.

The first step towards removing the challenges with off-flavours is to gain complete control over the water matrix. Part of the challenge can be overcome simply by optimising the cleaning capacity for the recirculation water. This removes part of the challenge.

The next step is to implement new technology in the water treatment systems.

Today off-flavours can be removed with ozone and within the near future it might be possible to do bio-degradation of the substances using selected bacterial strains of Chryseobacterium sp., Sinorhizobium sp. and Stenotrophomonas sp.

The final solution to the off-flavour challenge will probably be a mixture of water treatment using ozone, filters, skimmers and increased control over the bacterial communities both within the water and the filters.

• Early maturation – a multifactorial challenge

Numerous factors are influencing the time of maturation for and solving the challenge with early maturation which will take a multi-factorial effort.

The growth conditions in RAS must be optimised for late maturation.

First of all water quality and water matrix should be optimised and this takes sensors, monitoring systems and digitalization. As we say in OxyGuard – do not spend billions on concrete and save a buck on the technology that will determine the operational success of your farm.

We need to access data on all the parameters of influence – their correlation of feedback systems. This knowledge must be collated into management procedures. With the introduction of digitalisation and strong algorithms such as AI and machine learning, it will soon be possible to draw information across all these factors and develop guidelines for production based on this.

Choose your digitalisation tools with care! Besides improving production methodology, both sex and genetics play a large role. Some subspecies are genetically better in these production systems than others.

• Energy consuming factories – when it cost a billion to make a million

Yes, RAS comes with steep energy costs affecting the environmental footprint of the production. To make RAS feasible both economically and environmentally this must be addressed.

Small improvements can be done through facility design, for example not keeping equipment that produces heat in water that must be kept cold, and optimising water flow.

However, the long-term solution will be to introduce renewable energy. This will take RAS high up on the ladder of environment-friendly protein production.

On a general note, RAS could become one of the world's most efficient ways to produce good healthy protein. By bringing fish on land and growing them in enclosed enclosures we gain full control over all inputs and outputs. We could, in theory, reuse every single molecule from these facilities, thereby creating an almost perfect food production system, seen from an environmental point-of-view.

• RAS – a business in the red

Closely tied to the above challenges are the economical disadvantages of RAS. Often economy is the ultimate argument when critiques explain why RAS will never be a success.

As for today, they seem to be right.

RAS facilities are struggling with establishing profitable production. The expenses are high and often the amount of produced fish is low – giving a high per kg price. But this is not a law of nature. The economy is struggling for many reasons; reasons that have solutions as pointed to in the above challenges. Solving these challenges will make RAS a good business option both for the economy and for nature.

We have our heads deep in the task of trying to deliver the needed technological innovation that will solve current and upcoming challenges. We strongly believe in land-based RAS until someone gives us a significant reason not to!? We do not expect everything to be in place and perfect at this point. It wouldn't make sense. wnd as Aristotle said, We have to learn by doing.

About the Author

Mette Cristine Schou Frandsen (1976) holds a Masters Degree in Biology and a PhD degree in environmental science from the University of Copenhagen, Denmark. Prior to her academic career, she was educated as a farmer on Ladelund Academy of Agricultural Business. She is the founder of the Danish innovation platform Future Foods (now part of the national organisation World's Best Food) and have been working with food security and sustainable food production for more than five years. Currently she is employed as a communications adviser for OxyGuard International.

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