Risk assessment of 21 land-based aquaculture systems in Norway – what can be learned?
A new study presents a comprehensive risk assessment of 21 land-based aquaculture facilities in Norway from the RM (Risk Management) Akva-project using a standardized risk evaluation methodology developed by Akvaplan-niva, Norway. Facilities varied widely in age, technology (FTS, HYB, RAS), and production scale, with assessments focusing on technical and operational risk factors affecting fish mortality. The results showed no clear correlation between system complexity and overall risk. Instead, effective design, good operational routines, and built-in safety margins were key factors in reducing risk.
In recent years, the aquaculture industry in Norway has faced challenges related to undesirable events and mortality in land-based systems for Atlantic salmon. These incidents, which predominantly occur in land-based smolt production facilities but are also expected to occur in land-based facilities for larger salmon, pose serious concerns for fish welfare and may result in high mortality and substantial economic losses.
A workshop will be held in connection with this study at Aqua Nor (Wednesday, August 20, 9:30–10:30 AM). Location: Meeting room Munkholmen. Here there will be an opportunity to ask questions about the survey.
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To address these challenges, the industry is focusing on risk-reducing measures such as improved system design to avoid dead zones and particle sedimentation, as well as efforts to bridge the gap between planned production capacities and achievable production. The importance of technical assessments and risk evaluation in land-based aquaculture systems cannot be overstated, not only for ensuring operational efficiency and fish welfare but also for securing assets and enabling farmers to adequately insure their investments.
The insurance industry has an important interest in this area, recognizing the high value of both the facilities and the biomass they contain. The Norwegian insurance company Gjensidige, which is the owner of the RM (Risk Management) Akva-project, has contributed significantly to this field by sharing an extensive dataset from risk assessments of 21 land-based aquaculture systems from the The RM (Risk Management) Akva-project, all evaluated using a common standardized methodology developed by Akvaplan-niva, in colaboration with NIVA.
The primary objectives of these risk assessments and subsequent analyses are to reduce mortality, improve fish welfare, and mitigate economic risks. By increasing fish farmers' awareness of potential risks and enabling them to implement corrective measures, this approach aims to create a more resilient and sustainable land-based aquaculture industry.
Results
The assessments of 21 land-based aquaculture facilities, varying in size, technology, and water treatment intensity, revealed no consistent pattern linking increased complexity, water reuse, or specific system types (FTS, HYB, RAS) to higher overall risk. While more advanced systems like RAS were associated with greater operational complexity and production intensity, both low- and high-risk scores were observed across all facility types. Notably, the two highest and two lowest overall scores were found among facilities using RAS or FTS+RAS, demonstrating that effective risk management is achievable even in highly complex systems.
The somewhat high proportion of medium-risk scores among FTS facilities may reflect the influence of fewer departments, where isolated risks have a stronger impact on the overall average. RAS facilities, while more frequently linked to deviations in water quality, typically involved parameters expected to accumulate with water reuse, such as nitrogen compounds and metals. Low-risk outcomes in some RAS facilities were associated with robust system design, adequate treatment capacity, and strong operational routines.
System resilience also depends on design and operation. FTS facilities often rely on gravity-fed intake water, making them less vulnerable to power outages. RAS, with minimal use of intake water, are less exposed to external water quality issues but are more sensitive to internal failures. Mechanical breakdowns, sensor faults, or power loss can escalate rapidly due to their integrated nature.
Most facilities showed good redundancy and backup systems for critical resources like water, oxygen, and electricity. However, personnel at facilities with a longer operational history typically exhibited greater awareness and had progressively refined their practices over time. In contrast, higher risk was more common during start-up phases, implementation of new technologies, or shifts in production strategies, stages that require time to build system understanding and improve design.
The key risk factors related to water chemistry were more critical for the overall risk score in RAS facilities compared to FTS/HYB, because of the increasing complexity of water treatment and the accumulation of some compounds. The risk of H₂S production was higher in RAS and increased with more use of seawater, but our results also indicate that this risk can be mitigated by proper water treatment, good measurements and good routines, since several seawater RAS did not have problems with H₂S.
There were several mortality cases where H₂S was suspected as the cause. All of these cases were in facilities with MBBR systems and involved design and mixing issues causing particle accumulation. These observations highlights design and operational challenges with MBBR. However, it is often difficult to draw definitive conclusions in cases where H₂S may be involved, as suspicions are typically based on the exclusion of other plausible causes. These assessments are often supported by the absence of other abnormal parameters and the nature of the mortality pattern, which is usually acute and without clear clinical symptoms.
Finally, increased awareness around chemical use is needed. In many cases, chemicals were applied to resolve acute issues like particle buildup or foam, but all potential consequences were not adequately assessed. While chemical treatment may offer short-term relief, addressing root causes, such as improving solid removal or using physical foam control are generally a more sustainable and effective approach.
Acknowledgement:
The authors gratefully acknowledge Gjensidige Forsikring for funding this project and for providing the technical reports that form the foundation of this study.
The findings emphasize the importance of robust system design, informed operational practices, and continuous monitoring to ensure good fish welfare and reduce economic losses in land-based aquaculture.