Feasibility and challenges of Recirculating Aquaculture Systems

On Wednesday May 6th at 9:00, Otso Kalle Sinisalo will defend his master´s thesis in Coastal and Marine Management at the University Centre of the Westfjords. The thesis presentation is open to the public on the University Centre YouTube Channel due current COVID-19 outbreak restrictions in place in Iceland.

The thesis is titled, “Feasibility and challenges of Recirculating Aquaculture Systems (RAS) in rainbow trout (Oncorhynchus mykiss) post-smolt production in the coastal subarctic Finland.”

The thesis advisor is Markus Kankainen, M.Sc. Research Scientist at Luke Natural Resource Institute Finland. The external reader is Dr. Ólafur Ögmundarson, Adjunct Lecturer at the Faculty of Food Science and Nutrition, University of Iceland.


Due to the strict national environmental legislation and as a mitigation measure for aquaculture nutrient emissions, the Finnish National Aquaculture Location Management Plan (NALMP) is pushing rainbow trout aquaculture production in offshore units. The coast, however, has only a limited smolt production capacity with hardly any growth prospects with traditional cultivation methods. The situation has created high demand for post-smolt that can eventually be cultivated to slaughter size during the short subarctic growth season.

This study aims to determine how seasonality challenges and affect the feasibility of recirculating aquaculture systems (RAS) in rainbow trout (Oncorhynchus mykiss) post-smolt production in the northernmost coast of Finland. Through a comprehensive literature review and aquaculture expert interviews, challenges in RAS post-smolt production were identified. Based on the findings, different post-smolt production scenarios were created to combine RAS post-smolt production with offshore open net pen food fish production. The production planning was based on a unique growth model developed specifically for rainbow trout by the Author. Finally, a feasibility analysis was executed for different production scenarios.

The results indicate that cultivating rainbow trout post-smolt in a recirculating aquaculture system can be economically feasible in Finland. Self-cultivated RAS post-smolt can not only decrease the post-smolt cost but can also provide better smolt delivery reliability and time savings for the offshore operator. Additionally, a RAS facility can lower the nutrient emissions from the post-smolt production and provide food fish for summer markets when there is scarcity of cultured fish. Further research is required to identify proper acclimatization methods before transferring post-smolt form RAS to sea. Additionally, further research endeavours should be focused on validating and verifying the growth model determined in this thesis as well as investigating how well RAS post-smolt from domestic or imported eyed-eggs grow in offshore sites compared with one another. Finally, this work should inspire readers on out-of-the-box thinking when it comes to RAS production planning.

Otso Kalle Sinisalo defends his master´s thesis on the feasibility and challenges of recirculating aquaculture systems in post-smolt production.