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Marine Donut for closed-system salmon farming at sea

Marine Donut is a new, escape-proof technology for closed or semi-closed fish farming at sea. Once fully developed, it will produce premium quality salmon with a minimal environmental footprint.Published 22 Nov 2022 (updated 7 Feb 2024) · 2 min read

Fish farming can be an important part of the solution for feeding a growing global population. The industry helps to provide seafood without the risks of overfishing.

The growing aquaculture industry, however, is facing many challenges, including disease, sea lice, waste and other threats to local ecosystems. To increase the volume of produced fish while reducing the associated problems, new technology is needed.

Closed-system fish farming

Bluegreen Technologies has created the Marine Donut, a submerged closed or semi-closed system for farming salmon. The facilities have a deep-water intake to ensure optimal water quality, while at the same time disposing waste inside a closed loop.

The shape of the system offers a good hydrodynamic flow pattern and gives the fish the opportunity to continuously swim against the current.

The closed system, moreover, gives fish producers complete control of the farmed fish and its surroundings. This means that sea lice can be avoided, and that any disease outbreaks will not spread to nearby areas.

The Marine Donut is particularly useful for the latter stages of fish production, in the period before slaughter, as the largest fish are most susceptible to sea lice, as well as regular fish cycles.

Concrete benefits

The Marine Donut could contribute to more sustainable fish farming through improved fish health and reduced environmental impact. The system features comprehensive sludge treatment, efficient feed factor and well-organised logistics – preventing sea lice, fish escapes and local pollution and facilitating the production of high-quality salmon.

Market potential

The global market for closed-system fish farming is expected to grow dramatically over the next years in parallel with improved cost-efficiency and smarter logistics.

The Marine Donut concept is owned by Bluegreen Technologies and is currently being developed by Mowi Norway.

At a glance

  • Concept for closed-system fish farming at sea
  • Gives producers complete control of the fish and its surroundings
  • Prevents fish escapes and pollution, while improving fish health and quality

Solution status

Under development

The solution is a concept, prototype, close to piloting, or the like.



Asdalstrand 171, 3962 STATHELLE, Norway


Nils-Johan Tufte


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