Marine Donut

Marine Donut is a cost-efficient floating closed containment system for fish farming. It provides supreme fish quality with minimal environmental footprints. It enables completely new and profitable production strategies.

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Marine Donut is a donut-shaped closed fish farm. It prevents escape and contamination, and minimizes the risk of disease, algae and sea lice. The need for antibiotics and other medicines and preparations is significantly reduced. As a breeder, you get full control over the fish and the environment through digitization and monitoring. You also have good control over the efficient feed factor, which further reduces costs.

Fish welfare

Marine Donut is a flow system that exercises the fish, where the flow can be adjusted according to the breeder's desire. This recreates the environment that the salmon experiences in the rivers. The dimensions and geometry are designed the way the salmon likes best and with the right pressure in terms of depth. The design provides good fish density throughout the facility - not just the upper part.


Marine Donut is the result of engineering at its best. A pilot plant has been tested in the pool at SINTEF and it is now ready for commercialization. Mowi ASA has been granted two development licenses by the Norwegian Directorate of Fisheries exclusively for the Marine Donut concept. The facility is tailored to fit and utilize the expected licensing and production regime of the future, and can be used for the production of both post-smolt and market fish.

In the letter of commitment, the Directorate of Fisheries writes: - As a result of the concept being able to contribute to solving several of the environmental and area challenges facing the industry, the Directorate of Fisheries considers that the project involves new and significantly improved production technology.

How it works:

Marine Donut consists of a closed breeding unit shaped like a donut (torus). The main structure is made of High Density Polyethylene (HDPE) and acts like a tight barrier against the external environment to prevent lice infestation and infection into the plant. Marine Donut has floating pipes at the top and bracing pipes at the bottom in addition to vertical ballast tanks on the sides. This allows the system to be raised and submerged. On top of the facility, there will be a working platform. The plant has a solution for collecting sludge as well as inlets below the sea lice belt. Marine Donut is designed to withstand high exposure to both waves and currents. It is just as suitable for breeding yellowtail kingfish in the tropics as salmon and trout in colder waters.

1 Marine Donut can hold 1.100 MTB (metric tons of biomass).

Marine Donut can be used in these Production Strategies

Production Strategy 1

A Marine Donut is used for post-smolt for 1,000,000 fish up to 1.1 kg. These are then transferred to five Marine Donuts with 200,000 fish each. There, the fish grows up to 5.5 kg.

Production Strategy 2

A Marine Donut is used for post-smolt for 1,000,000 fish up to 1.1 kg. These are then transferred to five cages with 200,000 fish in each. There, the fish grows up to 5.5 kg.

Production Strategy 3

In areas with a large lice infestation, Marine Donut can work well for the last phase, where the fish grows from about 2.5 kg to 5.5 kg.

Production Strategy 4

Marine Donuts can also be used throughout the production phase from smolt to ready-to-slaughter fish.

Production Strategy 5

Marine Donut is a good alternative for producing post-smolt for off-shore fish farms.

Production Strategy 6

The flexibility of Marine Donut means that it will also work well as a pre-slaughter cage.

Available research results indicates that Marine Donut will give:

Improved production strategy - increased profitability and fish health.
No lice treatment.
Better feed conversion ratio and the possibility of collecting sludge.
Better water quality – increased fish welfare – less disease.
Less mortality – better fish health.
Less «downtime» / more efficient maintenance.
Escape proof.
Increased fish density due to control and monitoring.
Reduced production time / flexibility / optimization.

Nils-Johan Tufte

Partner / CEO

Email E-mail

Phone +47 48 30 48 35

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