The next level of fish farming

The TracStar® iSeries has officially arrived in Norway. And it’s being used for an exciting new type of fish farming.

Bluegreen Fusion AS, McElroy’s Scandinavian distributor, is part of a team pioneering the “marine donut,” a closed-system fish farm that provides supreme fish quality with minimal environmental footprint. The butt fusion for piping systems for the donut are being performed using McElroy equipment.

Like its name suggests, the marine donut is an underwater, enclosed donut-shaped structure that houses a fish farm. It prevents the fish from escaping, while also preventing contamination and minimizing the risk of disease, algae, and sea lice. Because it’s fully enclosed, breeders have full control over the fish and their environment.

Once constructed, the outer portion of the donut will stand 57.5 feet (17.51 meters) tall, with a 48-foot (14.64 m) tall inner portion. Its total diameter, including the jetty, will be 180 feet (55 m). In all, it has a 22,000 cubic meter capacity.

The exterior of the marine donut is built to withstand high exposure to both waves and currents.

The main structure is made of HDPE and acts as a barrier against the external environment, with floating pipes at the top and bracing pipes at the bottom. Vertical ballast tanks on the side allow the system to be raised or lowered. A working platform is situated on top of the donut.

The donut provides a flow system that exercises the fish. The flow itself can be adjusted, depending on the breed – for example, a river-like current can be provided for salmon, with fine-tuned pressure, dimensions, and geometry to best mimic the fish’s natural environment.

When complete, this marine donut will be able to hold 1.100 metric tons of biomass.

Because the donut protects from parasites and disease, the fish’s overall health is improved, leading to lower mortality and less downtime.

The Norwegian Directorate of Fisheries, a Norwegian government agency that promotes sustainable management of marine resources, has issued development licenses for the marine donut concept, noting that the project contributes to solving several environmental and area challenges facing the commercial fish farming industry. The project, the agency added, involves new and “significantly improved” production technology.