Deep thinking

Subfarm pictured with Sevan SSP feed barge

Norway’s Subfarm plans to take salmon farming to new depths – and exciting new locations – as Robert Outram reports

The ocean is wide. Despite that, however, competition for marine space is growing. As fish farmers increasingly look to deeper, more exposed locations, they are vying for the prime spots with the catch fishing sector, oil and gas operators and, more than ever, the renewable energy industry.

It makes sense, then, to team up with other marine users where possible, and look for ways to co-locate fish farms with other types of infrastructure. That is the thinking behind a collaborative project announced earlier this year involving Freja Offshore, a joint venture between energy businesses Mainstream and Hexicon, and the Norwegian company Subfarm.

The initiative aims to establish a fish farm inside the proposed 2.5 GW Mareld offshore wind farm, in Swedish waters 40 kilometres west of Lysekil.

The fish farms will be placed between the wind turbine platforms, and they will be anchored with their own mooring system. The submersible fish cages will be lowered to a depth of 50-70 metres and hoisted up to the surface position for checks and harvesting. They would then be transported by ship to land.

Lysekil Municipality, the research institute DHI and the Norwegian industrial cluster Blue Maritime Cluster are also involved in the collaboration.

Sweden’s Västra Götaland region needs to triple its electricity production in the coming years to meet energy demand, and offshore wind will play a key role in this. At the same time, wind power must be able to coexist with other important interests, not least the fishing industry and sea-based food production.

“Seafood and offshore wind power are two industries that Sweden will need more of in the future, that’s why we want to find ways for these two industries to co-exist,” says Magnus Hallman, CEO of Freja Offshore.

So who are Subfarm? The Norwegian company has been working since 2018 to develop submersible sea cages for locations where conventional surface-based net-pens are unsuitable.

Karl Strømsem, Paal Hylin, Morten Lyssand

Karl Strømsem, Paal Hylin, Morten Lyssand

The three founders of Subfarm – Karl Strømsem, Paal Hylin and Morten Lyssand – have worked together for some time developing technology, initially with Global Maritime Group.

They had first-hand experience helping to create one of the most well-known offshore salmon farming projects, SalMar’s Ocean Farm 1.

Then, as the co-founders of technology start-up Noerd, they started working on what they believe is a less expensive, simpler solution to the offshore question: submersible fish cages.

Chief Technology Officer Morten Lyssand explains: “In exposed locations or even just offshore, being on the surface is harsh for the structure, the net and the fish.”

Being placed below the surface protects the structure from waves and storms. Recent research also suggests that, at greater depths, salmon are less exposed to sea lice and jellyfish. A further advantage is that deeper water is much more stable in terms of temperature. This means that salmon could thrive in warmer climates such as the Atlantic coast of Span and Portugal, or even the Mediterranean.

Lyssand says: “In Portugal, for example, if you go below 40 metres you will find temperatures of 14-15ºC all year round. So you can open up new areas.”

The submersible cages can be co-located with a floating wind farm

The submersible cages can be co-located with a floating wind farm

Portugal was chosen as the first location for a trial of the technology, in collaboration with Jerónimo Martins, the country’s biggest food retail group. The project came to an end in 2020 with the onset of the Covid-19 pandemic, with the team having gained some valuable experience.

As CEO Paal Hylin puts it: “We learned what we cannot do!”

The next step was to create two new companies: Subfarm, to develop the submersible cage system, and Open Ocean Farming, to put the new technology into practice with a commercial farming operation.

Working with Norway’s Sea Technology, one of Subfarm’s investors, Subfarm has now built a one-tenth scale prototype and is now working on a full scale pilot system, for testing off the Norwegian coast.

The revised system is a fully submersible cage, designed to remain underwater for the majority of the time. An air dome will allow the salmon to refill their swim bladders without have to swim to the surface. Feed will be distributed from a specially designed feed barge (the design for the barge was developed in collaboration with Sevan SPP). Feed distribution will use a water-pumped system – which as Paal Hylin points out, uses less energy than blowing feed using an air pump.

Subfarm anticipates the submersible farms would be remotely operated, controlled from the shore and monitored using underwater cameras.

Morten Lyssand says: “You don’t need people walking around the cage anymore, it’s ‘precision farming’. You can count the fish with cameras and have a good view of the biomass inside the cage.”

Subfarm submersible cage

Subfarm submersible cage

This model would be more expensive than the typical net-pen used in inshore waters, but considerably less costly than the large offshore structures that have been developed in the past few years.

Subfarm has a twofold business model: in established salmon farming regions, it aims to sell its cages as a turnkey solution for established producers; while in new areas, it would seek to farm on its own account, probably in collaboration with established aquaculture businesses.

The first location selected for the latter is Croatia, where Subfarm is applying for licences to farm in the Adriatic.

So, when could all this happen? Lyssand says: “The timescale depends on equity, as we are a start-up company, but if we pushed the button tomorrow, we could have a prototype ready for sea trials in five to seven months.”

The Subfarm team believe they are, for now anyway, ahead of their larger competitors in terms of this technology. And they are convinced that the time is right for it, if the salmon industry is to meet the growing demand for its product.

As Paal Hylin puts it: “To grow more salmon, we need to go offshore, and to go offshore, we need to go submerged”.


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