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Otervika site manager Rolf Skjærvø, from SinkabergHansen, at the cage edge. Photo: SinkabergHansen/Tom Lysø.
Otervika site manager Rolf Skjærvø, from SinkabergHansen, at the cage edge. Photo: SinkabergHansen/Tom Lysø.

Two submersible pens in which salmon are kept 30 metres below the surface for the duration of their stay have been stocked for the third and final time in Norway.

Fish with an average weight of between 1.5-2kg have been placed in the Atlantis Subsea Farming development project pens at the Otervika facility on the border between Nordland and Trøndelag. There are 170,000 fish in each pen.

This is the first time that fish of this size have been put in the pens. One of the aims of keeping the fish at that depth is to keep them below the lice layer, and therefore lice-free. A submerged air dome allows the fish to refill their swim bladders.

A drone photo of an Atlantis pen being submerged at Otervika after being stocked with 170,000 fish. Click on image to enlarge. Photo: Tina Oldham / Institute of Marine Research.
A drone photo of an Atlantis pen being submerged at Otervika after being stocked with 170,000 fish. Click on image to enlarge. Photo: Tina Oldham / Institute of Marine Research.

Autumn harvest

Atlantis Subsea Farming is owned by salmon farmer SinkabergHansen, industry equipment supplier AKVA Group and AKVA’s biggest shareholder, Egersund Net.

The fish, from both Atlantis and SinkabergHansen, will remain in the submersible pens until harvesting this autumn. When the fish has been harvested, the project will be evaluated and conversion of the development permit to a permanent licence will be considered.

The fish were in good health and virtually free of lice when stocked. The lice development will be closely monitored by the Aquabyte automatic lice counting system.

Air dome

“The fish quickly calmed down after release and we are now closely monitoring swimming speed, behaviour and feeding. The fish will learn to use the air dome to fill the swim bladder and get used to life at depth,” said project manager Trude Olafsen.

“There has been a fantastic effort from the entire project team to prepare everything for the release - not least from those who work at the site.”

The facility is rigged with four submersible pens to gain experience with several pens at one frame mooring. Based on the experiences from previous rounds, technical changes have been made to the cable and control system, buoys and air dome.

Fish with an average weight of 1.5-2kg being stocked in one of the Atlantis cages. Photo: SinkabergHansen/Tom Lysø.
Fish with an average weight of 1.5-2kg being stocked in one of the Atlantis cages. Photo: SinkabergHansen/Tom Lysø.
One of the Atlantis cages being submerged to a depth of 30 metres. Photo: Tina Oldham / Institute of Marine Research.
One of the Atlantis cages being submerged to a depth of 30 metres. Photo: Tina Oldham / Institute of Marine Research.