Full-scale trial for electric fence that protects fish from lice and jellyfish
Harbor Fence will be installed for a year at two Cermaq salmon farms in northern Norway
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The innovative Norwegian company Harbor is to install electric fences around the pens at two of salmon farmer Cermaq's locations in Finnmark, to evaluate the technology's effectiveness in preventing harm to fish from sea lice and string jellyfish (Apolemia uvaria).
The Harbor Fence generates a protective electromagnetic field around a pen.
"This field is created by using special electrode cables that are 10 metres deep and that hang on the outside of the cage under the floating collar," Harbor Fence head of biology and R&D Tarald Kleppa told Fish Farming Expert's Norwegian sister site, Kyst.no.
Fewer lice
Kleppa says that Harbor has worked closely with Norwegian research prganisations NORCE and SINTEF to validate the pulse technology against early-stage sea lice.
"The most important results from the research are that Harbor's pulsing technology significantly reduced new infestations as it immobilises the lice when they are in the infectious stage."
Immobilising the lice means they are unable to attach and develop further on the salmon. The electric fence is also supposed to have an effect on the string jellyfish, in that the electromagnetic pulse triggers the jellyfish's venemous stings.
"That means the poison is released before the jellyfish enters the cage and it can no longer harm the salmon," says Kleppa.
Doesn't harm salmon
The company has developed the technology so that it has a pulse pattern that does not affect salmon.
"This has also been central to the R&D work to ensure that fish health is maintained. As we have designed a special pulsation pattern that is only effective within a certain frequency, we have significantly eliminated the impact of the system on other creatures," says Kleppa.
The Harbor Fence hangs outside the cage and will not come into contact with the farmed fish. The developers of the system do not believe that either lice or jellyfish will be able to evolve to adapt to the electric shocks.
When the pearl jellyfish is hit by the current pulse, it shoots out its venom in self-defence. Video: Harbor Fence
Real-world testing
Harbor is now conducting a long-term study of over a year where the Harbor Fence system will be tested in the sea under real operating conditions. The project is funded by the Research Council of Norway, a state agency, and is being carried out in collaboration with the Norwegian Computing Centre and AquaLife R&D, which will conduct analyses and effect calculations to document the system's ability to reduce sea lice.
“An important element of the study is that we will turn Harbor Fence on and off for controlled periods. This will provide clearer data on how the technology actually affects sea lice levels, and ensure a scientifically rigorous evaluation,” says Kleppa.
He also thanks Cermaq for being an active participant in the project.
“Their commitment demonstrates a strong interest from the industry in innovative and sustainable solutions to the sea lice problem. This project will provide valuable insights that can help shape the future of aquaculture.”
