Sea lice control

Sea lice are naturally occurring in the ocean, and have been feeding on wild salmon for millennia. Salmon farms, with high fish density, provide good conditions for sea lice to multiply. Therefore, it is essential that salmon farmers work continuously to control sea lice.

High levels of sea lice, especially when the vulnerable wild salmon smolt are passing farms on their way from the rivers to the ocean. may affect the health and possibly the survivability of wild salmon. They can also impact welfare of our farmed salmon. It is our responsibility to avoid impacting wild salmon with sea lice.

Controlling sea lice is the single biggest challenge that the salmon farming industry faces. Grieg Seafood’s main approach is to control sea lice preventatively, and by using as few treatments as possible. Preventative sea lice control, gives better fish welfare as well as an lower environmental impact.

Fundaments to our preventative sea lice control strategy is:

• Breeding
  When available, we use roe from salmon that has proven resistant to sea lice. When further developed, it is likely to be an important part of future sea lice control.
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  Post smolt
  With post smolt, we will reduce the time that the fish is exposed to sea lice in the sea, which will improve our ability to keep sea lice levels low without treatments. Initial findings from Rogaland indicate that post smolt reduces the number of sea lice treatments needed.
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  Creating barriers
  If suitable conditions, we use sea “lice skirts”, to prevent the sea lice from entering our pens. Most sea lice live down to seven meters below the ocean surface. Sea lice skirts are specialized tarps that we put around the pens 10 – 15 meters down from the ocean surface. We see good effect of this measure on some farms, but have to ensure that oxygen levels behind the skirt are not impacted.
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  Cleaner fish
  In some areas, we use cleaner fish that naturally eat sea lice on the salmon. The cleaner fish has proven effective on some farms, but we recognize that the health and welfare of cleaner fish must improve.
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  Area Based Management
  With Area Based Management, all farms in one area fallow at the same time. In some regions, this is an important measure to remove all sea lice and also diseases connected to salmon farms within a fjord system, and has helped us reduce the number of sea lice treatments over the last years.
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  Digital tools to control sea lice
  We take part in artificial intelligence projects, which aim to be able to predict sea lice levels in advance and use preventative methods in cases of outbreaks.
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  Treatments
  If preventative measures are not enough, we use mechanical treatments, such as fresh water, to avoid affecting the environment. The methods are selected when conditions are favorable. Only as a last resort do we use medical sea lice treatments, and always in compliance with the strict regulations.