Salmon lice

Salmon lice are external parasites on salmonids in the marine environment. They occur naturally on wild salmonids in the North Atlantic and North Pacific oceans. The effect of of salmon lice on wild salmonid populations are potentially problematic in areas with intensive fish farming activity.

Lakselus. Foto © Kari Sivertsen/NINAHigh salmon lice levels cause problems both for farmed and wild salmonids.  Photo © Kari Sivertsen/NINA

As the salmon farming industry has grown, the infestations of salmon lice have multiplied in coastal areas with aquaculture. Salmon lice infestations can result in increased susceptibility to disease, reduced growth, and increased mortality in host fish. Favourable conditions for the salmon lice ahead of the smolt migration may intensify the infection pressure at this critical stage for Atlantic salmon. At the same time sea trout and Arctic charr may experience a prolonged increase in infection pressure.

NINA has worked with issues related to salmon lice since 1992. We have established a good collaboration with the aquaculture industry and the  management authorities, and we collaborate with other research institutes in several projects related to this issue.     

Current research:

  • Monitoring salmon lice infestations in wild, and farmed salmonids
  • Tolerance thresholds in salmonids in relation to salmon lice infestations (field and laboratory tests)
  • Population effects of salmon lice on salmonids
  • Risk analyses of the interactions between lice in aquaculture and on wild fish
  • Optimal siting of salmon farms in relation to populations of wild salmon 

Salmon lice, sea trout, and Atlantic salmon

The salmon louse is an external parasite found naturally on wild salmonids. The increased pressure of salmon lice infestations on wild fish over recent years has lead to extensive, negative consequences, especially for sea trout. This film describes NINA’s monitoring of salmon lice on wild salmonids in the summer of 2014.