Novel tools and knowledge for a future with no lice infestations in Norwegian aquaculture

The overall aim of this project is to identify naturally produced compounds that are associated with Atlantic salmon susceptibility and resistance to two parasitic sea lice species that are of major concern because of their effects on fish welfare and to develop tools that can be applied to boost Atlantic salmon resistance and reduce lice infestation in Norway. We have previously established that there is substantial genetic variation in susceptibility to lice infestation within farmed Norwegian Atlantic salmon populations and also detected some compounds released by the skin of Atlantic salmon that are associated with this variation. However the mechanisms triggering the release of these compounds, and their underlying genetic basis is still unknown. This project will identify host-specific compounds associated with susceptibility to lice parasitisation, test whether measurement of these compounds could provide an accurate and more ethical phenotype (without challenge testing) for breeding to boost resistance, identify and test feed additives that could potentially block production of attractant compounds or boost mucosal secretion of compounds repelling lice and test for additional effects on the reproductive capacity of the lice and its epidemiology that might be derived from breeding for resistance. The research objectives and results of this project will integrate with those of a separate research project funded by FHF, and utilise results from our previous projects, to enhance genetic improvement with selective breeding and prioritise candidate genes for manipulation via feed additives to produce salmon with full or high resistance. Outcomes will include improved fundamental knowledge of lice resistance mechanisms and development of tools that can be applied to boost genetic and non-genetic resistance to sea lice.

The overall aim of this project is to identify compounds (semiochemicals) that are associated with Atlantic salmon susceptibility and resistance to the parasitic copepodids Lepeophtheirus salmonis and Caligus elongatus and to develop tools that can be applied to boost Atlantic salmon resistance and reduce lice infestation in Norway. We have previously established that there is substantial genetic variation in susceptibility to L. salmonis within farmed Norwegian Atlantic salmon populations and also detected some compounds released by the skin of Atlantic salmon that are associated with this variation. However the mechanisms triggering the release of these compounds, and their underlying genetic basis is still unknown. This project will identify host-specific semiochemicals (kairomones that attract and/or allomones that deter lice) within the Atlantic salmon population associated with the level of lice parasitisation, test whether measurement of semiochemical production could provide an accurate and more ethical phenotype (without challenge testing) for breeding to boost resistance, identify and test feed additives that could potentially block semiochemical attractant production or boost mucosal secretion of semiochemicals repelling lice and test for additional effects on the reproductive capacity of the lice and its epidemiology that might be derived from breeding for resistance. The research objectives and results of this project will integrate with those of a separate research project funded by FHF, and utilise results from our previous projects, to enhance genomic selection and prioritise candidate genes for manipulation via feed additives to produce salmon with full or high resistance. Outcomes will include improved fundamental knowledge of lice resistance mechanisms and development of tools that can be applied to boost genetic and non-genetic resistance to sea lice.