Parasitic sea lice are one of the main
causes of economic loss in farmed Atlantic salmon, but the effect of host genetic
diversity on sea lice loads is unclear. We examined the association between genetic
diversity at neutral and immune-related loci and sea lice in farmed Atlantic
salmon sampled at two production life stages. Sea lice loads increased with
time spent in sea cages and was also influenced by diversity at MHC-related loci,
but not by diversity at neutral loci. Our study suggests that consideration of immune-related
genes could help improve selective breeding for sea lice resistance in farmed
salmon.