Atlantic salmon genes influencing resistance to salmon lice (Lepeophtheirus salmonis)

This project aims to investigate the potential for identifying molecular markers linked with differences in susceptibility to infection with salmon lice. These may be used to assist a selective breeding programme to reduce susceptibility of farmed Atlanti c salmon to infection with salmon lice. This will be achieved by establishing (through salmon lice challenge experiments) susceptible and resistant Atlantic salmon families for two different year classes of the main Norwegian farmed Atlantic salmon strain s (held by the industrial partner Aquagen). MHC genetic variation will be screened in resistent and susceptible families in order to investigate potential connection between genetic variation of these loci and variation in susceptibility to infection with salmon lice. In addition, the relative importence of the immune system in the salmons defence against salmon lice infection will be investigated by comparing infection levels in susceptible and rsistent families receiving cortisol (i mmune suppressed) and placebo inplants. Finally, a repeat infection challenge will be carried out in order to investigate the stability over repeated infections of differences in susceptibility to infection at the individual and family level. This will be to investigate the stability of the parameter by which usceptible and resistant salmon families may be judged by.