These days marks the termination of an industrial controlled research project that has been a collaboration between the Institute of Marine Research and Aqua Gen. The project has had the following title: Atlantic salmon genes influencing resistance to salmon lice (Lepeophtheirus salmonis). The main conclusion is that it is more difficult to breed for resistance to salmon lice than for resistance to bacterial and viral infections.

When lice were counted on a population of 30 full-sibling families, moderate variation in mean lice infection per family were observed. However, a relatively small component of this variation (approx. 10%) is under genetic control. This means that whilst it is possible to increase the resistance of farmed salmon to salmon lice, the genetic response to a selection program for this trait is likely to be low to moderate.

Within the project experiments were also run looking at whether or not it is the same individuals within a single family that display the highest and lowest infection when challenged several times with lice. The experiments were run in both tanks and sea-cages. The results demonstrated that an individual’s infection in the first challenge was not a good predictor of its relative infection level in a subsequent infection. Consequently, it is difficult to identify individual fish displaying genuine resistance towards lice, and, the within family component of selection is likely to be unreliable as a result. A preliminary cost/benefit analysis indicates that including resistance to lice in the salmon breeding program is not necessarily the most efficient way to deal with salmon lice. This is discussed further in “Havforskningsnytt nr. 8 – 2005” ( http://www.imr.no/__data/page/5338/Nr.8_Lakselus_-_kan_vi_avle_fram_en_resistent_laks.pdf).   A more complete description of the project can be seen in the final report here.

The project has received external funding from The Norwegian Research Council.