Action: Breed for resistance traits
- A replicated, controlled study in Norway found increased survival levels in salmon exposed to infectious pancreatic necrosis when the family was bred for high resistance to the disease compared to a family bred for low resistance to the disease.
Atlantic salmon cultured in commercial farms are at risk of contracting and transferring infectious bacterial diseases and other pathogens. Selective breeding aims to increase resistance against infectious diseases which may spread within the salmon farm, from wild salmon to cultured salmon and vice versa.
Supporting evidence from individual studies
In 2005, a study comprised of two replicated, controlled trials was conducted in Norway (Storset et al., 2007). Both trials determined that families of salmon, Salmo salar, bred with high resistance to infectious pancreatic necrosis, showed higher survivorship compared to salmon bred with lower resistance. Mortality levels in fry were 29.3% and 66.6%, respectively. The unexposed controls were 1.0% and 3.2%, respectively. The same result pattern was observed in smolt (32.0% and 79.0% mortality levels, respectively). Salmon used in the experiment were offspring from the 2001 and 2004-2005 breeding seasons. Families were selected either for high or low resistance to infectious pancreatic necrosis. The first experiment used fry in fresh water. Groups of high resistance and low resistance fish were exposed through bathing. One group of each remained unexposed as the control. Mortality levels were observed between 30-50 days after infection.