Keeping farmed salmon healthy
Salmon farming is a lucrative industry for several northern European countries, including Norway, Scotland and Ireland among others. The health of salmon, and consequently the health of the industry, is threatened by Pancreatic Disease (PD). Recent research has shed light on the alpha virus responsible for salmon PD and has sparked interest in developing screening procedures and vaccines. Intervet Norbio, a Norwegian company specialising in aquaculture and disease prevention, received funding from the Fifth Framework Programme to work on salmon PD. They injected various isolates of PD into pre-smolt Atlantic salmon and monitored them closely, along with a control group, for the following five months. Analysis of blood and tissue samples provided valuable insight into PD pathogenesis. Significant variation was observed between isolates, but also within groups infected with the same isolate. Overall, the Norwegian subtype 3 PD proved to be more virulent than the Irish subtype 1, both in terms of duration and lesion development. Until now a useful tool for detecting the disease has not been available, but Intervet Norbio successfully applied real-time Reverse Transcription Polymerase Chain Reaction in this respect. They also uncovered evidence of the possibility of a PD carrier state. Finally, the results of this research effort are to be used in the development of vaccines to protect future generations of farmed salmon against PD.