Abstract
Pancreas disease ( PD ) in N orwegian salmonid aquaculture has traditionally been caused by salmonid alphavirus ( SAV ) subtype 3. Following the isolation of a novel SAV subtype in 2010, marine SAV 2, two separate endemic areas have developed. It has been debated whether disease outbreaks due to marine SAV 2 result in milder clinical manifestations compared to outbreaks caused by SAV 3. The aim of this study was to descriptively investigate site‐level differences in the clinical manifestations of marine SAV 2 and SAV 3 at N orwegian seawater sites diagnosed with PD in 2012. The findings suggest that N orwegian PD outbreaks caused by marine SAV 2 result in lower mortality and milder clinical signs compared to outbreaks caused by SAV 3. For sites without reported PD ‐related mortality, there was no difference in the mortality levels between sites infected by marine SAV 2 and SAV 3. The results also indicate that there are no differences in grading quality at slaughter between the SAV subtypes.