Study Finds Viral Heart Disease More Widespread on B.C. Salmon Farms Than Previously Reported
New research published in Aquaculture has found that heart and skeletal muscle inflammation (HSMI), a disease caused by piscine orthoreovirus (PRV), was more widespread on B.C. open-net pen salmon farms than previously documented.
Researchers examined 749 farmed Atlantic salmon from seven farms in the Broughton Archipelago, diagnosing HSMI at five sites. Nearly seven per cent of the fish showed signs of the disease, verified by three independent pathologists. The research was conducted through the First Nations-led Broughton Aquaculture Transition Initiative.
The study also found that PRV levels in farmed salmon better predicted virus levels in surrounding waters than the number of fish diagnosed with HSMI. This suggests that monitoring disease alone may overlook the potential for farms to release the virus into the ocean.
PRV affects Atlantic and Pacific salmon differently. In B.C. Chinook salmon, previous research has associated the virus with jaundice and anemia. The authors are calling on Fisheries and Oceans Canada to reassess PRV’s ability to cause disease and its standards for diagnosing HSMI.
For Wild First, the findings reinforce the importance of reducing preventable pathogen exposure to protect wild Pacific salmon. Pacific Salmon Foundation