A recent study by the Pacific Salmon Foundation has revealed that viral heart disease, known as heart and skeletal muscle inflammation (HSMI), is more prevalent in open-net salmon farms in British Columbia than previously acknowledged. The research, published in the Aquaculture journal, identified HSMI in five out of seven open-net pen salmon farms located in the Broughton Archipelago near Vancouver Island.
The study highlighted that the disease-causing virus, piscine orthoreovirus (PRV), can spread from farmed fish in the pens to wild fish in the surrounding waters. Lead author Emiliano Di Cicco emphasized that the incidence of HSMI is significantly higher than previously believed, challenging earlier assumptions.
The study examined 749 salmon across the farms, with nearly seven percent showing signs of HSMI upon evaluation by three independent pathologists. While the role of PRV in causing HSMI was once uncertain, recent experiments by Norwegian researchers in 2017 established the link between the virus and the disease, according to Di Cicco.
The researchers highlighted the detrimental effects of PRV on Pacific salmon, including anemia, heart inflammation, liver and kidney damage, and jaundice. Di Cicco urged the Department of Fisheries and Oceans (DFO) to reclassify PRV as a pathogenic virus and align diagnostic criteria for HSMI with international standards, as current standards in B.C. differ.
The DFO stated that it would review the study findings and incorporate them into future research efforts. While the DFO emphasized the rigorous scientific basis of its diagnostic criteria for HSMI, Di Cicco advocated for a broader understanding of the disease as a chronic, low-level condition rather than solely relying on observable symptoms or large mortality spikes for diagnosis.
The collaboration between the Pacific Salmon Foundation and First Nations communities, including Mamalilikulla, ʼNa̱mǥis, and Ḵwiḵwa̱sut’inux̱w Ha̱xwa’mis, underscored the importance of salmon to Indigenous communities in British Columbia. Leaders from these First Nations expressed their long-standing concerns about the impact of open-net pen salmon farms on salmon populations and the ecosystem, emphasizing the need for conservation efforts and support for wild salmon.
