A recent study by the Pacific Salmon Foundation revealed that viral heart disease, specifically 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, east of Port McNeill on Vancouver Island. The study highlighted that the disease-causing virus, piscine orthoreovirus (PRV), has the potential to spread to wild fish in the surrounding waters.
Lead author Emiliano Di Cicco emphasized that the occurrence of HSMI is significantly higher than initially believed based on previous studies. This finding challenges the existing perceptions about the prevalence of the disease in open-net fish farms along the British Columbia coast, which have been a subject of ongoing debate due to concerns about disease transmission from farmed fish to wild salmon.
The study, involving the examination of 749 salmon by three independent pathologists, revealed that nearly seven percent of the analyzed fish exhibited signs of HSMI. While the link between PRV and HSMI was uncertain a decade ago, recent experiments by Norwegian researchers confirmed the connection, indicating that Pacific salmon can suffer from various health issues when infected by PRV.
Di Cicco urged the Department of Fisheries and Oceans (DFO) in British Columbia to reclassify PRV as a pathogenic virus and align the diagnostic criteria for HSMI with global standards. He highlighted discrepancies in the current diagnostic approach used by DFO, stating that the disease is recognized globally as a chronic, low-level condition that may not always present with observable symptoms or significant mortality spikes.
In response to the study, DFO stated its commitment to reviewing the findings and incorporating them into future assessments. The agency emphasized that the diagnostic criteria for HSMI were developed in collaboration with leading scientific experts to ensure scientific rigor and alignment with international standards.
The collaboration between the researchers and local First Nations communities, including the Mamalilikulla, ʼNa̱mǥis, and Ḵwiḵwa̱sut’inux̱w Ha̱xwa’mis, underscores the importance of salmon to Indigenous peoples in British Columbia. Community leaders expressed gratitude for the scientific validation of their concerns regarding the impact of open-net pen salmon farms on wild salmon populations and the marine ecosystem.