A recent study by the Pacific Salmon Foundation reveals that viral heart disease is more prevalent in open-net salmon farms in British Columbia than previously acknowledged. The research, published in the Aquaculture journal, identified heart and skeletal muscle inflammation (HSMI) in five out of seven open-net pen salmon farms in the Broughton Archipelago. The study also highlights the potential for the disease-causing virus, piscine orthoreovirus (PRV), to spread to wild fish in the surrounding waters.
Lead author Emiliano Di Cicco emphasized that the incidence of the disease is significantly higher than previously believed. Previous findings had suggested a lower prevalence, but the new study challenges this notion. Di Cicco’s team’s earlier research in 2017 had identified the disease in one out of four farms, indicating a broader issue than initially perceived.
The study examined 749 salmon, with nearly seven percent showing signs of HSMI across the farms. While the role of PRV in causing HSMI had been uncertain in the past, recent experiments by Norwegian researchers have established a clear link. The disease can lead to various health issues in Pacific salmon, including anemia, inflamed hearts, damaged livers and kidneys, and jaundice when infected with PRV.
Di Cicco is urging the Department of Fisheries and Oceans (DFO) in British Columbia to reconsider the classification of PRV as non-pathogenic. He advocates for aligning diagnostic criteria for the disease with international standards, arguing that the current criteria may overlook the presence of the disease due to its chronic and low-level nature.
The DFO has stated that it will review the study’s findings and incorporate them into future work. While acknowledging the detection of viruses in farmed fish, the DFO emphasized the need for scientific rigor in evaluating the impacts on wild salmon populations. The agency defended its diagnostic criteria for HSMI, developed in collaboration with scientific experts to meet global standards.
The B.C. Salmon Farmers Association has not yet responded to requests for comment on the study. This industry group has previously dismissed concerns about PRV as “fearmongering,” asserting that the virus is common, relatively benign, and widely distributed in marine environments. Industry representatives highlight the economic significance of salmon farming in British Columbia, providing high-paying jobs and accounting for the majority of Canada’s salmon production.
The study was conducted in collaboration with the Mamalilikulla, ʼNa̱mǥis, and Ḵwiḵwa̱sut’inux̱w Ha̱xwa’mis First Nations. Indigenous leaders expressed their longstanding concerns about salmon health and ecosystem well-being, emphasizing the importance of supporting salmon populations in the region. They called for increased efforts to protect the ecosystem and the vital role of salmon in their cultural heritage and environmental balance.