A recent study by the Pacific Salmon Foundation 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 also highlighted the potential transmission of the disease-causing virus, piscine orthoreovirus (PRV), from farmed fish to wild fish in surrounding waters.
Lead author Emiliano Di Cicco emphasized that the incidence of the disease is significantly higher than previously believed. Previous research in 2017 by Di Cicco and colleagues detected the disease in one out of four farms, indicating a more widespread issue than initially recognized.
The study examined 749 salmon from various farms, with approximately seven percent showing signs of HSMI. While the role of PRV in causing HSMI was previously uncertain, recent experiments have solidified the link, according to Di Cicco. The virus can lead to various health issues in Pacific salmon, including anemia, inflamed hearts, damaged livers and kidneys, and jaundice.
Di Cicco urged the Department of Fisheries and Oceans (DFO) in British Columbia to reclassify PRV as a pathogenic virus, as it is currently considered non-pathogenic. He also advocated for aligning the diagnostic criteria for HSMI with international standards, as the current criteria used by DFO may overlook cases of the disease due to strict requirements.
In response to the study, DFO stated that it would review the findings and incorporate them into future assessments. The agency emphasized that the detection of a virus in farmed fish alone does not necessarily indicate negative impacts on wild salmon populations. DFO highlighted its collaboration with scientific experts in establishing rigorous diagnostic criteria for HSMI.
The B.C. Salmon Farmers Association did not immediately comment on the study’s findings. The association has previously dismissed concerns about PRV, calling it a common and relatively harmless marine virus.
The research was conducted in collaboration with the Mamalilikulla, ʼNa̱mǥis, and Ḵwiḵwa̱sut’inux̱w Ha̱xwa’mis First Nations. Indigenous leaders expressed gratitude for the scientific validation of their concerns regarding salmon health and stressed the importance of supporting salmon populations for both environmental and cultural reasons.
