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 study, published in the Aquaculture journal, identified the presence of heart and skeletal muscle inflammation (HSMI) caused by the piscine orthoreovirus (PRV) in five out of seven open-net pen salmon farms in the Broughton Archipelago.
The research team, led by Emiliano Di Cicco, emphasized that the disease can spread into the surrounding waters, potentially infecting wild fish. This finding contradicts earlier assumptions about the disease’s prevalence in these fish farms.
Open-net fish farms along the British Columbia coast have long been a topic of controversy, especially regarding the transmission of diseases from farmed fish to wild salmon. Previous research in 2017 by Di Cicco and colleagues had detected HSMI in one of the four farms studied at that time, indicating a need for further investigation.
The study revealed that approximately seven percent of the 749 examined salmon across the farms exhibited signs of HSMI. While the role of PRV in causing HSMI was uncertain a decade ago, recent experiments by Norwegian researchers established a definitive link between the virus and the disease.
Despite the Department of Fisheries and Oceans (DFO) classifying PRV as non-pathogenic, Di Cicco urges the government to reclassify it as pathogenic. He also advocates for aligning the diagnostic criteria for HSMI with international standards, as current criteria may overlook cases of the disease due to differing evaluation methods.
DFO has announced its intention to review the study’s findings and incorporate them into future assessments. The agency emphasizes that detecting a virus or disease in farmed fish does not automatically imply negative impacts on wild salmon populations.
The study was conducted in collaboration with the Mamalilikulla, ʼNa̱mǥis, and Ḵwiḵwa̱sut’inux̱w Ha̱xwa’mis First Nations. Indigenous leaders, such as Rick Johnson and Don Svanik, have expressed their concerns about the impact of open-net pen salmon farms on salmon populations, emphasizing the need to protect these vital resources.