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Eight years ago the Pacific Salmon Foundation embarked on a partnership with DFO and Genome BC to better understand how infectious agents were affecting the health of wild salmon. Naturally, this touched on the contentious topic of salmon farming, and the disease risk it might pose to wild fish. There was general suspicion that open-net-pen aquaculture operations were contributing to salmon declines, but the issue lacked scientific clarity. Research from that partnership has confirmed that open-net-pen salmon farms do indeed pose a risk due to the transfer of parasites and disease-causing pathogens between wild and farmed salmon. The findings prompted PSF to take a clear position that salmon farming needed to transition away from operating in the water where wild salmon and hatchery stocks could be affected. Since then our findings have informed decisions to phase-out open-net-pen operations in the Discovery Islands and the Broughton Archipelago – both major migration routes for salmon. And in 2020, the federal government announced their commitment to transition away from open-net-pen facilities by 2025 – a commitment that was again reflected in the recent federal budget.
PSF pens letters to P.M. and B.C. Premier regarding Sea Lice and Discovery Islands
In August, PSF wrote letters to the Prime Minister and B.C. Premier regarding alarming unnatural sea lice loads on out-migrating Pacific salmon in Discovery Islands. The letters reiterate the PSF position that in the absence of strong proof otherwise, and given the current state of many salmon populations in southern BC, government should immediately and significantly reduce the number of open-net pen salmon farms in the Discovery Islands and Johnstone Strait. The letters also outline a five-point plan to encourage a transition to closed containment salmon farming in British Columbia. PSF wrote the letters to add support for the concerns and objectives expressed in a recent open letter from a co-operative group of commercial and recreational fishing organizations, religious organizations, marine tourism operators, environmental groups, and First Nations.
Salmon farms and salmon disease are a contentious topic in BC because we are passionate about our wild salmon. In the scientific community, there is also a strong belief that disease may be a significant factor in salmon mortality, but not enough is known about what disease agents might affect Pacific salmon in their natural habitats.
Click Here to access 2020 findings from the Strategic Salmon Health Initiative (SSHI) related to Piscine orthoreovirus (PRV) in British Columbia.
View the full publication list for the Strategic Salmon Health Initiative here: Click Here
Learn more about the project and Genome BC:
Models informed by a decade of infection data in juvenile Chinook salmon sampled during early marine residence has revealed that temperature is the most significant driver of infection, with exposure to aquaculture, proximity to freshwater, age at ocean entry, hatchery or wild origin, stock, and latitude associated with a more limited number of pathogens.
Models are also beginning to resolve the pathogens most closely correlated with year-class strength, some transmitted in freshwater, and others in the early marine environment. Climate warming is a major factor for salmon to contend with. Impacts can directly cause stress in salmon, but also indirectly impact prey availability and predator distributions, as well as disrupting the natural balance between pathogens and their hosts.
Research from the SSHI was published September 3, 2019 in the online journal eLife. Three newly discovered viruses—including one from a group of viruses never before shown to infect fish—have been found in endangered Chinook and Sockeye salmon populations. The impact of these viruses on salmon health isn’t yet known, but we do know that two of the viruses impact the same tissues in salmon as other species, and cause serious diseases in those species. Of note, two of the three viruses were found in wild salmon, one was observed in hatchery facilities and all three were associated with Chinook aquaculture. The paper raises questions about whether these viruses are contributing to declines in wild Chinook and sockeye stocks. Further research is required to understand the full implications of these findings.
Prior to these findings, an outbreak of Heart and Skeletal Muscle Inflammation (or HSMI) was found via the SSHI in fish from one farm. The lesions in the fish are the same as those previously identified by the same histopathologist in farm audit samples collected from farms during 2011-2013. The HSMI finding was formally reported to the industry and Fisheries and Oceans Canada as per the scientific protocol for the project and announced by Fisheries and Oceans Canada – click here for the release. As HSMI is not an OIE reportable disease, it was not reported to the Canadian Food Inspection Agency. A slide presentation on the HSMI finding can be viewed here.
Dr. Kristi Miller (Saunders) is an aquatic molecular biologist with expertise in genetics, genomics, transcriptomics, immunogenetics, and fish health, with research on Pacific and Atlantic salmon spanning 27 years. Fisheries and Oceans Canada; University of British Columbia (adjunct).