Briefing on PRV impact paper
On May 7, 2018 a scientific paper was released on the impact of piscine orthoreovirus on Chinook salmon was released. Dicicco et al 2018, provides critical information for everyone trying to pull the southern resident orca back from extinction.
https://scirate.com/arxiv/1805.01530
In summary, a highly contagious Norwegian virus infecting 80% of BC farm salmon is causing Chinook salmon red blood cells to burst with catastrophic impact on their survival.
Introduction to PRV in British Columbia
Piscine orthoreovirus (PRV) was discovered in Norway 2010.[1] By then 30 million Atlantic salmon eggs had entered BC without screening for this virus. PRV is highly durable, capable of spreading long distances in seawater[2]. The science on PRV is rapidly emerging and in BC we have learned that PRV is Norwegian,[3],[4] it spreads to wild salmon when they are exposed to salmon farms throughout BC,[5] it is causing disease in BC farm salmon,[6] 80% of BC farm salmon are infected[7] and PRV-infected wild salmon are exhibiting reduced success swimming upriver to spawn[8],[9].
What we didn't know until the release of Di Cicco et al (2018) is whether PRV is causing disease in Pacific salmon.
Federal scientists are the leads on the paper. The Canadian government is arguing in Federal Court that PRV is harmless. Section 56 of the Fisheries (General) Regulations prohibits transfer of fish carrying a disease agent into Canadian waters.
Marine Harvest admits that 5/6 of their hatcheries are infected and that their industry would be “severely” impacted if they were prohibited from using PRV- infected fish.
Di Cicco et al. 2018 key findings
There is only one strain of PRV in BC, PRV-1, which was first described in farm salmon in Norway[10]. The BC and Norwegian strains of PRV-1 are 99.7% identical, and where the genetic sequence differs, is in the region of the RNA that controls virulence.
PRV infection targets the salmon’s red blood cells (RBCs) and the impact on the host fish depends on how these cells respond. PRV converts the RBCs into “viral factories”[11] to replicate itself. In Atlantic salmon, which co-evolved with the virus, the virus leaks out of the cells, relieving pressure and causes heart and skeletal muscle inflammation (HSMI), critically weakening the fish. Farm salmon, protected from predators can heal and regain the ability to swim.
However, Di Cicco et al. (2018) report that in Chinook salmon, PRV causes the red blood cells to burst “en masse” when the virus load becomes too great for the cells to contain. This results in a release of haemoglobin and its iron content (heme) kills the liver cells that are trying to clean this up. As the liver cells become damaged and die, yellowing of the liver occurs and in extreme cases the skin of the fish becomes jaundice. Liver and kidney failure and death are one of the outcomes of this chain reaction. As well, the massive reduction of RBCs causes anemia in the fish, which is expected to significantly reduce oxygen uptake and hence lower the fish’s performance and substantially elevate direct and predator-mediated mortality. A fish in this condition will also be ill prepared to ascend rivers to spawn, particularly through canyons such as Hells Gate in the Fraser River.
Di Cicco et al. (2018) provide no information on other Pacific salmon. This work was conducted in the Creative Salmon farms in Clayoquot Sound, who invited Miller’s lab to research their fish because they were unable to figure out why their Chinook farm salmon were turning yellow and dying. Salmon farms are ideal experimental environments for research into the impact of virulent pathogens, because they hold schools of fish in wild salmon habitat, while excluding predators, which are known to rapidly remove weakened fish[12], making it nearly impossible to study disease progression in wild fish.
Government handling of PRV in British Columbia
In 2007, government veterinarians and scientists created a novel diagnostic method for the disease HSMI caused by PRV in Atlantic salmon. The international scientific community studying PRV use PRV-specific lesions to diagnose HSMI[13], but the BC industry and provincial government fish farm veterinarians added a behavioural component to the diagnosis in 2007. This method relies on industry to provide the behavioural component of the diagnosis[14]. Marine Harvest co-published a series of papers with a provincial veterinarian 2014 – 2016 suggesting PRV is harmless and endemic in BC, without revealing that they had altered the diagnostic for PRV[15]. Had Marine Harvest et al. used the published PRV diagnostic, PRV would have been classified as a “disease agent” in BC in 2010[16].
In 2017, Di Cicco et al (2017) examined the same fish farm as the provincial vet, and while the provincial vet did not diagnose HSMI, Di Cicco et did[17].
In 2015, I won a lawsuit that ruled that the Minister of Fisheries must screen farm salmon from PRV prior to issuing a permit to transfer the fish from hatcheries on land into sea pens. Minister of Fisheries, Dominic LeBlanc, refuses to acknowledge legal decision and so I have filed a second lawsuit.[18] The ‘Namgis’ First Nation of Alert Bay also filed last month against the Minister of Fisheries and Marine Harvest to stop transfer of PRV – infected fish into their territory. These cases will be heard in September.
Document production during these lawsuits includes information that 5/6 of Marine Harvest’s Atlantic salmon hatcheries are infected with PRV and they state the salmon farming industry would be “severely” impacted if they lost the Minister’s permission to bypass the law and transfer PRV infected farm salmon into fish farms on wild salmon migration routes.
Summary
80% of BC farm salmon are carrying a highly contagious, Norwegian virus that is being released into marine waters from the Salish Sea to central Coast BC that is causing Chinook salmon’s cells to rupture en mass. The virus has been detected in the Nass and Skeena Rivers as well, but at much lower prevalence. Given the collapsing state of wild Chinook salmon that spawn in heavily farmed areas, such as Clayoquot Sound and the Broughton Archipelago, this finding suggests that significant, rapid relief could be provided to wild Chinook salmon populations if the Minister of Fisheries upheld the laws of Canada, screened all farm salmon prior to transfer and prohibited transfer of farm salmon smolts from infected hatcheries into Canadian marine waters.
All salmon farm provincial tenures in the Broughton Archipelago of North-eastern Vancouver Island will expire on June 20, 2018, and while this is outside southern resident orca habitat, if these farms are removed, we would be able to observe the impact of this on wild chinook salmon populations in the 7 major rivers of the archipelago.
PRV has also been detected in herring, trout, all species of salmon, oolichans and mussels. Impact on these species is unknown. Di Cicco et al (2018) report ongoing research on other species with the powerful research tool, rapid Viral Disease Detection (VDD) that can quickly assess presence/absence of a disease state in wild salmon.
6 Minute video on spread of PRV in BC: https://vimeo.com/258135790
[1] Palacios et al. 2010 Heart and Skeletal Muscle Inflammation of Farmed Salmon Is Associated with a Novel Reovirus. PLoS ONE. 2010; 5:
[2] Palacios et al. 2010 Heart and Skeletal Muscle Inflammation of Farmed Salmon Is Associated with a Novel Reovirus. PLoS ONE. 2010; 5:
[3] Kibenge et al. 2013. Whole-genome analysis of piscine reovirus (PRV) shows PRV represents a new genus in family Reoviridae and its genome segment S1 sequences group it into two separate sub-genotypes. Virol J. 10: 230–250.
[4] Kibenge et al. 2017 Formal comment on: Piscine reovirus: Genomic and molecular phylogenetic analysis from farmed and wild salmonids collected on the Canada/US Pacific Coast. PLoS ONE 12(11):
[5] Morton et al. 2017 The effect of exposure to farmed salmon on piscine orthoreovirus infection and fitness in wild Pacific salmon in British Columbia, Canada. PLoS ONE 12
[6] Di Cicco E, Ferguson HW, Schulze AD, Kaukinen KH, Li S, Vanderstichel R, et al. (2017) Heart and skeletal muscle inflammation (HSMI) disease diagnosed on a British Columbia salmon farm through a longitudinal farm study. PLoS ONE 12(2)
[7] http://marineharvest.ca/globalassets/canada/pdf/other-pdfs/piscine-reovirus-prv-information-sheet_gary-marty_2013.pdf
[8] Miller et al. 2014 Infectious disease, shifting climates, and opportunistic predators: cumulative factors potentially impacting wild salmon declines. Evolutionary Applications. 7:812-855.
[9] Morton et al. 2017 The effect of exposure to farmed salmon on piscine orthoreovirus infection and fitness in wild Pacific salmon in British Columbia, Canada. PLoS ONE 12
[10] Palacios et al. 2010 Heart and Skeletal Muscle Inflammation of Farmed Salmon Is Associated with Infection with a Novel Reovirus. PLoS ONE. 2010; 5:
[11] Wessel et al. 2015 Piscine orthoreovirus (PRV) replicates in Atlantic salmon (Salmo salar L.) erythrocytes ex vivo. Veterinary Research (2015) 46:26
[12] Bergh Ø. The dual myths of the healthy wild fish and the unhealthy farmed fish, Dis Aquat Organ. 2007; 75: 159–164.
[13] Biering, E, and Garseth, ÅH. 2012. Heart and skeletal muscle inflammation (HSMI) of farmed Atlantic salmon (Salmo salar L.) and the associated Piscine reovirus (PRV). ICES Identification Leaflets for Diseases and Parasites of Fish and Shellfish, Leaflet 58. 6p.
[14] http://alexandramorton.typepad.com/alexandra_morton/2018/04/briefing-for-chief-scientist-of-canada-hsmi.html
[15] Marty, G. D., Morrison, D. B., Bidulka, J., Joseph, T. and Siah, A. 2014. Piscine reovirus in wild and farmed salmonids in British Columbia, Canada: 1974-2013. Journal of Fish Diseases, 38: 159-164.
Siah et al. 2015 Piscine Reovirus: Genomic and Molecular Phylogenetic Analysis from Farmed and Wild Salmonids Collected on the Canada/US Pacific Coast. PLoS ONE :10
Garver et al. 2016. Piscine Orthoreo- virus from Western North America Is Transmissible to Atlantic Salmon and Sockeye Salmon but Fails to Cause Heart and Skeletal Muscle Inflammation. PLoS ONE. 11
[16] http://alexandramorton.typepad.com/alexandra_morton/2018/04/briefing-for-chief-scientist-of-canada-hsmi.html
[17] Di Cicco E, Ferguson HW, Schulze AD, Kaukinen KH, Li S, Vanderstichel R, et al. (2017) Heart and skeletal muscle inflammation (HSMI) disease diagnosed on a British Columbia salmon farm through a longitudinal farm study. PLoS ONE 12(2):
[18] https://www.ecojustice.ca/pressrelease/minister-of-fisheries-and-oceans-sued-for-putting-wild-salmon-at-risk/