Background material for:
Discovery of variant of infectious salmon anaemia (ISAV) of European genotype in British Columbia, Canada
Kibenge, J.T., Iwamoto, T., Wang, Y., Morton, A., Routledge, R., Kibenge, F.S.B.,
Standard molecular tests (PCRs) developed in Norway, were used to screen 397 farmed salmon purchased from markets, 708 wild salmon caught throughout British Columbia (see map) and one sea louse for the infectious salmon anaemia virus (ISAV), a member of the influenza family.
This paper provides the first published scientific evidence that ISAV, the most feared salmon virus worldwide, is present in British Columbia, Canada.
The next steps include designing a test to better detect this variant of ISAV.
European ISA virus genetic material was identified in ~ 8% of samples.
Detection across all tests was three-fold greater in farmed fish (6.8%), than in wild fish (2.3%).
Phylogenetic analysis revealed the BC variant of ISA virus is closely related to European ISA virus strains found in the Atlantic salmon farming industry in Norway, Chile and elsewhere.
This ISAV variant is exceptionally difficult to detect because it carries a mutation in precisely the region of the virus that the standard tests are designed to target.
Like a lock and key, a slight variation in the lock makes it more difficult for the key to work. There are dozens of ISAV variations in salmon aquaculture and many PCR tests designed to detect them.
The study’s authors caution that they used what samples were available, i.e. farmed salmon from markets and wild salmon, but that to "confirm" ISA virus, as per Canadian regulations, access to live salmon in the farms will be required.
The findings of this study support unpublished Canadian government results released as exhibits by the Cohen Commission.
Cultus Lake - old problem, new evidence.
This paper provides important new insight into Canada’s most endangered Fraser River sockeye salmon population found in Cultus Lake. Government attempts to restore Cultus Lake sockeye including fishing bans, enhancement and habitat restoration have failed to restore Cultus Lake sockeye since 1995.
This study detected European ISA virus genetic sequence in 35% of the cutthroat trout that reside in Cultus Lake (see map), the highest rate of detection from any area in this study, 76% of trout overall.
This raises the question - is ISAV impacting Cultus sockeye and other BC wild salmon populations?
What this means to the USA
Wild salmon know no borders. US fish swim through BC waters and BC fish mingle with Alaskan salmon. A salmon virus found in BC may not stay in BC.
In the US a lawsuit has been filed against the US Environmental Protection Agency for allowing wild salmon to be put at risk from farmed salmon diseases.
Compares with other research.
Preliminary results from this study were released in 2011.
In response, the $37 million federal Cohen Commission into the decline of the sockeye salmon of the Fraser River reopened it doors for 3 days of hearings. As well, the Canadian Food Inspection Agency (CFIA) embarked on province-wide ISAV surveillance and the USA embarked on ISAV surveillance in Washington State.
Here is how the results compare:
The Cohen Commission uncovered ISAV test results in BC by Canadian government scientists, including in the Cultus Lake sockeye, farmed salmon and Fraser River sockeye. These results remain unpublished, but are similar to the findings reported in the newly published paper.
The CFIA completed two years of ISAV surveillance in BC, but they did not test Atlantic farmed salmon, they did not test for the newly discovered ISAV variant and did not report on what molecular tests they used, so the two studies are not easily compared.
The U.S. surveillance in Washington State also did not test for this variant of ISAV and did not use the same combination of tests as this study.
- The research team hopes to gain access to salmon farms to collect the samples required for Canada’s confirmatory test.
- A test will be designed and validated for this variant of ISAV.
- Cohen Commission recommendations # 11,12 and 13 state that access to farmed salmon health data, samples and monitoring results should be made available to government and non-government researchers.
- Wider testing of wild salmon stocks in trouble should be conducted for the BC variant of ISAV to better understand its role in the increasingly unpredictable wild salmon returns to BC. In Alaska, wild salmon returns continue to be predictable and abundant.
“I have been following this work for many years. ISA virus is a serious matter,” says Dr. Daniel Pauly, one of the world’s leading fisheries scientists based at UBC. “A member of the influenza family in open ocean feedlots is a risk Canada should not be taking.”
"The potential that viruses such as ISAV are contributing to widespread decline in sockeye salmon populations cannot be taken lightly," states co-author Dr. Rick Routledge. "The findings in this paper should lead to development of a more sensitive screening test for this specific virus. This opportunity needs to be pursued with vigour."
“Finding ISA virus genetic material in a sea louse in the Discovery Islands, a heavily salmon farmed region, significantly elevates my concern that the pathogen release from the open net farming industry is far more serious than anyone knows,” Dr. Craig Orr, Conservation Adviser, Watershed Watch.
"This is a difficult strain of ISAV to detect," says co-author Alexandra Morton, "it is easy to see how it was missed, but we have cracked its code, completed the test of science: large sample size, validated methods, peer review. It is critical that we learn from what happened to Chile. In my view, this work gives BC the opportunity to avoid tragic consequences."
A Brief History of ISAV.
Infectious Salmon Anemia, a member of the influenza family, is referred to as the most feared salmon virus in the world. First discovered in Norway in 1984, ISAV has spread globally through the Atlantic salmon farming industry, mutating periodically and causing massive mortality in farmed Atlantic salmon. There is no region where ISAV exists indefinitely without an outbreak of the disease.
ISAV in Chile
When accidentally introduced to Chile from Norway in Atlantic salmon eggs, the ISA virus lay dormant for many years without an outbreak. Then in 2007, a highly virulent strain appeared, HPR7b, that killed so many farmed salmon it cost the Chilean salmon farming industry $2b in damages. Chile has not successfully eradicated European-strain ISA virus. Chile does not have wild salmon and so impact was confined to the salmon farming industry.
ISAV in British Columbia
Unlike Chile, B.C. has significant wild salmon populations which means an ISAV outbreak could threaten commercial fishing, tourism, whale populations and coastal economies, in addition to the salmon farming industry and its shareholders.
30 million Atlantic salmon eggs have been imported to BC since 1986, (DFO). While there are no public reports of Atlantic salmon eggs entering BC directly from Norway, the domestic Atlantic salmon of choice in BC is the Mowi strain, which originated in Norway.
The authors of a 2003 study reporting that Pacific salmon are resistant to ISAV concluded the potential for this virus to mutate into a strain that can kill Pacific salmon is a risk: "the potential for ISAV to adapt to Oncorhynchus spp. should not be ignored." Study link
The ISAV evidence presented at the Cohen hearings include:
- Exhibit 1549 Province of BC Animal Health Centre - frequent reporting on “classic lesions associated with ISAV infection” in BC farmed Atlantic salmon
- Exhibit 2040 National Animal Health Lab, (DFO) Moncton, New Brunswick - weak positive results on Rivers Inlet sockeye salmon, a similar result on these samples as included in this paper
- Exhibit 2043 Pacific Biological Station (DFO) ISAV test results on adult Fraser River sockeye salmon,
- Exhibit 2053 Pacific Biological Station (DFO) ISAV test results for farmed Chinook salmon in Clayoquot Sound suffering from high mortality and severe jaundice
- Exhibit 2052 Pacific Biological Station genomic profiling results on BC farmed salmon tested for ISAV indicated an immune system influenza response
Corresponding author, Dr. Fredrick Kibenge chair of the Department of Pathology and Microbiology, Atlantic Veterinary College at the University of Prince Edward Island has been publishing on the ISA virus in Chile and Canada since 2004.
Lead author, Dr. Molly Kibenge is a research associate in the Department of Virology, Pathology and Microbiology and an Adjunct & Graduate Faculty member.
Dr. Yingwei Wang is an assistant professor with the Department of Computer Science and Information Technology
Toki Iwamoto is a Laboratory Technologist, University of Prince Edward Island
Dr. Richard Routledge is a professor in the Department of Statistics and Actuarial Science, Simon Fraser University and has spent 14 years studying the decline of the sockeye salmon in Rivers Inlet.
Alexandra Morton, independent field biologist with Raincoast Research Society has published extensively on sea lice impacts of net pen salmon farming.
Photos and Visuals:
The study area spans the length of the British Columbia coast and deep into the interior throughout the Fraser River watershed.
708 wild salmon were sampled from the green regions on this map. The red dots are salmon farms and the blue line is the largest wild salmon migration route in BC which passes through densely salmon farmed regions.
397 Atlantic farmed salmon and farmed steelhead were purchased from markets throughout British Columbia, in many cases just the heads.
Studies on ISA virus have not previously been restricted to obtaining samples from markets. All other published research had access to salmon in the farms.
Salmon found in markets generally exclude clinically diseased fish and are several days old, which is not optimal for testing.
Photo by Alexandra Morton
Dr. Rick Routledge has done extensive research to find out why the once abundant Rivers Inlet sockeye salmon have declined so much.
Photo courtesy of Rick Routledge
Alexandra Morton sampled farmed Atlantic salmon throughout British Columbia as well as wild salmon throughout the Fraser River and Vancouver Island with permission from First Nations.
Photo by Clio Nelson
Each salmon farm in British Columbia holds ~ 600,000 Atlantic salmon in net pens. They are sited on wild salmon migration routes. The nets bring clean water to the farmed salmon, but allow viruses to pass easily back and forth between farmed and wild salmon.
Photo by Tavish Campbell
Alexandra Morton capturing juvenile wild salmon which requires a 150' beach seine.
Photo by Nik West
Alexandra Morton taking samples from wild adult spawning salmon on the Fraser River.
Photo by Anissa Reed