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Viruses are the most abundant organisms on the planet. All fish viruses present in B.C. farm-raised salmon are naturally occurring in the Pacific Ocean. Most viruses are not harmful to fish and are not a risk to human health. However, because farmed fish live in greater density than wild fish – like people living in a city compared to people living in the country – some viruses can pose health risks to farmed salmon. As a result, fish health is monitored regularly by farm company veterinarians, and by the government.
Thousands of fish health screenings on wild, hatchery-raised, and farm-raised salmon have been completed by professionals in B.C., Alaska, and Washington State and not a single test confirms the presence of any exotic fish viruses or diseases, including ISA. In addition, all salmon producing members of the BCSFA have developed a viral outbreak management plan, which allows for a quick and decisive industry-wide response if a virus of concern is ever detected in any B.C. salmon farm.
Ongoing monitoring and research is key to the health and survival of both wild and farm-raised fish. B.C. salmon farmers stringently monitor and test their fish, and take great pride in raising healthy fish by keeping the environment in good condition for all species. Farmers participate in sampling programs run by the Canadian Food Inspection Agency (CFIA) and Fisheries and Oceans Canada (DFO) to assist with viral monitoring. Regular sampling by government, companies and independent third parties ensure very clear picture of the health of B.C farm-raised salmon.
Vaccines are an integral part of fish health management. B.C. salmon farming companies administer vaccines to all fish - prior to leaving the hatchery - to protect them against common bacterial and viral pathogens that occur naturally in the Pacific marine environment, such as Infectious Hematopoietic Necrosis (IHN).
Farmers understand the connection between a healthy ecosystem and healthy fish.
Antibiotics are an important part of animal and human welfare. In aquaculture, antibiotics are rarely used and, if required, are only available through prescription by a licensed veterinarian for the purpose of managing bacterial illnesses in fish.
Over the past two decades B.C. salmon farmers have significantly reduced their use of antibiotics and continue to manage the health of fish stocks responsibly, with as little antibiotic use as possible - working toward the elimination of its use in the future. The goal is to avoid microbial resistance and environmental factors.
As a whole, the aquaculture industry in B.C. continually strives to set a high standard for antibiotic reporting.
Sea lice in B.C. marine waters
Sea lice are a naturally-occurring parasite of marine environment and have evolved to attach to migrating salmon as they travel through the ocean. There are 12 species of sea lice in B.C.’s coastal waters but Caligus clemensi (or C. clemensi, commonly known as the herring louse) and Lepeophtheirus salmonis (or L. salmonis, commonly known as the salmon louse) are the two most commonly studied species in the B.C. coastal environment.
Sea lice management on farm-raised salmon
While juvenile salmon are free of sea lice when they enter into the ocean pens, they are susceptible to sea lice infestations, particularly caused by L. salmonis. B.C. salmon farmers take proactive and preventative measures to ensure their fish host low levels of sea lice - following a range of best management practices and monitoring programs to manage sea lice abundance and ensure that any potential increases in abundance is mitigated.
Atlantic salmon farm employees are required by regulation to examine their fish every two weeks, at a minimum, for regular sea lice counts during March 1 to June 30, to coincide with Out Migration of wild salmon. If those counts show an average of three motile lice per fish, companies are required to take action to reduce the absolute lice count over subsequent weeks. This means either treating the fish (see “Treatments”) or removing them, if a harvest is planned. When exceeding the three motile abundance, numbers and the planned management response must be reported to DFO within 7 days.
During the rest of the year, salmon farmers are required to conduct sea lice counts at least once a month. Again, if the abundance threshold of three motile lice has been exceeded, monitoring must increase to every two weeks, and actions must be taken within 30 days to manage motile lice abundance. Reporting to DFO is monthly, no later than the 15th of the following month, and DFO also performs random quarterly checks of all active B.C. salmon farms to verify the accuracy of industry reporting.
In order to forecast mitigative measures or actions that might be needed to ensure that farm-raised salmon are not further contributing to the sea lice number on wild fish, B.C. have established wild salmon sea lice monitoring programs in all farming regions of the provinces - working collaboratively with researchers in academia and the government.
B.C. salmon farming companies are transparent in sharing information and reporting data. Atlantic salmon farmers have committed to posting monthly updates of sea lice monitoring data collected on their farm sites, which can be found online:
Despite our current knowledge, some public concern remains about the potential effect of sea lice (from salmon farms) on B.C.’s wild salmon stocks. The BC Salmon Farmers Association Sea Lice Report - January 2016 addresses these concerns.
The rate of sea lice infestation changes from year to year on both farm-raised and wild salmon. This is directly linked to annual changes in wild host populations and environmental conditions. Factors such as high numbers of Pacific herring, for example, can be correlated to elevated lice counts of C. clemensi on farm-raised salmon in the same region, at that particular time. Similarly, it has been found that high wild salmon returns in the autumn months of one year can be correlated to elevated lice counts of L. salmonis in the following spring, for wild and farm-raised salmon in the same region.
Sea lice prevalence can also be related to environmental conditions, with sea lice thriving in warm (higher-than-average) water temperatures . Pairing high temperatures with high salinity (due to decreased freshwater mountain run off, and decreased levels of precipitation in an area) create an optimal environment for sea lice to flourish.
2015 Research Results
Studies have shown that, in British Columbia regardless of the presence or absence of salmon farms, there is wide variability in sea lice prevalence in coastal locations. Research over the past decade shows lice levels are significantly linked with ocean conditions and variations in wild hosts.
Since the early 2000's, there has been much study on sea lice prevalence on B.C.’s wild and farm-raised salmon. In 2015, researchers noted an increase in sea lice prevalence on juvenile wild salmon compared to the previous year. This occurrence was quite similar to levels observed in 2003, 2005, 2006, and 2010, and much lower than levels observed in 2004.
The state of knowledge on L. salmonis and C. clemensi sea lice species has grown extensively over the last several years through collaborative research, mostly driven by the need to better understand the relationship between far-raised salmon and sea lice numbers on wild salmon. For example, the Broughton Archipelago Management Program, which began in 2010 as a multi-year sea lice monitoring and research program, has produced several important studies on the ecology and behavior of sea lice with respect to salmon farms. The collaborative work included the federal government, industry, academia and conservation groups. For more information see Broughton Archipelago Monitoring Program and some related studies:
Fisheries and Oceans Canada has also held two scientific peer-review processes to assess the state of knowledge and provide regulatory scientific advice on the management measures, monitoring and interactions of sea lice, with respect to wild and farm-raised fish. These processes again engaged a wide range of participants from academia, conservation groups, industry and government. As a result two documents have been produced, summarizing the scientific literature with respect to sea lice knowledge and management in Canada. For the reports resulting from these processes, summarizing what is known about sea lice population ecology, monitoring and mitigation, see:
B.C. salmon farmers emply a number of techniques to manage sea lice on farm-raised salmon. These measures include decreasing the number of cultured fish on farms through harvest, and the use of therapeutants Emamectin benzoate (SLICE©) and Paramove 50©.
SLICE© has been used in British Columbia since 1999 as an effective tool to control sea lice, and is only authorized for use under the professional guidance of a licensed veterinarian. It is milled directly into the feed and used sparingly to ensure sea lice levels on farm-raised salmon remain low and are not a threat to out-migrating juvenile wild salmon.
In 2015, therapeutant use in B.C. farm-raised salmon averaged 1.4 treatments per production cycle. The average quantity of in-feed therapeutant used to treat sea lice on B.C. salmon farms in 2015 was 1.25g of active ingredient per tonne of salmon produced, a reduction of 0.35g per tonne in 2014 (GSI, 2016).
For more information on studies of the effectiveness and safety of emamectin benzoate see the following references:
Salmon farmers continue to research and implement alternative controls for sea lice such as vaccines and non-medicinal controls – including hydrogen peroxide (H2O2) treatments.
Because hydrogen peroxide, in this case, is used for pest control, it is classified as a pesticide. Federal approval and a permit for its use from the BC Ministry of Environment has been granted to salmon farmers in B.C.
Hydrogen peroxide breaks down quickly in water into water and oxygen and does not accumulate in sediment or have a withdrawal period for treated fish.It is not considered a contaminant by the BC Ministry of Environment and is actually recommended by MOE as an alternative cleaner for boaters to use instead of bleach. It is also listed by third-party certification group, the Aquaculture Stewardship Council, as the only parasiticide treatment with a 0 rating for persistence and toxicity in the environment.
For additional information concerning sea lice research, please see the below links and studies.
Over November 27 and 28, 2017, our Association, in collaboration with the BC Centre for Aquatic Health Sciences, hosted a workshop entitled ‘Exploring PRV & HSMI in Europe & BC’ in Campbell River, BC. The objective of the workshop was to better understand Piscine orthoreovirus (PRV) andits association with Heart and Skeletal Muscle Inflammation (HSMI) in Norway and British Columbia.
This workshop brought together 13 leading, international experts in PRV and HSMI research and was moderated by Dr. George Iwama, President and Vice Chancellor of Quest University, BC.
The BC Salmon Farmers Association has worked collaboratively with all experts involved in the workshop over the past number of weeks to develop this report as an accurate representation of the research presented at this workshop. Much of what was presented and discussed at the workshop is new and on-going research, and has yet to be published.
Our members recognize that rigourous, peer-reviewed science is at the core of understanding complex issues such as the relationship between PRV and HSMI and the variance in how this pathogen and disease are recognized in Norway, British Columbia and elsewhere, globally. Therefore, although there are some areas where consensus of all speakers could not be found on the points recorded in this report, the Association supports the communication of all perspectives and research discussed.
PRV First Evidence:Archived samples indicate the presence of PRV in the environment over twenty years before its initial identification in Norway, in 2010 (1988, Norway, and 1977, BC).
PRV Range, Globally:Several genotypes of PRV have evolved regionally and have been identified globally in the marine environment, to date, in Norway, Chile, the North Pacific (BC and Washington), Atlantic Canada, and Japan.
PRV Hosts:The known host range of PRV globally includes: Cutthroat Trout, wild and farmed Chinook Salmon, Sockeye Salmon, Steelhead Trout, Coho Salmon, Chum Salmon, Pink Salmon and wild and farmed Atlantic Salmon, and a range of non-salmonid species.
PRV Prevalence (North Pacific Coast):On the west coast of North America, reports in 2014 and 2015 indicated that the prevalence of PRV in wild Pacific salmon was less than 20% (from BC studies, Miller et al. 2014 and Marty et al. 2015) but more recently, new US research (Purcell et al. 2017), revealed that PRV prevalence within adult Pacific Salmon and trout stocks was, on average, very low at 3.4%.
Effects of laboratory-based studies of PRV infections on pathology, immune function and respiratory physiology performed in BC: Several studies onAtlantic Salmon and Sockeye Salmon infected with PRV have shown no pathological evidence of disease. Moreover, in Atlantic Salmon, a comprehensive examination of the fish’s respiratory physiology revealed no effect of PRV infection on overall fitness. This research is currently underway on Sockeye Salmon.
HSMI First Evidence:HSMI was first characterized in 1999 in Norway.
Correlation between PRV and HSMI:In 2017, PRV was correlated with the development of HSMI, in Norway. In contrast, in BC, HSMI has not been induced to date using BC Atlantic and Sockeye Salmon exposed to a BC strain of PRV.
To date, HSMI has only been described in farmed fish, globally (never diagnosed in wild fish). Like any other disease, the development and severity of HSMI is likely dependent upon the interactions of the host, pathogen, and environment.
Salmon Farms and HSMI: In Norway, HSMI is a production concern for farmed salmon but only accounts for approximately 2% of industry mortality. In contrast to the 600+ farms that develop HSMI each year in Norway, HSMI has rarely been diagnosed on salmon farms in B.C. and it has never been associated with an elevation in mortality.
Read the report.
Infectious Salmon Anemia (ISA) is a viral disease that principally affects Atlantic salmon – the species most commonly farmed in British Columbia – and doesn’t pose any risk to human health. It has never been confirmed in the North Pacific despite thousands of wild, hatchery and farm-raised fish being tested.
Because of the risk ISA poses to Atlantic salmon, members of the BCSFA have participated in regular testing of our farm-raised fish for ISA, and roughly 6,000 tests so far have shown no ISA on our sites. In 2012, around 1,000 fish were tested: all returning negative results. Our farms continue to see good fish health and high survival rates. Given the susceptibility of Atlantic salmon to the disease, this is another indicator that ISA is not present.
In recent years there has also been expanded testing of wild fish by the CFIA, which has shown no ISA presence in B.C. ISA is a reportable disease in Canada, which means that anyone who suspects ISA in finfish they own (or work with) is required by law to notify the CFIA.
Confirmed cases of ISA:
Infectious Salmon Anaemia Reports - CFIA
To detect viruses, such as ISA, scientists use Polymerase chain reaction (PCR) tests, which are highly sensitive. Presumptive positive tests require further testing before they can be deemed valid or confirmed. The additional testing includes isolating a suspected virus or sequencing of the virus - both of which has never been successful in B.C.
The quality of samples, which organs are tested, and the size of the sample all play a key role in the success of PCR tests. There are important guidelines to the collection, preservation and treatment of samples that need to be followed for the most reliable results.
To reduce the chance of ISA or other disease being introduced to B.C., any imports of fish eggs, milt and broodstock have been highly regulated. Along with disinfection and quarantine requirements, these products also have to be sourced only from ISA-free facilities and geographic areas.
Infectious Heaematopoietic Necrosis (IHN) is a natural virus of the Pacific Ocean that has no effects on human health. Studies have shown that IHN can be carried regularly by wild salmon who have a natural resistance to it without any negative impacts on their health. However, the health of Atlantic salmon can be affected by IHN, as they have not developed immunity to it.
The routine fish health monitoring programs for B.C. salmon farmers include regular tests and sampling for the health status of their stocks, which includes checking for IHN. In May and July of 2012, two Cermaq Canada farm sites tested positively for IHN after routine testing. In both cases, this was identified early and Cermaq immediately reported it to CFIA and isolated the farm sites. The company also informed their farming colleagues and enacted a pre-determined action plan to manage the situation. All other required and appropriate parties, such as community partners, were notified and the company has continued to act proactively.
Kudoa thyrsites is a marine organism that is carried by many fish species in all oceans. While it causes the salmon flesh to soften quickly after harvest, which is unsightly, it does not harm the fish in any way during their lifecycle, nor is it harmful to human health.
Salmonoid Rickettsial Septicaemia (SRS) is a fish disease that is caused by the bacterium Piscirickettsia salmonis. It affects multiple species, including Pacific and Atlantic salmon. This is a variant that is unique to the North Pacific Ocean, and it is suspected that a reservoir for the bacteria exists in the marine environment, in non-salmon fishes and shellfish. The infection is managed using antibiotics.
There are three types of Salmon Alphavirus (SAV) that can affect Atlantic salmon and Rainbow trout in freshwater and saltwater, causing damage to the pancreas. To test for viruses, researchers generally use a preliminary screening test called PCR, and then follow that with cell culture to confirm presence.
Government labs have tested for SAV on B.C. salmon farms and have never found it. It is not a federally-reportable disease because of the low risk that it poses to fish. SAV does not pose any risks to human health.
Viral Hemorrhagic Septicemia Virus (VHSV) is a naturally-occurring ocean fish virus with several strains found in the waters of B.C. It is found in herring populations and reports in other species are often associated with the migration of herring. VHSV can be passed to salmonids, both wild and farm-raised, but it is not highly pathogenic to salmonids and rarely causes the clinical symptoms of VHS. It can, however, be lethal to Pacific herring, Pacific hake, Pacific sardines and walleye Pollock. VHSV does not pose any risks to human health.
VHS, which is caused by the VHS virus, is a reportable disease in Canada. If salmon farmers suspect the disease on their farms they must report it to the CFIA. The CFIA publishes all confirmed cases of VHSV in Canada.