Fish Health

Salmon farmers in B.C. take pride in being transparent and accountable about industry practices and operational data. For the longevity of the marine environment they strive to meet the requirements of ‘Gold Standard’ environmental programs, having minimal impact on the nature while relieving pressure on wild fish stocks.

B.C. salmon farmers are passionate about raising healthy fish in a healthy environment. By applying the best standards and fish husbandry practices, and using preventative vaccinations, diagnostic testing and regular fish health examinations by trained fish health professionals and licensed veterinarians, an average of 90% of salmon survive through to harvest. This shows a consistently healthy population that is unstressed and well cared for.

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Fish Health Monitoring

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.

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Vaccinations and Reducing Antibiotic Usage


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.

  • By vaccinating fish and preventing pathogen outbreaks in farm-raised salmon, the risk of disease transmission between farm-raised salmon and wild salmon
  • By giving fish a better start right out of the hatchery, understanding how best to reduce any stress while in the ocean, and paying more attention to potential side effects of excessive usage, B.C. salmon farmers have steadily reduced the level of antibiotics used over the past two decades.


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.



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Sea Lice Management

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.

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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.

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Annual variations

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.


Extensive studies

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.


Additional Resources

For additional information concerning sea lice research, please see the below links and studies.

Piscine Reovirus (PRV) / Heart and Skeletal Muscle Inflammation (HSMI)

Piscine Reovirus (PRV) is known to occur in both wild and farm-raised fish in the North Pacific.

Although PRV has been proposed to be the causal agent of HSMI (Palacious et al., 2010; øvoll et al., 2012) recent studies using molecular diagnostics have found PRV to be present in farmed Atlantic salmon that are clinically healthy, as well as those suffering from HSMI, and has been found in wild salmon that have not been shown to have HSMI (øvoll et al., 2012; Garseth et al., 2013, Garver, et al., 2016). Neither in Europe nor in British Columbia have researchers been able to prove that PRV is the cause of HSMI. The high prevalence of PRV in fish without HSMI symptoms signifies the need for more research to investigate the link between the two.

There have been no diagnosed cases of heart and skeletal muscle inflammation in either wild or farm-raised Pacific salmon.

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Infectious Salmon Anemia (ISA)

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.

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Infectious Heaematopoietic Necrosis (IHN)

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.

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Kudoa Thyrsites

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.

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Salmonoid Rickettsial Septicaemia (SRS)

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.

Salmon Alphavirus (SAV)

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.

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Viral Hemorrhagic Septicemia Virus (VHSV)

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.