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Science Response 2017/041

Residual infectious pancreatic necrosis (IPN) transmission risk from Arctic Char transfers into British Columbia

Context

Infectious pancreatic necrosis (IPN) is a disease affecting some freshwater and saltwater finfish. It is caused by the infectious pancreatic necrosis virus (IPNv), which belongs to the family Birnaviridae. The IPNv can be spread by moving infected live or dead finfish, contaminated equipment, or contaminated water. Infectious pancreatic necrosis can cause death in fry, fingerlings, and smolts; including smolts transferred to seawater.  There are no treatment options currently available in Canada for IPN. A number of species of fish are susceptible to, or can carry IPN including but not exclusive to:

Because of the seriousness of the disease, it is a legal requirement to report known or suspected IPN infections to the Canadian Food Inspection Agency (CFIA). Within Canada, British Columbia is designated free of IPN, New Brunswick (NB) and Nova Scotia (NS) are considered endemic, and the virus has also been detected in many other regions of Canada.

Arctic Char (Salvelinus alpinus) are not indigenous to British Columbia; however, they are commercially cultured in the province on a small scale with most of the stock originating from the Yukon. While IPNv has been detected in the Arctic watershed portion of the Yukon, eggs come from an area that is considered free from the virus, and the province of BC continues to be IPN free.  An application was submitted to the British Columbia Introductions and Transfers Committee in 2016 to import Arctic Char eggs from a facility in New Brunswick (an IPN endemic province), to a land based fresh water facility located in the interior of BC. Because the application indicated that waste water from the facility was direct discharge, and may enter fish bearing waters, information on the potential risk of IPNv entering aquatic environments in BC through fish introductions was needed. The facility in NB identified as the source for Arctic Char eggs held a valid fish health certificate under the DFO Fish Health Protection Regulations (FHPR) at the time this transfer was requested. Although IPNv had not been detected at the donor facility in over 10 years of testing under the FHPR, uncertainty remained regarding whether the level of testing associated with this certification would be sufficient to ensure an infection free status.  Arctic Char has been shown to be a carrier of the IPN virus, often without showing symptoms of disease.  Detection of IPNv in Arctic Char that are not exhibiting symptoms of the virus requires a high test sensitivity; conventional diagnostic methods will often not detect infection in sub-clinical animals.  DFO Aquaculture Management Branch requested Science Branch provide advice regarding the potential risk associated with the introduction of Arctic Char into a BC facility.

The assessment and advice arising from this Canadian Science Advisory Secretariat (CSAS) Science Response (SR), will be used to evaluate risks to wild and farmed BC fish as part of the review process for both aquaculture licence applications and Introductions and Transfers licence applications, as well as to inform decisions related to Arctic Char aquaculture conditions of licence. This Science Response Report results from the January 2017 Science Response Process on the Residual Infections Pancreatic Necrosis (IPN) transmission from Arctic Char transfers into British Columbia.

The specific objectives of this Science Response are to:

  1. Document evidence of impacts in other regions where IPN has been introduced.
  2. Document the likelihood of Arctic Char being infected with IPNv, and describe potential impact from an import if the Arctic Char were infected to BC wild and farmed fin fish.
  3. Determine whether the risk of introducing IPNV to BC differs based on the life stage of fish being imported (e.g. eggs, milt, fry, juvenile, adult, brood stock etc.)
  4. Determine the effectiveness of IPNv diagnostics and management practices in assessing virus infection status of facilities within IPNv positive areas.
  5. Recommend management measures to mitigate the potential risks associated with transferring Arctic Char from facilities in IPNv positive area
  6. Identify any knowledge gaps or uncertainties associated with the advice.

This Science Response Report results from the Science Response Process April 2017 on the Residual Infectious Pancreatic Necrosis (IPN) Transmission Risk due to Arctic Char Transfers into British Columbia.

Complete document (PDF, 554 KB)

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