- About Us
Stay informed on our latest news!
During routine fish health tests May 14, Mainstream Canada's Dixon Bay farm tested positive for the IHN (Infectious Haematopoietic Necrosis) virus.
Third-party lab PCR test results have shown the presence of the virus. Sequencing has confirmed the presence of IHN virus in these fish.
The farm site has been isolated and is currently being prepared for depopulation, if deemed necessary upon completion of the investigation. The company is following strict protocols to limit the spread of the virus. The protocols are part of Mainstream Canada's fish health management plan as well as an industry viral disease management plan.
The Canadian Food Inspection Agency (CFIA) has been notified and is investigating the finding. Fisheries and Oceans Canada's National Laboratory is conducting confirmatory testing.
"We are very concerned about this fish health event and are taking every step to make sure it is contained and any risks minimized," said Fernando Villarroel, Mainstream Canada's managing director. "This shows our disease monitoring programs work. We were able to quickly detect IHN while in its early stages and react decisively. Early detection is crucial to minimizing the risk in any fish health situation."
The IHN virus is naturally carried by Pacific salmon, trout and herring. Studies show wild Pacific salmon have a natural resistance to the virus and very rarely suffer ill effects from it.
However, the virus causes Infectious Haematopoietic Necrosis disease in farmed Atlantic salmon. Since Atlantic salmon are not native to the Pacific coast, they have not had hundreds of years to develop a natural immunity to the virus, like their Pacific cousins. The disease can cause high degrees of mortalities on Atlantic salmon farms if not quickly managed and contained.
"This is the first diagnosis of IHN among farmed Atlantic salmon in BC since 2003. Although IHN kills up to 100% of exposed Atlantic salmon, wild salmon in marine waters are very resistant to IHNV infection," said Gary Marty, fish pathologist for the BC Animal Health Centre.
A lab study (Traxler et al, 1993) demonstrated this resistance under controlled laboratory exposure conditions. 25 virus-free sockeye salmon were added to a tank with 10 IHNV-injected Atlantic salmon. After 37 days, only 1 of the 25 sockeye salmon died, and the viral load in that fish was low.
For more information contact Laurie Jensen, Communications and Corporate Sustainability Manager, at email@example.com or 250.286.0022 ext. 2232
IHN or Infectious Haematopoietic Necrosis is caused by a virus native to the West Coast of North America. It is an infectious disease of trout and Pacific salmon. The virus can be carried by wild salmon, trout and herring. IHN poses no human health risk.
IHN occurs naturally in wild fish. They can carry the virus without the virus ever causing any disease. There is a very low risk of IHN affecting wild salmon due to the fact that wild fish are more resistant to the virus, having lived with background levels of the virus in the ocean for centuries.
Atlantic salmon, due to the fact that they are not native to the area and have not had hundreds of years to develop a natural resistance, are susceptible to the virus and the disease it causes. The virus can be spread horizontally (from fish to fish) in both freshwater and saltwater, including from wild fish to Atlantic salmon. It can also pass vertically (from parents to offspring) through infected ovarian fluid.
This virus can cause high mortalities in farmed salmon and has done so in the past. Since then, management practices have been put in place to prevent the virus from entering farms, and to quickly react if the virus is detected on a farm.
Good overall fish health conditions decreases the susceptibility of the fish to infection. We have strict control policies and sound hygiene practices to stop the virus from entering the sites. This includes disinfection of fertilized eggs and regular fish health checks to screen for the presence of the virus.
The three Atlantic salmon farming companies in BC have a salmon farming industry viral disease management plan to co-ordinate their reaction in the eventuality that IHN infected salmon are discovered. These include protocols for limiting the spread of the virus, as well as the secure disposal of infected fish.
IHN is a reportable disease in Canada. If the virus is discovered, the appropriate government agencies must be contacted immediately (DFO, CFIA).