Salmon, aquaculture, and the spread of Infectious Salmon Anemia

Coho salmon - public domain image

Coho salmon - public domain image

In 2008, a deadly virus decimated Chilean aquaculture facilities, causing $2 billion in damage and crippling an industry. This week, preliminary reports suggest that this same disease may have infected wild salmon in the north Pacific. The internet has been blowing up with news reports of Infectious Salmon Anemia (ISA) detected in wild salmon populations. Reports range from balanced – Deadly Fish Farm Virus Found in Wild Pacific Salmon – to hyperbolic – B.C.’s salmon feedlots need to be closed – but all hinge on the fact that ISA, a lethal salmon-infecting virus previously resigned to aquaculture facilities, has been detected in wild salmon populations in British Columbia. This has the potential to be a very big deal. ISA is 90% lethal and mortality occurs in 10 days or less. The virus is waterborn, but can also be transmitted through handling with contaminated equipment. There is no treatment once a fish is infected.

Before I go on, a couple points need to be clarified:

  1. ISA does not infect humans, though as it threatens a fishery and a major agricultural industry, it most certainly affects humans.
  2. ISA was isolated from 2 wild sockeye salmon. It has not been confirmed from independent test yet, although one statement indicates that the current infection is from a non-infectious strain of ISA (which raises some interesting questions about who currently knows what about this outbreak).

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