Sometimes natural is not good.   Actually, a lot of the time natural is bad but we live in in era where anti-science types have a 'natural' fetish, believing anything natural is good.

But not always. Weeds are natural yet if you leave them alone your vegetables will die.  And that goes for plenty of other invasive species.  Even wild salmon.

There's long been precautionary principle hysteria that farm-raised salmon - created so we could all benefit from the health effects of eating fish without risking overfishing - would cause disease among the wild population.  Who knew that they were so delicate after millions of years of evolution?  

Doesn't matter, it seems they have struck first. Infectious haematopoietic necrosis, known as IHN, has been discovered on an Atlantic salmon farm off the coast of British Columbia, but it came from passing wild fish and led to the quarantine of Mainstream Canada's Dixon Bay farm.  At the end of it all, the disease-ridden wild salmon caused a cull of more than 560,000 young, farm-raised Atlantic salmon.

IHN is native to Pacific waters and Pacific salmon have a natural resistance to it but Atlantic salmon do not and the virus can spread through feces and mucus.  Thus a reason to keep the farm-raised salmon away from the dangerous natural kind. 

"It basically kills the blood forming cells in the fish, and that includes white blood cells so the fish cannot fight disease, and red blood cells which carry oxygen," Gary Marty, a veterinarian and fish pathologist for B.C.'s Ministry of Agriculture told The Canadian Press. "Both things essentially shut down. The fish dies."

There is a vaccine for IHN but Mainstream Canada did not vaccinate fish at the company's Dixon Bay farm. I guess that wouldn't be natural. And actual science could allow us to have fish that didn't catch the disease at all but even a thoroughly tested, completely harmless, genetically optimized salmon has been trapped in review due to anti-science Frankenfood hysteria.