More revelations expected after disease found in farmed salmon

When Kristi Miller released news that a new disease had been confirmed in farmed salmon in British Columbia, it marked the beginning of what will be a series of revelations about fish health.

The diagnosis of heart and skeletal muscle inflammation in farmed Atlantic salmon, announced on Friday, did not raise any immediate alarms because HSMI is not fatal, it has not been found in any wild Pacific salmon, and it does not pose a human health risk.

But it was a surprising diagnosis nonetheless, because the disease had not been detected before in B.C., although it is found in aquaculture operations globally.

It might be argued that HSMI should have been discovered much earlier, given all the testing routinely done on farmed fish on the West Coast.

But Dr. Miller, head of molecular genetics for Fisheries and Oceans Canada, said the disease may have escaped detection because it was not fatal to the infected fish, and did not affect the productivity of the farm – that is, the sick fish looked healthy.

She has found it now, however, as part of a long-term study of fish health that is using revolutionary DNA sequencing technology developed in her lab.

What is exciting about Dr. Miller's finding is that it is just the first discovery in a long-term project that is the most comprehensive study of salmon health in the world.

Dr. Miller and her colleagues are analyzing more than 26,000 samples from farmed, wild and hatchery-raised salmon. The technology allows researchers to test at one time samples from 96 individual fish for 45 microbes that are known to cause diseases or are suspected of doing so.

What will emerge from that screening will be a detailed map of what diseases are out there in wild stocks, farmed salmon and the federally run hatcheries that pump billions of fish into the ocean each year.

Many people will be looking to the study to indicate whether farmed fish are spreading disease to wild fish.

The results, released during a teleconference on Friday, did not show any such link, but Dr. Miller said more work is needed.

"Our program will be conducting the pathological investigations and the microbe monitoring as well as some other molecular investigations on wild fish … which include fish that are swimming by salmon farms," she said. "So we will ultimately have some information on that … but we are in the very early days in our program."

The B.C. Salmon Farmers Association, which supports Dr. Miller's research and provided fish to be sampled, said in a statement "there is no consensus amongst the scientific community about the [HSMI] finding," and the industry wants to know more.

"Government and industry should expedite the science, provide necessary funding, and work collaboratively for the sake of the aquaculture industry and for wild salmon," the association said.

Stan Proboszcz, a biologist with the Watershed Watch Salmon Society, also wants to see more research, but in the meantime, he is concerned about the detection of HSMI, saying it is troubling that the disease lay undetected until now.

"Given we've heard in the past that HSMI isn't in farm fish (and now this has been disproven) we have to ask ourselves whether government is operating in a precautionary way?" he said in an e-mail.

Mr. Proboszcz does not think the fish farming industry should be allowed to expand, and that farms in the Discovery Islands, which lie on the migration route of Fraser River sockeye salmon, should be removed "until we know for sure HSMI isn't a risk to wild salmon."

People on either side of the fish-farm debate in B.C. seldom agree on anything, which is what makes Dr. Miller's work so important.

She and her colleagues, notably Brian Riddell of the Pacific Salmon Foundation, are providing unbiased, ground-breaking science. They are not pandering to any interest group, but are providing the facts as they find them.

The discovery of HSMI was an important first step. More revelations are soon to come.