Are fish farms harmfully impacting wild salmon?

Photo Credit: BC Salmon Farmers Association

Since salmon aquaculture was established along BC’s coast beginning in the 1980s, there have been debates about whether fish farms have a negative impact on wild salmon populations. During the Cohen Commission hearings, many of these issues resurfaced. In the past, fish farms have been blamed for causing wild salmon declines due to sea lice, diseases, and pollution. Few of these claims have been supported by “hard scientific evidence.”

Dr. David Welch and a team of fisheries researchers are intent on resolving the controversy.

“Whether fish farming caused the widespread decline of southern British Columbia salmon stocks is hotly debated, and it is unlikely that evidence reported at the Cohen Judicial Inquiry can resolve the controversy,” Dr. Welch writes in an overview of his proposal. “[But] if fish farms reduce survival by disease transfer, parasite load, or some unknown agent, then there should be a measurable decline in survival of the exposed smolts relative to controls.”

He says the project should not only show whether fish farms are killing salmon – but how many salmon are killed.

In previous studies using acoustic tracking devices, Dr. Welch determined that salmon smolts were vanishing in the Queen Charlotte Strait, past the northern tip of Vancouver Island. Fish farms in Discovery Passage are clustered on the northeast coast of Vancouver Island.  According to Dr. Welch’s research, as the wild salmon migrate past the farms they might be exposed to disease and lice, and then dying shortly thereafter.

Dr. Welch, along with a prominent team of researchers – including Scott Hinch of the University of British Columbia and Kristi Miller of the Department of Fisheries and Oceans –  propose to tag thousands of salmon smolts with acoustic transmitters and to track them up the coast.

“We believe that the statistical power of the design we have identified is high enough that by the end of 3-5 years a clear decision can be made about whether fish-farm impacts are unacceptably large and the industry should be regulated to minimize interaction with wild stocks,” writes Dr. Welch. [Read full article.]

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