How the science behind salmon farms and sea lice became so controversial

Members of the DFO routinely visit farms around British Columbia to ensure the health of salmon populations on fish farms is up to standard.  (The Canadian Press/Jonathan Hayward - photo credit)

Members of the DFO routinely visit farms around British Columbia to ensure the health of salmon populations on fish farms is up to standard. (The Canadian Press/Jonathan Hayward – photo credit)

A federal decision to close 15 open-net Atlantic salmon farms around BC’s Discovery Islands is being hailed as a victory for wild salmon conservation and a major blow to the fish farming industry – while also addressing a decades-old debate between industry and scientists.

Ottawa’s decision came just weeks after a Fisheries and Oceans Canada (DFO) report found no “statistically significant association” between sea lice infestations in wild young chums and pink salmon and the fish farms that host them along the BC coast pass by, had noticed.

The report, based on data from fish farm operators, found that since 2013 there has been an upward trend in sea lice infestations in the surveyed areas, which include Clayoquot Sound and the Discovery Islands.

The science linking salmon farms and increased sea lice infestations has been the subject of heated debate for years, with industry representatives, academics, DFO scientists and environmental activists citing conflicting data sets.

Even after announcing the decision to permanently close the 15 farms, the DFO did not comment directly on the correlation between the two, saying it was taking an “enhanced precautionary approach” in closing the farms.

“Recent scientific evidence indicates that there is uncertainty regarding the risks posed to wild Pacific salmon from aquaculture farms in the Discovery Islands area and the cumulative impact of any farm-related impacts on this iconic species,” it said in a statement from the Office of Fisheries and Oceans Secretary Joyce Murray.

“It was a difficult but necessary decision.”

A focal point on the coast

At the heart of the debate is whether wild salmon become infected with sea lice as they pass fish farms along the BC coast.

The Discovery Islands area is an important migratory route for wild salmon, where narrow passages bring migrating juvenile salmon into close contact with the farms.

Parasitic sea lice occur naturally in the Pacific Ocean but tend to thrive in fish farms due to the high density of fish. While sea lice generally do not harm adult fish, they can weaken or even kill young fish once they have attached themselves to their skin.

Salmon farms are required to carry out monthly sea lice counts on their fish and make these numbers publicly available. Counts are self-reported, but fisheries officials occasionally conduct pre-arranged checks to ensure numbers are accurate.

Submitted by Mack Bartlett

Submitted by Mack Bartlett

A 2020 study found that mandatory sea lice counts performed by fish farm operators drop by 15 to 50 percent when they are not performed during an audit.

Brian Kingzett, executive director of the BC Salmon Farmers Association, said industry and First Nations stakeholders were caught off guard by the federal announcement after years of collaboration and consultation. Kingzett said the salmon farming industry has become a target for environmental activists and “a convenient scapegoat for the demise of wild salmon.”

“Years of data have been provided by farm monitors, by our licensed veterinarians and an independent game fish monitor commissioned by the industry,” said Kingzett, speaking from Nanaimo.

“They couldn’t find a causal link there. This goes along with what we have known for a long time from our internal data and the Minister has chosen to ignore all that science.”

In the first press release about the decision, the DFO said wild salmon face a range of threats, including climate change, habitat destruction and both regulated and illegal fishing – threats, Kingzett said, are not being addressed as aggressively as the farms.

“It will not stop commercial fishing. It will not stop recreational fishing. It doesn’t ensure fewer pollutants get into the Georgia Straits,” he said.

Jonathan Hayward/The Canadian Press

Jonathan Hayward/The Canadian Press

Alexandra Morton, a marine biologist and independent researcher with 30 years’ experience campaigning to save wild salmon populations, said she was relieved to see Murray’s decision.

“It’s a brave decision by the minister because I know it wasn’t easy,” she said.

Morton said the January DFO study’s conclusions reflected unreliable sample data provided by farmers and consultancies they hire — a claim the farms dispute. The DFO study references previous reports that found infestations of farmed and wild salmon to be correlated within 30 kilometers of farms.

After the report was published, a group of 16 scientists slammed the report, citing inconsistencies and the lack of a formal peer review.

“All these scientists see the same as I do. If you have salmon farms, you will get sea lice on young wild salmon. There’s also infection with the viruses and bacteria that thrive on these farms,” ​​Morton said.

Morton, who says her findings are supported by researchers from the University of British Columbia, the University of Toronto and other labs, has urged industry to make their data available through open access so academics can do their own analysis and replicate the findings self-employed.

“If you want to clarify that, just release your data,” she said. “Let’s take a look and have a reasonable discussion about it.”

According to Morton, among the most reliable research methods that have found a correlation between infections and farms is genomic profiling, which can detect when the fish’s immune systems react and become weakened.

Toxic Debate

Researchers agree that the question has become not only divisive but toxic, leading to online mud fights and allegations of cherry picking.

When asked about the province’s understanding of where the science stands, the Department of Water, Land and Resource Management said in an email that the DFO “has the authority and scientific expertise in relation to the licensing of aquaculture farms and BC from.” expects them to do so in a manner that protects the health of wild salmon.”

Kingzett said that while the industry doesn’t always like the results of DFO results, it stands by them.

“We have a situation where we have campaign groups that have their scientists, we have our scientists, but we’re always viewed as an industry,” he said.

“We see that all the time on social media, that it’s fraudulent, that there’s a conspiracy.”

Morton said the issue has become so polarized in part because scientists within the DFO are divided into two separate camps, putting the responsible minister in an impossible position.

“The DFO needs to reconcile in its own house. How can the regulator have polar opposite scientists inside?” She said.

“It’s a fabricated debate and extremely dangerous because at this point in the world we really need to look at the impact we’re having on wildlife.”


Murray said the federal government is committed to developing a “responsible plan for the transition from open-air salmon farming in BC’s coastal waters.”

The province said it was disappointed that the federal announcement “does not outline a federal support plan for First Nations, communities and workers who depend on salmon aquaculture for their livelihoods.”

Kingzett said the farm closures will deal a devastating blow, with production down 24 percent, up to 1,500 jobs at risk and up to 10.7 million eggs and fry euthanized. Fish from Chile and Norway are now being imported to compensate for the decline in locally farmed salmon.

“It’s a big problem related to food security, climate change and wild fisheries. Instead of finding comprehensive solutions, we make an argument that basically says we’re burning everything down. We’re farmers trying to do a good job,” he said.


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