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Research comparing salmon farming regulations in four countries finds that Canada’s rules fall short when it comes to protecting wild fish populations from one of the key threats posed by aquaculture: sea lice infestations.

In a recent study, Irja Vormedal, a research professor specializing in political science and environmental policy at the Fridtjof Nansen Institute in Norway, investigated how the governments of Norway, Scotland, Ireland, and Canada regulate sea lice in Atlantic salmon farms.

Parasitic lice occur naturally in the ocean, but they’re a frequent scourge on salmon farms where fish are crowded together in net pens. The pests’ free-swimming larvae can leave the pen and infect wild fish passing through the area. Adult salmon can typically withstand the lice, which feed on their skin, blood, and mucus, but juveniles carrying as few as one or two of the freeloaders may die.

In her study, Vormedal examined how each of the four countries require farms to monitor for sea lice and initiate treatment when levels become too high. The nations have different species of wild salmon and sea lice, ecological conditions, sizes of salmon farms, and numbers of farmed fish within each pen. Yet, looking across all the differences, she found that, in general, Norway has the strictest rules governing sea lice, followed by Scotland—thanks to that country’s recent plans to adopt more stringent limits. Ireland’s regulations are more lenient. And in Canada, where Vormedal focused on the salmon farms in British Columbia, she found that rules are the least stringent.

Vormedal reviewed government documents and peer-reviewed science papers, and interviewed 23 experts from governments, nonprofits, universities, and private research institutions.

She discovered that the level of scientific agreement within each country about how sea lice affect wild salmon plays a role in how carefully governments regulate the parasites.

For instance, in 2011, the Norwegian government acknowledged that sea lice from fish farms could be a serious hazard to wild salmon. That understanding, held by government and scientists, led the country to base its sea lice thresholds at least partly on research, Vormedal notes in her study.

Norwegian fish farmers, the world’s largest producers of farmed salmon, are required to file weekly reports on sea lice among their penned stocks year round. When levels exceed an average of one adult female louse for every five fish, operators must undertake delousing operations. (Delousing technologies, such as hydrolicer machines that spray salmon with high-pressure water to remove parasites, can also prove deadly to smaller wild fish.)

In comparison, Scottish operators must notify authorities and increase monitoring when levels reach two adult female lice per fish. When levels reach six lice per fish, operators must treat fish until parasite numbers fall to one for every two salmon.

In Ireland, farmers are limited to one egg-bearing louse for every two fish during the spring migration of wild salmon. During the rest of the year, the limit is two lice per fish. Vormedal notes, though, that there are “no procedures for enforcement in place” and “no rule about how fast levels must go down.”

In Canada, where scientists within and outside the federal government have clashed over the risk posed by sea lice, farm operators must assess their fish every two weeks during the spring wild salmon migration. If more than three lice per fish are at the motile life stage—growing quickly, moving about the salmon, and generally posing a greater threat—operators have 42 days to bring levels down. But, by then, some wild salmon species may have already migrated past the farm.

Marty Krkosek, a biologist at Ontario’s University of Toronto who did not participate in Vormedal’s study, says that while there is a level of scientific uncertainty in all jurisdictions, Europe has taken the lead in precautionary management.

“The issue of the environmental effects of salmon aquaculture is much more accepted in Europe, and that shows in what they do to protect wild salmon,” says Krkosek, who has studied salmon and sea lice for 20 years. “In Canada, the science is more contested, and our regulations are not as thorough or strong.”

A contributing issue to the regulatory conflict in British Columbia is that Fisheries and Oceans Canada (DFO), the federal agency responsible for managing both farmed and wild salmon, has a dual role: to protect wild stocks and promote aquaculture. Those priorities can clash when it comes to measuring and regulating the impacts of fish farming on wild salmon.

Indigenous community members protest a fish farm in British Columbia in defense of wild salmon. “When I did my research on Canada, I understood how culturally important the wild salmon is,” says Irja Vormedal, a research professor specializing in political science and environmental policy at the Fridtjof Nansen Institute in Norway. Of the four countries in Vormedal’s recent study, only Canada boasts wild salmon populations that continue to support First Nations, commercial, and recreational fisheries. Photo by Rolf Hicker Photography/Alamy Stock Photo

In an emailed statement, DFO spokesperson Jennifer Young said that “departmental scientists, as well as other Canadian and international researchers, continue to conduct research on sea lice. This body of science informs the scientific peer-reviewed advice generated by DFO through the Canadian Science Advisory Secretariat (CSAS).”

Young wrote, “as new, completed research becomes available, the department will continue to review and incorporate the information as part of its risk-based, science-informed adaptive management process.”

The most recent CSAS report, which concluded that fish farms do not affect the number of sea lice on wild salmon, was criticized by Krkosek and 15 other fisheries experts for cherry-picking data, downplaying previously published evidence, and excluding input from independent scientists.

In July 2023, independent scientists published a paper critiquing DFO for, among other concerns, allowing representatives from the aquaculture industry to sit on the secretariat providing scientific advice to the government.

Controversy around sea lice science has prevented Canada and Ireland from adopting stricter aquaculture regulations. While Canada did strengthen its enforcement of sea lice limits in 2020, Ireland has undertaken no reforms since 2008.

Canada’s ranking among the four countries could change dramatically, though, if the federal government fulfills its 2019 commitment to transition British Columbia away from open-net-pen salmon farming by 2025.

In February 2023, the Canadian government decided not to renew 15 licenses for salmon farms near northern Vancouver Island, British Columbia—an apparent step toward the phaseout. However, the We Wai Kai and Wei Wai Kum Nations, along with aquaculture companies Grieg Seafood, Mowi Canada West, and Cermaq Canada, are challenging the decision in federal court.

Meanwhile, a coalition of 121 First Nations is urging Canadian Prime Minister Justin Trudeau to keep his election promise to remove all open-net-pen farms from provincial waters. The federal government has not yet released the plan to do so.

For Vormedal, the notion that Canada is looking to shut down, rather than regulate, the industry reveals how culturally important wild salmon are in British Columbia. “It’s a very interesting difference. Given the economic importance of salmon farming in Norway, they wouldn’t even consider that.”

Marty Krkosek’s research was previously supported by the Hakai Institute. The Hakai Institute and Hakai Magazine are separate and independent parts of the Tula Foundation.