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In the mid-1950s, the fishing industry in modern-day Russia was determined to do something that may seem unusual today: introduce an invasive species in hopes of creating a new fishery.
That species was pink salmon. While a salmon might not scream “invasive,” the fish is not native to the White Sea, where they were stocked and restocked until the early 2000s. It took decades of effort for the fish to call Russia home and become self-sustaining without stocking, but they did.
However, they started calling other places home, too: Most recently, Canada, following significant spread in places like Norway, Iceland and Greenland.
The spread of the fish, which gradually swam to waters outside of Russia, is alarming to some. A press release from the North Atlantic Salmon Conservation Organization, summing up a June 2022 meeting, says it “considered with alarm the threat that Pacific pink salmon, an invasive species, spreading throughout the North Atlantic, is now posing to wild North Atlantic salmon.”
Pink salmon pose possible threats to wild Atlantic salmon: diseases and parasites from the pinks, as well as more competition for habitat and food.
Generally, salmon have a high level of natal homing, which is when animals go back to their birthplace — in this case, a river — to reproduce. However, when populations are expanding, they sometimes look for new habitat, which could account for the pinks travelling all the way across the Atlantic to Canada, explained Ian Bradbury, a research scientist with Fisheries and Oceans Canada (DFO). Warming waters due to climate change are also a likely factor in their spread, he said, noting salmon are known to be adaptable. Young pink salmon specifically have been found to prosper in warmer water.
Now, biologists in Canada are starting to notice the presence of pinks, said Bradbury. A pink salmon here and there started turning up in waters off Newfoundland and Labrador in 2017. Two pinks were caught: one in Gander River, one off Cartwright. They’ve also been spotted as far north as Iqaluit.
Pink salmon are not endemic to Newfoundland and Labrador, which only has one type of naturally occurring salmon, the Atlantic. That species saw declining numbers in most rivers last year, although some rivers in Labrador had higher counts. However, concern for the future of salmon remains on mainland Newfoundland. Indigenous groups have depended on the fish since time immemorial for food and cultural purposes, and anything that stands to put further pressure on the fish raises alarm bells.
A pink salmon here and there started turning up in Newfoundland and Labrador rivers a few years ago. Scientists say numbers will only increase, and they're not sure exactly what it could mean for wild populations.
Decades after the Russian fishery began, Bradbury suspects descendants of those same fish are turning up thousands of miles away off the coast of Newfoundland and Labrador, which also unsuccessfully attempted to introduce pink salmon to the North Harbour River in the 1960s.
“It's possible that they could be coming through the Arctic, but we don't see large numbers of pink salmon in the eastern Arctic,” said Bradbury. “So it makes much more sense that this is coming across the Atlantic because we're seeing them ... in Iceland and in Greenland and now coming down through Labrador.”
Over the past six years, numbers of pinks have been slowly increasing, explained Bradbury, who said last year, the population in Newfoundland and Labrador rivers was in the teens. Pink salmon have a two-year lifespan, so they spawn every other year in freshwater before dying. The fish Bradbury expects are making their way to Canada are an odd-year population, so they will be coming back to spawn this spring.
While the numbers aren’t shocking, they show a clear upward trend.
“There's no reason to expect that that will stop any time soon. They're really exploding and they look like they're getting established in the East Atlantic, where we're seeing successful reproduction,” explained Bradbury. “The numbers are really going up. So it's something that we're probably gonna be dealing with for the next while.”
What dealing with it will mean, Bradbury is not too sure. So far, there has been limited research on the salmon’s presence in Canada, and it’s too early to tell what impact they could have on wild populations of Atlantic salmon and other fish. He’s quick to say there isn’t cause for alarm yet but that scientists have some “uncertainty” about their effects. If numbers increase, interactions between pinks and other species will increase, and so will any affiliated impacts, positive — like the fish acting as a nutrition source for other animals — or negative.
“There could … be negative interactions due to disease, parasite transfer, competition for breeding habitat, these sorts of things. But that's just in freshwater. There's some evidence in the marine environment that when things are really abundant, there might be some competition for food availability,” he said. “So there's potential interactions there, but the short answer is we don't know.”
In 2019 and 2021, Bradbury and other scientists sampled river water to get an idea of where pink salmon were going in Newfoundland and Labrador. The office of Fisheries and Oceans Minister Joyce Murray confirmed that they will continue to monitor for the fish this year, and said they encourage anyone who catches a pink salmon while out fishing “to provide a sample of the fish to their local Fishery Officers.”
A sign of what’s to come?
Meanwhile, a pink salmon explosion is occurring in Norway, where they are also considered invasive. The species is now thriving in the Norwegian Sea and along the Norwegian coast, but it's just in recent years that numbers have really spiked.
According to the Iceland Review, around 7,000 pink salmon were caught in Norwegian rivers between 2017 and 2019, and that number jumped to 200,000 in 2021. Iceland also saw record numbers of fish — 339 — caught in 2021.
As Norwegian scientist Kjell Rong Utne puts it, “nobody cared” about the fish before 2017, even though some were present. Since, there have been more efforts to understand the presence of the fish and also remove them from rivers.
One such effort has been spearheaded by Chinese tech giant Huawei in partnership with local angler and hunter groups in Berlevåg, a fishing village in northern Norway. A blog post by Huawei describes its project as “machine vision, a type of artificial intelligence technology” where the company built “an automated fish trap with a built-in camera system utilizing AI to recognize and remove the invading humpback salmon.”
The project began in the summer of 2021, and the trap worked to identify pink salmon, which were then “stopped and sorted out to a separate area where they can be removed and potentially processed,” said Huawei.
Now, for the first time, the Norwegian government is stepping in. The government’s Climate and Environment Ministry has put forward around $2.3 million for traps along rivers to catch pink salmon. The fisheries department in Scotland has also stepped in amid rising numbers of pinks by launching apps where locals are encouraged to “search and destroy alien pink salmon,” according to a Scottish news site.
Addressing the spread of invasive pink salmon is going to require international co-operation, said Utne, who is part of a pink salmon expert group, which includes scientists from countries seeing invasive pink salmon who are concerned and interested in their spread, as well as members from the North American West Coast, where pink salmon are native.
“It's early in the process,” said Utne of the expert group. “The focus has been to share knowledge because a lot of countries, potentially, are going to have a problem with [pink] salmon. Nobody really knows how to deal with those issues. So it's to learn from each other and to learn from what's happening in the Pacific side.”
The group met in October 2022 in Vancouver to discuss how existing research and monitoring could be applied to pink salmon. Notes from the meeting said the group will meet a minimum of once per year to touch base on what they’re all doing to prepare for the presence of the species and look at how they can work together.