Where Arctic Cod Goes, Marine Mammals Follow

Increased ship traffic in the warming Arctic drives fish away, study shows, spelling larger impacts on the marine food web and the communities that depend on it.

A centerpiece of the marine food web, Boreogadus saida swims among the ice floes of the Arctic archipelago. A slender fish but high in fat, the Arctic cod, the northernmost marine fish, eats krill and plankton — and transfers that energy up the food chain as the preferred prey for a host of seabirds and marine mammals like ringed seals and beluga whales.

photo of arctic cod
An increase in ship traffic in a warming Arctic Ocean displaces Arctic cod (pictured) and disrupts the food chain. Photo by Erling Svensen.

“The Arctic cod is critical [to this region’s food web],” says Silviya Ivanova, an ecologist at the University of Windsor. “It’s the single species that links the lower trophic levels to the higher trophic levels.” (Trophic levels are the different positions species occupy in a food chain.)

But an increase in ship traffic in a warming Arctic Ocean displaces cod and disrupts that food chain, causing a cascade effect that impacts both human and nonhuman communities that occupy this seascape. In a recent study published in Ecological Applications, researchers in Resolute Bay along the Northwest Passage — the route connecting the Atlantic and Pacific Oceans — found that underwater noise from ships drives Arctic cod away from nearshore schooling areas. It is in these areas where marine mammals typically feed on cod and where subsistence hunters from nearby Inuit communities pursue these mammals.

“Where cod goes, marine mammals follow,” says Ivanova, the study’s lead author. “That’s why [these communities] have their concerns for ship traffic in the area.”

This is far from the first study targeting noise pollution as a major disruption in marine ecosystems. A recent meta-analysis demonstrated that anthropogenic noise — typically from commercial shipping activity — is widely known to negatively impact fish behavior and physiology, which in turn can cause lasting changes in marine ecosystems.

But in the Arctic, the environmental impacts associated with vessel noise are still relatively unknown. That’s because historically, there haven’t been that many ships. In the last few years, researchers have worked to fill that knowledge gap, particularly as ship traffic in the Arctic Ocean increases with warming temperatures and related sea ice decline. “Arctic-wide, the shipping season has been getting longer. More ships can come through,” says William Halliday, who studies Arctic underwater acoustics as a conservation biologist with Wildlife Conservation Society, Canada. “We expect to see even more [ships] as the Arctic becomes more ice-free during summertime.”

In 2012, the National Oceanic and Atmospheric Administration observed that summer sea ice in the Arctic Ocean had been reduced by more than a third in just three decades. That sea ice decline alone can have drastic effects on marine wildlife in the archipelago. Polar bears, for instance, are spending up to a month longer each year on land, rather than out hunting on sea ice, which is leaving them malnourished.

But to some, sea ice decline represents an opportunity. In the Canadian Arctic, ship traffic nearly tripled between 1990 and 2015. This includes government icebreakers, research ships, cargo vessels, and pleasure craft like cruise ships and private yachts. Over a century ago, explorers like Roald Amundsen competed to steer the first ship through the ice-bound north. In some ways, the opening of the Arctic has sparked a second race for the Northwest Passage.

Photo by
More accessible Arctic waters present potential opportunities for local communities, including a growing tourist economy and more frequent resupply of goods, even as ship noise poses a potential threat to marine ecosystems. Photo by Martha de Jong-Lantink.

At a meeting of the Arctic Council in Finland last May, United States Secretary of State Mike Pompeo displayed his frontier ideology when he called the Arctic “the forefront of opportunity and abundance” that “houses 13 percent of the world’s undiscovered oil, 30 percent of its undiscovered gas, an abundance of uranium, rare earth minerals, gold, diamonds, and millions of square miles of untapped resources, fisheries galore.” Pompeo then added that sea ice decline represents “new passageways and new opportunities for trade.” An ice-free Arctic, he said, would cut travel time between Asia and Europe via sea “by as much as 20 days.”

For the communities at Resolute Bay and throughout the Canadian Arctic, a longer open-water season presents certain potential opportunities as well — from a growing tourist economy to more frequent resupply of goods. Despite those trade-offs, however, a prominent concern among northerners is that ship noise is disrupting the marine food web and, by extension, the cultural and subsistence practices that depend on it. “It’s our food insecurity or food sovereignty that’s impacted,” Okalik Eegeesiak, former chair of the Inuit Circumpolar Council, recently told The Toronto Star.

Not coincidentally, Inuit communities are situated close to these nearshore areas where Arctic cod schools and marine mammals feed. Subsistence hunting remains a vital component in northern Indigenous foodways. In some parts of Nunavut, more than half of the Inuit diet consists of ringed seal and other marine mammals.

Displacing Arctic cod could exacerbate food insecurity in a region already facing exorbitant food costs due to its remote location, but subsistence hunting isn’t only about access to food. “It’s about being on the land, being able to participate in culture,” says Jackie Dawson, an associate professor in the Department of Geography at the University of Ottawa. “It’s part of the overall wellbeing of people in the north.”

In 2016, Canada’s Prime Minister Justin Trudeau launched an Oceans Protection Plan that would, among other things, establish low impact shipping corridors — trade routes through the Canadian Arctic designed to minimize environmental impact. The problem, explains Dawson, was that many of the proposed corridors didn’t include direct input from Arctic communities. For that reason, Dawson and her research team worked with Inuit communities — in a project called Arctic Corridors and Northern Voices — to compile northern perspectives and recommendations for regulating the shipping industry through such corridors, including places ships should avoid for ecological and cultural reasons, ice and weather conditions permitting. The most recent summary of these recommendations was recently published in Environmental Science & Policy.

According to Dawson, most mariners in the Arctic would willingly work with these local considerations. The next step is integrating this local insight into Arctic-wide policy. “In the absence of this [local knowledge], there could be major impacts to food sources and cultural activities, and it could be dangerous to hunters,” Dawson says. “But with this information now, we’re hoping to mitigate a lot of that risk.”

In the meantime, researchers are continuing to build up the scientific literature on how vessel noise impacts Arctic wildlife. Last year, an Arctic Council working group called Protection of the Arctic Marine Environment, or PAME, published a state of knowledge report on underwater noise in the Arctic. This report made clear that beyond Arctic cod and a few other species, not much is known about how wildlife in this region reacts to ship noise and how far this impact goes. What we do know, says Halliday, who co-authored the PAME report, is that beluga whales and narwhals have both been found to flee the noise from icebreakers, while bowhead whales tend to avoid noise from oil and gas activities. This latest research on Arctic cod, in other words, fits a pattern.

But in a heterogenous region with dozens of marine mammals, hundreds of fish species, and thousands of invertebrate species, not to mention various government and industry stakeholders and an increasing rate of sea ice decline due to climate change, the impacts of a burgeoning Arctic shipping industry remain in question.

“The next step is trying to estimate how much underwater noise from ships occurs across the Arctic, highlighting important areas and management measures, and trying to address policy change to deal with the issue of underwater noise,” Halliday says. “There’s a lot of work to be done.”

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