Tariffs are Spurring Shipping Noise in the St. Lawrence Seaway

Cargo ships are loud. Extremely loud. At up to 190 decibels, a cargo container ship’s roaring engines, vibrating machinery, and churning propellers are louder than a jet taking off. This cacophony is unpleasant, but for all sorts of marine life, it’s also dangerous. And in the St. Lawrence Seaway, which connects the Great Lakes to the Atlantic Ocean along the Canada-United States border, the noise is set to grow much louder.

Pierre Cauchy, a marine biologist at the University of Québec at Rimouski, has been working since 2021 to understand the effects of underwater noise on wildlife in the St. Lawrence River. Though charismatic creatures like whales are the poster children for the issue, sonic pollution impacts everything along the food chain. “All animals, from mussel larvae to whales, are potentially affected by noise,” Cauchy says.

The St. Lawrence’s growing issue with noise is directly related to global trade patterns. Or rather, the upending of them. In response to wide-reaching tariffs imposed on Canada and other countries by the United States in early 2025, shipping traffic in the section of the St. Lawrence between Montréal and the Gulf of St. Lawrence is soaring.

The data may be chaotic as the Trump Administration continuously revises its policies, but it’s clear that Canadian trade with other international destinations is up. Notably, the Port of Montréal—the largest container port in Eastern Canada—has seen trade increase with Africa by 39 percent and with Latin America by 12 percent. On the flip side, the flow of ships to U.S. ports in the Great Lakes and St. Lawrence region is down by more than 6 percent.

The 3,700-kilometer (2,340-mile) St. Lawrence Seaway is an important trade route that connects many of Canada’s industrial centers, and the changing shipping patterns reflect Canada’s bid to prioritize new trading partners. Taken together, shifting geopolitical tensions and reactive trade markets mean more container ships traversing the St. Lawrence River. That’s bad news for a region famous for its marine mammals and other wildlife, including its population of endangered North Atlantic right whales, which currently numbers fewer than 400 individuals.

The right whales are one of a dozen species of migrating whales that hang around the region from late spring to fall, making them yet another group caught in the crossfire as President Trump makes his geopolitical about-faces. 

At its extreme, very loud underwater noise, like military bomb tests, can kill marine life. More often, says Cauchy, shipping noise pollution leads to serious disruptions to animals’ behaviors. For example, underwater noise interrupts communication between whale mothers and their babies, causes stress, and makes animals flee for safety.

In the best-case scenario, startled animals waste a bit of energy. But a spooked whale may also ascend too quickly, which can cause decompression sickness and lead to damaging gas bubbles forming in their skin. Increased shipping also raises the risk of ship strikes—the leading cause of death for North Atlantic right whales.

Meanwhile, recent research by Delphine Veillard, at the University of Québec at Rimouski, helped discover that noise pollution alters how mussels and scallops latch onto all sorts of things, from rocks to ship hulls. These are important commercially caught species in the seaway, meaning increasing noise pollution is not only an ethical consideration but an economic one. 

Lindy Weilgart, a marine biologist and ocean noise specialist at Dalhousie University in Halifax, Nova Scotia, has been tackling the problem of ocean noise pollution since the 1990s. She notes that studies from the 1960s to the 1990s show that underwater noise increased by 3 decibels per decade on average. And a 2022 paper found that global underwater noise from shipping has doubled in 11.5 years, with regional variations.

As global waterways grow louder, Weilgart says, “regulatory agencies have to just put their foot down and make a [noise] limit, and then the rest will follow.” The problem, she adds, is that there are very few ways to reduce vessel noise pollution. “We can’t demand alternatives if they don’t exist yet.”

Right now, the most effective measure available is to have ships slow down. 

Canada has two mandatory slow-down zones. One is on the West Coast, around the Port of Vancouver where killer whales roam. The other is in the Gulf of St. Lawrence, which connects the St. Lawrence River to the Atlantic Ocean. Although the shipping industry has a strong record of participating in voluntary slow-downs, according to Parks Canada, Cauchy hopes to see more stringent, centralized measures, such as fines for noisy vessels. 

“We don’t need to wait to have convinced everyone to make less noise in the St. Lawrence. There are things that can change immediately,” Cauchy says. 

That’s not to say authorities are doing nothing. Later in 2026, Québec’s Saguenay-St. Lawrence Marine Park, a protected area where a fjord dumps fresh water into the salty seaway, attracting whales and tourists alike, is set to grow. This serendipitously-timed expansion will see the marine park jump from 1,245 to nearly 4,500 square kilometers (481 to 1,737 square miles). The park already has some voluntary speed-reduction measures in place, as well as mandatory slowdowns in particularly sensitive areas, and these measures will grow with the park expansion. 

But even these efforts, implemented by the Group on Marine Traffic and Protection of Marine Mammals (G2T3M), a coalition of marine conservation organizations, academics, government, and the shipping industry, can’t keep up with the breakneck speed of tariffs and commercial trade pivots.