An increasingly ice-free Arctic could test the adaptability of marine mammals, a new study has found, as hundreds of ships in recent years have used the newly open polar seas to transport goods and people.
Ship strikes, increased pollution and light, and a noisier ocean could all potentially cause problems for whales, seals and bears, especially as scientists expect the number of vessels — as well as the routes open to them — to rise.
“Even going right over the North Pole may be passable within a matter of decades,” Donna Hauser, a marine ecologist and the study’s lead author, said in a statement. “It raises questions of how to allow economic development while also protecting Arctic marine species.”
To get a better idea of what all this new traffic will mean for seven marine mammal species that live in this part of the world, Hauser and her colleagues looked at 80 subpopulations of the animals living in the vicinity of two important shipping routes: The Northern Sea Route runs roughly parallel to most of Russia’s northern coastline, while the Northwest Passage connects the Atlantic to the Pacific passing through high-latitude Canada and around northern Alaska.
Until recently, these routes were only an option for vessels that had powerful icebreaking ships plowing a path ahead of them. But the authors report that commercial ships are already using the Northern Sea Route, and other research shows that the Northwest Passage could be a viable option by around 2050.
The team pinpointed the locations of the different species in relation to the routes during September, the time of year when polar waters are the most open. They also looked at each species’ sensitivity to factors such as spikes in noise, which could interfere with their hunting or communication, and the likelihood that they’d be hit. From these, they compiled a set of “vulnerability scores.” Based on these analyses, they found that the new ship traffic could negatively impact 42 of the subpopulations.
The findings indicate that narwhals (Monodon monoceros), a whale species best known for its long spiraling tusk, are most apt to be affected.
“Narwhals have all the traits that make them vulnerable to vessel disturbances,” Kristin Laidre, a polar scientist at the University of Washington and co-author of the paper, said in the statement. “[They] stick to really specific areas, they’re pretty inflexible in where they spend the summer, they live in only about a quarter of the Arctic, and they’re smack dab in the middle of shipping routes.
“They also rely on sound, and are notoriously skittish and sensitive to any kind of disturbance,” Laidre added.
Walruses (Odobenus rosmarus), bowhead whales (Balaena mysticetus) and beluga whales (Delphinapterus leucas) also rated high on the vulnerability scale.
The researchers found that the risks for marine mammals rose by a factor of two or three at several “pinch points” along the route, such as the Bering Strait between the land masses of Asia and North America.
“These obligatory pinch points are used by migratory species to get in and out of the Arctic, but they are also necessary passageways for vessels using these sea routes,” Hauser said. “Identifying the relative risks in Arctic regions and among marine mammals can be helpful when establishing strategies to deal with potential effects.”
Elsewhere, scientists have studied the interplay between ships and whales, including fin, blue, and North Atlantic right whales, Laidre said. Those insights have led to changes in the way ships operate when passing through high-risk areas.
“I think we can learn a lot from areas that have already been thinking about these kinds of conflicts between ships and marine mammal populations,” Laidre said. “We could aim to develop some mitigation strategies in the Arctic that help ships avoid key habitats, adjust their timing taking into account the migration of animals [and] make efforts to minimize sound disturbance.”
Banner image of a bowhead whale by Kristin Laidre/University of Washington.
Hauser, D. D. W., Laidre, K. L., & Stern, H. L. (2018). Vulnerability of Arctic marine mammals to vessel traffic in the increasingly ice-free Northwest Passage and Northern Sea Route. Proceedings of the National Academy of Sciences.