By Martin Robards, Stephen Insley, and William Halliday
After a quarter century living and working in the Arctic, it continues to take our breath away on a regular basis. Mostly it’s the wildlife: a stupendous aggregation of migrating Sandhill cranes or caribou, a beach overflowing with fur seals, a close up encounter with a wolverine. Other times it could be a phenomenal display of northern lights.
But sometimes the news impinges on that wonderment. Increasingly, we read reports of previously unimaginable levels of melting Arctic sea ice or the arrival of new vessels and industries in the fabled and treacherous waters north of Alaska and Canada.
The effects of the climate-related changes are often acutely visible – whether female walrus and their calves crowded on remote shorelines in the tens of thousands, polar bears wandering through coastal villages rather than staying on the retreating summer ice, or the 1000-passenger Crystal Serenity cruise ship that now glides through once-frozen Arctic waters.
Yet some of the changes are less obvious to our land-based senses. Take, for instance, new human-generated ocean noise. Numerous studies highlight the importance of understanding and reducing the impacts of noise in the marine environment, but we know relatively little about it in the Arctic.Pacific walrus in Bering Strait. Photo: Ricardo Antunes/WCS.
Acute noise sources from military operations and seismic surveys during oil and gas exploration can have a range of well documented impacts on marine life. More chronic noises such as propeller sounds or those of ice breakers are often pervasive and cumulatively can cause stress to marine mammals. A study off the coast of Boston described the profound decline in stress among local whales during the period immediately after 9/11, when trade vessels stopped plying those waters.
Working and living in the coastal Arctic, we have a particular interest in the impacts of noise on marine mammals and how that affects both their health and vitality and that of our indigenous partners, who rely on marine mammals for their food and economic security.
With a range of colleagues within and outside WCS, we are developing an understanding of soundscapes, which helps us define and implement conservation strategies to protect these iconic animals in two of the most critical marine mammal habitats in the Western Arctic: Bering Strait, separating Alaska from the Russian Federation just 82 kilometers away; and the narrow passages around Banks Island, at the western entrance to the Northwest Passage in northern Canada.
The concept of minimizing noise disturbance is nothing new. On land we’ve embraced practices to reduce noise from planes, trains, and automobiles. Why not do likewise in the Arctic’s shipping lanes before it rises to a cacophony? If we don’t address noise in the ocean, marine species that rely on sound to communicate, navigate, and hunt could suffer as they have in busier areas elsewhere in the world, moving away from areas that they prefer to feed or from where local communities rely on them for food security.
To understand soundscapes as scientists, we translate the noise in the water to something we can interpret with our own senses. Groans, chugs, hisses and just plain quiet recorded by underwater microphones are converted to simple numbers and graphs called spectrograms. Since 2014, our program has deployed a total of 27 recorders in the Bering and Beaufort Seas, most of which remain under the ice during winter.
Despite the currents and shifting sands of these dynamic areas, we have retrieved enough data to start seeing results, some of which are published in three recent papers from our monitoring in the Canadian Arctic. We have detected vocalizations from seasonal visiting bowhead, minke, beluga, and killer-whales, along with walrus and bearded seals.
Others have documented calls of southerly species like humpback whales that are increasingly taking advantage of increasing open waters of the Arctic. We have also recorded noise levels of ships as they pass through these vital areas where marine mammals are concentrated.
In our recent research published by the Arctic Institute of North America, the Marine Pollution Bulletin, and Arctic Science, we find that some ships can likely be heard by marine mammals as far as 100 km away. Given that the marine mammals, particularly bowhead whales, migrate close to shore, keeping vessels further from land is an obvious way to reduce the impacts of that noise.
Additional opportunities to mitigate noise include slowing vessels in areas that cannot be avoided by ships (slower vessels generally make less noise), although this can lead to longer exposure to that noise. Finally, the development and use of quieter diesel-electric propulsion systems is a promising trend for new vessels.
Finally, we are looking at how losing the sound blanket provided by summer sea ice has both opened opportunities for more vessels to enter the Arctic, with their associated noise, and changed the range of natural noises. The newly melted waters now roil in the wind, punctuating naturally quieter soundscapes with the churning of storms and waves, which are now cumulatively responsible for a new mélange of noise in the Arctic.
We certainly don’t have all the information we need to recommend appropriate noise thresholds. For now, we’ll continue to ply these remote and challenging waters with local partners as we seek to understand the appropriate sound levels that minimize stress and sensory overload for the marine-based residents that have prospered in these waters for millennia and continue to take our breath away.
Dr. Martin Robards is Regional Director for the Arctic Beringia Program at WCS (Wildlife Conservation Society). Dr. Stephen Insley is a Conservation Scientist for the Arctic Beringia Program and WCS-Canada. Dr. William Halliday is a Post-Doctoral Research Fellow with WCS-Canada.