New baseline set for marine mammals exposure to ship traffic in the Pacific Arctic

Ship traffic in the Arctic is at an all-time high due to declining sea ice, which has opened opportunities for greater development in the Pacific Arctic. The Bering Strait, the Pacific Arctic and associated ecosystems encompass the northern Bering Sea, Chukchi Sea, Beaufort Sea, and East Siberian Sea. 

Bering Strait is a narrow 53-mile-wide waterway connecting the Pacific and Arctic Oceans. It is a seasonal migration chokepoint for hundreds of thousands of marine species, including birds, fish, and marine mammals such as the ringed seal and bowhead whale. It is home to Indigenous communities that rely on marine mammals for food security,  traditional and cultural practices. It is also the only passage for ships of all types between the two oceans. 

Two new studies in this region establish a baseline on vessel traffic exposure and its potential impacts on two species of marine mammals. These studies advance our understanding of how increasing marine traffic overlaps with migratory marine mammal populations over time as sea ice continues to decline.

The long-term impacts of vessel traffic on mammals in this region are still somewhat unknown. According to Donna Hauser, “Large, fast moving, and often loud vessels are relatively novel in the Pacific Arctic, but we know from other parts of the world that marine traffic can impact marine mammal behavior, disrupt habitat use, or at worse lead to serious injury or death from collision. For example, Arctic bowhead whales share similar behaviors to closely-related right whales, including the critically endangered North Atlantic right whale that are extremely vulnerable to ship strikes.”  

Hauser is a research associate professor at the University of Alaska Fairbanks International Arctic Research Center, and is the lead author of the article, Year-round potential exposure of ringed seals to vessel traffic in the Pacific Arctic, 2013-2022, published recently in the journal Endangered Species Research*.

Hauser and her colleagues established the first baseline understanding of how often ringed seals are exposed to traffic throughout the year, including months when sea ice is present.  

“Almost all research on vessels and Arctic marine mammals has previously focused on bowhead or beluga whales, which are at a higher risk during the open water season. But ringed seals, in particular, rely on sea ice as a platform to give birth and raise their pups on, making them particularly vulnerable to vessels at different times and habitats.” Hauser says. 

During the ice-covered season, vessel traffic, such as from icebreakers, has the potential to disturb mothers and pups or break up critical reproductive habitat. For now, however, the research suggests that ringed seal exposure to vessels during the ice-covered season remains relatively low compared with other times of the year. However, less is known about other impacts affecting ringed seals, such as engine noise, which travels much farther in water than in air, and ship-related pollution.

Hauser is also a coauthor on a recent publication from Frontiers in Marine Research on bowhead whales, Changes in sea ice influence bowhead whale distribution and overlap with vessel transits in the Pacific Arctic, along with lead author Angela Szesciorka from Oregon State University. This study examined how changes in sea ice affected bowhead whale fall–winter distribution in the region and explored risks associated with numbers of vessels, speed, and transit time for bowhead whales. 

“Less sea ice is leading to more vessels in the Arctic, and in some months, larger and faster vessels. This could create a hotspot of overlap between vessel traffic and bowhead whales, especially in Bering Strait.” Szesciorka says. “We know so little about bowhead whale vessel encounters and strike risk. Our hope is that studies like this will provide information that policymakers can use to put measures in place to prevent unnecessary bowhead whale deaths due to vessel strikes.” 

Some of the results of this study were surprising. Vessel activity in areas of higher sea-ice concentration is increasing at a greater rate than in open water. The increase is driven largely by icebreakers operating along the Russian coast, which account for roughly one third of this traffic. Bowhead whales shifted their distribution northward to follow sea ice in years of lower ice cover so they experienced less overlap with the non-icebreaker vessels which tend to avoid ice. 

“A nice thing we confirmed in this study is that bowhead whales can adjust their distributions in response to changing conditions. If the ice is further north or south, they’ll follow it.” Szesciorka says that bowhead whales may stay within the seasonal ice edge to find food and avoid predators.

Working with very different data sets is a huge challenge and these studies looked at over thirty component relationships over a ten year period. Both involved processing massive datasets with over ten years of location data for 16 types of marine vessels and 14 years of location data for bowhead whales and ringed seals. Combined with data on sea ice extent, the data were complex.

“It was powerful to put all these pieces together,” Szesciorka says. “Understanding how the sea ice variability dictates bowhead whale distribution, and seeing how that, in turn, affects their overall overlap with vessel traffic – it showed the importance of doing more studies like this to monitor changes over time and to develop proactive management strategies.”

*Other co-authors included researchers from Durham University, the North Slope Borough Department of Wildlife Management and the Alaska Department of Fish and Game.

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For more information, contact: Donna Hauser, 907-474-1553, dhauser2@alaska.edu; Angela Szesciorka, angela@szesciorka.com.