Reductions in sea ice in the Arctic have a clear impact on animals such as polar bears that rely on frozen surfaces for feeding, mating and migrating. But sea ice loss is changing Arctic habitat and affecting other species in more indirect ways, new research finds.

Beluga whales that spend summers feeding in the Arctic are diving deeper and longer to find food than in earlier years, when sea ice covered more of the ocean for longer periods, according to a new analysis led by 91̽»¨ researchers. The , published this month in the journal Diversity and Distributions, is one of the first to consider the indirect effects of sea ice loss on Arctic species that dwell near the ice, but don’t necessarily depend on it for survival.

“I think this paper is novel in that we’re presenting some of the first indirect effects of sea ice loss for an Arctic whale species,” said lead author , a postdoctoral researcher at the UW’s Polar Science Center and former doctoral student at the School of Aquatic and Fishery Sciences. “As changes in sea ice affect oceanographic properties, that could be affecting the distribution, abundance or species composition of prey for belugas.”

Two genetically distinct beluga populations spend winters in the Bering Sea, then swim north in the early summer as sea ice melts and open water allows them passage into the Beaufort and Chukchi seas. There they feast all summer on fish and invertebrates before traveling back south in the fall. Both populations are considered healthy.

The researchers analyzed migration data collected intermittently from two different periods — referred to in the paper as “early” and “late” — for two beluga populations, covering the years 1993-2002 and 2004-2012. Satellite-linked tags attached to the whales tracked their movements around and away from the high Arctic feeding grounds. Dive-depth data were collected for only one population, the Chukchi belugas, because the other population’s tags did not have those capabilities.

Researchers also tracked sea ice cover in the Arctic over these two periods and found that the ice declined substantially from the first to the second period.

“We have documented loss of sea ice and reductions of habitat for Arctic marine mammals across most of the circumpolar Arctic, so this area is not unique,” said co-author , a 91̽»¨associate professor in the School of Aquatic and Fishery Sciences and the Polar Science Center. “We’re seeing this ice loss broadly in all areas where belugas occur.”

Sea ice loss appears to affect how the Chukchi belugas dove for their food. During the later period, when there was less sea ice, the whales dove significantly longer and deeper than in the earlier period — presumably in search of prey as the animals, in turn, changed their habits because of different ocean conditions brought on by sea ice loss.

Specifically, during the earlier period belugas dove for 20 minutes or longer only once per day, compared to nearly three times a day during the later period. Similarly, their average daily dive depth increased from about 50 meters (164 feet) to 64 meters (210 feet) between the two periods.

The belugas might be diving longer and deeper to follow prey that has dispersed or been driven deeper itself from changing ocean conditions. It’s also possible that feeding opportunities are actually better for belugas in an ocean with less sea ice.

“Reduced sea ice cover over a longer period of time over the summer could mean improved foraging for belugas,” said Hauser, who is also a researcher at the University of Alaska Fairbanks. “But it’s also important to recognize these changes in diving behavior are energetically costly.”

It’s unclear whether diving changes are positive or negative for belugas, and studies on body condition and health are needed to understand the implications of these changes, she added.

Aside from changes in how belugas dove for food, the nearly two decades of data show that the whales were able to thrive in their summer and fall ocean habitats, despite less ice cover. This adaptability to changes in Arctic conditions speaks to the whales’ resiliency, the researchers said.

“Belugas feed on a lot of different prey and use many different habitats, across open water and dense sea ice and everything in between,” Hauser said. “Because they are such generalists, that could buffer them under climate change.”

Other co-authors are of the UW; Robert Suydam of North Slope Borough in Utqiaġvik, Alaska; and Pierre Richard of Fisheries and Oceans Canada.

This analysis was funded by the National Science Foundation’s 91̽»¨IGERT Program on Ocean Change, NASA and the 91̽»¨School of Aquatic and Fishery Sciences. Many individuals and organizations supported beluga whale tagging, including the Alaska Beluga Whale Committee, North Slope Borough, Village of Point Lay, the Inuvialuit Hunter and Trapper Committees, Fisheries and Oceans Canada, National Marine Fisheries Service, Alaska Department of Fish and Game, National Fish and Wildlife Foundation and the Minerals Management Service.

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For more information, contact Hauser at dhauser@uw.edu or 907-474-1553 and Laidre at klaidre@uw.edu.

The annual migration of some beluga whales in Alaska is altered by sea ice changes in the Arctic, while other belugas do not appear to be affected.

A led by the 91̽»¨ finds that as Arctic sea ice takes longer to freeze up each fall due to climate change, one population of belugas mirrors that timing and delays its migration south by up to one month. In contrast, a different beluga population, also in Alaska, that migrates and feeds in the same areas doesn’t appear to have changed its migration timing with changes in sea ice.

The paper was published Dec. 21 in the journal Global Change Biology.

“The biggest take-home message is that belugas can respond relatively quickly to their changing environment, yet we can’t expect a uniform response across all beluga populations,” said lead author , a postdoctoral researcher at the UW’s .

“If we’re trying to understand how these species are going to respond to climate change, we should expect to see variability in the response across populations and across time,” Hauser said. “That may complicate our predictions for the future.”

Two genetically distinct beluga populations spend winters in the Bering Sea, then swim north in the early summer as sea ice melts and open water allows them passage into the Beaufort and Chukchi seas. There they feast all summer on fish and invertebrates before traveling back south in the fall. Other research suggests the whales are taught by their mothers when to migrate and which route to take, so it was unclear if belugas would be responsive to sea ice changes.

The Chukchi beluga population’s response to follow sea ice timing and delay migration likely means the whales are opportunistically feeding later into the fall, but researchers don’t yet know if that delay is overall beneficial. On one hand, the whales might be gaining valuable food resources, but they also risk getting blocked from their migration path south if the ice quickly freezes up and catches them off guard.

In contrast, the Beaufort beluga population’s apparent indifference to sea ice timing is surprising, Hauser said, given that both populations frequent many of the same feeding areas and otherwise appear to have similar life histories. Perhaps the Beaufort whales have a tradition of feeding elsewhere that requires they move away earlier in the fall, regardless of sea ice characteristics, she explained.

“This all suggests that beluga whales can respond to their changing Arctic conditions, although all populations will not necessarily respond the same,” Hauser said.

Very few studies exist on beluga whales, a marine mammal that lives in some of the Earth’s harshest conditions. Analyses on their body condition or population trajectories will need to take place before researchers can say whether their response — or lack thereof — to environmental change is beneficial or detrimental to the health of the populations.

Researchers, however, note that when they do see changes, they are happening quickly — within a 10-year span for whales that often live to be over 60 years old. That means migration patterns that are inherited over generations are changing within the lifespans of multiple generations of whales, Hauser said.

In this study, the researchers used migration data collected intermittently from two different periods — referred to in the paper as “early” and “late” — for both populations, corresponding roughly to the 1990s and 2000s decades. Satellite-linked tags attached to the whales tracked their movements around and away from the high Arctic feeding grounds.

They also used acoustic data from two underwater hydrophones that recorded the vocalizations of marine mammals each day for about six years. The social signals — an assortment of squeaks, whistles and cries — told researchers when belugas were present up to about 3 miles from the instrument. The use of underwater microphones is a good way to detect belugas in their dark, icy environment, said , a co-author and oceanographer at the UW’s Applied Physics Laboratory who uses the underwater microphones to study a range of animals in the Arctic.

These two datasets let the researchers track exactly when belugas passed certain key points along their fall migration, then correlate those days to regional sea ice information.

“One of the predictions of climate change is animals are going to change their seasonal presence in a region,” Stafford said. “This study shows that at least one population of belugas might be adapting to rapid changes in its environment. We can’t be sure, but this study is a start in documenting how an Arctic species is reacting to these changing conditions.”

Other co-authors are and of the UW; of North Slope Borough in Utqiaġvik, Alaska; and of Fisheries and Oceans Canada.

This analysis was funded by the National Science Foundation’s , NASA and the UW’s . Passive acoustic data collection was funded by grants from the National Science Foundation’s Arctic Observing Network and the Russian-American Long-term Census of the Arctic.

Many individuals and organizations supported beluga whale tagging, including the Alaska Beluga Whale Committee, North Slope Borough, Village of Point Lay, the Inuvialuit Hunter and Trapper Committees and Fisheries and Oceans Canada.

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For more information, contact Hauser at dhauser@uw.edu or 907-474-1811.

Children’s singer and songwriter Raffi may have brought beluga whales into popular culture with his 1980 song “Baby Beluga,” but surprisingly little is actually known about the life and ecology of these elusive marine mammals that live in some of the world’s most remote, frigid waters.

Two distinct populations spend winters in the Bering Sea, then move north as sea ice melts and open water allows them passage into the Beaufort and Chukchi seas. There they feast on Arctic cod, frequently diving to depths of 200 to 300 meters — and sometimes over 900 meters (0.5 miles) — to find food.

As the Arctic continues to change due to rising temperatures, melting sea ice and human interest in developing oil and shipping routes, it’s important to understand belugas’ baseline behavior, argue the authors of a published this winter in the journal . Its authors drew upon a rare dataset that spans 15 years of dive information for 30 whales to produce a comprehensive analysis of beluga migration and feeding patterns in the Arctic.

“This study gives us a benchmark of the distribution and foraging patterns for these two beluga populations,” said lead author , a doctoral student in the 91̽»¨’s . “However, there still needs to be additional work to see how beluga behavior has changed in concert with changing sea ice conditions in the Arctic.”

Beginning in 1993, researchers worked with Alaska Native communities in Northwest Alaska and Aboriginal tribes in Canada to tag beluga whales. The whales often swim close to shore during early summer, making it possible to capture a whale and attach a satellite-linked tag to the dorsal ridge along its back.

The tags are designed to turn on when the whale surfaces to breathe, then transmit locations and dive depth to a satellite that then relays data back to researchers electronically. Tag technology has improved over time, with one tag remaining on a whale and transmitting data for 18 months.

“It’s a really fantastic system for getting relatively high-resolution information for these animals that spend most of their time underwater and offshore,” Hauser said. “In addition to their inaccessibility, these populations use remote areas of the Arctic, so they are generally hard animals to research.”

For this study, the researchers also looked at the distribution of Arctic cod, a primary food source for both beluga populations, and compared that data to the locations and depths where the whales dove. They found the whales most frequently dove to depths where Arctic cod congregate (200-300 meters or 650-1,000 feet), confirming these fish are a significant source of food for belugas, and that the whales will dive to depths that maximize their encounters with prey.

The data evidenced this second finding by recording diving behavior that was all over the map, literally. Both beluga populations frequently dove to the bottom of the sea to feed on bottom-dwelling organisms in the northern Bering Sea and Chukchi Sea, but then dove in more mid-depth ranges along areas that sloped from shallow to deep. They were likely looking for opportunities to eat based on where prey was concentrated by oceanographic features, Hauser said.

Ultimately, this study helps illuminate aspects of a yearly migration that spans thousands of kilometers in a region that’s experiencing rapid change.

“The results of this work can be used not only to understand ecological relationships for Arctic top predators but also inform the management of beluga whales, which are an important subsistence resource for northern communities,” said co-author , a 91̽»¨assistant professor of aquatic and fishery sciences.

The researchers will look next at how the timing of beluga fall migration south may be affected by later sea ice freeze-up in the northern Arctic under climate change.

Other co-authors are Sandra Parker-Stetter of 91̽»¨aquatic and fishery sciences and the Northwest Fisheries Science Center; John Horne of 91̽»¨aquatic and fishery sciences; Robert Suydam of Alaska’s North Slope Borough Department of Wildlife Management; and Pierre Richard of Fisheries and Oceans Canada’s Freshwater Institute.

Beluga tagging was funded and supported by a number of organizations, including the Alaska Beluga Whale Committee, village of Point Lay, North Slope Borough and National Marine Fisheries Service ( for a full list). Funding for Hauser’s analysis came from the National Science Foundation through UW’s Integrative Graduate Education and Research Traineeship (IGERT) .

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For more information, contact Hauser at dhauser@uw.edu.

Grant number: NSF DGE-1068839