Alaska is home to two recognized subpopulations of polar bears, both tied to the state’s northern and northwestern coastlines and the sea ice that extends from them. The Southern Beaufort Sea population ranges along the north coast from roughly Icy Cape east into Canada, while the Chukchi Sea population occupies waters off Alaska’s northwest coast and is shared with Russia. Together these groups face a convergence of pressures: shrinking sea ice, shifting prey access, rising exposure to disease, and growing contact with coastal communities. The picture is not uniformly bleak across both populations, but the overall trajectory gives researchers real concern.
Two Populations, Two Coasts
Alaska’s polar bears belong to two of the 19 subpopulations recognized across the circumpolar Arctic. The Southern Beaufort Sea (SB) group lives primarily along the northern Alaskan coast, using nearshore sea ice and the continental shelf for hunting ringed and bearded seals. The Chukchi Sea (CS) group occupies waters to the west, off Alaska’s northwest coast and extending into Russian territory. The boundary between them runs roughly near Point Barrow, though individual bears sometimes cross it. These two populations experience different ice conditions, prey availability, and rates of change, which means their health and numbers do not always move in lockstep.
The Chukchi Sea is a more productive body of water with a broader continental shelf, which supports a richer prey base. Researchers comparing the two populations found that Chukchi Sea bears were larger, in better body condition, and appeared to reproduce more successfully than their Southern Beaufort Sea counterparts.1PubMed. Variation in the response of an Arctic top predator experiencing habitat loss: feeding and reproductive ecology of two polar bear populations That gap matters because it suggests the Chukchi population has more of a buffer against the stresses that are already hitting southern Beaufort bears hard.
Population Numbers and Trends
Counting polar bears is exceptionally difficult. They roam enormous areas of remote sea ice, they move between jurisdictions, and weather routinely grounds the helicopters used in mark-recapture surveys. Estimates for Alaska’s populations carry wide confidence intervals, and you should treat any single number as a rough snapshot rather than a precise census.
The Southern Beaufort Sea population is the better-studied of the two. A mark-recapture analysis covering 2001 to 2010 found that low survival rates from 2004 through 2006 drove a decline of roughly 25 to 50 percent in abundance. The most likely cause was unfavorable ice conditions that cut bears off from prey over multiple seasons, possibly compounded by low prey numbers. Adult and cub survival improved after 2007 for reasons that remain unclear, and abundance stabilized at around 900 bears by 2010.2PubMed. Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline Subadult bears, however, continued to fare poorly throughout the entire study period, which is a worrying sign for long-term recruitment.
The Chukchi Sea population has historically been harder to assess because its range spans both U.S. and Russian waters. Integrated population modeling has produced the first rigorous abundance estimates for this group, referenced to the subpopulation boundary recognized by the IUCN Polar Bear Specialist Group.3Scientific Reports. Integrated Population Modeling Provides the First Empirical Estimates of Vital Rates and Abundance for Polar Bears in the Chukchi Sea Because Chukchi bears are in better condition and reproducing more successfully, this population is currently considered more stable than the Southern Beaufort group. But “more stable” is relative; the same long-term ice loss threatens both.
How Sea Ice Loss Reshapes Everything
Polar bears depend on sea ice for hunting, traveling, and breeding. Across all 19 subpopulation regions worldwide, researchers have documented a trend toward earlier spring ice retreat and later fall ice advance. The number of ice-covered days is declining at a rate of 7 to 19 days per decade depending on the region, while summer-to-fall ice concentration is dropping 1 to 9 percent per decade.4The Cryosphere. Sea-ice indicators of polar bear habitat For Alaska’s bears, this means the hunting season is getting shorter and the distances between viable ice platforms are growing.
The consequences show up in how much ground the bears need to cover. In the Beaufort Sea, polar bears that stayed on summer ice had average home ranges about 64 percent larger from 1999 to 2016 compared to the period from 1986 to 1998. The expansion was driven by summer ranges that now include far more open water and far less of the ice types bears actually prefer.5Ecosphere. Effects of sea ice decline and summer land use on polar bear home range size in the Beaufort Sea A bigger home range sounds like it might be neutral, but it is not. Covering more ocean to find the same amount of food burns energy that bears cannot easily replace.
In the Chukchi Sea, the picture is equally stark. Polar bears there showed no change in which habitat types they preferred between the periods before and after major ice loss. They still selected the same kinds of ice. The problem is that there is far less of it: summer brought a 75 percent reduction in the amount of highly selected habitat available.6PubMed Central. Invariant polar bear habitat selection during a period of sea ice loss The bears have not adapted their preferences; the habitat has simply contracted underneath them.
Coming Ashore and Changing Diets
As sea ice retreats farther and earlier, a growing number of polar bears are spending more time on land. In the Southern Beaufort Sea region, monitoring since the early 2000s has shown an increasing proportion of bears coming ashore in fall and early winter to scavenge on subsistence-harvested bowhead whale carcasses left by Alaska Native hunters. At the bone pile near Kaktovik, Alaska, researchers estimated that as many as 72 male and 76 female bears used the site in 2012, which represented roughly 16 percent of the entire Southern Beaufort subpopulation.7ARCTIC. Use of Subsistence-Harvested Whale Carcasses by Polar Bears in the Southern Beaufort Sea
Whale carcasses provide a substantial caloric windfall for individual bears, but the trend raises questions about what happens when bears concentrate in small coastal areas near human communities. Kaktovik has become an unexpected draw for wildlife tourism as well, with visitors arriving to watch dozens of bears feed just outside town. The ecological significance of land-based scavenging is still being evaluated. It is unclear whether the calories offset the energy lost from a shorter ice-hunting season, but the behavior strongly suggests that Southern Beaufort bears are under enough nutritional stress to seek out alternative food sources.
Terrestrial foraging has other consequences too. As summer sea ice diminishes, stranded bears are raiding the nests of coastal-nesting seabirds on Alaska’s barrier islands. Research has documented increasing polar bear predation on bird colonies, where bears eat eggs, nestlings, and sometimes adult birds.8Polar Research. Polar bear predation on barrier island bird colonies in Arctic Alaska increases with sea-ice decline For the bears, these are low-calorie snacks that barely register against their massive energy needs. For the bird colonies, however, the predation can be devastating to reproductive success during a single season.
Long-distance swimming is another side effect of ice loss. Bears are capable swimmers, but open-water crossings between ice floes or between ice and shore appear to demand significantly more energy than traveling over sea ice.9Canadian Journal of Zoology. Long-distance swimming by polar bears (Ursus maritimus) of the southern Beaufort Sea during years of extensive open water Cubs are especially vulnerable during these swims. As ice-free gaps widen, the energetic toll of simply getting from one hunting platform to the next could become a meaningful drain on bears that are already nutritionally stressed.
Human-Bear Encounters on the North Slope
More bears spending more time on land inevitably means more contact with the Alaska Native communities that dot the northern coast. Villages like Kaktovik, Utqiaġvik (formerly Barrow), and others along the North Slope now deal with bears wandering into town, especially in fall when ice has not yet formed and the whale carcass piles are drawing animals in. This is a safety issue for residents and a conservation issue for bears.
Community-based polar bear patrols have been established to respond to bears that enter or approach villages. These patrols use a combination of deterrents to haze bears away, and data from 2018 to 2019 show them to be remarkably effective. About 96 percent of hazing incidents ended with the bear leaving. The type of deterrent mattered a lot: all-terrain vehicles (ATVs) were the single most effective tool, roughly four to five times more effective than cracker shells or beanbag rounds, which did not significantly improve outcomes on their own. Bears in poor body condition took about 15 percent more effort to move, likely because a hungry bear is less willing to give up a potential food source. Later in the fall season, bears were easier to move, perhaps because freeze-up was approaching and the animals were more inclined to head back toward ice.10Wildlife Society Bulletin. Efficacy of deterrents for mitigating human‐polar bear conflict in northern Alaska
The success of these patrols is notable because lethal removal of problem bears would be both culturally and legally fraught. Under the Marine Mammal Protection Act, polar bears in the United States can only be harvested by Alaska Natives for subsistence purposes and the creation of traditional handicrafts. The U.S. Fish and Wildlife Service and the Alaska Nanuuq Commission share co-management responsibilities, a framework intended to balance species conservation with the rights and food security of indigenous communities. Non-lethal deterrence is therefore not just a preference but effectively a necessity, and the patrol data suggest it works.
Contaminants in a Changing Food Web
Polar bears sit at the top of the Arctic marine food web, which means pollutants that bioaccumulate through the food chain end up concentrated in their tissues. Mercury is the contaminant that has received the most attention in Alaska’s bears. A study of hair samples from Southern Beaufort Sea bears collected between 2004 and 2011 found total mercury concentrations ranging from 0.6 to 13.3 micrograms per gram, with a mean of about 3.5.11PubMed. Ecological Change Drives a Decline in Mercury Concentrations in Southern Beaufort Sea Polar Bears The wide range reflects individual variation in diet. Ongoing data collection from 2008 to 2019 has continued to track mercury levels in hair alongside diet composition and even gut microbiome diversity, looking at whether mercury acquired through food affects the microbial communities in the bears’ digestive systems.12U.S. Geological Survey. Mercury Concentrations, Diet, and Gut Microbiota Diversity of Southern Beaufort Sea Polar Bears, 2008-2019
An earlier survey comparing liver tissue from the Beaufort and Chukchi populations found that mercury concentrations varied widely, from 3.5 to 99 micrograms per gram dry weight, with mean levels comparable to what has been reported in other Arctic marine mammals. Copper levels were at the high end of the range seen in marine mammals generally. Lead and cadmium, on the other hand, were lower than those reported in polar bears from Greenland and Canada.13PubMed. Trace element concentrations in livers of polar bears from two populations in Northern and Western Alaska The geographic differences in contaminant loads highlight how much a bear’s specific diet and location within the Arctic influence its toxic burden.
What makes contaminant monitoring in polar bears particularly tricky is that the food web itself is changing. As sea ice declines and bears shift toward land-based food sources like whale carcasses and bird eggs, their contaminant exposure profile changes too. Researchers have noted that mercury trends in Southern Beaufort bears appear linked to ecological change, not just industrial emissions, because the bears are eating different proportions of prey species than they once did. A bear scavenging a bowhead whale carcass acquires a different contaminant mixture than one hunting ringed seals on the ice.
Rising Exposure to Disease
One of the less-discussed threats to Alaska’s polar bears is the apparent increase in their exposure to infectious pathogens. A study comparing blood samples from Southern Beaufort Sea bears across three decades found that seroprevalence (meaning the proportion of bears showing antibodies to a given pathogen, indicating past exposure) was 26 to 541 percent higher in bears sampled from 2008 to 2017 compared to those sampled from 1987 to 1994. Significant increases were found for the parasites Toxoplasma gondii and Neospora caninum, and the bacterium Francisella tularensis (the agent behind tularemia). Exposure to Brucella and canine distemper virus also rose, though those changes fell just short of statistical significance.14PLOS ONE. Increased pathogen exposure of a marine apex predator over three decades
The working explanation ties back to climate-driven behavioral change. Bears spending more time on land come into contact with a different suite of pathogens than they would encounter on the ice. Terrestrial prey, scavenged carcasses, freshwater sources, and closer proximity to other land-based wildlife all create new exposure pathways. Researchers have suggested that previously documented shifts in polar bear behavior, driven by sea ice loss, may have altered their risk of encountering both persistent organic pollutants and disease agents.15Scientific Reports. Environmental and behavioral changes may influence the exposure of an Arctic apex predator to pathogens and contaminants This is an area where the science is still emerging. No one has documented a disease-caused die-off in Alaska’s polar bears, but the trend in pathogen exposure is moving in the wrong direction.
What Climate Models Project
The long-term future for Alaska’s polar bears depends overwhelmingly on what happens to Arctic sea ice, which depends overwhelmingly on greenhouse gas emissions. Modeling studies have tried to connect the dots between emissions scenarios, projected ice loss, and bear population outcomes, and the results range from concerning to grim.
A demographic analysis linking population models to climate projections found that the Southern Beaufort Sea population faces drastic declines by the end of the 21st century under business-as-usual emissions. As the frequency of poor ice years increases, the projected population growth rate turns negative and stays there.16PubMed. Climate change threatens polar bear populations: a stochastic demographic analysis A broader analysis covering all four polar bear ecoregions found that the probability of population decline rises with both time and emissions levels. Under the worst-case scenario, the probability of decreased or greatly decreased populations reaches 90 percent or higher by end of century for every ecoregion except the Canadian Archipelago, which still faces a 60 to 80 percent probability of decline.17Ecological Indicators. Incremental evolution of modeling a prognosis for polar bears in a rapidly changing Arctic
Habitat-specific projections offer detail on where the losses hit hardest. Optimal polar bear habitat, defined by ice conditions most conducive to hunting, is projected to shrink dramatically in summer. From a baseline of about 1 million square kilometers of optimal summer habitat observed in the late 1980s and early 1990s, multi-model projections point to roughly 320,000 square kilometers by the 2090s, a loss of about 68 percent. Winter habitat losses are smaller, around 17 percent. The losses in optimal habitat are greatest in the southern seas, especially the Chukchi and Barents seas, the exact areas Alaska’s bears depend on. The researchers note that the modeled rates of habitat loss during the study’s own historical period actually lagged behind the observed real-world losses, meaning these projections may be conservative.18Ecological Monographs. Predicting 21st‐century polar bear habitat distribution from global climate models
Lower emissions pathways produce better outcomes, but none of the scenarios analyzed project stability for Alaska’s populations. The question is one of degree: how much decline, how fast, and whether the bears can persist in reduced numbers through the worst decades of ice loss.
New Tools for Tracking a Hard-to-Count Species
Traditional polar bear research relies heavily on helicopter-based capture, sedation, and tagging, which is expensive, logistically brutal in Arctic conditions, and stressful for the animals. Newer approaches are starting to supplement these methods. One promising avenue involves extracting environmental DNA from polar bear snow tracks. Researchers have shown that nuclear DNA can be recovered from tracks left in snow, opening the possibility of genetic mark-recapture studies that do not require handling the animals at all.19Frontiers in Conservation Science. Capturing environmental DNA in snow tracks of polar bear, Eurasian lynx and snow leopard towards individual identification The technique is still in early stages and would need scaling before it could replace aerial surveys, but it represents the kind of low-disturbance monitoring that works well for a species spread thinly across a vast and inhospitable landscape.
Satellite telemetry, particularly GPS collars fitted to adult females, remains the backbone of movement and habitat-use studies. Males cannot be collared reliably because their necks are wider than their heads, so collars slip off. This creates a persistent sex bias in tracking data. Remote sensing of ice conditions from satellite imagery is what makes the habitat-loss projections possible, and combining bear movement data with ice data has become the standard approach for understanding how the animals respond to a changing environment. As ice conditions continue to shift, the demand for long-term monitoring data only grows.