Reproductive rates of ringed seals and survival of pups in Northwestern Hudson Bay, Canada, 1991–2000

Reproductive parameters were determined from a sample of ringed seals collected by Inuit hunters during their annual open water harvest in autumn at Arviat, Nunavut, on the western coast of Hudson Bay, Canada, in 1991–1992 and 1998–2000. Ovulation rates of adult females were high and similar to rates recorded from studies of ringed seals in other geographic areas. However, pregnancy rates averaged only 55% and were significantly lower than in other studies, and the proportions of young-of-the-year were only 4.8, 4.2, 7.5, 4.1, and 23% for the mentioned years, respectively, instead of being >30% as expected. These results appear to indicate that reproductive parameters of ringed seals and survival of their young are exhibiting long-term shifts rather than short-term fluctuations, and that the trend is downward. Furthermore, these downward trends in reproduction, in conjunction with changes in the proportions of different seal species in the diet of polar bears, climatic warming in western Hudson Bay, and progressively earlier breakup of sea ice over the last 25 years, suggest that major changes are occurring in the marine ecosystem of Hudson Bay. The pathways involved are poorly understood and merit further study.     

Effects of Earlier Sea Ice Breakup on Survival and Population Size of Polar Bears in Western Hudson Bay

ABSTRACT Some of the most pronounced ecological responses to climatic warming are expected to occur in polar marine regions, where temperature increases have been the greatest and sea ice provides a sensitive mechanism by which climatic conditions affect sympagic (i.e., with ice) species. Population-level effects of climatic change, however, remain difficult to quantify. We used a flexible extension of Cormack-Jolly-Seber capture-recapture models to estimate population size and survival for polar bears (Ursus maritimus), one of the most ice-dependent of Arctic marine mammals. We analyzed data for polar bears captured from 1984 to 2004 along the western coast of Hudson Bay and in the community of Churchill, Manitoba, Canada. The Western Hudson Bay polar bear population declined from 1,194 (95% CI = 1,020-1,368) in 1987 to 935 (95% CI = 794-1,076) in 2004. Total apparent survival of prime-adult polar bears (5–19 yr) was stable for females (0.93; 95% CI = 0.91-0.94) and males (0.90; 95% CI = 0.88-0.91). Survival of juvenile, subadult, and senescent-adult polar bears was correlated with spring sea ice breakup date, which was variable among years and occurred approximately 3 weeks earlier in 2004 than in 1984. We propose that this correlation provides evidence for a causal association between earlier sea ice breakup (due to climatic warming) and decreased polar bear survival. It may also explain why Churchill, like other communities along the western coast of Hudson Bay, has experienced an increase in human-polar bear interactions in recent years. Earlier sea ice breakup may have resulted in a larger number of nutritionally stressed polar bears, which are encroaching on human habitations in search of supplemental food. Because western Hudson Bay is near the southern limit of the species' range, our findings may foreshadow the demographic responses and management challenges that more northerly polar bear populations will experience if climatic warming in the Arctic continues as projected.     

Temporal variation in distribution and density of ice-obligated seals in western Hudson Bay, Canada

Recent unidirectional climatic trends and changes in top predator population ecology suggest that long-term modifications may be happening in Hudson Bay, Canada. Effects of such changes on ice-obligated seal populations are expected but long-term studies are required to differentiate climate-induced changes from natural variation. We conducted strip-transect surveys in late spring in 1995–1997, 1999–2000 and 2007–2008 to estimate distribution, density and abundance of ice-obligated ringed (Phoca hispida) and bearded (Erignathus barbatus) seals in western Hudson Bay. When hauled out, ringed seals preferred land-fast and consolidated pack ice, whereas bearded seals preferred unconsolidated pack ice. Bearded and ringed seal density estimates varied from 0.0036 to 0.0229 seals/km² of ice and from 0.46 to 1.60 seals/km² of ice, respectively. Strong inter-annual variations were recorded in the abundance estimates of both species, with the largest abundance estimates in 1995 (104,162 and 1,494 ringed and bearded seals, respectively) and the lowest in 2008 for ringed seals (33,701) and 1997 for bearded seals (278). A sine function best described seal density estimates in western Hudson Bay and suggested a decadal cycle. Previous studies that reported low ringed seal demographic parameters in the 1990s and a recovery in the 2000s supported our interpretation of the survey results. We discuss our results in the context of climate warming and suggest that a long-term decline in ice-obligated seal density estimates may overlay a possible natural decadal cycle.     

The early bear gets the goose: climate change,polar bears and lesser snow geese in western Hudson Bay

As climate change advances the date of spring breakup in Hudson Bay, polar bears are coming ashore earlier. Since they would have lost some of their opportunities to hunt ringed seals from a sea ice platform, they may be deficient in energy. Subadult polar bears appear to come ashore before more mature individuals and the earliest subadults are beginning to overlap the nesting period of the large colony of snow geese also occupying the Cape Churchill Peninsula. The eggs these bears are known to eat could make up some of their energy shortfall. The earlier these eggs are consumed during the snow goose nesting period, the greater would be the energy that is available. Recent studies have shown that the annual survival rate for subadult bears declined in contrast to that of prime aged individuals. If this reduction in survival is related to an increasing energy deficit, as suggested by some, the consumption of goose eggs may reverse the trend and help stabilize the population, at least for some period of time. The total number of polar bears that could benefit from this resource will depend on the increasing temporal overlap with the nesting period and on the foraging behaviors of individuals eating the eggs. It is likely that other food sources will also have to play a role if the polar bears are to persist.     

Immobilization of polar bears (Ursus maritimus) with Telazol in the Canadian Arctic

In 1986, 213 polar bears (Ursus maritimus) were immobilized with Telazol on the sea ice of the eastern Beaufort Sea during April and May, and 106 along the western coast of Hudson Bay near Churchill, Manitoba (Canada) in September. No animals died from handling. The efficacy of this drug at different seasons and the physiological responses of the immobilized bears were compared. A single injection of 8 to 9 mg of Telazol per kg of body weight gave a rapid full immobilization with satisfactory analgesia, and faster recovery than other drugs for which there is no antagonist. The reactions of the bears could be reliably and easily interpreted from a safe distance before the animal was approached. There was a wide range of tolerance to high dosages and bears appeared able to thermoregulate while immobilized. The mortality rate due to handling was lower than with any other drug used to date.     

Spatial and temporal patterns of problem polar bears in Churchill,Manitoba

Human–bear interactions near the town of Churchill, Manitoba occur annually because the Western Hudson Bay polar bear population spends 4–5 months on-land each year when the sea ice melts completely. Significant changes have occurred in the Hudson Bay ecosystem and in the bear population as a result of climate warming; however, how these changes may have influenced human–bear interactions near Churchill is unclear. This study examined the temporal and spatial patterns of 1,487 problem bears captured in the Churchill area from 1970 to 2004. We also examined the relationship between problem bears and environmental variables as well as the Nunavut harvest. The number of individual problem bears caught near Churchill varied from 10 to 90 individuals per year and increased over time. Subadult males comprised 39%, subadult females 23%, adult males 18%, females with young 14%, and solitary females 6% of captures. Bears that became problem individuals were in closer proximity to the Churchill area. Nutritional stress and a northward shift in the distribution of the bears that spend the summer on-land in northeastern Manitoba may account for the increase in problem bear numbers. The date of sea ice freeze-up, which is getting progressively later, was the best predictor explaining the annual variation in the occurrence of problem bears. These results provide an understanding of how a warming climate may directly impact polar bear behaviour. This information may allow wildlife managers to predict relative levels of human–bear interactions and thereby implement effective management strategies to improve human safety and the conservation of polar bears.     

Using stable isotopes to understand changes in ringed seal foraging ecology as a response to a warming environment

Trends toward increased temperatures, reduced sea ice extent, and longer open water seasons have resulted in changing Arctic ecosystem dynamics. Expected changes include shifts in distribution and abundance of prey species for seabirds and marine mammals. Using stable isotope analysis, we studied spatial and interannual variation in ringed seal (Pusa hispida) feeding ecology in Hudson Bay in relation to environmental variables, between 2003 and 2010. Ringed seal muscle and hair samples collected from Arviat and Sanikiluaq, Nunavut, were analyzed for stable isotope ratios of nitrogen (δ¹⁵N) and carbon (δ¹³C). Seals from western Hudson Bay (Arviat) had higher δ¹⁵N and lower δ¹³C than seals from eastern Hudson Bay (Sanikiluaq), and stable isotope ratios varied interannually within each region. Peak δ¹⁵N occurred in years with spring air temperatures between approximately ?5°C and ?2°C. This temperature range was characteristic of warm years in western Hudson Bay and cool years in eastern Hudson Bay. We hypothesize that the high δ¹⁵N observed in ringed seals is indicative of greater importance of capelin (Mallotus villosus) in ringed seal diet. A comparison of ringed seal isotopic niche widths indicated greater dietary differences between western and eastern Hudson Bay with warming, suggesting a possible ecological divergence related to climate change.     

Trophic matches and mismatches: can polar bears reduce the abundance of nesting snow geese in western Hudson Bay?

Climate change driven advances in the date of sea ice breakup will increasingly lead to a loss of spring polar bear foraging opportunities on ringed seal pups creating a phenological trophic ‘mismatch’. However, the same shift will lead to a new ‘match’ between polar bears and ground nesting birds. This new match will be especially prevalent along the Cape Churchill Peninsula of western Hudson Bay where both polar bears and nesting snow geese are abundant. Easily foraged goose eggs will provide at least some of the earlier arriving polar bears with compensation for the energy deficit accrued through lost seal hunting opportunities. We examine the potential impact of changes in the extent and pattern of polar bear egg predation on snow goose abundance using projection models that account not only for increases in the temporal overlap of the two species but also for autocorrelation and stochasticity in the processes underlying polar bear onshore arrival and snow goose incubation. Egg predation will reduce reproductive output of the nesting lesser snow geese and, under all but trivial rates, will lead to a reduction in the size of their nesting population on the Cape Churchill Peninsula. Stochasticity associated with the asymmetrical advances in polar bear onshore arrival and the snow goose incubation period will lead to periodic mismatches in their overlap. These, in turn, will allow snow goose abundance to increase periodically. Climate driven changes in trophic matches and mismatches may reduce snow goose numbers but will not eliminate this over‐abundant species that poses a threat to Arctic landscapes.     

What to eat now? Shifts in polar bear diet during the ice-free season in western Hudson Bay

Under current climate trends, spring ice breakup in Hudson Bay is advancing rapidly, leaving polar bears (Ursus maritimus) less time to hunt seals during the spring when they accumulate the majority of their annual fat reserves. For this reason, foods that polar bears consume during the ice‐free season may become increasingly important in alleviating nutritional stress from lost seal hunting opportunities. Defining how the terrestrial diet might have changed since the onset of rapid climate change is an important step in understanding how polar bears may be reacting to climate change. We characterized the current terrestrial diet of polar bears in western Hudson Bay by evaluating the contents of passively sampled scat and comparing it to a similar study conducted 40 years ago. While the two terrestrial diets broadly overlap, polar bears currently appear to be exploiting increasingly abundant resources such as caribou (Rangifer tarandus) and snow geese (Chen caerulescens caerulescens) and newly available resources such as eggs. This opportunistic shift is similar to the diet mixing strategy common among other Arctic predators and bear species. We discuss whether the observed diet shift is solely a response to a nutritional stress or is an expression of plastic foraging behavior.     

CLIMATE CHANGE AND RINGED SEAL (PHOCA HISPIDA) RECRUITMENT IN WESTERN HUDSON BAY

Climate warming is predicted to reduce the extent of ice cover in the Arctic and, within the Hudson Bay region, the annual ice may be significantly decreased or entirely lost in the foreseeable future. The ringed seal ( Phoca hispida ), a key species that depends on sea ice, will likely be among the first marine mammals to show the negative effects of climatic warming. We used 639 ringed seals killed by Inuit hunters from western Hudson Bay (1991–1992, 1999–2001) to assess trends in recruitment relative to snow depth, snowfall, rainfall, temperature in April and May, North Atlantic Oscillation (NAO) from the previous winter, and timing of spring break-up. Snowfall and ringed seal recruitment varied from lower than average in the 1970s, to higher in 1980s and lower in 1990s. Prior to 1990, seal recruitment appeared to be related to timing of spring ice break-up which was correlated with the NAO. However, recent 1990–2001 environmental data indicate less snowfall, lower snow depth, and warmer temperatures in April and May when pups are born and nursed. Decreased snow depth, particularly below 32 cm, corresponded with a significant decrease in ringed seal recruitment as indicated by pups born and surviving to adults that were later harvested. Earlier spring break-up of sea ice together with snow trends suggest continued low pup survival in western Hudson Bay.     

Polar bear predatory behaviour reveals seascape distribution of ringed seal lairs

Ringed seal (Pusa hispida) breeding distribution has been extensively studied across near-shore habitats, but has received limited attention at a seascape scale due to the difficulty in accessing offshore sea ice environments. Employing highly visible predation attempts by polar bears (Ursus maritimus) on ringed seals in subnivean lairs observed by helicopter, the spatial relationship between predatory behaviour and ringed seal breeding habitat was examined. Resource selection functions were used to determine the relative probability of predation attempts on ringed seals in lairs as a function of habitat during a period of low ringed seal natality (2004–2006). Ringed seal pup kill locations were compared between years of low (2003–2006) and high (2007–2011) natality to assess the effect of reproductive output on habitat use. During years of low natality, polar bear hunting attempts were more likely in near-shore fast ice, and pup kills were observed predominately in fast ice (fast = 65 %, pack = 29 %, P = 0.002) at a median distance of 36 km from shore. In years of high natality, pup kills were observed farther from shore (median = 46 km, P = 0.03), and there was no difference in the proportion of observations in fast ice and pack ice (fast = 43 %, pack = 52 %, P = 0.29). These results suggest that the facultative use of adjacent offshore pack ice by breeding ringed seals may be influenced by natality. This study illustrates how documenting the behaviour of a predator can facilitate insight into the distribution of a cryptic prey.     

Satellite tracking of ringed seals Phoca hispida off northwest Greenland

We monitored movements and haul-out patterns of four ringed seals Phoca hispida , off Northwest Greenland between 5 June and 31 October 1988 using the Argos Data Collection and Location System When the seals were hauled out on fast ice their locations were accurately determined, but when they were at sea, few accurate locations were obtained, evidently because these seals spent little time at the surface between dives The seals remained within the fjord where they were tagged, and hauled out often to early July Thereafter, as fast-ice disappeared, they dispersed widely and spent less time hauled out Time of day had no significant effect on haul-out patterns Haul-out periods declined significantly from June to August and increased in September-October Satellite contact with one seal was lost after 16 d while the seal was still in the fjord in late June One seal travelled over 200 km southwest and was located 4 July in offshore waters of Smith Sound 30 d after instrumentation Another seal moved southeast along the Greenland coast where contact was lost after 49 d on 23 July The fourth seal moved north along the Greenland coast, hauled out regularly on ice, and returned south along the coast in late September and October after 181 d of contact with the satellite     

Effects of climate warming on polar bears: a review of the evidence

Climate warming is causing unidirectional changes to annual patterns of sea ice distribution, structure, and freeze‐up. We summarize evidence that documents how loss of sea ice, the primary habitat of polar bears (Ursus maritimus), negatively affects their long‐term survival. To maintain viable subpopulations, polar bears depend on sea ice as a platform from which to hunt seals for long enough each year to accumulate sufficient energy (fat) to survive periods when seals are unavailable. Less time to access to prey, because of progressively earlier breakup in spring, when newly weaned ringed seal (Pusa hispida) young are available, results in longer periods of fasting, lower body condition, decreased access to denning areas, fewer and smaller cubs, lower survival of cubs as well as bears of other age classes and, finally, subpopulation decline toward eventual extirpation. The chronology of climate‐driven changes will vary between subpopulations, with quantifiable negative effects being documented first in the more southerly subpopulations, such as those in Hudson Bay or the southern Beaufort Sea. As the bears' body condition declines, more seek alternate food resources so the frequency of conflicts between bears and humans increases. In the most northerly areas, thick multiyear ice, through which little light penetrates to stimulate biological growth on the underside, will be replaced by annual ice, which facilitates greater productivity and may create habitat more favorable to polar bears over continental shelf areas in the short term. If the climate continues to warm and eliminate sea ice as predicted, polar bears will largely disappear from the southern portions of their range by mid‐century. They may persist in the northern Canadian Arctic Islands and northern Greenland for the foreseeable future, but their long‐term viability, with a much reduced global population size in a remnant of their former range, is uncertain.     

VARIABILITY IN THE BLUBBER FATTY ACID COMPOSITION OF RINGED SEALS (PHOCA HISPIDA) ACROSS THE CANADIAN ARCTIC

We determined the blubber fatty acid (FA) composition of 281 ringed seals ( Phoca hispida ) across the Canadian Arctic to make inferences about spatial, temporal, and demographic patterns of foraging. Seals were sampled in nine locations between 1992 and 2004. Regional differences in FA signatures were related to the distance between groups, with the greatest similarity occurring among seals sampled in three locations within the Beaufort Sea-Amundsen Gulf. Seals in the western and southeastern portions of Hudson Bay also had similar FA signatures. Discriminant analysis on seventeen FAs classified ringed seals to their correct geographic region with 95% accuracy. Although location accounted for most of the variability in FA signatures, adult and juvenile ringed seals in Frobisher Bay-Labrador Sea and Jones Sound showed significant FA differences, as did male and female ringed seals in Jones Sound and Qaanaaq. Demographic differences were not detected among ringed seals in the Beaufort Sea-Amundsen Gulf or in western Hudson Bay. Seals off the coast of Labrador showed significant seasonal variability in FA signatures. Overall, seasonal, regional, and demographic patterns in FA signatures were consistent with differences in ringed seal diets, as inferred from stomach content and stable isotope analyses.     

The First Record of a New Haul-Out Site of Ringed Seals,Pusa hispida (Schreber, 1775) (Phocidae), on Sakhalin Island

Russian Journal of Marine Biology - A new coastal haul-out site of ringed seals, Pusa hispida (Schreber, 1775), has been found on the coast of Sakhalin Island. Information on the timing of...     

Response to Dyck et al. (2007) on polar bears and climate change in western Hudson Bay

The “viewpoint” article by Dyck et al. (2007) [Dyck. M.G., Soon, W., Baydack, R.K., Legates, D.R., Baliunas, S., Ball, T.F., Hancock, L.O., 2007. Polar bears of western Hudson Bay and climate change: are warming spring air temperatures the “ultimate” survival control factor? Ecol. Complexity 4, 73–84. doi:10.1016/j.ecocom.2007.03.002.] suggest that factors other than climate warming are responsible for a decline in the polar bear population of Western Hudson Bay. They propose: (1) that there is no evidence that the climate has warmed significantly in western Hudson Bay, (2) that any negative effects on the polar bear population likely result from interactions with humans (such as research activities, management actions, or tourism), (3) that studies suggesting climate warming could influence polar bear populations are confounded by natural fluctuations and (4) that polar bears will adapt to climate warming by eating vegetation, hunting other marine mammal species, and evolving new physiological mechanisms. In our examination of their alternative explanations, and the data available to evaluate each, we found little support for any.Research conducted since 1997 (when the last data were collected for the analyses in Stirling et al., 1999 [Stirling, I., Lunn, N.J., Iacozza, J., 1999. Long-term trends in the population ecology of polar bears in western Hudson Bay in relation to climate change. Arctic 52, 294–306.]) continues to be consistent with the thesis that climate warming in western Hudson Bay is the major factor causing the sea ice to breakup at progressively earlier dates, resulting in polar bears coming ashore to fast for several months in progressively poorer condition, resulting in negative affects on survival of young, subadult, and older (but not prime) adults and reproduction. When the population began to decline, the hunting quota for Inuit in Nunavut was no longer sustainable, which in turn probably resulted in the decline accelerating over time as a result of overharvesting (Regehr et al., 2007 [Regehr, E.V., Lunn, N.J., Amstrup, S.C., Stirling, I., 2007. Survival and population size of polar bears in western Hudson Bay in relation to earlier sea ice breakup. J. Wildl. Manage. 71, 2673–2683.]).     

Observations of a wild polar bear (<Emphasis Type="Italic">Ursus maritimus</Emphasis>) successfully fishing Arctic charr (<Emphasis Type="Italic">Salvelinus alpinus</Emphasis>) and Fourhorn sculpin (<Emphasis Type="Italic">Myoxocephalus quadricornis</Emphasis>)

Polar bears, Ursus maritimus, throughout their range, are nutritionally dependent on ringed (Phoca hispida) and bearded seals (Erignathus barbatus), which are predominantly caught on the sea ice. Other marine prey species are caught and consumed, but less frequently. As the annual sea ice retreats, polar bears throughout their range are forced ashore, where they mostly live off their stored adipose tissue. However, while land-bound they have been observed catching birds and terrestrial mammals. Although polar bears evolved from brown bears (U. arctos), direct observations of polar bears diving for and catching fish have not been reported. Here, we document observations of a young male polar bear catching Arctic charr (Salvelinus alpinus) and Fourhorn sculpin (Myoxocephalus quadricornis) by diving in Creswell Bay, Nunavut. We recorded six search bouts, where six fish were caught during dives, which were preceded by a snorkel. The average dive and snorkel length was (mean ± SD) 13 ± 5 and 6 ± 2 s, respectively.     

Diet composition of polar bears in Svalbard and the western Barents Sea

We estimated both the numerical and biomass composition of the prey of polar bears (Ursus maritimus) from 135 opportunistic observations of kills in Svalbard and the western Barents Sea collected from March to October 1984-2001. By number, the prey composition was dominated by ringed seals (Phoca hispida) (63%), followed by bearded seals (Erignathus barbatus) (13%), harp seals (P. groenlandica) (8%) and unknown species (16%). However, when known prey were converted to biomass, the composition was dominated by bearded seals (55%), followed by ringed seals (30%) and harp seals (15%). Results indicated that bearded seals are an important dietary item for polar bears in the western Barents Sea. We believe that different patterns of space use by different bears may result in geographic variation of diet within the same population.     

Spring fasting behavior in a marine apex predator provides an index of ecosystem productivity

The effects of declining Arctic sea ice on local ecosystem productivity are not well understood but have been shown to vary inter‐specifically, spatially, and temporally. Because marine mammals occupy upper trophic levels in Arctic food webs, they may be useful indicators for understanding variation in ecosystem productivity. Polar bears (Ursus maritimus) are apex predators that primarily consume benthic and pelagic‐feeding ice‐associated seals. As such, their productivity integrates sea ice conditions and the ecosystem supporting them. Declining sea ice availability has been linked to negative population effects for polar bears but does not fully explain observed population changes. We examined relationships between spring foraging success of polar bears and sea ice conditions, prey productivity, and general patterns of ecosystem productivity in the Beaufort and Chukchi Seas (CSs). Fasting status (≥7 days) was estimated using serum urea and creatinine levels of 1,448 samples collected from 1,177 adult and subadult bears across three subpopulations. Fasting increased in the Beaufort Sea between 1983–1999 and 2000–2016 and was related to an index of ringed seal body condition. This change was concurrent with declines in body condition of polar bears and observed changes in the diet, condition and/or reproduction of four other vertebrate consumers within the food chain. In contrast, fasting declined in CS polar bears between periods and was less common than in the two Beaufort Sea subpopulations consistent with studies demonstrating higher primary productivity and maintenance or improved body condition in polar bears, ringed seals, and bearded seals despite recent sea ice loss in this region. Consistency between regional and temporal variation in spring polar bear fasting and food web productivity suggests that polar bears may be a useful indicator species. Furthermore, our results suggest that spatial and temporal ecological variation is important in affecting upper trophic‐level productivity in these marine ecosystems.     

Global change effects on the long‐term feeding ecology and contaminant exposures of East Greenland polar bears

Rapid climate changes are occurring in the Arctic, with substantial repercussions for arctic ecosystems. It is challenging to assess ecosystem changes in remote polar environments, but one successful approach has entailed monitoring the diets of upper trophic level consumers. Quantitative fatty acid signature analysis (QFASA) and fatty acid carbon isotope (δ¹³C‐FA) patterns were used to assess diets of East Greenland (EG) polar bears (Ursus maritimus) (n = 310) over the past three decades. QFASA‐generated diet estimates indicated that, on average, EG bears mainly consumed arctic ringed seals (47.5 ± 2.1%), migratory subarctic harp (30.6 ± 1.5%) and hooded (16.7 ± 1.3%) seals and rarely, if ever, consumed bearded seals, narwhals or walruses. Ringed seal consumption declined by 14%/decade over 28 years (90.1 ± 2.5% in 1984 to 33.9 ± 11.1% in 2011). Hooded seal consumption increased by 9.5%/decade (0.0 ± 0.0% in 1984 to 25.9 ± 9.1% in 2011). This increase may include harp seal, since hooded and harp seal FA signatures were not as well differentiated relative to other prey species. Declining δ¹³C‐FA ratios supported shifts from more nearshore/benthic/ice‐associated prey to more offshore/pelagic/open‐water‐associated prey, consistent with diet estimates. Increased hooded seal and decreased ringed seal consumption occurred during years when the North Atlantic Oscillation (NAO) was lower. Thus, periods with warmer temperatures and less sea ice were associated with more subarctic and less arctic seal species consumption. These changes in the relative abundance, accessibility, or distribution of arctic and subarctic marine mammals may have health consequences for EG polar bears. For example, the diet change resulted in consistently slower temporal declines in adipose levels of legacy persistent organic pollutants, as the subarctic seals have higher contaminant burdens than arctic seals. Overall, considerable changes are occurring in the EG marine ecosystem, with consequences for contaminant dynamics.