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The Chukchi Sea environment changes considerably in physical and biological conditions, driven by the expanding volume of warm Pacific summer water. These environmental changes can affect the migration timing of baleen whales in the southern Chukchi Sea. However, few studies have been conducted in this area to determine the migration timing of bowhead whales (Balaena mysticetus), the only baleen whale species endemic to the Arctic region. In this study, we conducted a fixed passive acoustic monitoring of bowhead whales in the southern Chukchi Sea from July 2012 to October 2015 and compared the occurrence patterns of vocalizations to physical and biological environmental factors. Bowhead whale calls were detected in fall/winter and spring during the ice-freezing and retreating periods, respectively. The fall migration timing of bowhead whales through the southern Chukchi Sea was delayed in the years when the timing of sea ice formation was late, and it formed increasingly later in the years 2013, 2014, and 2012, in that sequence. Moreover, the sea surface temperature decreased before freeze-up, which affected the timing of fall migration of bowhead whales. There was no clear relationship between the occurrence of bowhead whale calls and the abundance of prey, especially in spring, suggesting that most bowhead whales use the southern Chukchi Sea as a corridor during their spring northward migrations. However, the occurrence of bowhead whales and high abundance of zooplankton in October–November present the possibility that bowhead whales expand their feeding area in the southern Chukchi Sea.

An ice-based visual survey of the Bering-Chukchi-Beaufort Seas stock of bowhead whales (Balaena mysticetus) was conducted in spring 2019 near Utqiaġvik (formerly Barrow), Alaska. A Horvitz-Thompson-type estimator is used to estimate population abundance from the resulting data, correcting for detection probabilities, whale availability within visual range, and whale passage during periods of missed effort. Analytical methods mirror those used by Givens et al. (2016) for the 2011 survey as much as possible; however, unlike 2011, no simultaneous acoustic monitoring was conducted in 2019, so the availability correction factor had to be estimated from past years. The estimated abundance was 12,505 with 95% confidence interval of (7,994, 19,560) and a CV of 0.228. This estimated abundance is markedly lower than the 2011 estimate of 16,820, but the 2019 confidence interval wholly encompasses the 2011 interval. We do not interpret this finding as evidence of a decline for many reasons including: highly unusual ice conditions, an unusual migration route that was sometimes too distant from observers to detect whales, failure to conduct watch because of closed leads during the early weeks of the migration when numerous whales likely passed, an unusually short perch, and hunters’ heavy use of powered skiffs near the observation perch which likely disturbed the whales during the survey. Furthermore, bowhead health assessment information for 2019 suggests that harvested bowheads did not exhibit obvious reductions in health condition, and aerial surveys in summer 2019 indicated high calf production (Stimmelmayr et al. 2020). Despite the challenges of the 2019 survey, the estimate is adequate for use with the International Whaling Commission’s management procedure and complies with the survey requirements of the Aboriginal Whaling Scheme.

We used satellite telemetry to examine bowhead whale movement behavior, residence times, and dive behavior in the Alaskan Beaufort Sea, 2006 – 18. We explored the timing and duration of use of three subregions (western, central, eastern) within the Alaskan Beaufort Sea and applied a two-state switching state-space model to infer bowhead whale behavior state as either transiting or lingering. Transiting whales made direct movements whereas lingering whales changed direction frequently and were presumably feeding. In spring, whales migrated across the Alaskan Beaufort Sea in 7.17 ± 0.41 days, primarily off the continental shelf over deep water. During the autumn migration, whales spent over twice as much time crossing the Alaskan Beaufort Sea than in spring, averaging 18.66 ± 2.30 days, spending 10.05 ± 1.22 days in the western subregion near Point Barrow. Most whales remained on the shelf during the autumn migration and frequently dove to the seafloor, where they spent 45% of their time regardless of behavioral state. Consistent dive behavior in autumn suggests that the whales were looking for food while migrating, and the identification of lingering locations likely reflects feeding. The lack of lingering locations in the eastern and central subregions suggests that prey densities are rarely sufficient to warrant whales pausing their migration for multiple days, unlike in the western subregion near Point Barrow, where bowhead whales regularly lingered for long periods of time.

This paper examines Neo-Inuit (ca. AD 1250 to present) responses to the decreased temperatures of the Little Ice Age (LIA) climate change episode (ca. AD 1300–1900) in the Foxe Basin region of central Nunavut, Arctic Canada. Cooler temperatures (and increased sea ice) would be expected to have reduced both bowhead whale (Balaena mysticetus) and Atlantic walrus (Odobenus rosmarus rosmarus) habitats, forcing Neo-Inuit to refocus their hunting activities on landfast-ice-dwelling small seals (e.g., Pusa hispida) during winter months. However, an analysis of faunal remains from Foxe Basin's largest-known Neo-Inuit (Thule, historic and modern Inuit) archaeological site, Pingiqqalik (NgHd-1), reveals a long-term subsistence economy based largely on multi-seasonal walrus hunting. Two interrelated factors may explain these results: (1) a system of recurring polynyas provided a degree of ecological stability for local walrus populations, and (2) the development of a distinctive walrus caching regime—a form of which continues among the region's contemporary Inuit—allowed residents to adeptly exploit an ecological niche, thereby ensuring food security. Together, these factors likely insulated northern Foxe Basin Neo-Inuit from the worst effects of the LIA.

—The bay waters of the Sea of Okhotsk near the Shantar Islands are the most important summer grazing areas for bowhead whales (Balaena mysticetus) of the Okhotsk population. A hydrobiological survey during the period from July 12–28th, 2016, demonstrated that waters around the Shantar archipelago are characterized by high concentrations of humic substance supplied by the peat-laden banks of rivers flowing into the bays. The average chlorophyll concentrations in bottom waters of Uda and Academy bays were 1.1 and 4.3 mg/m3, respectively. Uda and Academy bays are mainly considered heterotrophic and autotrophic basins, respectively. The measured zooplankton biomass in Uda Bay ranged from 9.5 to 2513 mg/m3, averaging 736 mg/m3; the corresponding characteristics in Academy Bay were 0.38 to 3620 mg/m3, averaging 458 mg/m3. In the Shantar water area, copepods of the species Calanus glacialis were the dominant contributor in terms of zooplankton biomass and species abundance. During early summer, nine bowhead whales were sighted south off Feklistov Island and lone whales were recorded in the North Strait and at the mouth of Nikolai Bay. The low density of polar whales in the Shantar water area in early summer may be due to the low zooplankton biomass after spring bloom and the last spawning.

The availability of a food subsidy has the potential to influence the condition, behavior, fitness, and population dynamics of a species. Since the early 2000s, monitoring efforts along the coast of northern Alaska have indicated a higher proportion of polar bears (Ursus maritimus) of the southern Beaufort Sea (SB) subpopulation coming onshore to feed on subsistence-harvested bowhead whale (Balaena mysticetus) carcasses during the fall and early winter seasons. Concurrently, Indigenous communities annually hunt bowhead whale and deposit the unused remains at localized “bone piles,” creating the potential for human-bear interactions. Our objective was to determine the annual number of polar bears feeding at the bone pile near Kaktovik, Alaska. Using a hair snag surrounding the bone pile, we collected hair samples to identify individual bears via microsatellite genotypes during 2011 – 14. We used capture-mark-recapture data in the POPAN open-population model to estimate the number of bears visiting the bone pile. We estimated that as many as 72 (SE = 9) and 76 (SE = 10) male and female polar bears, respectively, used the bone pile located at Kaktovik, Alaska, in 2012, which represents approximately 16% of the SB polar bear subpopulation. It will be important to monitor the number of bears using the bone pile and subsequent human-bear interactions and conflicts along the northern coast of Alaska, if sea ice continues to recede.

Bowhead whales (Balaena mysticetus) in the western Beaufort Sea (west of 140°W, south of 72°N) exhibit considerable spatiotemporal variability in distribution, density, and behavior that can be largely explained by variability in feeding opportunities, both local and remote. Bowhead whale feeding opportunities are dynamic and ephemeral, dependent on interannual variability driven by biological and physical forces. These insights were made possible by multidisciplinary investigations centered around the Aerial Surveys of Arctic Marine Mammals (ASAMM, https://www.fisheries.noaa.gov/alaska/marine-mammal-protection/aerial-surveys-arctic-marine-mammals ) time series, a long-term (1979–2019) dataset of line-transect surveys in the western Beaufort and eastern Chukchi Seas conducted during summer (July–August) and autumn (September–October). Seasonal patterns of bowhead whale distribution and density in the western Beaufort Sea during two time periods, prior to 2000 and since 2000, are evident in spatially explicit models of relative density that were created using ASAMM data. These models illustrate a general transition in bowhead distribution toward shallower waters as the open-water season (July–October) progresses. Notably, however, the location and number of high-density areas and the timing of the spatial transition have shifted between the two periods. The association between bowhead whales and sea ice in the western Beaufort Sea is rather enigmatic, as exemplified by the similarities in bowhead whale distribution in autumn 2019 (when sea ice retreat was extensive) with the distribution observed when sea ice extent was heavy in the 1980s and 1990s. Anthropogenic factors also affect bowhead whale distribution and density. The effects of anthropogenic and environmental factors on bowheads may be confounded, especially lacking sufficient understanding of the underlying environmental variability inherent in the ecosystem. Variability is a defining characteristic of the Arctic, but the parameters appear to be changing, sometimes in unexpected ways. Improving our understanding and capacity to predict arctic variability is fundamentally important to sound natural resource management. It follows that sound natural resource management is founded on continued monitoring of the ecosystem so that our understanding of the ecological linkages that shape animal distributions and densities tracks the changes occurring, and expected to continue to occur, in the Arctic.

The current subsistence harvest of bowhead whales (Balaena mysticetus) allows Inuit from Greenland, Canada, Alaska, and Chukotka to help fill important nutritional and cultural needs. Greenland and Canada primarily hunt from the East Canada–West Greenland stock and Alaska and Chukotka hunt from the Bering–Chukchi–Beaufort (BCB) Seas stock. There is no hunting on the Spitzbergen and Sea of Okhotsk stocks. The hunts for bowheads in Greenland, Canada, and Chukotka are small, numbering only one or two per year. The hunts on the BCB stock are considerably larger with a landed quota of 56 whales per year. The quota is established by the International Whaling Commission based on the cultural and nutritional needs of Inuit communities and on the population size and trend of bowheads. Data on harvested BCB whales have been collected since the mid-1970s. Between 1974 and 2018, hunters from 12 villages in Alaska, extending from the Bering Sea to the eastern Alaskan Beaufort Sea, harvested 1493 bowheads. Hunters at Barrow landed the most whales (n=748), while Shaktoolik only landed one and Little Diomede landed two. Some villages hunt only in the spring, some only in the autumn, while Barrow, Wainwright, and the Saint Lawrence Island villages (Gambell and Savoonga) hunt in both the spring and autumn/winter. The average size of whales differs among the villages. Gambell, Savoonga, and Wainwright harvest larger whales than do Point Hope and Barrow. It is not clear whether these differences are due to hunter selectivity, whale availability, or both. The size of landed whales changes during the migration in at least some villages. During the spring, larger whales tend to be taken more frequently near the end of the migration. The opposite is true for the autumn whereby larger whales tend to be taken early while small whales tend to be taken later. Overall, the sex ratio is equal. Generally, males and females do not appear to segregate during the spring or autumn migration. However, large females appear to comprise much of the tail end of the migration as they tend to be more common in late May in northern Chukchi Sea. The efficiency (no. of whales landed/no. of whales struck) of the hunt has increased markedly over this period. Currently, the efficiency is about 0.80. The bowhead harvests in West Greenland, Canada, Chukotka, and Alaska represent only a fraction of the estimated population size, indicating that the hunts are sustainable.

Bowhead whales (Balaena mysticetus) are divided into four stocks: the Okhotsk (OKH) Sea stock, the Bering-Chukchi-Beaufort (BCB) Seas stock, the East Canada-West Greenland (ECWG) stock, and the East Greenland-Svalbard-Barents (EGSB) Sea stock. Genetic data have contributed to the understanding of the differentiation among these stocks, rates of migration between them, and have been used to test hypotheses of stock substructure. Moreover, historical and recent demography of the BCB stock has been investigated using multiple genetic markers. No evidence of a genetic bottleneck from commercial whaling has been found, and models of recent population expansion are supported. Population genetic data is one source of data used by the International Whaling Commission (IWC) to issue an aboriginal whaling quota for the BCB stock.

The hunting of bowhead whales (Balaena mysticetus) is an integral part of Inuit culture. An up-to-date abundance estimate of the entire Eastern Canada – West Greenland (EC-WG) bowhead population is necessary to support sustainable management of this harvest. The High Arctic Cetacean Survey (HACS) was conducted in August 2013, primarily to update abundance estimates for known stocks of Baffin Bay narwhal (Monodon monoceros). As the ranges of narwhal and bowhead largely overlap, the survey area was expanded to cover the summer range of bowhead whales. Bowhead whale abundance was estimated using 3 aircraft to cover the large survey area within a short time frame. Distance sampling methods were used to estimate detection probability away from the track line. Double platform with mark-recapture methods were used to correct for the proportion of whales missed by visual observers on the track line (perception bias). Abundance in Isabella Bay, an area known for high bowhead density, was estimated using density surface modelling to account for its complex shape and uneven coverage. Estimates were corrected for availability bias (whales that were not available for detection because they were submerged when the aircraft passed overhead) using a recent analysis of satellite-linked time depth recorders transmitting information on the diving behaviour of bowhead whales in the study area in August of the same survey year. The fully corrected abundance estimate for the EC-WG bowhead whale population was 6,446 (95% CI: 3,838–10,827). Possible sources of uncertainty include incomplete coverage and the diving behaviour of bowhead whales. These results confirm earlier indications that the EC-WG stock is continuing to recover from past overexploitation.

The subpopulation of the bowhead whale Balaena mysticetus in the East Greenland-Svalbard-Barents Sea is endangered and until recently was believed to number in the tens. Recent studies have suggested that this subpopulation appears to be increasing. Here, we report on unusual aggregations of bowhead whales within the Fram Strait. We present opportunistic and effort-corrected observations of bowhead whales made from a small expedition vessel during cruises in June (2015-2018). Bowhead whales were sighted on 85 occasions (220-227 whales). An aggregation in 2015 (n = 84 whales) and high numbers in 2018 (n = 104-110) exceeded all previous records. The index of whale abundance was significantly higher in open water-leads (1.08-1.14 whales km-1 of survey effort) compared to areas with drift-ice (0.51-0.53 whales km-1). The highest abundance index was measured in deep waters where the bottom slope was relatively steep. Our findings highlight the temporal and spatial consistency of this species in areas with relatively loose ice cover (open water-leads) and steep slopes. It is unknown how global warming and resultant changes in ice-extent are going to affect bowhead whales within the Strait and whether they will find new feeding grounds due to an expanding open-ocean habitat. These slopes may become increasingly important to bowhead whales and Arctic top predators as a spring/early summer feeding ground. These relatively large numbers of bowhead whales are encouraging and can help direct future research monitoring programs to study the population ecology of these endangered whales.

The range of the Bering-Chukchi-Beaufort (BCB) population of bowhead whales (Balaena mysticetus) extends across the seasonally ice-covered waters of the Pacific Arctic region. The majority of whales summer in the eastern Beaufort Sea and winter in the Bering Sea, migrating across the Chukchi Sea in fall and spring. As arctic sea-ice extent rapidly diminishes, the increasing length and variability of the open water season is changing bowhead habitat substantially, with many areas now regularly ice-free when whales are present. This study examines changes in the number of open water days (OWD) between 1979 and 2014 within annual bowhead whale core-use areas as defined by satellite tagging data, and within the western Beaufort Sea (140–157°W; to 72°N) sampled by fall aerial surveys. Ice cover has decreased more in the core-use areas in the northern extent of the range than in core-use areas in the southern extent. The numbers of OWD within the core-use areas near Point Barrow and along the northern Chukotka Coast during peak use have increased by 13 and 10 days/decade, respectively. The most dramatic reductions in sea-ice cover have taken place in the western Beaufort Sea where the number of OWD on the shelf and slope have increased by 20 and 25 days/decade, respectively. In contrast, sea-ice cover has not significantly changed within the winter core-use area near the Gulf of Anadyr. Using aerial survey data, we found that bowheads in the Beaufort Sea during the fall migration have a preference for being closer to shore than to the ice edge, and that their distance to shore decreases as the fraction of open water increases. This distribution may be due to increased feeding opportunities closer to shore as a result of greater upwelling along the shelf break when the ice cover is farther from shore. Furthermore, the aerial survey data also revealed a substantial shift westward toward Point Barrow in the whales’ use of the western Beaufort Sea during fall in the period 1997–2014 compared to 1982–1996. The extent and timing of sea-ice coverage has changed relatively little over time in the Bering Sea. Bowheads typically migrate north prior to spring ice melt and retreat; therefore, large changes in the timing of the spring migration are not expected. We anticipate that bowheads will spend increasingly more time within summer and fall feeding areas, delaying their arrival to wintering areas in the Bering Sea. Reduced ice coverage and thickness in the southern Chukchi Sea may make wintering there more common in the future. Summer and fall movements may be more variable as productivity and zooplankton aggregations in existing feeding areas are altered in response to sea ice thinning and retreat, and as new areas become available.

We collated available satellite telemetry data for six species of ice-associated marine mammals in the Pacific Arctic: ringed seals (Pusa hispida; n = 118), bearded seals (Erignathus barbatus, n = 51), spotted seals (Phoca largha, n = 72), Pacific walruses (Odobenus rosmarus divergens, n = 389); bowhead whales (Balaena mysticetus, n = 46), and five Arctic and sub-arctic stocks of beluga whales (Delphinapterus leucas, n = 103). We also included one seasonal resident, eastern North Pacific gray whales (Eschrichtius robustus, n = 12). This review summarized the distribution of daily locations from satellite-linked transmitters during two analysis periods, summer (May–November) and winter (December–April), and then examined the overlap among species. Six multi-species core use areas were identified during the summer period: 1) Chukotka/Bering Strait; 2) Norton Sound; 3) Kotzebue Sound; 4) the northeastern Chukchi Sea; 5) Mackenzie River Delta/Amundsen Gulf; and 6) Viscount Melville Sound. During the winter period, we identified four multi-species core use areas: 1) Anadyr Gulf/Strait; 2) central Bering Sea; 3) Nunivak Island; and 4) Bristol Bay. During the summer period, four of the six areas were centered on the greater Bering Strait region and the northwestern coast of Alaska and included most of the species we examined. The two remaining summer areas were in the western Canadian Arctic and were largely defined by the seasonal presence of Bering-Chukchi-Beaufort stock bowhead whales and Eastern Beaufort Sea stock beluga whales, whose distribution overlapped during both summer and winter periods. During the winter period, the main multi-species core use area was located near the Gulf of Anadyr and extended northwards through Anadyr and Bering Straits. This area is contained within the Bering Sea “green belt”, an area of enhanced primary and secondary productivity in the Bering Sea. We also described available telemetry data and where they can be found as of 2017. These data are important for understanding ice-associated marine mammal movements and habitat use in the Pacific Arctic and should be archived, with appropriate metadata, to ensure they are available for future retrospective analyses.

The acoustic environment of two focal Arctic species, bowhead (Balaena mysticetus) and beluga (Delphinapterus leucas) whales, varied among the three core-use regions of the Pacific Arctic examined during the months in which both species occur: (1) January-March in the St. Lawrence Island/Anadyr Strait region, (2) November-January in the Bering Strait region, and (3) August-October in the Barrow Canyon region. Biological noise (consisting of the signals of bowhead whales, walrus and bearded seals) dominated the acoustic environment for the focal species in the St. Lawrence Island/Anadyr Strait region, which was covered with ice throughout the months studied. In the Bering Strait region whales were exposed primarily to environmental noise (in the form of wind noise) during November, before the region was ice-covered in December, and biological noise (from bowhead and walrus) again was prevalent. Anthropogenic noise dominated the Barrow Canyon region for the focal species in late summer and fall (August through October); this was also the only region in which the two species did not overlap with sea ice. Under open water conditions both near Barrow Canyon and in Bering Strait, noise levels were tightly correlated with wind. However, with climate-change driven increases in open water leading to rising noise levels across multiple fronts (atmospheric, biological, anthropogenic), the relatively pristine acoustic environment of Arctic cetaceans is changing rapidly. Characterizing the acoustic habitat of these regions before they are further altered should be considered a management and conservation priority in the Arctic.

The data on sightings of the bowhead whale (Balaena mysticetus Linnaeus, 1758) in the western Sea of Okhotsk collected during eight field seasons, as well as information obtained from interviews with local residents in the study region, are presented. The major areas of concentration of the bowhead whale population in the ice-free period are determined; the whale behavior in bays is described. Data on sea surface temperature, salinity, and depth measurements at the sites of bowhead whale sightings are provided. The possible causes of whale concentrations close to the shoreline and in apical parts of mainland shallow-water bays, as well as the potential threats to the population associated, inter alia, with this pattern of distribution, are discussed.

Each spring, most Bowhead Whales (Balaena mysticetus) of the Bering-Chukchi-Beaufort (BCB) population migrate to the Canadian Beaufort Sea and Amundsen Gulf for summer feeding. Occasionally, Inuvialuit hunters and others observe beachcast (stranded) or adrift Bowhead Whale carcasses. From 1987 to 2016, 26 such occurrences were recorded. Most (65%) were found by Inuvialuit hunters travelling on the land, with the majority (54%) reported during 2000–2006. Bowhead Whale carcasses were found widely distributed throughout the region, with twice as many in Amundsen Gulf (65%) compared with the southeastern Beaufort Sea (35%). It was possible to measure or estimate standard length for 17 of 26 specimens, and all were either provisional ‘subadults’ (7–9.5 m; n = 10; 59%) or provisional ‘mature adults’ (13–16 m; n = 7; 41%). The cause(s) of mortality was not determined for any of the specimens. Whales in the ‘subadult’ group were likely 1–4 years old, while the ‘mature adult’ group were likely mostly mature animals (~25 y), including some potentially very old (>100 y). There was evidence or direct observation of Polar Bears (Ursus maritimus) and/or Grizzly Bears (U. arctos) scavenging at 60% of the carcasses for which presence or absence of bears or bear sign (scats and/or tracks) was reported. It is important to continue to record incidental observations of beachcast Bowhead Whales, as this may enable stranding rates to be evaluated.

Plasticity in the physiological and behavioural responses of animals to prolonged food shortages may determine the persistence of species under climate warming. This is particularly applicable for species that can “adaptively fast” by conserving protein to protect organ function while catabolizing endogenous tissues. Some Ursids, including polar bears (Ursus maritimus), adaptively fast during winter hibernation—and it has been suggested that polar bears also employ this strategy during summer. We captured 57 adult female polar bears in the Southern Beaufort Sea (SBS) during summer 2008 and 2009 and measured blood variables that indicate feeding, regular fasting, and adaptive fasting. We also assessed tissue δ13C and δ15N to infer diet, and body condition via mass and length. We found that bears on shore maintained lipid and protein stores by scavenging on bowhead whale (Balaena mysticetus) carcasses from human harvest, while those that followed the retreating sea ice beyond the continental shelf were food deprived. They had low ratios of blood urea to creatinine (U:C), normally associated with adaptive fasting. However, they also exhibited low albumin and glucose (indicative of protein loss) and elevated alanine aminotransferase and ghrelin (which fall during adaptive fasting). Thus, the ~ 70% of the SBS subpopulation that spends summer on the ice experiences more of a regular, rather than adaptive, fast. This fast will lengthen as summer ice declines. The resulting protein loss prior to winter could be a mechanism driving the reported correlation between summer ice and polar bear reproduction and survival in the SBS.

The distribution of the Bering-Chukchi-Beaufort Sea population of bowhead whales (Balaena mysticetus) is largely centered in the Chukchi Sea in autumn (September–November), which is also when sea ice is at minimum extent allowing for increased ship traffic and industrial activity. Prior work paired autumn movements of bowhead whales in the Chukchi Sea with simulated hydrographic information and concluded whales followed relatively cold, saline waters of Pacific origin during migration (

Sea ice loss associated with a changing climate is resulting in increased levels of ship traffic in the Arctic, which in turn is causing increased underwater noise levels and associated impacts on marine life. Estimating the possible, present levels of exposure of marine life to underwater noise is a crucial step in understanding and managing contemporary exposures and underwater noise levels, and will inform future planning actions and mitigation. In this study, we examined the overlap between modeled underwater noise from ship traffic from 2015 to 2017 and monthly utilization distributions of beluga (Delphinapterus leucas) and bowhead whales (Balaena mysticetus) calculated from satellite telemetry data collected between 1995 and 2018 in the Beaufort and Chukchi seas. We first modeled noise propagation from observed vessel traffic in the Pacific Arctic from Amundsen Gulf in the east to Bering Strait in the west. We modeled the propagation loss of underwater noise from different classes of vessels that were transiting the area, and then applied these values to actual ship tracks (derived from satellite automatic identification system data) to model monthly noise footprints between July and October in each year between 2015 and 2017. We overlaid the monthly noise footprints with monthly 50% utilization distributions for satellite-tagged eastern Beaufort Sea beluga whales (1993–1997, 2004–2006) and Bering-Chukchi-Beaufort bowhead whales (2006–2018). Vessel traffic and its associated underwater noise were highest in all months in the southern Chukchi Sea near Bering Strait, particularly along the Russian and Alaskan coastlines. In comparison, traffic was lower in the western Canadian Arctic and in offshore areas; within the western Canadian Arctic, traffic was higher in August and September than in July and October. In July, low ship traffic resulted in low levels of overlap between modeled underwater noise and the utilization distributions for both whale species because the whales tend to use habitats in the eastern Beaufort Sea and Amundsen Gulf. Conversely, in August through September, there was medium to high overlap between underwater noise and the distributions for both species as ship traffic increased in those months and the distribution of both species began shifting towards the Chukchi Sea. Both beluga and bowhead whales migrate through areas with the highest levels of traffic in the Pacific Arctic, and are potentially exposed to a high number of acoustic disturbance events in three national jurisdictions. Without proactive vessel management and effective mitigation measures, acoustic disturbance of whales is expected to increase, and eventually expand to more months of the year, as ship traffic continues to increase in step with increases in the length of the open water season.

Polar bear (Ursus maritimus) subpopulations in several areas with seasonal sea ice regimes have shown declines in body condition, reproductive rates, or abundance as a result of declining sea ice habitat. In the Foxe Basin region of Nunavut, Canada, the size of the polar bear subpopulation has remained largely stable over the past 20 years, despite concurrent declines in sea ice habitat. We used fatty acid analysis to examine polar bear feeding habits in Foxe Basin and thus potentially identify ecological factors contributing to population stability. Adipose tissue samples were collected from 103 polar bears harvested during 2010–2012. Polar bear diet composition varied spatially within the region with ringed seal (Pusa hispida) comprising the primary prey in northern and southern Foxe Basin, whereas polar bears in Hudson Strait consumed equal proportions of ringed seal and harp seal (Pagophilus groenlandicus). Walrus (Odobenus rosmarus) consumption was highest in northern Foxe Basin, a trend driven by the ability of adult male bears to capture large‐bodied prey. Importantly, bowhead whale (Balaena mysticetus) contributed to polar bear diets in all areas and all age and sex classes. Bowhead carcasses resulting from killer whale (Orcinus orca) predation and subsistence harvest potentially provide an important supplementary food source for polar bears during the ice‐free period. Our results suggest that the increasing abundance of killer whales and bowhead whales in the region could be indirectly contributing to improved polar bear foraging success despite declining sea ice habitat. However, this indirect interaction between top predators may be temporary if continued sea ice declines eventually severely limit on‐ice feeding opportunities for polar bears.

Climate change is altering habitats and causing changes to species behaviors and distributions. Rapid changes in Arctic sea ice ecosystems have increased the need to identify critical habitats for conservation and management of species such as polar bears (Ursus maritimus). We examined the distribution of adult female and subadult male and female polar bears tracked by satellite telemetry (n = 64 collars) in the southern Beaufort Sea, Canada, to identify summer refugia in 2007–2010. Using utilization distributions, we identified terrestrial and sea ice areas used as summer refugia when nearshore sea ice melted. Habitat use areas varied between months, but interannual variation was not significant. Overall, bears made high use of ice over shallow waters, and bears that remained near terrestrial areas used sea ice (presumably to hunt from) when it was available. The majority of the bears remained on sea ice during summer and used the edge of the pack ice most notably west of Banks Island, Canada. A mean of 27 % (range 22–33 %) of bears used terrestrial areas in Alaska and use was concentrated near the remains of subsistence harvested bowhead whales (Balaena mysticetus). Energetic expenditure is anticipated to increase as bears are required to travel further on a seasonal basis.

This work was supported in part by a contract between BP Exploration (Alaska) Inc. and the University of California, Santa Barbara (E.F.), and by the North Slope Borough. Potential responses of marine mammals to anthropogenic underwater sound are usually assessed by researchers and regulators on the basis of exposure to a single, relatively loud sound source. However, marine mammals typically receive sounds from multiple, dynamic sources. We developed a method to aggregate modeled sounds from multiple sources and estimate the sound levels received by individuals. To illustrate the method, we modeled the sound fields of 9 sources associated with oil development and estimated the sound received over 47 d by a population of 10 000 simulated bowhead whales Balaena mysticetus on their annual migration through the Alaskan Beaufort Sea. Empirical data were sufficient to parameterize simulations of the distribution of individual whales over time and their range of movement patterns. We ran 2 simulations to estimate the sound exposure history and distances traveled by bowhead whales: one in which they could change their movement paths (avert) in response to set levels of sound and one in which they could not avert. When animals could not avert, about 2% of the simulated population was exposed to root mean square (rms) sound pressure levels (SPL) ≥ 180 dB re 1 mu Pa, a level that regulators in the U.S. often associate with injury. When animals could avert from sound levels that regulators often associate with behavioral disturbance (rms SPL > 160 dB re 1 μPa)

Information about the occurrence of marine mammals near the Colville River Delta (CRD), Beaufort Sea, Alaska is limited for most species expected to occur in this region. As part of marine mammal monitoring and mitigation for a seismic acquisition program August 25–September 30, 2014, we recorded marine mammal occurrence in a ~ 30 km2 survey area between the Spy Islands and Oliktok Point near Simpson Lagoon using a combination of visual and acoustic monitoring methods. Visual effort totaled 632 h, occurring 18–20 h/day during all daylight hours by observers aboard three small survey vessels. In addition, an Inupiat observer and seal hunter from the village of Nuiqsut conducted a small-vessel survey to investigate locations of Phoca largha haul-out sites. A total of 102 individual marine mammals were recorded from five species: P. largha, Pusa hispida, Ursus maritimus, Erignathus barbatus, and Delphinapterus leucas. Over 400 h of acoustic data were recorded using second-generation Ecological Acoustic Recorders deployed on the seafloor at three locations. Calls were identified for D. leucas, Balaena mysticetus, E. barbatus, and P. hispida. Results provide valuable information on marine mammal occurrence for the Beaufort Sea CRD during summer/fall, an area proposed for potential offshore oil and gas development.

Reduction of summer sea ice extent has led some polar bear (Ursus maritimus) populations to increase their use of land during the summer/autumn open-water period. While terrestrial food resources are generally not sufficient to compensate for lost hunting opportunities on the sea ice, marine mammal carcasses, where available, could help reduce the energetic cost of longer periods of land use. Subsistence-harvested bowhead whale (Balaena mysticetus) remains are available annually near local communities along the Alaskan portion of the Beaufort Sea coast to bears that come to shore. Relatively large numbers of polar bears and some grizzly bears (U. arctos) use these resources, creating a competitive environment among species and social classes. We documented competitive interactions among polar bears and between polar and grizzly bears for bowhead whale remains adjacent to a small community in northeastern Alaska in September 2005–2007. We observed temporal partitioning of the resource by bears, with lone a...

Bowhead whales, Balaena mysticetus, in the Bering–Chukchi–Beaufort (BCB) population, experience a variable acoustic environment among the regions they inhabit throughout the year. A total of 41,698 h of acoustic data were recorded from 1 August 2009 through 4 October 2010 at 20 sites spread along a 2300 km transect from the Bering Sea to the southeast Beaufort Sea. These data represent the combined output from six research teams using four recorder types. Recorders sampled areas in which bowheads occur and in which there are natural and anthropogenic sources producing varying amounts of underwater noise. We describe and quantify the occurrence of bowheads throughout their range in the Bering, Chukchi, and Beaufort seas over a 14-month period by aggregating our acoustic detections of bowhead whale sounds. We also describe the spatial–temporal variability in the bowhead acoustic environment using sound level measurements within a frequency band in which their sounds occur, by dividing a year into three, 4-month seasons (Summer–Fall 2009, August–November 2009: Winter 2009–2010, December 2009–March 2010: and Spring–Summer 2010, April–July 2010) and their home range into five zones. Statistical analyses revealed no significant relationship between acoustic occurrence, distance offshore, and water depth during Summer–Fall 2009, but there was a significant relationship during Spring–Summer 2010. A continuous period with elevated broadband sound levels lasting ca. 38 days occurred in the Bering Sea during the Winter 2009–2010 season as a result of singing bowheads, while a second period of elevated levels lasting at least 30 days occurred during the early spring–summer season as a result of singing bearded seals. The lowest noise levels occurred in the Chukchi Sea from the latter part of November into May. In late summer 2009 very faint sounds from a seismic airgun survey approximately 700 km away in the eastern Beaufort Sea were detected on Chukchi recorders. Throughout the year, but most obviously during the November into May period, clusters of intermittent, nearly synchronized, high-level events were evident on multiple recorders hundreds of miles apart. In some cases, these clusters occurred over 2–5 day periods and appear to be associated with high wind conditions.

The article of record as published may be found at http://dx.doi.org/10.1016/j.pocean.2014.08.012 The Bering–Chukchi–Beaufort (BCB) population of bowhead whales (Balaena mysticetus) ranges across the seasonally ice-covered waters of the Bering, Chukchi, and Beaufort seas. We used locations from 54 bowhead whales, obtained by satellite telemetry between 2006 and 2012, to define areas of concen- trated use, termed ‘‘core-use areas’’. We identified six primary core-use areas and describe the timing of use and physical characteristics (oceanography, sea ice, and winds) associated with these areas. In spring, most whales migrated from wintering grounds in the Bering Sea to the Cape Bathurst polynya, Canada (Area 1), and spent the most time in the vicinity of the halocline at depths

We examined the response of bowhead whale (Balaena mysticetus) body condition to summer sea ice conditions and upwelling-favorable winds. We used a long-term dataset collected from whales of the Bering–Chukchi–Beaufort Seas (BCB) stock to estimate various body condition indices (BCI’s) for individual whales that were harvested by Alaskan Eskimos. A series of offshore regions frequented by bowhead whales in summer were delineated and used to quantify interannual summertime environmental conditions including: (a) mean open water fraction, (b) duration of melt season, (c) date of continuous freeze-up, and (d) mean upwelling-favorable wind stress. Body condition was analyzed relative to these metrics for both the preceding summer feeding season and the previous three seasons combined. Our analysis indicates a significant increase in the long-term trend in an axillary girth-based body condition index (BCIG) over the study period (1989–2011). The increase in BCIG is likely associated with the trend in overall reduction of sea ice, including increased duration of open water, changes in upwelling potential (wind stress), and possibly higher primary production in the Pacific Arctic marine ecosystem favoring water-column invertebrates. We found strong significant positive correlations between BCIG and late summer open water fraction in the Beaufort Sea and smaller nearshore areas off the Mackenzie Delta and west of Banks Island. Additionally, BCIG was positively and significantly correlated with duration of melt season, later date of freeze-up in the Beaufort Sea, and upwelling-favorable winds on the Mackenzie shelf and west of Banks Island. A strong seasonal difference in BCI’s was noted for subadult bowheads, presumably associated with summer feeding; however, yearlings were found to drop in BCI over at least the first summer after weaning. Our results indicate an overall increase in bowhead whale body condition and a positive correlation with summer sea ice loss over the last 2.5 decades in the Pacific Arctic. We speculate that sea ice loss has positive effects on secondary trophic production within the BCB bowhead’s summer feeding region. While not part of this study, the abundance of BCB bowheads increased markedly over the same period.

The critically endangered Spitsbergen stock of bowhead whale (Balaena mysticetus) seems to be increasing. However, research effort has also been increasing confounding a firm conclusion. A systematic aerial survey for walrus (Odobaenus rosmarus), applying distance sampling methodology in part of the Northeast Water Polynya (NEW), revealed a ‘bycatch’ of several observations of bowhead whales, which resulted in an estimated abundance of 102 (95 % CI 32–329) individuals. This is the largest abundance of bowhead whales reported from the Greenland Sea since the days of whaling in the sixteenth to seventeenth centuries. The NEW was inaccessible to vessels during the whaling period because of heavy pack ice, and it is only recently that researchers have visited this area; thus only a few sightings of bowhead whales within the NEW exist prior to the survey in 2009. The NEW may nevertheless be one of the most important summering grounds for the Spitsbergen stock, and the whales may benefit from advection of calanoid copepods from the productive deep basins along the coast of Svalbard east of the NEW. This discovery provides renewed hope for the Spitsbergen stock of bowhead whales that until now has shown only inconclusive signs of recovery despite more than 100 years of protection from whaling.

Almost all mammals communicate using sound, but few species produce complex songs. Two baleen whales sing complex songs that change annually, though only the humpback whale ( Megaptera novaeangliae ) has received much research attention. This study focuses on the other baleen whale singer, the bowhead whale ( Balaena mysticetus ). Members of the Spitsbergen bowhead whale population produced 184 different song types over a 3-year period, based on duty-cycled recordings from a site in Fram Strait in the northeast Atlantic. Distinct song types were recorded over short periods, lasting at most some months. This song diversity could be the result of population expansion, or immigration of animals from other populations that are no longer isolated from each other by heavy sea ice. However, this explanation does not account for the within season and annual shifting of song types. Other possible explanations for the extraordinary diversity in songs could be that it results either from weak selection pressure for interspecific identification or for maintenance of song characteristics or, alternatively, from strong pressure for novelty in a small population.

Polar bear (Ursus maritimus) diet may become more variable in some Arctic regions due to climate warming and altered sea ice habitat. We surveyed carbon and nitrogen stable isotope profiles of five polar bear tissues sampled from adult females in the Southern Beaufort Sea of Alaska in order to assess inter-tissue isotopic variability and to determine whether any dietary shifts are occurring in this population. We did not detect any significant shifts from historical means in population-level tissue stable isotope values. A number of sectioned hair samples, however, were significantly depleted in 15N relative to the mean. We hypothesized that lower hair δ15N values were due to the consumption of bowhead whale (Balaena mysticetus) tissue. Telemetry data showed that polar bears with 15N-depleted hair sections were located on multiple dates near known subsistence-harvested bowhead whale bone piles and had spent 90 % of the prior year within 50 km of the shore. Bears with hair section δ15N values at or above the mean spent no time near bowhead whale bone piles and less than half of the year nearshore. An isotopic mixing model estimation of diet proportions determined that bowhead whale comprised approximately 50–70 % of fall diet for bears with lower hair δ15N values. We conclude that these results offer emergent evidence of an alternative foraging strategy within this population: ‘coastal’ bears, which remain near to shore for much of the year and use bowhead whale bone piles when they are present. In contrast, ‘pelagic’ bears follow a more typical strategy and forage widely on sea ice for seals.

Unmanned aerial systems (UAS) have the potential to collect high-resolution photographs of marine mammals for life-history studies without disturbing the species being studied. We conducted a pilot study near Igloolik, Nunavut, in early July 2013 to col- lect identification-quality photographs of bowhead whales and record the responses of the whales to overflights by an UAS. Operating under a restrictive line-of-sight permit from Transport Canada, we successfully collected high quality photographs of bowhead whales and none of the whales overflown responded to the overflights in an observable manner. If the UAS were operated under a beyond-line-of-sight permit, the UAS could be used to search for whales ahead of and to the side of the survey vessels making it more efficient to find whales to photograph. Even when operating under the restrictive line-of-sight permit, large numbers of whales could be photographed, which would provide important life-history information on the poorly studied Eastern Canada - West Greenland population. Resume : Les systemes aeriens sans pilote (UAS) peuvent recueillir des photographies de haute resolution de mammiferes marins, aux fins d'etudes sur les cycles biologiques, sans pour autant deranger les especes a l'etude. On a mene une etude pilote pres d'Igloolik, au Nunavut, au debut de juillet 2013 pour recueillir des photographies d'une qualite permet- tant l'identification des baleines boreales et pour consigner les reactions des baleines a des survols d'un UAS. Utilisant un UAS en vertu d'un permis de visibilite directe restrictive de Transport Canada, on a recueilli des photographies de haute qualite de baleines boreales, et aucune des baleines que l'UAS a survolees n'y a reagi de maniere observable. Si l'UAS etait utilise en vertu d'un permis au-dela de la visibilite directe, celui-ci pourrait servir a chercher les baleines en avant et a cote des navires hydrographiques, ce qui rendrait la tâche de reperer des baleines a photographier plus efficace. Meme en utilisant un UAS en vertu d'un permis de visibilite directe restrictive, il serait possible de photographier un grand nombre de baleines, ce qui apporterait des informations importantes sur le cycle biologique de la population de l'Est du Canada et de l'Ouest du Groenland, population peu etudiee. Mots-cles : baleines boreales, derangement, identification photographique, systeme aerien sans pilote, visibilite directe.

During summer 2012 Shell performed exploratory drilling at Sivulliq, a lease holding located in the autumn migration corridor of bowhead whales (Balaena mysticetus), northwest of Camden Bay in the Beaufort Sea. The drilling operation involved a number of vessels performing various activities, such as towing the drill rig, anchor handling, and drilling. Acoustic data were collected with six arrays of directional recorders (DASARs) deployed on the seafloor over ~7 weeks in Aug-Oct. Whale calls produced within 2 km of each DASAR were identified and localized using triangulation. A "tone index" was defined to quantify the presence and amplitude of tonal sounds from industrial machinery. The presence of airgun pulses originating from distant seismic operations was also quantified. For each 10-min period at each of the 40 recorders, the number of whale calls localized was matched with the "dose" of industrial sound received, and the relationship between calling rates and industrial sound was modeled using negative binomial regression. The analysis showed that with increasing tone levels, bowhead whale calling rates initially increased, peaked, and then decreased. This dual behavioral response is similar to that described for bowhead whales and airgun pulses in earlier work. Increasing call repetition rates can be a viable strategy for combating decreased detectability of signals arising from moderate increases in background noise. Meanwhile, as noise increases, the benefits of calling may decrease because information transfer becomes increasingly error-prone, and at some point calling may no longer be worth the effort.

As a precautionary measure to protect the culturally-significant bowhead whale ( Balaena mysticetus ) from vessel strike, this paper explores the potential for having the International Maritime Organization endorse ships׳ routeing measures in the Bering Strait region. The confined nature of the Bering Strait forces both vessel traffic and the migrating Bering–Chukchi–Beaufort stock of bowhead whales to occupy the same narrow space, thus putting individual animals at risk of vessel strike. The potential for vessel strike may become exacerbated as the reduction of Arctic sea ice makes the Arctic increasingly accessible, allowing vessels to transit through the Strait in greater densities. In drawing from lessons learned in the successful reduction of vessel strike to the North Atlantic right whale ( Eubalaena glacialis ), the author provides broad recommendations for implementing ships׳ routeing measures in the Bering Strait region based on findings by Citta et al. (2012). It is recommended that both the western side of Big Diomede Island and the western side of St. Lawrence Island be designated as seasonal Areas To Be Avoided (ATBA) during fall months when bowheads are known to inhabit the area. Alternatively, it is proposed that Traffic Separation Schemes (TSSs) be implemented so that vessels must keep to the eastern side of both Big Diomede Island and St. Lawrence Island during this time. Both measures would reduce the amount of overlap between migrating bowhead whales and transiting vessel traffic, effectively reducing the potential for vessel strike.

We contrast two methods for estimating the trends of bowhead whales (Balaena mysticetus) in West Greenland: (1) double platform visual aerial survey, corrected for missed sightings and the time the whales are available at the surface; and (2) a genetic capture-recapture approach based on a 14-yr-long biopsy sampling program in Disko Bay. The aerial survey covered 39,000 km2 and resulted in 58 sightings, yielding an abundance estimate of 744 whales (CV = 0.34, 95% CI: 357–1,461). The genetic method relied on determining sex, mitochondrial haplotypes and genotypes of nine microsatellite markers. Based on samples from a total of 427 individuals, with 11 recaptures from previous years in 2013, this resulted in an estimate of 1,538 whales (CV = 0.24, 95% CI: 827–2,249). While the aerial survey is considered a snapshot of the local spring aggregation in Disko Bay, the genetic approach estimates the abundance of the source of this aggregation. As the whales in Disko Bay primarily are adult females that do not visit the bay annually, the genetic method would presumably yield higher estimates. The studies indicate that an increase in abundance observed between 1998 and 2006 has leveled off.

Radiocarbon-dated marine mammal remains from emergent Arctic coastlines have frequently been used to reconstruct Holocene sea-ice histories. The use of such reconstructions has hitherto been complicated by uncertain marine reservoir corrections precluding meaningful intercomparisons with data reported in calibrated or sidereal years. Based on an exhaustive compilation of previously published marine mammal radiocarbon dates (both live-harvested materials and subfossils) from the Canadian Arctic Archipelago (CAA), new, statistically-derived δ13C and ΔR values are provided. Average δ13C values are: −16.1 ± 1.1‰ (bone collagen; n = 193) for bowhead (Balaena mysticetus); −14.4 ± 0.5‰ (n = 44; dentine) for beluga (Delphinapterus leucas); −14.8 ± 1.9‰ (teeth and tusks; n = 18) and −18.0 ± 4.7‰ (n = 9; bone collagen) for walrus (Odobenus rosmarus). ΔR values are 170 ± 95 14C years for bowhead (n = 23) and 240 ± 60 14C years for beluga (n = 12). Scarce data preclude calculation of meaningful, statistically robust walrus ΔR. Using the new ΔR values, an expanded and revised database of calibrated bowhead dates (651 dates; many used in previous CAA sea-ice reconstructions) shows pronounced late Quaternary spatio-temporal fluctuations in bone abundance. Though broadly resembling earlier bowhead subfossil frequency data, analysis of the new expanded database suggests early- and mid-Holocene increases in whale abundance to be of longer duration and lower amplitude than previously considered. A more even and persistent spread of infrequent low-abundance remains during “whale free” intervals is also seen. The dominance of three eastern regions (Prince Regent Inlet & Gulf of Boothia; Admiralty Inlet; Berlinguet Inlet/Bernier Bay) in the CAA data, collectively contributing up to 88% of all subfossil remains in the mid-Holocene, is notable. An analysis of calibrated regional sea-level index points suggests that severance of the Admiralty Inlet-Gulf of Boothia marine channel due to isostatically-driven regression may have played a significant role in enhanced whale mortality during this interval. Comparisons between the newly calibrated bowhead data and other regional sea-ice proxy data further highlight spatial and temporal discrepancies, potentially due to regional asynchronicities and variable sensitivities in proxy response to climate and oceanographic forcing. However, the limited number of deglacial–postglacial marine records continues to hamper extensive intercomparisons between marine mammal and other proxy datasets. Nevertheless, an examination of assumptions inherent in linking bowhead subfossil frequencies, population densities, and sea-ice thickness and distribution, shows that such relationships are highly complex. Factors such as broad sea-ice preferences, variable mortality rates and causes, long distance carcass transport, variable coastline and basin/channel geometries, and changing emergence rates all complicate the correlation of whale bone abundance to sea-ice histories.

The Arctic is one of the fastest-changing parts of the planet. Global climate change is already having major impacts on Arctic ecosystems. Increasing temperatures and reductions in sea ice are particular conservation concerns for ice-associated species, including three endemic cetaceans that have evolved in or joined the Arctic sympagic community over the last 5 M years. Sea ice losses are also a major stimulant to increased industrial interest in the Arctic in previously ice-covered areas. The impacts of climate change are expected to continue and will likely intensify in coming decades. This paper summarizes information on the distribution and movement patterns of the three ice-associated cetacean species that reside year-round in the Arctic, the narwhal ( Monodon monoceros ), beluga (white whale, Delphinapterus leucas ), and bowhead whale ( Balaena mysticetus ). It maps their current distribution and identifies areas of seasonal aggregation, particularly focussing on high-density occurrences during the summer. Sites of oil and gas exploration and development and routes used for commercial shipping in the Arctic are compared with the distribution patterns of the whales, with the aim of highlighting areas of special concern for conservation. Measures that should be considered to mitigate the impacts of human activities on these Arctic whales and the aboriginal people who depend on them for subsistence include: careful planning of ship traffic lanes (re-routing if necessary) and ship speed restrictions; temporal or spatial closures of specified areas (e.g. where critical processes for whales such as calving, calf rearing, resting, or intense feeding take place) to specific types of industrial activity; strict regulation of seismic surveys and other sources of loud underwater noise; and close and sustained monitoring of whale populations in order to track their responses to environmental disturbance.

Autonomous passive acoustic recorders were deployed to record sounds of bowhead whales (Balaena mysticetus) in the southeast Beaufort Sea for periods of 30-55 days during the late summer, open-water seasons of 2008-2010. Recordings were made in three areas licensed for hydrocarbon exploration, spanning the continental slope and adjacent outer shelf, and in a shallow inner-shelf area where bowheads have been observed congregating to feed in recent decades. Bowhead sounds were counted in samples comprising 10% of each recorded hour. In mid-August and September in all 3 years, the rate of bowhead calling at outer shelf sites exceeded that at adjacent continental slope sites by one to two orders of magnitude. Higher rates of calling occurred on the slope in late July and early August than at later dates. Calling rates varied by an order of magnitude between years in the one area that was monitored in different years. The highest rates of calling occurred on the inner shelf, offshore of the northern Tuktoyaktuk Peninsula. These trends are consistent with patterns of habitat use previously reported from aerial surveys in this and nearby areas of the Beaufort Sea and with the results of satellite tagging studies.

Several cetacean and pinniped species use the northeastern Chukchi Sea as seasonal or year-round habitat. This area has experienced pronounced reduction in the extent of summer sea ice over the last decade, as well as increased anthropogenic activity, particularly in the form of oil and gas exploration. The effects of these changes on marine mammal species are presently unknown. Autonomous passive acoustic recorders were deployed over a wide area of the northeastern Chukchi Sea off the coast of Alaska from Cape Lisburne to Barrow, at distances from 8 km to 200 km from shore: up to 44 each summer and up to 8 each winter. Acoustic data were acquired at 16 kHz continuously during summer and on a duty cycle of 40 or 48 min within each 4-h period during winter. Recordings were analyzed manually and using automated detection and classification systems to identify calls. Bowhead ( Balaena mysticetus ) and beluga ( Delphinapterus leucas ) whale calls were detected primarily from April through June and from September to December during their migrations between the Bering and Beaufort seas. Summer detections were rare and usually concentrated off Wainwright and Barrow, Alaska. Gray ( Eschrichtius robustus ) whale calls were detected between July and October, their occurrence decreasing with increasing distance from shore. Fin ( Balaenoptera physalus ), killer ( Orcinus orca ), minke ( Balaenoptera acutorostrata ), and humpback ( Megaptera novaeangliae ) whales were detected sporadically in summer and early fall. Walrus ( Odobenus rosmarus ) was the most commonly detected species between June and October, primarily occupying the southern edge of Hanna Shoal and haul-outs near coastal recording stations off Wainwright and Point Lay. Ringed ( Pusa hispida ) and bearded ( Erignathus barbatus ) seals occur year-round in the Chukchi Sea. Ringed seal acoustic detections occurred throughout the year but detection numbers were low, likely due to low vocalization rates. Bearded seal acoustic detections peaked in April and May during their breeding season, with much lower detection numbers in July and August, likely as a result of reduced calling rates after breeding season. Ribbon seals ( Histriophoca fasciata ) were only detected in the fall as they migrated south through the study area toward the Bering Sea. These results suggest a regular presence of marine mammals in the Chukchi Sea year-round, with species-dependent seasonal and spatial density variations.

The Western Arctic bowhead whale (Balaena mysticetus) is highly adapted to sea ice and annually migrates through the Bering, Chukchi, and Beaufort seas. While the overall distribution and seasonal movements of bowhead whales are mostly understood, information about their distribution in the Alaskan Beaufort Sea in early to mid-summer has not been well documented. In July 2011, we conducted an exploratory flight in the Alaskan Beaufort Sea, north of Camden Bay (71°N 144°W), near the location of a single satellite-tagged bowhead whale. Eighteen bowhead whales were observed, and behavior consistent with feeding was documented. To our knowledge, this is the first documentation of behavior consistent with feeding north of Camden Bay in mid-July. Few studies have focused on bowhead whale distribution in the Alaskan Beaufort Sea in early to mid-summer, and no long-term, region-wide surveys have been conducted during summer. Bowhead whales are already exposed to anthropogenic disturbance in the Canadian Beaufort Sea in summer, the Alaskan Beaufort Sea in fall, and the Chukchi and Bering seas from fall through spring. The presence of bowhead whale aggregations in the Alaskan Beaufort Sea in summer should be considered when assessing the cumulative effects of human-related activities.

Zooarchaeologists continue to experience difficulty defining the importance of bowhead (Balaena mysticetus) whaling in Neoeskimo coastal deposits. The large size of bowhead bones, combined with their use as structural elements in Neoeskimo architecture, creates a suite of taphonomic issues that tend to obscure their usefulness as a measure of relative abundance, and thus as an overall economic indicator. Here we present a regional approach that focuses on contrasts in relative taxonomic abundance between sites with diverse economic signatures, supported by related differences in element frequencies, site locations, features, artefact frequencies, and manufacturing detritus. Using this approach, a generalized picture of the relative importance of bowhead whales in Neoeskimo subsistence economies can be assembled. Such an analysis, applied to the archaeological record of the Mackenzie Inuit, or Siglit, reveals the role that bowhead whaling played in subsistence economies from the 15 th to 19 th centuries AD. Specifically, the archaeological record indicates that the prehistoric Qikiqtaryungmiut and Nuvugarmiut practiced specialized bowhead whaling at coastal promontories, though the seasonal scheduling and success rate of these hunts contrasted considerably.

The expansion of hydrocarbon exploration in northwest Greenland has made it increasingly important to understand the occurrence of marine mammals in the region. We describe the seasonal occurrence of marine mammals and the spatial distribution of their calls in Baffin Bay and Melville Bay. Four Autonomous Multichannel Acoustic Recorders (AMARs) were deployed during summer 2012 (late July to early October), five recorders during September 2013, and two recorders from late September 2013 to early September 2014. The call presence of several species was analyzed using automatic call detection and manual verification analysis methods. A novel approach to discern narwhal (Monodon monoceros) clicks from beluga (Delphinapterus leucas) clicks was implemented during the verification process. Narwhal calls were detected in spring and fall, showing a south-to-north migration pattern in spring and a north-to-south migration pattern in fall. Few beluga whales were detected during fall 2013 and spring 2014. Bearded seal (Erignathus barbatus) calls were detected mainly during spring (mating period). A small number of bowhead whale calls (Balaena mysticetus) were detected during fall 2013 and spring and summer 2014. For the first time at this latitude in Baffin Bay, long-finned pilot whales (Globicephala melas) and sperm whales (Physeter macrocephalus) were detected during summer and fall. Our results suggest that the presence of marine mammals in Baffin Bay and Melville Bay is governed mainly by the annual cycle of sea ice formation and decay.

We analyzed scarring data for Bering-Chukchi-Beaufort (BCB) Seas bowhead whales (Balaena mysticetus) harvested by Alaska Native hunters to quantify the frequency of line entanglement, ship strikes, and killer whale-inflicted injuries. We had 904 records in our database for whales landed between 1990 and 2012, and after data quality screening, we found 521 records containing information on scarring. Logistic regression was used to evaluate different combinations of explanatory variables (i.e., body length, sex, year, year-group) to develop a prediction model for each scar type. We also list bowhead whales that were harvested, found dead, or observed alive entangled in commercial line/fishing gear. Our findings suggest that about 12% of harvested bowheads show entanglement scars. Their frequency is highly correlated with body length and sex: about 50% of very large bowheads (> 17 m) show such scars, while whales under 9 m rarely do, and males show a significantly higher rate than females. Scars associated with ship strikes are infrequent and occur on ~2% of all harvested whales; body length, sex, and year were not significant factors. Scarring from attempted killer whale predation was evident on ~8% of landed whales. As with entanglement injuries, the frequency of killer whale scars was much higher (> 40%) on whales more than 16 m in length and statistically more frequent in the second half of the study (2002 – 12). Increased killer whale injuries in the recent decade are consistent with studies conducted on bowheads of the Eastern Canada-West Greenland population. The findings presented here reflect the most thorough analysis of injury rates from entanglement, ships, and killer whales for the BCB bowheads conducted to date. They indicate that (1) entanglement rates primarily from pot fishing gear (crab or cod or both) are relatively high for very large and presumably older bowheads, (2) collisions with ships are infrequent at present, and (3) scarring from killer whales is frequent on very large adult whales (> 17 m). Considering that bowhead habitat is changing rapidly (e.g., sea ice reduction), industrial ship traffic in the Arctic is increasing, and commercial fishing operations are expanding to the north, we strongly recommend that monitoring of scarring and injuries on harvested bowheads continue into the future as a means of documenting change.

Reports of bowhead whales (Balaena mysticetus) outside the Arctic Circle are scarce. On 15 May 2016, a juvenile bowhead whale was recorded in shallow water in Mount's Bay (Cornwall, UK) much further south than the species' normal dis- tribution. Fifteen months earlier, another such sighting was made involving a juvenile bowhead whale in the shallow water of an offshore island, St Martin's (Isles of Scilly, Cornwall), only 60 km from Mount's Bay. Other observations of suspected/confirmed immature bowhead whales include (1) an unconfirmed sighting involving a whale without a dorsal fin off Cornwall (13 May 2016), (2) a confirmed sighting off France (10 May 2016), and (3) a confirmed sighting in Carlingford Lough (border of Northern Ireland/ Republic of Ireland; 29 May 2016). These extra- limital encounters present the first confirmed sightings of bowhead whales within temperate European waters. Apart from the whale sighted in 2015, the sightings in 2016 probably all involve the same juvenile whale. Indeed, photographs depicting natural scars/marks suggest that the Carlingford Lough bowhead whale is the same individual as the Mount's Bay. The whale was displaying behaviour indicative of ram feeding in a sheltered, shallow bay (< 10 m water depth). Do these records present vagrant animals from nearby endangered Arctic stocks? Whatever trig- gered these immature bowhead whales to venture well outside the Arctic Circle remains unknown, yet these observations suggest an unexpected adaptability to foraging in temperate shallow waters.

Bowhead whales (Balaena mysticetus) have a nearly circumpolar distribution, and occasionally occupy warmer shallow coastal areas during summertime that may facilitate molting. However, relatively little is known about the occurrence of molting and associated behaviors in bowhead whales. We opportunistically observed whales in Cumberland Sound, Nunavut, Canada with skin irregularities consistent with molting during August 2014, and collected a skin sample from a biopsied whale that revealed loose epidermis and sloughing. During August 2016, we flew a small unmanned aerial system (sUAS) over whales to take video and still images to: 1) determine unique individuals; 2) estimate the proportion of the body of unique individuals that exhibited sloughing skin; 3) determine the presence or absence of superficial lines representative of rock-rubbing behavior; and 4) measure body lengths to infer age-class. The still images revealed that all individuals (n = 81 whales) were sloughing skin, and that nearly 40% of them had mottled skin over more than two-thirds of their bodies. The video images captured bowhead whales rubbing on large rocks in shallow, coastal areas-likely to facilitate molting. Molting and rock rubbing appears to be pervasive during late summer for whales in the eastern Canadian Arctic.

Bowhead whales (Balaena mysticetus) of the Bering-Chukchi-Beaufort population form annual late-summer feeding aggregations offshore of the eastern Tuktoyaktuk Peninsula and Cape Bathurst. This region is strongly influenced by episodic upwelling events. A systematic aerial survey (10% coverage) was flown over the eastern shelf on 2 August 2008, revealing large numbers of bowheads (est. 3500 individuals) in a clumped distribution over the continental shelf. Between 7 and 11 August 2008, zooplankton samples and hydrography were obtained from the vicinity of two bowhead feeding aggregations, one at the northeast edge of the continental shelf, and the second off the northeast shore of the Cape Bathurst. Dense aggregations of zooplankton were found in the lower part of the water column (below 40 m), on the shelf, in water with an upwelling signature. The zooplankton were largely resting phases of calanoid copepods (Calanus hyperboreus and C. glacialis) and collectively had twice the abundance, twice the biomass, three times the caloric density and thus six times the energy content of contemporaneous zooplankton samples from the western Canadian Beaufort Shelf. Although upwelling at Cape Bathurst is wind-driven and thus episodic in nature, its consistent delivery of zooplankton to the bowhead foraging area creates conditions attractive to bowhead whales, with an estimated 33% of the bowhead population present on the eastern portion of the shelf at the time of the August 2008 aerial survey.

Sea ice is believed to be a major factor shaping gene flow for polar marine organisms, but it remains unclear to what extent it represents a true barrier to dispersal for arctic cetaceans. Bowhead whales are highly adapted to polar sea ice and were targeted by commercial whalers throughout Arctic and subarctic seas for at least four centuries, resulting in severe reductions in most areas. Both changing ice conditions and reductions due to whaling may have affected geographic distribution and genetic diversity throughout their range, but little is known about range-wide genetic structure or whether it differed in the past. This study represents the first examination of genetic diversity and differentiation across all five putative stocks, including Baffin Bay-Davis Strait, Hudson Bay-Foxe Basin, Bering-Beaufort-Chukchi, Okhotsk, and Spitsbergen. We also utilized ancient specimens from Prince Regent Inlet (PRI) in the Canadian Arctic and compared them with modern stocks. Results from analysis of molecular variance and demographic simulations are consistent with recent and high gene flow between Atlantic and Pacific stocks in the recent past. Significant genetic differences between ancient and modern populations suggest PRI harbored unique maternal lineages in the past that have been recently lost, possibly due to loss of habitat during the Little Ice Age and/or whaling. Unexpectedly, samples from this location show a closer genetic relationship with modern Pacific stocks than Atlantic, supporting high gene flow between the central Canadian Arctic and Beaufort Sea over the past millennium despite extremely heavy ice cover over much of this period.

Both bowhead Balaena mysticetus and North Pacific (NP) right whales Eubalaena japonica were reduced to low levels by historical whaling. Despite their protected status, it is known that the USSR illegally killed both species in the NP and Okhotsk Sea (OS). Here, we pro- vide revised Soviet catch totals, as well as other new information on the distribution and other details of these catches. Right whale catches were made from 1962 to 1968 in the eastern NP and in 1967 and 1968 in the OS. Our best estimate of total right whale catches is 661, consisting of 529 for the eastern NP (compared to the previously published figure of 372) and 152 for the OS (cf. a previous figure of 136). Catches were distributed in the Bering Sea (BS, 115), eastern Aleutian Islands (28), Gulf of Alaska (GOA, 366), OS (132), and other areas (20). Detailed information on catches of 112 right whales taken in May/June 1963 shows a broad distribution in offshore waters of the GOA, consistent with 19th century historical whaling records. Other major areas in which right whales were caught include south of Kodiak Island, western Bristol Bay (southeastern BS), and the central OS off eastern Sakhalin Island. The best estimate of bowhead whale catches in the OS in 1967 and 1968 is 145 animals, although this is contingent upon certain assumptions regard- ing species identity. Of these, 79 were killed in the Shantar Islands region and 66 in Shelikhov Bay. The catches of both species primarily involved large mature animals, thus greatly inhibiting recovery of the populations concerned.

Bowhead whales Balaena mysticetus are long-lived cetaceans, uniquely adapted among the baleen whales to live year-round in the Arctic. All bowhead whale populations were greatly reduced by commercial whaling from the 1600s through the 1800s, with the largest, the Spitsber- gen population in the North Atlantic, depleted to the point of extinction. Recent sightings of bow- head whales west of Svalbard precipitated an effort to listen for their vocalizations via 2 re - corders deployed in 2008 on oceanographic moor- ings spaced 95 km apart at 78.8° N latitude in the Fram Strait. Year-round acoustic records were examined for the occurrence of bowhead whale sounds. Simple calls, call sequences, and complex songs were recorded. Repeated call sequences or bowhead whale songs were detected nearly every hour from early November 2008 through late April 2009 on the western Fram Strait recorder. More than 60 unique songs were recorded from October 2008 to April 2009. In contrast, simple calls and call sequences were the most common signals recorded on the central Fram Strait instrument. Peak levels of song production coincided with the period of lowest water temperature, dense ice con- centration, and almost complete darkness. Given the diversity, loudness, and period over which songs were recorded, western Fram Strait appears to be a wintering ground — and potentially a mat- ing area — for this Critically Endangered popula- tion of bowhead whales.

Laidre, K. L., and Heide-Jørgensen, M. P. 2012. Spring partitioning of Disko Bay, West Greenland, by Arctic and Subarctic baleen whales. – ICES Journal of Marine Science, 69: . Movements of co-occurring bowhead (Balaena mysticetus) and humpback (Megaptera novaeangliae) whales in Disko Bay, West Greenland, were examined using satellite telemetry. Data on movements, habitat use, and phenology were collected from tagged 49 bowheads and 44 humpbacks during the transition from sea-ice breakup to open water between 2008 and 2010. Bowhead whales began their northward spring migration around 27 May (median day-of-the-year departure date = 147, interquartile range 141–153) and were distributed broadly in northern and central Disko Bay in water depths between 100 and 400 m. Humpback whales arrived in Disko Bay no later than 2 June and were located in shallow water (

Bowhead whale Balaena mysticetus critical habitat was identified as a key informa- tion gap by the Eastern Arctic Bowhead Whale Recovery Team. To fill this gap, data on eastern Canadian Arctic (ECA) bowhead whales and their habitat were collected and analyzed. We selected governmental, private, and historical whaling bowhead location datasets which differed in temporal and spatial extent, sample size, and quality. Sufficient data were available only for the 'reduced-ice' period (June to October) and pooled by month. Data for 6 ecogeographical variables (EGVs) were integrated into a geographical information system (GIS): sea surface temperature, chlorophyll, ice, depth, slope, and distance to shore. A monthly ecological niche factor analysis was performed for each whale and EGV dataset to determine habitat suitability in the ECA. Eleven habitat suitability models were produced, and a composite map of predicted high suitabil- ity habitat, for all 5 months, was developed. Twenty-one areas within the ECA were identified as highly suitable habitat and ranked according to analytical confidence. Six critical habitats were identified and are supported by recent scientific evidence and Inuit knowledge. Recently, the pop- ulation estimate, conservation status, and management of the Eastern CanadaWest Greenland bowhead population have changed dramatically (bowhead whales of this population also inhabit the ECA). In parallel, evidence of ecological change from climate warming has increased and associated loss of sea ice is anticipated to increase interactions between bowheads and anthro- pogenic activity. As envisioned by the recovery team, this study provides resource managers with a timely tool for population recovery, conservation, and protection.