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The mercury pollution status in the northwestern Sea of Okhotsk remains largely unexplored. In this study, hair samples were collected from 40 bearded seals harvested between August and October 2021 in the region. Total mercury (THg) concentrations in the samples exhibited a wide range from 137 to 1885 ng/g (median: 407 ng/g). While no significant differences in THg concentrations were found between male and female seals, distinctions were observed between young and potentially mature seals. Stable nitrogen isotope analysis indicated that juveniles and mature adults did not differ, although sample sizes were limiting. The higher THg concentrations in juveniles were attributed to variations in the seals' diets and/or variations in foraging locations during the juvenile stage which likely contribute to THg differences due to greater seasonal migration to offshore habitats. Notably, THg levels in bearded seals from the northwestern Sea of Okhotsk were lower in comparison to other pinniped species in the North Pacific. These findings, representing the first dataset for this pinniped species in the Russian segment of its habitat, contribute insights into mercury exposure in the Sea of Okhotsk mammalian population. [ABSTRACT FROM AUTHOR]

A comparative study of some parameters of erythrocytes of bearded seals of different ages (three years, five years, and ten years) was carried out. It was established that the resistance of erythrocyte membranes to hemolysis increases with age. During puberty, the intensity of glycolysis in erythrocytes of the bearded seals increases and then decreases in adult animals. Differences in the content of potassium, calcium, and magnesium in the erythrocytes of animals of the studied age groups are shown. [ABSTRACT FROM AUTHOR]

To estimate abundance, surveys of marine mammals often rely on samples of satellite‐tagged individuals to correct counts for the proportion of animals that are unavailable to be detected. However, naïve application of this correction relies on the key assumption that availability of the tagged sample resembles that of the population. Here, we show how matrix population models can be used to estimate stable age‐ and stage‐proportions, and how these can be used to adjust aerial survey correction factors so that they represent population‐level availability. We illustrate this procedure using data from ice‐associated seals in the Bering, Chukchi, and Beaufort Seas. After compiling life history data for bearded (Erignathus barbatus), ribbon (Histriophoca fasciata), ringed (Pusa hispida), and spotted seals (Phoca largha), we find that correction factors ignoring age‐sex composition can positively bias spotted seal abundance by an average of 13% and negatively bias ribbon seal abundance by an average of 5%. Note that we did not examine potential bias for bearded or ringed seals due to low sample sizes; as such, we urge caution in interpretation of abundance estimates for these species. [ABSTRACT FROM AUTHOR]

Bearded (Erignathus barbatus), ringed (Pusa hispida), spotted (Phoca largha), and ribbon (Histriophoca fasciata) seals rely on seasonal sea-ice in Arctic and sub-Arctic regions. Many aspects of the biology and physiology of these seals are poorly known, and species-typical health parameters are not available for all species. Such information has proven difficult to obtain due to the challenges of studying Arctic seals in the wild and their minimal historic representation in aquaria. Here, we combine diagnostic information gathered between 2000 and 2017 from free-ranging seals, seals in short-term rehabilitation, and seals living in long-term human care to evaluate and compare key health parameters. For individuals in apparent good health, hematology, and blood chemistry values are reported by the source group for 10 bearded, 13 ringed, 73 spotted, and 81 ribbon seals from Alaskan waters. For a smaller set of individuals handled during veterinary or necropsy procedures, the presence of parasites and pathogens is described, as well as exposure to a variety of infectious diseases known to affect marine mammals and/or humans, with positive titers observed for Brucella, Leptospira, avian influenza, herpesvirus PhHV-1, and morbillivirus. These data provide initial baseline parameters for hematology, serum chemistries, and other species-level indicators of health that can be used to assess the condition of individual seals, inform monitoring and management efforts, and guide directed research efforts for Alaskan populations of ice-associated seals.

The last extensive (pan-Arctic) review on knowledge available on the bearded seal (Erignathus barbatus) was conducted by Cameron et al. in 2010. As bearded seals are hunted off Svalbard and Greenland but no stock assessments are available, NAMMCO requested a status review, and if possible, an assessment of the species in its area. This literature review attempts to summarise the knowledge that has become available post 2010, with a focus on the Atlantic Arctic. A large amount of information has become available on the behaviour of the bearded seal, with hearing, vocalisation, haul-out behaviour and movement patterns (through satelitte tagging), and their phenology, being well studied. A database of baseline blood parameters is slowly being built but is still limited. New data on distribution has emerged from PAM studies and non-targeted surveys. Abundance estimates are missing for Svalbard, but partial estimates have become available for the North Water Polynya in 2009 and 2014. Additionally, observations of bearded seals from aerial line-transect surveys are available for several areas of Greenland but have not been analysed. More information has become available on the impact of anthropogenic stressors, such as climate change and other related environmental changes, although demographic impacts of changes are missing. Catch data exists for both Svalbard and Greenland, but for the latter the data needs to be thoroughly validated. In summary, information on stock structure as well as local and global abundance estimates, which are both important to assess the sustainability of current catches, are still missing. However other lines of evidence can inform the delineation of management areas and the results of a pan-arctic genetic study should become available shortly. There is survey data available from Greenland that could be used to generate local abundance estimates, the analysis of which should be prioritised.

Abstract Background Health assessment of seals in captivity include haematology and serum biochemistry measurements. Because such parameters differ between species, it is crucial to have species-specific reference values for the interpretation of clinical samples. Furthermore, differences in nutrition and environment, life cycles as well as seasonal/annual cycles and varying physiological conditions can potentially affect serum chemistry and haematology parameters. Blood samples from four captive adult bearded seals (initially caught as pups in Svalbard, Norway, now held at Polaria, an Arctic experience centre in Tromsø, Norway) collected over a 16-month period were analysed for haematology (n = 22) and serum chemistry (n = 25) parameters. Serum chemistry analyses were also conducted on blood samples from 74 wild bearded seals (1995–2007) collected from Svalbard, Norway. Results We found higher activity of creatine kinase (CK) and higher concentrations of cortisol in the wild animals when compared to the captive seals, probably reflecting the physical restraint and concomitant stress induced during sampling. For the captive bearded seals, we did not find marked differences in haematology or serum chemistry parameters throughout the different seasons of sampling. Conclusions This study presents haematology and serum chemistry reference values for captive and wild bearded seals. Comparing physiological parameters for captive seals with wild seals indicated that having wild-caught bearded seals under the conditions offered at Polaria for several years did not markedly affect physiological parameters of the animals, and that training may have helped to alleviate stress associated with blood sampling and veterinary inspection.

This study presents comprehensive mapping of the current distribution of pinnipeds and polar bears (Ursus maritimus) around Svalbard based on a regional marine mammal sightings programme and explores time-trends (2005–2018). Walruses (Odobenus rosmarus) were observed with high frequency and in high numbers around previously identified haul-out sites. At-sea walruses were seen close to the coast in shallow waters. Ringed seals (Pusa hispida) were observed in coastal areas throughout Svalbard, often in association with tidewater glacier fronts. There was no increase in the mean latitude for ringed seal observations, but there was an increased frequency of observations at around 82°N, which reflects their following a northward shift in the ice edge during summer foraging trips. Bearded seals (Erignathus barbatus) were observed frequently in north-western Spitsbergen and shared many habitat features with ringed seals. There was a slight increase in the mean latitude of bearded seal observations and a decreased frequency of observation in the southern parts of the archipelago, suggesting that this species might be shifting its distribution. Harbour seal (Phoca vitulina) observations within fjords have increased, likely as a consequence of increased inflow of Atlantic water into west coast fjords. Harp seals (Pagophilus groenlandicus) were observed with high frequency north of Svalbard. Hooded seals (Cystophora cristata) were observed only rarely. Polar bears were reported most frequently, undoubtedly as a result of an effort bias favouring this species. In spite of biases, citizen-based observations are useful for assessing broad distributional patterns of marine mammals through time.

Quantifying the energy needs of individual animals and understanding the relationship between food intake and physical growth are necessary to determine species-level food requirements and to model potential responses to changing environmental conditions. To provide fine-scale information about developmental and seasonal patterns in the energetic requirements of Arctic phocid seals, we documented longitudinal changes in food intake, body mass, and standard length in four spotted seals (Phoca largha), three ringed seals (Pusa hispida), and two bearded seals (Erignathus barbatus). The seals were studied for up to 9 years in subarctic and/or temperate climates while living under human care. Seals were fed using behavioral criteria that allowed their food intake and body mass to vary naturally. Gross energy intake (GEI) increased with age in all species, reaching a plateau as seals matured. GEI was greatest for the largest species (bearded seals) and lowest for the smallest (ringed seals). Massspecific GEI declined with age and was similar between spotted and ringed seals, with bearded seals consuming about half as much as the smaller species. Overlaid upon long-term developmental changes were predictable seasonal cycles in food intake and body mass which became more pronounced as seals matured. Seasonal cycles in food intake and body mass did not always reflect simple cause-and-effect relationships. For example, seasonal peaks in food intake were regularly associated with simultaneous declines in body mass. The consistency of energy intake patterns, despite seals being maintained in semi-artificial conditions in different local climates, supports the hypothesis that seasonal oscillations are guided by underlying hormonal changes linked to key life history events and mediated by the physical environment. The described physiological patterns serve to highlight times of year when free-ranging Arctic seals may be more sensitive to environmental perturbations. [ABSTRACT FROM AUTHOR]

Background: Health assessment of seals in captivity include haematology and serum biochemistry measurements. Because such parameters differ between species, it is crucial to have species-specific reference values for the interpretation of clinical samples. Furthermore, differences in nutrition and environment, life cycles as well as seasonal/annual cycles and varying physiological conditions can potentially affect serum chemistry and haematology parameters. Blood samples from four captive adult bearded seals (initially caught as pups in Svalbard, Norway, now held at Polaria, an Arctic experience centre in Tromsø, Norway) collected over a 16-month period were analysed for haematology (n = 22) and serum chemistry (n = 25) parameters. Serum chemistry analyses were also conducted on blood samples from 74 wild bearded seals (1995–2007) collected from Svalbard, Norway. Results: We found higher activity of creatine kinase (CK) and higher concentrations of cortisol in the wild animals when compared to the captive seals, probably reflecting the physical restraint and concomitant stress induced during sampling. For the captive bearded seals, we did not find marked differences in haematology or serum chemistry parameters throughout the different seasons of sampling. Conclusions: This study presents haematology and serum chemistry reference values for captive and wild bearded seals. Comparing physiological parameters for captive seals with wild seals indicated that having wild-caught bearded seals under the conditions offered at Polaria for several years did not markedly affect physiological parameters of the animals, and that training may have helped to alleviate stress associated with blood sampling and veterinary inspection. [ABSTRACT FROM AUTHOR]

This study presents comprehensive mapping of the current distribution of pinnipeds and polar bears (Ursus maritimus) around Svalbard based on a regional marine mammal sightings programme and explores time-trends (2005-2018). Walruses (Odobenus rosmarus) were observed with high frequency and in high numbers around previously identified haul-out sites. At-sea walruses were seen close to the coast in shallow waters. Ringed seals (Pusa hispida) were observed in coastal areas throughout Svalbard, often in association with tidewater glacier fronts. There was no increase in the mean latitude for ringed seal observations, but there was an increased frequency of observations at around 82°N, which reflects their following a northward shift in the ice edge during summer foraging trips. Bearded seals (Erignathus barbatus) were observed frequently in north-western Spitsbergen and shared many habitat features with ringed seals. There was a slight increase in the mean latitude of bearded seal observations and a decreased frequency of observation in the southern parts of the archipelago, suggesting that this species might be shifting its distribution. Harbour seal (Phoca vitulina) observations within fjords have increased, likely as a consequence of increased inflow of Atlantic water into west coast fjords. Harp seals (Pagophilus groenlandicus) were observed with high frequency north of Svalbard. Hooded seals (Cystophora cristata) were observed only rarely. Polar bears were reported most frequently, undoubtedly as a result of an effort bias favouring this species. In spite of biases, citizen-based observations are useful for assessing broad distributional patterns of marine mammals through time. [ABSTRACT FROM AUTHOR]

There is limited information about the biology and seasonal distribution of bearded seals (Erignathus barbatus) in Greenland. The species is highly ice-associated and depends on sea ice for hauling out and giving birth, making it vulnerable to climate change. We investigated the seasonality and distribution of bearded seal vocalizations at seven different locations across southern Baffin Bay and Davis Strait, West Greenland. Aural M2 and HARUphone recorders were deployed on the sea bottom during 2006–2007 and 2011–2013. Recordings were analyzed for presence/absence of bearded seal calls relative to location (including distance to shore and depth), mean sea ice concentration and diel patterns. Calling occurred between November and late June with most intense calling during the mating season at all sites. There was a clear effect of depth and distance to shore on the number of detections, and the Greenland shelf (< 300 m) appeared to be the preferred habitat for bearded seals during the mating season. These results suggest that bearded seals may retreat with the receding sea ice to Canada during summer or possibly spend the summer along the West Greenland coast. It is also possible that, due to seasonal changes in bearded seal vocal behavior, animals may have been present in our study area in summer, but silent. The number of detections was affected by the timing of sea ice formation but not sea ice concentration. Diel patterns were consistent with patterns found in other parts of the Arctic, with a peak during early morning (0400 local) and a minimum during late afternoon (1600 local). While vocalization studies have been conducted on bearded seals in Norwegian, Canadian, northwest Greenland, and Alaskan territories, this study fills the gap between these areas. [ABSTRACT FROM AUTHOR]

Bearded seals (Erignathus barbatus) are abundant in the Pacific Arctic and are an important subsistence resource for many Alaska Native communities. The Pacific Arctic is warming rapidly with substantial consequences predicted for ice-associated marine mammals, such as the bearded seal, which led to its 2012 listing as Threatened under the U.S. Endangered Species Act. We provide the most comprehensive description of juvenile bearded seal movement, diving, and haul-out behaviors for the Pacific Arctic, obtained from 24 seals tagged with satellite-linked data recorders along Alaska's coast from 2014 to 2018. Most seals (19 of 24) made north–south movements with the seasonal extent of sea ice, however, all three seals tagged north of Bering Strait made minimal north–south movements and two seals tagged in the Bering Sea moved north as sea ice advanced south. All seals primarily occupied shallow coastal waters and areas with intermediate-concentration pack ice or that were near the ice edge. Seals spent half their time near the sea floor. Hauling out occurred less in the winter and increased during spring and summer, coinciding with the annual molting period. When ice was at its minimum extent, seven seals frequently hauled out on land. Juvenile bearded seals made use of much of the continental shelf in the Bering, Chukchi and Beaufort Seas, and their use of a broad range of ice concentrations and willingness to haul out on land suggests some resilience to changing sea ice conditions. However, whether the behaviors we documented in juveniles are similar for adult bearded seals remains unclear. [ABSTRACT FROM AUTHOR]

Icebreaker vessels are important scientific tools, enabling access and research within the polar regions of the world, including the High Arctic. These vessels have the potential to overlap with marine mammal habitats in infrequently studied areas. Marine mammal behavioral responses to icebreaker vessel presence and distance at which responses occur are not well documented or understood. During the Petermann 2015 Expedition on the icebreaker Oden, seal and polar bear (Ursus maritimus) data were collected in Petermann Fjord (Northwest Greenland), the adjacent Nares Strait region, and transit to and from Thule, Greenland over 31 days (July 30 to August 30, 2015). We examined behavioral responses from 4 pinniped species: bearded seal (Erignathus barbatus), ringed seal (Pusa hispida), harp seal (Pagophilus groenlandicus), and hooded seal (Crystophora cristata), as well as the polar bear to an icebreaker vessel in a rarely studied region of northwest Greenland. We investigated the rate of flush response, entering the water from a previously hauled out (i.e., resting) location on ice in relation to seal distance to the vessel. Our results showed a significant difference (independent t-test, P ≤ 0.001) between seal distance to the vessel when a flush response occurred (mean = 467.1 m, SD = 212.39 m) and when no flush response occurred (mean = 1334.0 m, SD = 433.89 m). There were fewer flush responses by seals to the icebreaker at distances >600 m and no flush responses by seals to the icebreaker at distances >800 m. We used a logistic model to describe the relationship between the proportion of seals that flushed and distance from the icebreaker. Results of the logistical model showed the estimated distance at which 50% of the seals flushed to be 709.45 m (SE = 9.24, t = 76.8, P < 0.0001). Three polar bears were recorded during the transit, and a behavioral response (e.g., look, approach, move away) was recorded for all 3 sightings. Our preliminary findings are relevant to assess potential impacts of increasing vessel activity in the High Arctic and to assist in the development of effective monitoring and mitigation strategies.

Bearded (Erignathus barbatus), ringed (Pusa hispida), spotted (Phoca largha), and ribbon (Histriophoca fasciata) seals rely on seasonal sea-ice in Arctic and sub-Arctic regions. Many aspects of the biology and physiology of these seals are poorly known, and species-typical health parameters are not available for all species. Such information has proven difficult to obtain due to the challenges of studying Arctic seals in the wild and their minimal historic representation in aquaria. Here, we combine diagnostic information gathered between 2000 and 2017 from free-ranging seals, seals in short-term rehabilitation, and seals living in long-term human care to evaluate and compare key health parameters. For individuals in apparent good health, hematology, and blood chemistry values are reported by the source group for 10 bearded, 13 ringed, 73 spotted, and 81 ribbon seals from Alaskan waters. For a smaller set of individuals handled during veterinary or necropsy procedures, the presence of parasites and pathogens is described, as well as exposure to a variety of infectious diseases known to affect marine mammals and/or humans, with positive titers observed for Brucella, Leptospira, avian influenza, herpesvirus PhHV-1, and morbillivirus. These data provide initial baseline parameters for hematology, serum chemistries, and other species-level indicators of health that can be used to assess the condition of individual seals, inform monitoring and management efforts, and guide directed research efforts for Alaskan populations of ice-associated seals.

The seasonal habitat use of bearded seals is important information in terms of conservation of this species. However, their distribution outside the breeding season has not been well documented. We investigated seasonal variations in the call occurrence of bearded seals by using passive acoustic monitoring in the southern Chukchi Sea, which has some of the greatest benthic biomass in the Pacific sector of the Arctic Ocean. Underwater sounds were recorded between 2012 and 2015. Calls of bearded seals were detected from mid-September or early October to the end of each recording period (mid-May 2013, early March 2014, and mid-June 2015). Two peaks in call occurrence were noted; the first peak occurred during the open-water periods in November, and the second peak occurred during ice-covered periods. This suggest that bearded seals utilize the southern Chukchi Sea not only for the breeding site but also for the autumn foraging site. We could complement the information about the southward autumn migration pattern of bearded seals, and the southern Chukchi Sea was suggested as the south limit of bearded seals' autumn distribution. Additionally, their vocal activity during autumn in this site was suggested to have some role in social interaction. Our results indicated that the southern Chukchi Sea would be an important monitoring site for understanding the habitat use and the vocal activity of bearded seals, especially outside the breeding season. [ABSTRACT FROM AUTHOR]

Icebreaker vessels are important scientific tools, enabling access and research within the polar regions of the world, including the High Arctic. These vessels have the potential to overlap with marine mammal habitats in infrequently studied areas. Marine mammal behavioral responses to icebreaker vessel presence and distance at which responses occur are not well documented or understood. During the Petermann 2015 Expedition on the icebreaker Oden, seal and polar bear (Ursus maritimus) data were collected in Petermann Fjord (Northwest Greenland), the adjacent Nares Strait region, and transit to and from Thule, Greenland over 31 days (July 30 to August 30, 2015). We examined behavioral responses from 4 pinniped species: bearded seal (Erignathus barbatus), ringed seal (Pusa hispida), harp seal (Pagophilus groenlandicus), and hooded seal (Crystophora cristata), as well as the polar bear to an icebreaker vessel in a rarely studied region of northwest Greenland. We investigated the rate of flush response, entering the water from a previously hauled out (i.e., resting) location on ice in relation to seal distance to the vessel. Our results showed a significant difference (independent t-test, P ≤ 0.001) between seal distance to the vessel when a flush response occurred (mean = 467.1 m, SD = 212.39 m) and when no flush response occurred (mean = 1334.0 m, SD = 433.89 m). There were fewer flush responses by seals to the icebreaker at distances >600 m and no flush responses by seals to the icebreaker at distances >800 m. We used a logistic model to describe the relationship between the proportion of seals that flushed and distance from the icebreaker. Results of the logistical model showed the estimated distance at which 50% of the seals flushed to be 709.45 m (SE = 9.24, t = 76.8, P < 0.0001). Three polar bears were recorded during the transit, and a behavioral response (e.g., look, approach, move away) was recorded for all 3 sightings. Our preliminary findings are relevant to assess potential impacts of increasing vessel activity in the High Arctic and to assist in the development of effective monitoring and mitigation strategies. [ABSTRACT FROM AUTHOR]

Abstract 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. [ABSTRACT FROM AUTHOR]

Climate-mediated changes in the phenology of Arctic sea ice and primary production may alter benthic food webs that sustain populations of Pacific walruses ( Odobenus rosmarus divergens) and bearded seals ( Erignathus barbatus). Interspecific resource competition could place an additional strain on ice-associated marine mammals already facing loss of sea ice habitat. Using fatty acid (FA) profiles, FA trophic markers, and FA stable carbon isotope analyses, we found that walruses and bearded seals partitioned food resources in 2009-2011. Interspecific differences in FA profiles were largely driven by variation in non-methylene FAs, which are markers of benthic invertebrate prey taxa, indicating varying consumption of specific benthic prey. We used Bayesian multi-source FA stable isotope mixing models to estimate the proportional contributions of particulate organic matter (POM) from sympagic (ice algal), pelagic, and benthic sources to these apex predators. Proportional contributions of FAs to walruses and bearded seals from benthic POM sources were high [44 (17-67)% and 62 (38-83)%, respectively] relative to other sources of POM. Walruses also obtained considerable contributions of FAs from pelagic POM sources [51 (32-73)%]. Comparison of δC values of algal FAs from walruses and bearded seals to those from benthic prey from different feeding groups from the Chukchi and Bering seas revealed that different trophic pathways sustained walruses and bearded seals. Our findings suggest that (1) resource partitioning may mitigate interspecific competition, and (2) climate change impacts on Arctic food webs may elicit species-specific responses in these high trophic level consumers. [ABSTRACT FROM AUTHOR]

Bearded seals are pan-Arctic ice-obligate phocids; for the threatened Beringia population, the majority of the population feeds in the summer in the Chukchi Sea, then migrates south to overwinter in the northern Bering Sea. Contemporary information on the impact of rapidly changing climatic conditions on bearded seal distribution is essential for effective management. To monitor for marine mammals, passive acoustic recorders were deployed throughout the eastern Chukchi and northern Bering seas (64° N to 72° N), sampling at a rate of 16 kHz on a duty cycle of either 80 or 85 min every 5 h. Data from year-long deployments at nine sites over four years (2012–2016) were manually analyzed, totaling 13,275 days (∼75,000 h). Bearded seal calling activity was present at every site in every year. Calling activity increased from September through February and reached sustained and saturated levels from March through June, at which point calling ceased abruptly regardless of ice cover. The timing of calling and its abrupt cessation correspond with the known breeding season of bearded seals. However, the timing of the cessation of calling occurred earlier each year, corresponding with an earlier sea ice retreat. The sustained calling detected overwinter at all locations suggests that this is more than just a few animals that are remaining in the Chukchi Sea. Preceding this main pulse was a smaller peak in calling that progressed southward, corresponding with the fall migration of bearded seals to the Bering Sea. These results increase our knowledge on the year-round spatio-temporal distribution and migration patterns of this pagophilic species, and the relationship between calling activity and sea ice concentration. [ABSTRACT FROM AUTHOR]

Bearded seal (Erignathus barbatus) calls were recorded using autonomous passive acoustic recorders deployed in the northeastern Chukchi Sea between October 2007 and October 2010. Continuous acoustic data were acquired during summer (August to mid-October), and overwinter data (mid-October through July) were acquired on a duty cycle of 40/48 min every 4 h. We investigated the spatio-temporal distribution and acoustic behavior of vocalizing bearded seals in this multiyear data set. Peaks in calling occurred in spring, coinciding with the mating period, and calls stopped abruptly in late June/early July. Fewer calls were detected in summer, and the vocal presence of seals increased with the formation of pack ice in winter. Vocal activity was higher at night than during the day, with a peak around 0400 (AKST). Monthly patterns in proportional use of each call type and call duration were examined for the first time. The proportion and duration of AL1(T) and AL2(T) call types increased during the mating period, suggesting that males advertise their breeding condition by producing those specific longer trills. The observed seasonal and diel trends were consistent between years. These results improve our understanding of occurrence and acoustic behavior of bearded seals across the northeastern Chukchi Sea. [ABSTRACT FROM AUTHOR]

The Argos satellite telemetry system is popular for studying the movement and space use of marine animals. The life histories of marine mammals, in particular, result in a relatively large proportion of inaccurate locations, thus making analysis methods that do not account for location measurement error inappropriate for these data. Using a new Kalman filtering algorithm, Argos now provides locations and estimated error ellipses associated with each satellite fix, but to our knowledge, the location error ellipse has yet to be incorporated into analyses of animal movement or space use., We first present an observation model utilizing the Argos error ellipse and then demonstrate how this observation model can be combined with a simple three-dimensional movement model in a state-space formulation to infer activity budgets and movement characteristics from location and dive data of two species of seal, the bearded seal ( Erignathus barbatus) and the Hawaiian monk seal ( Monachus schauinslandi). These example data sets are of variable quality and represent species that differ in both space use and latitudinal range relative to the polar orbits of Argos satellites. We also compare the results from our error ellipse model with those from an approximate (isotropic) error circle model., We found the error circle to be a crude approximation of the actual anisotropic error ellipse for the higher quality bearded seal data, but inferences from the lower quality Hawaiian monk seal data were more robust to the choice of observation model. In both examples, we found the theoretical bivariate normal distribution corresponding to the error ellipse often failed to adequately explain the most extreme location outliers., In practice, we suspect the inferential consequences of using traditional isotropic location quality classes or other crude approximations in lieu of the error ellipse will be largely case-dependent. We support the Argos recommendation that practitioners wishing to more properly account for location measurement error utilize the error ellipse in analyses. However, the continued presence of outliers using the new algorithm suggests practitioners should consider using a fat-tailed distribution derived from the error ellipse (e.g. bivariate t-distribution) or filtering extreme outliers during data pre-processing. [ABSTRACT FROM AUTHOR]

Bearded seals ( Erignathus barbatus) are pan-Arctic pinnipeds that are often seen in association with pack ice, and are known for their long, loud trills, produced underwater primarily in the spring. Acoustic recordings were collected from August 2008 to August 2010 at two locations and a single year (2008-2009) at a third location, in the western Beaufort Sea. Three recorders in 2008-2009 had a 30 % duty cycle and a bandwidth of 10-4,096 Hz. One recorder in 2009-2010 had a 45 % duty cycle and a bandwidth of 10-4,096 Hz and the second had a 20 % duty cycle and bandwidth of 10-8,192 Hz. Spectrograms of acoustic data were examined for characteristic patterns of bearded seal vocalizations. For each recorder, the number of hours per day with vocalizations was compared with in situ water temperature and satellite-derived daily sea ice concentrations. At all sites, bearded seals were vocally active year-round. Call activity escalated with the formation of pack ice in the winter and the peak occurred in the spring, coinciding with mating season and preceding breakup of the sea ice. There was a change in the timing of seasonal sea ice formation and retreat between the two consecutive years that was reflected in the timing of peak bearded seal call activity. This study provides new information on fall and winter bearded seal vocal behavior and the relationship between year-round vocal activity and changes in annual sea ice coverage and in situ water temperature. [ABSTRACT FROM AUTHOR]

Climate change and sea-ice reduction may lead to modifications of food-web structure in the Arctic, and this may impact foraging of ice-associated predators. We examined the dietary history recorded in cornified claw sheaths of ringed seals ( Pusa hispida (Schreber, 1775)) and bearded seals ( Erignathus barbatus (Erxleben, 1777)) to describe potential seasonal and interannual changes in their foraging. Seasonal layers of cornified cells deposited in claws can document trophic history up to about 10 years; thereafter, the claws start to wear at the distal end. A total of 38 claws were collected during Alaska Native subsistence harvests in 2008-2010 and seasonal growth bands were examined for stable nitrogen and carbon isotope ratios to assess long-term diet patterns. During 2007 (record ice minimum), proportionally more ringed seals fed at a lower trophic level. Bearded seals may have been foraging more pelagically from 2008 to 2010. Interannual variations and high variability between the two ice seal species and among individual diets illustrate the opportunistic nature and flexibility of ice seals to changes in prey. [ABSTRACT FROM AUTHOR]