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Christian Lydersen - One of the best experts on this subject based on the ideXlab platform.
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Haul-out behaviour of Arctic ringed seals (Pusa hispida): inter-annual patterns and impacts of current environmental change
Polar Biology, 2018Co-Authors: Charmain D. Hamilton, Kit M. Kovacs, Rolf A. Ims, Christian LydersenAbstract:Hauling out onto a solid substrate is an integral part of most pinnipeds’ activity budgets. Ringed seals ( Pusa hispida ) are an Arctic species that hauls out on sea ice routinely throughout the year. In 2006, a sudden change in the sea-ice regime occurred in Svalbard (Norway). Amongst other changes, the amount of land-fast ice declined sharply. This study examined the intra- and inter-annual haul-out behaviour of 60 ringed seals equipped with Satellite Relay Data Loggers before [2002–2003 ( n = 22)] and after [2010–2012 ( n = 38)] the sea-ice decline occurred. In total, ringed seals hauled out 5–20% of the time (between August and May) with a mean haul-out duration of 3.3 h. The mean interval between haul-out events was 36 h, with a seasonal pattern that peaked in October (max 81 days). Haul-out probability was influenced by wind speed, temperature and solar hour to varying extents seasonally. After the sea-ice decline, intervals between haul-out events were significantly longer, and from December to March seals had shorter haul-out durations and hauled out a smaller proportion of the time. Haul-out probabilities in the winter and spring were more heavily influenced by weather conditions in 2010–2012 compared to 2002–2003, especially on the west coast where sea-ice declines have been greatest. These changes are likely due to ringed seals hauling out less often in snow lairs due to inadequate snow and ice conditions. Ringed seal haul-out behaviour will likely continue to be impacted negatively by ongoing environmental change, with concomitant impacts on their activity/energy budget and polar bears’ hunting behaviour.
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novel terrestrial haul out behaviour by ringed seals Pusa hispida in svalbard in association with harbour seals phoca vitulina
Polar Research, 2017Co-Authors: Christian Lydersen, Jade Vaquiegarcia, Espen Lydersen, Guttorm Christensen, Kit M. KovacsAbstract:ABSTRACTRinged seals (Pusa hispida) are the most ice-associated of all Arctic pinnipeds. In the Svalbard area, this species has always given birth, moulted and rested on sea ice. In addition, much of their food has been comprised of ice-associated prey. Recently, ringed seals have been reported to be using terrestrial substrates as a haul-out platform in some fjords on the west coast of Spitsbergen. In many cases the seals involved are harbour seals (Phoca vitulina), which are extending their distribution into new areas within the Svalbard Archipelago and which are being misclassified as ringed seals. However, this study reports that terrestrial haul-out by ringed seals is also now taking place on rocks exposed at low tide as well as on the coastline. Recent intrusions of warm Atlantic Water (with associated prey) have extended deep into the fjords of western Spitsbergen, resulting in deteriorated ice conditions for ringed seals and expanded habitat for harbour seals. Over the last decade, ringed seals ha...
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interdecadal changes in the marine food web along the west spitsbergen coast detected in the stable isotope composition of ringed seal Pusa hispida whiskers
Polar Biology, 2017Co-Authors: Andrew D Lowther, Aaron T. Fisk, Kit M. Kovacs, Christian LydersenAbstract:Recent influxes of warm Atlantic water into the fjords of west Spitsbergen have led to concomitant influx of more temperate and boreal fish species. The changes in the water masses within the fjords naturally affect all trophic levels of the sympagic, benthic, and pelagic food chains in the area. The most abundant marine mammal species in the fjords of west Spitsbergen is the ringed seal (Pusa hispida), which feeds, breeds, and moults in this area. In this study, we used isotopic data from whiskers of two cohorts of adult ringed seals (sampled in 1990 and 2013) to determine whether signals of ecosystem changes were detectable in this top marine predator. Acknowledging the limitations to our understanding of whisker growth in phocid seals, we interpreted the isotopic data from whiskers under two alternate hypotheses of whisker replacement dynamics and the dietary periods that might be represented. Even under the most conservative hypothesis, it is clear from our data that changes in the marine food web of the west Spitsbergen coast have occurred over the last 20 years, and that these are detectable in the isotopes incorporated into higher trophic predators. Concluding which aspect of the food web has been modified is complicated by a lack of recent ringed seal dietary studies, a knowledge gap that should be prioritised as the climate continues to change.
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historical population dynamics of ringed seals Pusa hispida of the svalbard archipelago predicting the response to climate change
27th Conference of the European Cetacean Society: Interdisciplinary approaches in the study of marine mammals, 2013Co-Authors: Andrea A Cabrera, Christian Lydersen, Kit M. Kovacs, Jon Aars, Morten Tange Olsen, Jurjan Van Der Zee, Lutz Bachmann, Oystein WiigAbstract:The ringed seal (Pusa hispida) is a pagophilic seal species with a life cycle closely associated with the sea ice and also the key prey species for the polar bear (Ursus maritimus). Global warming is rapidly diminishing the extent of summer sea ice in the Arctic, greatly reducing habitat availability for ringed seals and indirectly influencing the prey availability for polar bears. Predicting the effects of climate change on the abundance of ringed seals is essential for effective long-term management, but is challenging due to the complex relationship between climate change and ecological dynamics. Understanding how the historical population dynamics of ringed seals have responded to past climate may provide insights into the responses to current and future climate changes. In this study we have employed the Bayesian skyline plots, a coalescence-based method for inference of historical population dynamics, using mitochondrial DNA control region nucleotide sequences collected from ringed seals and polar bears at the Svalbard. Our analysis revealed a pattern of population expansion followed by contraction in ringed seals, suggesting a possible correlation with historical sea ice dynamics. Preliminary results from the polar bear suggest a correlation with ringed seal population dynamics. Additional on-going data analyses of a large number of high-resolution SNPs will add further rigor to our study. Our findings have implications for conservation of ringed seal and polar bear, in addition to providing insights into the evolutionary ecology of key polar marine mammals in the Arctic.
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a simple route to single nucleotide polymorphisms in a nonmodel species identification and characterization of snps in the artic ringed seal Pusa hispida hispida
Molecular Ecology Resources, 2011Co-Authors: Morten Tange Olsen, Christian Lydersen, Kit M. Kovacs, Rune Dietz, Veronica Hirsh Volny, Martine Berube, Richard S Dodd, Per J PalsbollAbstract:Although single-nucleotide polymorphisms (SNPs) have become the marker of choice in the field of human genetics, these markers are only slowly emerging in ecological, evolutionary and conservation genetic analyses of nonmodel species. This is partly because of difficulties associated with the discovery and characterization of SNP markers. Herein, we adopted a simple straightforward approach to identifying SNPs, based on screening of a random genomic library. In total, we identified 768 SNPs in the ringed seal, Pusa hispida hispida, in samples from Greenland and Svalbard. Using three seal samples, SNPs were discovered at a rate of one SNP per 402 bp, whereas re-sequencing of 96 seals increased the density to one SNP per 29 bp. Although applicable to any species of interest, the approach is especially well suited for SNP discovery in nonmodel organisms and is easily implemented in any standard genetics laboratory, circumventing the need for prior genomic data and use of next-generation sequencing facilities.
Kit M. Kovacs - One of the best experts on this subject based on the ideXlab platform.
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Haul-out behaviour of Arctic ringed seals (Pusa hispida): inter-annual patterns and impacts of current environmental change
Polar Biology, 2018Co-Authors: Charmain D. Hamilton, Kit M. Kovacs, Rolf A. Ims, Christian LydersenAbstract:Hauling out onto a solid substrate is an integral part of most pinnipeds’ activity budgets. Ringed seals ( Pusa hispida ) are an Arctic species that hauls out on sea ice routinely throughout the year. In 2006, a sudden change in the sea-ice regime occurred in Svalbard (Norway). Amongst other changes, the amount of land-fast ice declined sharply. This study examined the intra- and inter-annual haul-out behaviour of 60 ringed seals equipped with Satellite Relay Data Loggers before [2002–2003 ( n = 22)] and after [2010–2012 ( n = 38)] the sea-ice decline occurred. In total, ringed seals hauled out 5–20% of the time (between August and May) with a mean haul-out duration of 3.3 h. The mean interval between haul-out events was 36 h, with a seasonal pattern that peaked in October (max 81 days). Haul-out probability was influenced by wind speed, temperature and solar hour to varying extents seasonally. After the sea-ice decline, intervals between haul-out events were significantly longer, and from December to March seals had shorter haul-out durations and hauled out a smaller proportion of the time. Haul-out probabilities in the winter and spring were more heavily influenced by weather conditions in 2010–2012 compared to 2002–2003, especially on the west coast where sea-ice declines have been greatest. These changes are likely due to ringed seals hauling out less often in snow lairs due to inadequate snow and ice conditions. Ringed seal haul-out behaviour will likely continue to be impacted negatively by ongoing environmental change, with concomitant impacts on their activity/energy budget and polar bears’ hunting behaviour.
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novel terrestrial haul out behaviour by ringed seals Pusa hispida in svalbard in association with harbour seals phoca vitulina
Polar Research, 2017Co-Authors: Christian Lydersen, Jade Vaquiegarcia, Espen Lydersen, Guttorm Christensen, Kit M. KovacsAbstract:ABSTRACTRinged seals (Pusa hispida) are the most ice-associated of all Arctic pinnipeds. In the Svalbard area, this species has always given birth, moulted and rested on sea ice. In addition, much of their food has been comprised of ice-associated prey. Recently, ringed seals have been reported to be using terrestrial substrates as a haul-out platform in some fjords on the west coast of Spitsbergen. In many cases the seals involved are harbour seals (Phoca vitulina), which are extending their distribution into new areas within the Svalbard Archipelago and which are being misclassified as ringed seals. However, this study reports that terrestrial haul-out by ringed seals is also now taking place on rocks exposed at low tide as well as on the coastline. Recent intrusions of warm Atlantic Water (with associated prey) have extended deep into the fjords of western Spitsbergen, resulting in deteriorated ice conditions for ringed seals and expanded habitat for harbour seals. Over the last decade, ringed seals ha...
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interdecadal changes in the marine food web along the west spitsbergen coast detected in the stable isotope composition of ringed seal Pusa hispida whiskers
Polar Biology, 2017Co-Authors: Andrew D Lowther, Aaron T. Fisk, Kit M. Kovacs, Christian LydersenAbstract:Recent influxes of warm Atlantic water into the fjords of west Spitsbergen have led to concomitant influx of more temperate and boreal fish species. The changes in the water masses within the fjords naturally affect all trophic levels of the sympagic, benthic, and pelagic food chains in the area. The most abundant marine mammal species in the fjords of west Spitsbergen is the ringed seal (Pusa hispida), which feeds, breeds, and moults in this area. In this study, we used isotopic data from whiskers of two cohorts of adult ringed seals (sampled in 1990 and 2013) to determine whether signals of ecosystem changes were detectable in this top marine predator. Acknowledging the limitations to our understanding of whisker growth in phocid seals, we interpreted the isotopic data from whiskers under two alternate hypotheses of whisker replacement dynamics and the dietary periods that might be represented. Even under the most conservative hypothesis, it is clear from our data that changes in the marine food web of the west Spitsbergen coast have occurred over the last 20 years, and that these are detectable in the isotopes incorporated into higher trophic predators. Concluding which aspect of the food web has been modified is complicated by a lack of recent ringed seal dietary studies, a knowledge gap that should be prioritised as the climate continues to change.
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historical population dynamics of ringed seals Pusa hispida of the svalbard archipelago predicting the response to climate change
27th Conference of the European Cetacean Society: Interdisciplinary approaches in the study of marine mammals, 2013Co-Authors: Andrea A Cabrera, Christian Lydersen, Kit M. Kovacs, Jon Aars, Morten Tange Olsen, Jurjan Van Der Zee, Lutz Bachmann, Oystein WiigAbstract:The ringed seal (Pusa hispida) is a pagophilic seal species with a life cycle closely associated with the sea ice and also the key prey species for the polar bear (Ursus maritimus). Global warming is rapidly diminishing the extent of summer sea ice in the Arctic, greatly reducing habitat availability for ringed seals and indirectly influencing the prey availability for polar bears. Predicting the effects of climate change on the abundance of ringed seals is essential for effective long-term management, but is challenging due to the complex relationship between climate change and ecological dynamics. Understanding how the historical population dynamics of ringed seals have responded to past climate may provide insights into the responses to current and future climate changes. In this study we have employed the Bayesian skyline plots, a coalescence-based method for inference of historical population dynamics, using mitochondrial DNA control region nucleotide sequences collected from ringed seals and polar bears at the Svalbard. Our analysis revealed a pattern of population expansion followed by contraction in ringed seals, suggesting a possible correlation with historical sea ice dynamics. Preliminary results from the polar bear suggest a correlation with ringed seal population dynamics. Additional on-going data analyses of a large number of high-resolution SNPs will add further rigor to our study. Our findings have implications for conservation of ringed seal and polar bear, in addition to providing insights into the evolutionary ecology of key polar marine mammals in the Arctic.
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a simple route to single nucleotide polymorphisms in a nonmodel species identification and characterization of snps in the artic ringed seal Pusa hispida hispida
Molecular Ecology Resources, 2011Co-Authors: Morten Tange Olsen, Christian Lydersen, Kit M. Kovacs, Rune Dietz, Veronica Hirsh Volny, Martine Berube, Richard S Dodd, Per J PalsbollAbstract:Although single-nucleotide polymorphisms (SNPs) have become the marker of choice in the field of human genetics, these markers are only slowly emerging in ecological, evolutionary and conservation genetic analyses of nonmodel species. This is partly because of difficulties associated with the discovery and characterization of SNP markers. Herein, we adopted a simple straightforward approach to identifying SNPs, based on screening of a random genomic library. In total, we identified 768 SNPs in the ringed seal, Pusa hispida hispida, in samples from Greenland and Svalbard. Using three seal samples, SNPs were discovered at a rate of one SNP per 402 bp, whereas re-sequencing of 96 seals increased the density to one SNP per 29 bp. Although applicable to any species of interest, the approach is especially well suited for SNP discovery in nonmodel organisms and is easily implemented in any standard genetics laboratory, circumventing the need for prior genomic data and use of next-generation sequencing facilities.
Bjørn A. Krafft - One of the best experts on this subject based on the ideXlab platform.
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biomarker responses and decreasing contaminant levels in ringed seals Pusa hispida from svalbard norway
Journal of Toxicology and Environmental Health, 2008Co-Authors: Hans Wolkers, Christian Lydersen, Bjørn A. Krafft, Bert Van Bavel, Lisa Bjornsdatter Helgason, Kit M. KovacsAbstract:Blubber was analyzed for a wide range of contaminants from five sub-adult and eight adult male ringed seals sampled in 2004, namely, for polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), t ...
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serum chemistry values for free ranging ringed seals Pusa hispida in svalbard
Veterinary Clinical Pathology, 2006Co-Authors: Morten Tryland, Christian Lydersen, Bjørn A. Krafft, Kit Maureen Kovacs, Stein Istre ThoresenAbstract:Background: Diseases and abnormal physiologic conditions can alter the concentrations of enzymes, metabolites, minerals, and hormones in the blood of animals. The ringed seal (Pusa hispida) has been selected as a key species for environmental monitoring, but information on disease and health parameters for this species is scarce. Objectives: The aim of the study reported here was to obtain serum chemistry reference intervals for free-ranging ringed seals in Svalbard, and then to evaluate serum chemistry values in relation to age, body condition, and sex. Methods: Blood samples were collected after death from ringed seals in Wijdefjorden and Billefjorden, Svalbard (2002–2003; n575). Serum was analyzed for 24 selected serum chemistry parameters (enzymes, protein, metabolites, minerals, and cortisol). Results: Compared with younger or older animals, seals between 7 and 16 years of age had larger variations in the activities of alanine transaminase, aspartate transaminase, lactate dehydrogenase, and creatine kinase (CK). Animals classified as having low body condition status had more variation in the serum activity of these enzymes, compared with that in animals with higher condition scores. Serum cortisol concentration was higher in young animals (1–5 years) than in older animals. Serum CK activity was higher in males than in females. Conclusion: The data reported here may be useful in monitoring the health of ringed seals and for tracking the impact of environmental changes in the Arctic. (Vet Clin Pathol. 2006;35:405–412)
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serum haptoglobin concentrations in ringed seals Pusa hispida from svalbard norway
Journal of Wildlife Diseases, 2006Co-Authors: Bjørn A. Krafft, Christian Lydersen, Kit M. KovacsAbstract:Haptoglobin (Hp) levels were measured in blood serum from 185 apparently healthy ringed seals (Pusa hispida) from Svalbard (age range, 1–30 yr) collected during the spring seasons of 2002 through 2004. The Hp concentration was 0.26±0.02 g/l (mean±SE; range, 0.0–1.5 g/l). Maturity status, body condition index (CI), interactions between CI and maturity status, and sex and maturity status all had significant influences on Hp levels. Mature males had significantly higher Hp concentrations compared with mature females (0.30±0.03 vs. 0.17±0.01 g/l, F1,16=14.9, P<0.01). No differences were found between Hp levels in immature male and female seals (0.33±0.06 g/l). The Hp levels increased significantly in immature seals when the CI decreased. Despite the fact that mature males had a significantly lower CI than mature females, no direct correlation was found between Hp concentration and CI among adults. The elevated Hp values found in mature males might be related to injuries inflicted among males while fighting du...
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abundance of ringed seals Pusa hispida in the fjords of spitsbergen svalbard during the peak molting period
Marine Mammal Science, 2006Co-Authors: Bjørn A. Krafft, Christian Lydersen, Kit M. Kovacs, Magnus Andersen, Jon Aars, Torbjorn Ergon, Tore HaugAbstract:Ringed seal (Pusa hispida) abundance in Spitsbergen, Svalbard, was estimated during the peak molting period via aerial, digital photographic surveys. A total of 9,145 images, covering 41.7%‐100% of the total fast-ice cover (1,496 km 2 )o f 18 different fjords and bays, were inspected for the presence of ringed seals. A total of 1,708 seals were counted, and when accounting for ice areas that were not covered by images, a total of 3,254 (95% CI: 3,071‐3,449) ringed seals were estimated to be hauled out during the surveys. Extensive behavioral data from radio-tagged ringed seals (collected in a companion study) from one of the highest density fjords during the molting period were used to create a model that predicts the proportion of seals hauled out on any given date, time of day, and under various meteorological conditions. Applying this model to the count data from each fjord, we estimated that a total of 7,585 (95% CI: 6,332‐9,085) ringed seals were present in the surveyed area during the peak molting period. Data on interannual variability in ringed seal abundance suggested higher numbers of seals in Van Keulenfjorden in 2002
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spring haul out behavior of ringed seals Pusa hispida in kongsfjorden svalbard
Marine Mammal Science, 2006Co-Authors: Helen Carlens, Christian Lydersen, Bjørn A. Krafft, Kit M. KovacsAbstract:Haul-out behavior of ringed seals (Pusa hispida) was investigated during the spring molting period of 2003 (May‐July) in Kongsfjorden, Svalbard, Norway. Hourly counts were conducted on the land-fast ice in six spatially defined sectors in the inner fjord, from an elevated land-based vantage point from early May through until the ice began to break up in June, from 0600 to 2200 daily (total counts n = 478). Concomitantly, measurements were made of a variety of weather parameters. Multiple regression analyses revealed that time of day (P < 0.001) and date (P < 0.001) significantly affected the number of ringed seals hauled out on the ice surface. Other factors influencing the number of seals counted on the ice were air temperature (P = 0.011) and wind speed (P < 0.001). Daily peaks occurred in the early afternoon between 1300 and 1400 and the seasonal high (n = 385) was registered during the first week in June, after which the number of seals on the ice in the fjord declined. In addition to the visual counts, 24 ringed seals were equipped with VHF transmitters, and the haul-out behavior of individuals was monitored from May through July via an automatic recording station. The VHF-tagged seals exhibited the same diurnal pattern seen in the total counts, with haul-out most frequent from 1300 to 1400. Pups exhibited short and frequent haul-outs, whereas longer haul-out periods were seen in the older age classes; adult females had the greatest number of haul-out periods that exceeded 24 h. The seasonal peak of haul-out for the tagged seals preceded the peak seasonal counts by approximately 3 wk. This may reflect significant out- and influx of seals from and to the area, a phenomenon warranting further attention because of its implications for assessment studies.
J. Alikamik - One of the best experts on this subject based on the ideXlab platform.
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Temporal Trends in Polybrominated Diphenylethers (PBDEs) in Blubber of Ringed Seals (Pusa hispida) from Ulukhaktok, NT, Canada Between 1981 and 2015
Archives of Environmental Contamination and Toxicology, 2020Co-Authors: R. F. Addison, D. C. G. Muir, M. G. Ikonomou, C. Dubetz, T. G. Smith, J. AlikamikAbstract:Blubber taken from ringed seals ( Pusa hispida ) during a subsistence hunt at Ulukhaktok, NT (formerly Holman, NWT) at intervals between 2002 and 2015 was analysed for polybrominated diphenyl ether (PBDE) congeners. Results from these analyses were combined with others previously published to yield a data set of 18 tri- to hepta-substituted PBDE congeners in 102 animals sampled over a span of 19 year (females) and 34 year (males). In females, mean total PBDE concentrations increased between 1996 and 2015 by approximately 50%, from 1940 to 2780 pg/g wet wt., although not significantly so ( p > 0.05) by one-way ANOVA. In males, concentrations ranged from 376 to 6470 pg/g wet wt. between 1981 and 2015 ( p
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temporal trends in polybrominated diphenylethers pbdes in blubber of ringed seals Pusa hispida from ulukhaktok nt canada between 1981 and 2015
Archives of Environmental Contamination and Toxicology, 2020Co-Authors: R. F. Addison, M. G. Ikonomou, C. Dubetz, T. G. Smith, Derek C. G. Muir, J. AlikamikAbstract:Blubber taken from ringed seals (Pusa hispida) during a subsistence hunt at Ulukhaktok, NT (formerly Holman, NWT) at intervals between 2002 and 2015 was analysed for polybrominated diphenyl ether (PBDE) congeners. Results from these analyses were combined with others previously published to yield a data set of 18 tri- to hepta-substituted PBDE congeners in 102 animals sampled over a span of 19 year (females) and 34 year (males). In females, mean total PBDE concentrations increased between 1996 and 2015 by approximately 50%, from 1940 to 2780 pg/g wet wt., although not significantly so (p > 0.05) by one-way ANOVA. In males, concentrations ranged from 376 to 6470 pg/g wet wt. between 1981 and 2015 (p < 0.05). In males, the most rapid increase in PBDE concentrations occurred before 2000, but between 2002 and 2015 mean total PBDE concentrations increased by a further 50%. ANCOVA showed PBDE concentrations in females to be correlated (p < 0.05) with sampling year but not with age or condition (as measured by blubber thickness); in males, PBDE concentrations were strongly correlated (p < 0.01) with year, age and condition. The relative proportions of tetra-bromo- congeners declined weakly in both sexes over the sampling period, with a compensatory increase in penta-bromo-congener distribution. Overall, the results show no evidence yet of a decline in PBDE concentrations in western Arctic ringed seals in response to voluntary and regulated restrictions on PBDE use in the early 2000s.
Tore Haug - One of the best experts on this subject based on the ideXlab platform.
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helminth parasites in ringed seals Pusa hispida from svalbard norway with special emphasis on nematodes variation with age sex diet and location of host
Journal of Parasitology, 2010Co-Authors: Carina E Johansen, Tore Haug, Christian Lydersen, Paul E Aspholm, Kit M. KovacsAbstract:Complete gastrointestinal tracts from 257 ringed seals (Pusa hispida) from Svalbard, Norway, were examined for helminth parasites. Three different helminth groups were recorded (acanthocephalans 61.1%; nematodes 38%; cestodes 0.9%). Acanthocephalans (Polymorphidae) and cestodes (Anophryocephalus and Diphyllobothrium sp(p)., as well as unidentified species, were confined to the intestines. The anisakid nematodes Phocascaris phocae, Pseudoterranova sp(p)., Anisakis sp(p)., and Phocascaris/Contracaecum sp(p). were recorded in both stomachs and the anterior part of the small intestines. The abundance of nematodes and acanthocephalans varied significantly with sampling location of the seal hosts. This is likely due to the relative prevalence of Arctic versus Atlantic water in the different fjord systems, which strongly influences the age class and species of fish available as prey for the seals. Adult male ringed seals had significantly higher abundances of nematodes than did adult females or juveniles. Adult males also had significantly higher abundances of acanthocephalans than did adult females, but were not significantly different from juveniles in this regard. Nematode abundance increased significantly with age of male hosts, but this trend was lacking in female seals. Infection parameters appeared to be related to differences in the age of polar cod (Boreogadus saida) exploited by male, female, and juvenile seals.
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Diet of ringed seals (Pusa hispida) from Northeast Greenland
Polar Biology, 2010Co-Authors: Aili L Labansen, Tore Haug, Christian Lydersen, Nette Levermann, Kit M. KovacsAbstract:The diet of ringed seals (Pusa hispida) from coastal and offshore areas of Northeast Greenland was determined by identifying, to the lowest taxonomic limit possible, all hard-part contents from the gastrointestinal tract of 51 seals sampled (2002–2004) in spring (April to June, N = 35) and autumn (September to October, N = 16). The autumn diet was characterized by high numbers of Parathemisto libellula, and the spring diet was comprised primarily of polar cod (Boreogadus saida), with few invertebrates consumed. The coastal seal diet samples had a diverse fish prey composition (during both the spring and autumn), whereas the open water seals had eaten mostly crustaceans with P. libellula being most abundant. The sample sizes from the various locations and seasons were not large enough to explore age-class effects on diet in addition. Similar to earlier studies, this study suggests that the ringed seal is a generalist that exploits prey based on availability, with a few key species dominating the diet in an area at least on a seasonal basis.
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abundance of ringed seals Pusa hispida in the fjords of spitsbergen svalbard during the peak molting period
Marine Mammal Science, 2006Co-Authors: Bjørn A. Krafft, Christian Lydersen, Kit M. Kovacs, Magnus Andersen, Jon Aars, Torbjorn Ergon, Tore HaugAbstract:Ringed seal (Pusa hispida) abundance in Spitsbergen, Svalbard, was estimated during the peak molting period via aerial, digital photographic surveys. A total of 9,145 images, covering 41.7%‐100% of the total fast-ice cover (1,496 km 2 )o f 18 different fjords and bays, were inspected for the presence of ringed seals. A total of 1,708 seals were counted, and when accounting for ice areas that were not covered by images, a total of 3,254 (95% CI: 3,071‐3,449) ringed seals were estimated to be hauled out during the surveys. Extensive behavioral data from radio-tagged ringed seals (collected in a companion study) from one of the highest density fjords during the molting period were used to create a model that predicts the proportion of seals hauled out on any given date, time of day, and under various meteorological conditions. Applying this model to the count data from each fjord, we estimated that a total of 7,585 (95% CI: 6,332‐9,085) ringed seals were present in the surveyed area during the peak molting period. Data on interannual variability in ringed seal abundance suggested higher numbers of seals in Van Keulenfjorden in 2002
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growth and population parameters of ringed seals Pusa hispida from svalbard norway 2002 2004
Ices Journal of Marine Science, 2006Co-Authors: Bjørn A. Krafft, Tore Haug, Kit M. Kovacs, Anne Kirstine Frie, Christian LydersenAbstract:Krafft, B. A., Kovacs, K. M., Frie, A. K., Haug, T., and Lydersen, C. 2006. Growthand population parameters of ringed seals (Pusa hispida) from Svalbard, Norway,2002e2004. e ICES Journal of Marine Science, 63: 1136e1144.Samples were collected in Svalbard, Norway, during April and May 2002e2004 from 272ringed seals (Pusa hispida; 62.5% males, 37.5% females) to study growth and populationparameters. The age of the animals ranged from 1 to 32 years. Asymptotic values forstandard length and body mass were 127.7 1.6 (s.e.) cm and 69.0 2.7 kg for males(maxima: 144 cm and 92 kg) and 127.6 2.3 cm and 68.9 2.5 kg for females (maxima:141 cm and 91 kg). All animals were sexually mature at an age 6 years and the ovulationrate was 0.86. Mean Age at Maturity (MAM) was 4.2 0.2 years for males and 3.5 0.3years for females, values significantly lower than calculated for ringed seals from the samearea 20 years ago. This change in MAM suggests that either the prey base for ringed seals inthe area has increased or alternatively that the density of ringed seals has declined, such thatmore resources are available per capita. If the climate of the Arctic changes in the mannerpredicted by a host of climate-change scenarios, it is likely to have a strong impact onringed seal populations in future, although there are no data to suggest that dramaticchanges have taken place yet in fish and invertebrate populations in the Svalbard area.Although cause-and-effect cannot be firmly established, there is a possibility that the sub-stantial increase in the number of polar bears (Ursus maritimus) over the past 20 years,since hunting the species in Svalbard ceased in 1973, may have played a role in the ob-served change in the ringed seal population.
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Growth and population parameters of ringed seals (Pusa hispida) from Svalbard, Norway, 2002–2004
ICES Journal of Marine Science, 2006Co-Authors: Bjørn A. Krafft, Tore Haug, Kit M. Kovacs, Anne Kirstine Frie, Christian LydersenAbstract:Krafft, B. A., Kovacs, K. M., Frie, A. K., Haug, T., and Lydersen, C. 2006. Growthand population parameters of ringed seals (Pusa hispida) from Svalbard, Norway,2002e2004. e ICES Journal of Marine Science, 63: 1136e1144.Samples were collected in Svalbard, Norway, during April and May 2002e2004 from 272ringed seals (Pusa hispida; 62.5% males, 37.5% females) to study growth and populationparameters. The age of the animals ranged from 1 to 32 years. Asymptotic values forstandard length and body mass were 127.7 1.6 (s.e.) cm and 69.0 2.7 kg for males(maxima: 144 cm and 92 kg) and 127.6 2.3 cm and 68.9 2.5 kg for females (maxima:141 cm and 91 kg). All animals were sexually mature at an age 6 years and the ovulationrate was 0.86. Mean Age at Maturity (MAM) was 4.2 0.2 years for males and 3.5 0.3years for females, values significantly lower than calculated for ringed seals from the samearea 20 years ago. This change in MAM suggests that either the prey base for ringed seals inthe area has increased or alternatively that the density of ringed seals has declined, such thatmore resources are available per capita. If the climate of the Arctic changes in the mannerpredicted by a host of climate-change scenarios, it is likely to have a strong impact onringed seal populations in future, although there are no data to suggest that dramaticchanges have taken place yet in fish and invertebrate populations in the Svalbard area.Although cause-and-effect cannot be firmly established, there is a possibility that the sub-stantial increase in the number of polar bears (Ursus maritimus) over the past 20 years,since hunting the species in Svalbard ceased in 1973, may have played a role in the ob-served change in the ringed seal population.
