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  • 1
    Electronic Resource
    Electronic Resource
    DNA sequence analysis identifies genetically distinguishable populations of harp seals (Pagophilus groenlandicus) in the Northwest and Northeast Atlantic (2000)
    Springer
    Marine biology 137 (2000), S. 53-58 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Harp seals (Pagophilus groenlandicus Erxleben, 1777) comprise three populations based upon whelping areas in the Greenland Sea, White Sea, and Northwest Atlantic. The last comprises two subpopulations, one whelping in the Gulf of St. Lawrence (“Gulf ”) and one on the pack ice of the southern Labrador/northern Newfoundland coastal shelf (“Front”). A total of 40 female seals from the four whelping areas were collected during the 1990 and 1992 whelping seasons. DNA sequence variation was examined in a 307 bp region of the mitochondrial cytochrome b gene. Eleven variable nucleotide positions defined 13 genotypes: a significant fraction of the genotypic variance (F ST=0.12, or 0.09 as measured by Weir's coancestry coefficient θ) is attributable to differentiation between Northwest and Northeast Atlantic populations. There was no significant differentiation between the two whelping areas in the Northwest Atlantic, or between the Greenland Sea and White Sea. These findings suggest significant reproductive isolation exists between trans-Atlantic breeding populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002279900248
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  • 2
    Electronic Resource
    Electronic Resource
    ESTIMATING PUP PRODUCTION OF HARP SEALS, PAGOPHILUS GROENLANDICUS, IN THE NORTHWEST ATLANTIC (2003)
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 19 (2003), S. 0 
    Details
    ISSN: 1748-7692
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Photographic and visual aerial surveys to determine current pup production of Northwest Atlantic harp seals were conducted off Newfoundland and in the Gulf of St. Lawrence during March 1999-Photographic surveys were conducted on all whelping concentrations between 14 and 24 March, whereas a visual survey was made of the southern Gulf concentrations on 14 March. Pup production was estimated to be 739,100 (SE = 96,300, CV = 13.0%) at the Front, 82,600 (SE = 22,500, CV = 27.2%) in the northern Gulf, and 176,200 (SE = 25,400, CV = 14.4%) in the southern Gulf (Magdalen Island) for a total of 997,900 (SE = 102,100, 10.2%). Changes in aerial survey estimates indicate that pup production has increased since 1994. A new method to correct for the temporal change in the proportion of pups present on the ice was examined by fitting the percentage of pups observed in three age-dependent stages to a Normal distribution. The results were compared to those obtained from a more complex model used previously. The Simple model produced slightly higher, and hence more conservative, estimates of the proportion of births that had occurred before the time of the survey than the Complex model. When using the Simple model fewer assumptions regarding the start date of pupping and the proportion of older pups remaining on the ice were required, the herd had to be followed for a shorter period, and a more convenient means of calculating confidence limits was available.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1748-7692.2003.tb01098.x
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  • 3
    Electronic Resource
    Electronic Resource
    ESTIMATING STRUCK AND LOSS RATES FOR HARP SEALS (PAGOPHILUS GROENLANDICUS) IN THE NORTHWEST ATLANTIC (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 18 (2002), S. 0 
    Details
    ISSN: 1748-7692
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: One of the major sources of unreported mortality during the commercial harp seal (Pagophilus groenlandicus) hunt in the Northwest Atlantic is the number of animals that are killed but not recovered or reported, commonly referred to as struck and lost. With the significant expansion of the hunt in Canada and in Greenland during the mid-1990s, there is a concern that the number of seals lost may have reached a level that is not sustainable relative to current harvest levels. To address this problem a study examining struck and loss rates was initiated in 1998 and 1999. Loss rates for young seals taken on the ice varied from 0% to 1.9% and from 0% to 10.0% when taken in the water. Seals greater than one year of age had loss rates of 0%–4.9% when taken on the ice and 13.8%-50.0% when taken in the water. These estimates are lower than those recently reported for Northwest Atlantic harp seals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1748-7692.2002.tb01068.x
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  • 4
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    Variation in harp sea pup vocalisations and mother-pup behaviour between whelping patches in the Atlantic West-ice and the Canadian Front: effects of climate or geography? (2007)
    In:  EPIC317th Biennial Conference on the Biology of Marine Mammals, Cape Town, South Africa. November 29 - December 3, 2007 p.
    Details
    Publication Date: 2019-07-17
    Description: Harp seals breed in pack-ice, a substrate which can vary substantially between whelping patches depending on differing environmental and oceanographic conditions. This study demonstrates clear site differences in pup vocalizations and mother pup behaviour between Northeast (Greenland Sea) and Northwest (Canadian Front) Atlantic harp seal populations. Classification trees showed a distinctive split between Front and Greenland Sea pup vocalisations. No clear sex differentiation in vocalizations was present for pups at the Front; 42% (n = 12) of male and 38% (n = 13) of female calls could be attributed to a given individual. In the Greenland Sea, 55% (n = 42) of female vocalisations were attributed to individuals compared with only 8% for males (n = 47). In addition behavioural observations of mother pup pairs were conducted (Front, n = 58; Greenland Sea, n = 78). Greenland Sea pups were found to nurse more, and were more alert than Front pups. Female attendance patterns also differed between sites: females at the Front were more likely to attend their pups than those in the Greenland Sea. This marked difference in female presence between sites could have several origins such as variability in ice conditions, predation pressure, or female condition.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 5
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    Variation in pup vocalisations and mother-pup behaviour between harp seal whelping patches: effects of climate or geography? (2008)
    In:  EPIC3ASA-EAA joint conference Acoustics08. June 29 - July 4, Paris, France.
    Details
    Publication Date: 2019-07-17
    Description: Harp seals breed in pack-ice, a substrate which can vary substantially between whelping patches depending on differing environmental and oceanographic conditions. This study demonstrates clear site differences in pup vocalizations and mother pup behaviour between Northeast (Greenland Sea) and Northwest (Canadian Front) Atlantic harp seal populations. Classification trees showed a distinctive split between Front and Greenland Sea pup vocalisations. No clear sex differentiation in vocalizations was present for pups at the Front; 42% (n = 12) of male and 38% (n = 13) of female calls could be attributed to a given individual. In the Greenland Sea, 55% (n = 42) of female vocalisations were attributed to individuals compared with only 8% for males (n = 47). In addition behavioural observations of mother pup pairs were conducted (Front, n = 58; Greenland Sea, n = 78). Greenland Sea pups were found to nurse more, and were more alert than Front pups. Female attendance patterns also differed between sites: females at the Front were more likely to attend their pups than those in the Greenland Sea. This marked difference in female presence between sites could have several origins such as variability in ice conditions, predation pressure, or female condition.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 6
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    Variation in harp seal, Phoca groenlandica, pup vocalisations and behaviour between whelping patches in the Greenland Sea and Newfoundland, Canada (2009)
    In:  EPIC3Aquatic Biology 6:, pp. 109-120
    Details
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 7
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    Biologging in the global ocean observing system (2010)
    In:  EPIC3Proceedings of OceanObs 09: Sustained Ocean Observations and Information for Society (Vol. 2), Venice, Italy, 21-25 September 2009, Hall, J., Harrison D.E. & Stammer, D., Eds., ESA Publication WPP-306
    Details
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 8
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    Habitat selection by hooded seals (Cystophora cristata) in the Northwest Atlantic Ocean (2012)
    Oxford University Press
    Details
    Publication Date: 2012-12-12
    Description: Andersen, J. M., Wiersma, Y. F., Stenson, G. B., Hammill, M. O., Rosing-Asvid, A., and Skern-Maurizen, M. 2013. Habitat selection by hooded seals ( Cystophora cristata ) in the Northwest Atlantic Ocean. – ICES Journal of Marine Science, 70:173–185. We examined annual habitat use for 65 hooded seals (32 adult females, 17 adult males, and 16 juveniles) equipped with satellite relay data loggers (SRDLs) in spring or summer during five field seasons (2004–2008). A combined approach using first passage time (FPT) analysis and a generalized additive model (GAM) was applied to test for habitat selection, with a focus on environmental parameters of depth, slope, ice, sea surface temperature (SST), and chlorophyll. The models were run on adult males, adult females, and juveniles separately, and the results identified SST, depth, and chlorophyll as the most important factors influencing habitat selection across all categories. Furthermore, males and females preferred similar habitat conditions, but were separated geographically, and by depth, at various times of the year. Males appeared to be more localized in their habitat use patterns, focusing their search effort in areas of complex seabed relief such as Baffin Bay, Davis Strait, and the Flemish cap, while females concentrated their search effort along shelf areas (e.g. the Labrador shelf). These findings support our hypothesis that hooded seals prefer areas where topography and oceanographic processes create favourable foraging conditions.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
    Published by Oxford University Press
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  • 9
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    The impact of changing climate and abundance on reproduction in an ice-dependent species, the Northwest Atlantic harp seal, Pagophilus groenlandicus (2016)
    Oxford University Press
    Details
    Publication Date: 2016-01-23
    Description: As the northern hemisphere continues to warm, declines in sea ice seriously impact species that rely on ice for reproduction and/or feeding. One such species, the Northwest Atlantic harp seal, gives birth on ice and feeds along the southern edge of the seasonal pack ice. Unfortunately, little is known about the impact of climate change on ice-dependent species in sub-Arctic areas, although they are areas of rapid ecosystem change. While climate change has been shown to affect harp seals directly through increased mortality of young, it may also impact indirectly through changes in prey and subsequent reproductive rates. Over the past four decades, harp seals have also undergone a large change in abundance, increasing from 〈1.5 million seals in the early 1970s to ~7.4 million seals today and, since 1987, late-term abortions have been observed. To determine the importance of biological and environmental factors influencing reproduction, pregnancy and abortion rates of harp seals were estimated from samples collected between 1954 and 2014 off Newfoundland, Canada. Since the early 1980s, late-term pregnancy rates among mature females have declined while interannual variability increased, ranging from 0.2 to 0.86. Using a beta-regression model, we found that while the general decline in pregnancy is associated with increased population size, including the rate of late-term abortions captured much of the interannual variability. Changes in abortion rates were described by a model that incorporated capelin biomass and mid-winter ice cover (likely a proxy for ecosystem changes in overall prey abundance). Harp seals appear to respond to relatively small variations in environmental conditions when they are at high population levels. If the observed changes in climate continue, negative impacts on the Northwest Atlantic harp seal population will likely increase due to the predicted warming trend and associated reduction in ice cover.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
    Published by Oxford University Press
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  • 10
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    Error patterns in age estimation of harp seals (Pagophilus groenlandicus): results from a transatlantic, image-based, blind-reading experiment using known-age teeth (2011)
    Oxford University Press
    Details
    Publication Date: 2011-11-24
    Description: Frie, A. K., Fagerheim, K-A., Hammill, M. O., Kapel, F. O., Lockyer, C., Stenson, G. B., Rosing-Asvid, A., and Svetochev, V. 2011. Error patterns in age estimation of harp seals ( Pagophilus groenlandicus ): results from a transatlantic, image-based, blind-reading experiment using known-age teeth. – ICES Journal of Marine Science, 68: 1942–1953. Blind readings of known-age samples are the ultimate quality control method for age estimates based on hard tissues. Unfortunately, this is often not feasible for many species because of the scarcity of known-age samples. Based on a unique collection of known-age teeth of harp seals (age range: 1–18 years), ageing errors were evaluated in relation to true age, reader experience, sex, and tooth format (images vs. originals). Bias was estimated by linear models fitted to deviations from true age, and precision was estimated as their residual standard error. Image-based blind readings of 98 tooth sections by 14 readers, representing different levels of experience, generally showed high accuracy and precision up to a seal age of ~8 years, followed by an increasingly negative bias and increased variance. Separate analyses were therefore conducted for young seals (1–7 years) and older seals. For young seals, moderate associations were found between reader experience and levels of bias, precision, and proportions of correct readings. For older seals, only precision levels showed a significant association with reader experience. Minor effects of sex and tooth format are unlikely to affect these main patterns. Observed errors, even for highly experienced readers, may affect important age-related parameters, emphasizing the importance of known-age calibration of the output from all readers.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
    Published by Oxford University Press
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