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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Animal Behaviour 48 (1994), S. 1417-1425 
    ISSN: 0003-3472
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Animal Behaviour 46 (1993), S. 1213-1221 
    ISSN: 0003-3472
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The aim of this study was to describe growth, determine age at sexual maturity and investigate the condition of bearded seals (Erignathus barbatus) collected in the fjords of Spitsbergen, Svalbard, Norway. Morphometric data, teeth and sex organs were collected from 110 animals. Age was determined by reading the cementum layers in hard longitudinal sections of canine teeth. Sexual maturity in males was determined according to the size of the testes and bacula. Females were defined as being sexually mature according to findings of mature follicles or corpora lutea/albicantia. Von Bertalanffy growth curves were applied to both standard length and body mass, and asymptotic values for males and females were 231.1 ± 11.4 cm and 269.9 ± 26.2 kg, and 233.1 ± 7.5 cm and 275.3 ± 47.8 kg, respectively. Maximum recorded lengths and masses were 254 cm and 313 kg in males and 242 cm and 358 kg in females. All males older than 6 years were found to have been sexually mature. Females were found to attain sexual maturity at about 90% of the asymptotic length, corresponding to an age of 5 years. In males a significant decrease in condition was observed from June to August, with a subsequent increase in September. In adult females, condition decreased from May to June and increased again from June to September. The conditional changes seen are likely to be due to the extra energetic cost and reduced food intake associated with reproduction, lactation and molt.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Eleven bearded seals (Erignathus barbatus) were tagged with satellite-linked dive recorders in Kongsfjorden, Svalbard, Norway, in May 1994. These animals included four mother-pup pairs and three single pups. The seals were tracked for 21–258 days. A total of ˜207,000 dives were recorded. Bearded seal mothers showed limited movements during the nursing and moulting periods. After weaning, the pups moved out of the tagging area and dispersed coastally. One pup left Svalbard and moved far offshore to Greenland and Jan Mayen. Bearded seal adults displayed a bi-modal dive behaviour, with peaks of activity that were shallower than 10 m or from 50 to 70 m. Most dives for adult seals (97%) were shorter than 10 min. Young pups performed dives that were shallower and shorter in duration than their accompanying mothers, but diving skills improved rapidly with age. Six of the seven pups dived deeper than 448 m by the time they were 2 months old. Analyses of movement data with respect to separation of mother-pup pairs suggest a lactation period of about 24 days.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Polar biology 23 (2000), S. 651-656 
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seven post-moulting adult ringed seals (Phoca hispida) were equipped with Satellite Linked Dive Recorders in Svalbard in July 1996 to determine if ringed seals conduct long-distance post-moulting feeding excursions, and to obtain details of their diving behaviour. The mean duration of tags was 206 days (range 103–325). Two seals swam 400 km north to the drifting pack ice (82°N). The rest undertook more local movements. Forty-eight percent of all dives were shallower than 20 m and 90% were shallower than 100 m. Ninety-five percent of all dive durations were shorter than 10 min, and 99.5% were shorter than 15 min. This study has shown that adult ringed seals undertake varying patterns of post-moulting excursions.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The objective of the present study was to assess the feeding habits of bearded seals (Erignathus barbatus) from the Svalbard area, Norway. Stomach and/or intestine contents were collected from 47 individuals shot between May and September (1989–1996). Prey specimens were identified from whole specimens or hard items such as fish otoliths, crustacean exoskeletons, cephalopod beaks, polychaete jaws, gastropod operculae and mollusc shell remains. To show the dietary contribution of the different prey items found in the gastrointestinal tracts, the frequency of occurrence and the numerical frequency methods were used. Fifty-nine percent or more of the gastrointestinal tracts contained five or more prey organisms. The most frequent fish species recorded was polar cod (Boreogadus saida), which was found in 49% of the gastrointestinal tracts, followed by sculpins (Cottidae spp.) (44%), long rough dab (Hippoglossoides platessoides) (28%) and the stout eelblenny (Lumpenus medius) (18%). The most frequent crustaceans were the spider crab (Hyas araneus) (59%), Sabinea septemcarinatus (54%), Sclerocrangon boreas (46%) and Lebbeus polaris (18%). Of the molluscs, the whelk Buccinum spp. occurred in 18% of the gastrointestinal tracts. Other species such as cephalopods, polychaete worms, amphipods and echiuran worms occurred in small amounts. There were no significant differences in foraging behaviour between males and females. This study also shows that in the Svalbard area bearded seals are benthic feeders and utilise a wide variety of organisms.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Polar biology 14 (1994), S. 569-570 
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-136X
    Keywords: Key words Energetics  ;  Lactation  ;  Maternal investment  ;  Doubly labelled water  ;  Hooded seals ; Cystophora cristata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In this study we measured growth and milk intake and calculated energy intake and its allocation into metabolism and stored tissue for hooded seal (Cystophora cristata) pups. In addition, we measured mass loss, change in body composition and metabolic rate during the first days of the postweaning fast. The mean body mass of the hooded seal pups (n = 5) at the start of the experiments, when they were new-born, was 24.3 ± 1.3 kg (SD). They gained an average of 5.9 ± 1.1. kg · day−1 of which 19% was water, 76% fat and 5% protein. This corresponds to an average daily energy deposition of 179.8 ± 16.0 MJ. The pups were weaned at an average body mass of 42.5 ± 1.0 kg 3.1 days after the experiment was initiated. During the first days of the postweaning fast the pups lost an average of 1.3 ± 0.5␣kg of body mass daily, of which 56% was water, 16% fat and 28% protein. During the nursing period the average daily water influx for the pups was 124.6 ± 25.8 ml · kg−1. The average CO2 production during this period was 1.10 ± 0.20 ml · g−1 · h−1, which corresponds to a field metabolic rate of 714 ± 130 kJ ·  kg−1 · day−1, or 5.8 ± 1.1 times the predicted basal metabolic rate according to Kleiber (1975). During the postweaning fast the average daily water influx was reduced to 16.1 ± 6.6 ml · kg−1. The average CO2 production in␣this period was 0.58 ± 0.17 ml · g−1 · h−1 which corresponds to a field metabolic rate of 375 ± 108 kJ · kg−1 · day−1 or 3.2 ± 0.9 times the predicted basal metabolic rate. Average values for milk composition were 33.5% water, 58.6% fat and 6.2% protein. The pups drank an average of 10.4 ± 1.8␣kg of milk daily, which represents an energy intake of 248.9 ± 39.1 MJ · day−1. The pups were able to store 73.2 ± 7.7% of this energy as body tissue.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 170 (2000), S. 277-283 
    ISSN: 1432-136X
    Keywords: Key words Grey seals ; Mother-pup pairs ; Multivariate statistics ; Fatty acid composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Fatty acids were determined by gas chromatography followed by principal component analysis (PCA) and soft independent modelling of class analogy (SIMCA) in the blubber of 18 female grey seals, Halichoerus grypus, in their milk and in the blubber of their 1-week-old nursing pups. Large individual differences were observed in both blubber and milk content of fatty acids. The fatty acid composition of the milk was systematically different from the composition in maternal blubber, with higher relative amounts of the saturated acids, the monounsaturated with 20 carbon atoms and the n3 polyunsaturated, except 18:3n3. The composition of the fatty acids in the blubber of the pups was different from that of the milk. The same fatty acids that were enriched in the milk were depleted in the blubber of the pups. Therefore the fatty acid composition in the blubber of the pups was similar to that in the adults, although not identical. The results from this investigation imply that the composition of the fatty acids in the blubber of female seals and in the blubber of their pups cannot be determined directly by analysis of fatty acid composition of milk.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 166 (1996), S. 295-304 
    ISSN: 1432-136X
    Keywords: Key words Energetics ; Lactation ; Maternal investment ; Behaviour ; Harp seals ; Phoca groenlandica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  This study reports the findings of an integrated, comprehensive analysis of lactation energetics in harp seals conducted using longitudinal measurements of mass, body composition and milk composition from mother-pup pairs in conjunction with water flux measurements in pups. The nursing period of harp seals is a short, intense and relatively efficient period of energy transfer from mothers to pups. The average daily milk intake for pups was 3.65±0.24 kg which is equivalent to 79.5 MJ of energy. Eighty-one per cent of the energy received in the milk was metabolisable and 66% of the energy was stored by the pups as body tissue. The field metabolic rate of pups was 3.9±0.4 time basal metabolic rate. The pups were growing at a rate of 2.2 kg per day during the nursing period. The distribution of this mass gain varied in terms of tissue composition, depending on the age of the pups, but over the whole nursing period approximately half of the tissue was stored as fat. Harp seal mothers lost an average of 3.1 kg per day during lactation which was composed of 37% water, 50% fat, 11% protein and 2% ash. Mothers spent half of their time during the lactation period actively diving and only one-third of their time on the surface of the ice. Milk compositional changes followed the normal phocid pattern with increasing fat content and decreasing water content as lactation progressed. The mean mass transfer efficiency was 73%. However, this value cannot be used without qualification because female harp seals in this study fed to varying degrees, consuming an estimated 0–4.8 kg of fish per day. Feeding does not appear to be required in order to achieve the energy requirements for lactation, given the energy stores possessed by females, and some females do fast through the entire period so feeding may be considered opportunistic in nature.
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