Distribution and diving of harbour seals ( Phoca vitulina ) in Svalbard

Gjertz, Ian; Lydersen, Christian; Wiig, Øystein

doi:10.1007/s003000000197

Cited by 34 publications

(34 citation statements)

References 22 publications

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“…In an attempt to get more information on distribution and movements of the harbour seals in Svalbard, 14 animals were equipped with satellite transmitters during 1992-95 (Gjertz et al 2001 …”

Section: Distribution Abundance and Movementsmentioning

confidence: 99%

“…Several studies have been conducted on the harbour seals in Svalbard that shed light on their diving abilities (Gjertz et al 2001, Jørgensen et al 2001. Jørgensen et al (2001) neither development in blood oxygen stores or rates of oxygen consumption is restraining the diving development in these young harbour seal pups.…”

Section: Divingmentioning

confidence: 99%

“…Ten of the previously mentioned 14 satellite transmitters deployed by Gjertz et al (2001) had dive sensors (Wildlife Computers 0.5 W transmitters) and collected dive information from more than 160,000 dives. The 10 animals studied included subadult and adult individuals of both sexes (males: N=6, body mass range 48-103 kg; females: N=4, body mass range 52-92 kg).…”

Section: Divingmentioning

confidence: 99%

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Status and biology of harbour seals (<i>Phoca vitulina</i>) in Svalbard

Lydersen

Kovacs

2010

NAMMCOSP

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Harbour seals in Svalbard are the northernmost population of this species. This small population is comprised of ca. 1,000 individuals, most of which reside along the west coast of Prins Karls Forland (78°20'N). Satellite tracking studies have shown that adults are resident. Birthing occurs in the latter half of June. Newborns weigh about 11 kg and gain an average of 0.7 kg/d during the nursing period. Haulout patterns in Svalbard harbour seals are influenced by date (season), time of day, tidal cycle and temperature. Moulting takes place in early fall, first among juveniles, then in adult females and finally in adult males. Feeding studies show that polar cod (Boreogadus saida) is the dominant prey in terms of numbers, while Atlantic cod (Gadus morhua) is the dominant prey based on biomass, at least during the early autumn. Growth curves display significant sexual dimorphism with asymptotic values for standard length and body mass being greater for males. Testosterone levels in males showed an abrupt increase at 6 years of age, while estradiol levels in females increased abruptly from age 4 years. The reproductive rate for adult females was 0.93. Longevity of Svalbard harbour seals is very short compared with populations from other areas.Lydersen, C. and Kovacs, K. M. 2010. Status and biology of harbour seals (Phoca vitulina) in Svalbard. NAMMCO

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Section: Distribution Abundance and Movementsmentioning

confidence: 99%

Section: Divingmentioning

confidence: 99%

Section: Divingmentioning

confidence: 99%

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Status and biology of harbour seals (<i>Phoca vitulina</i>) in Svalbard

Lydersen

Kovacs

2010

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“…The haul-out behaviour of this population has been studied intensively (Reder et al 2003), and concomittantly with the current stud (see Hamilton et al 2014), but the at-sea behaviour of adult harbor seals re mains largely undocumented. A few animals in this population were tracked through the fall and early winter period via satellite tag deployments in the early 1990s (Gjertz et al 2001) and 3 time-depth recorders (TDRs) were deployed for some weeks in the autumn of 1994 (Krafft et al 2002). However, upto-date distributional information about areas occupied by this population in a broader seasonal perspective is not available.…”

Section: Introductionmentioning

confidence: 99%

Harbour seal Phoca vitulina movement patterns in the high-Arctic archipelago of Svalbard, Norway

Blanchet¹,

Lydersen²,

Ims³

et al. 2014

Aquat. Biol.

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Harbour seals Phoca vitulina are mainly considered a temperate species, but the world's northernmost population resides year-round in the high-Arctic archipelago of Svalbard. In this study we document post-moulting at-sea movements of 30 individuals from this population using satellite relay data loggers deployed in the autumns of 2009 and 2010. All of the seals showed a strong preference for the west side of the archipelago, staying mainly in coastal areas (< 50 km over the continental shelf), but seldom entering the fjord systems. Distance swam per day, individual home range size, and trip duration increased throughout the winter to a peak that was reached when drifting sea ice in the region was at a maximum. No effect of age was observed, but sex differences were significant; males occupied larger areas than females. Habitat selection was quantified by modelling time spent in area (TSA) as a function of environmental parameters using Cox proportional hazard models (CPH). The harbour seals avoided heavy ice concentrations (> 50%) but did occupy areas with substantial amounts of drifting ice (5 to 25%). Shallow water (<100 m) and steep bathymetric slopes were preferred to deep water or flat-bottom areas. Harbour seal distribution in Svalbard is largely restricted to coastal areas that are heavily influenced by Atlantic water brought northward in the West Spitsbergen Current; both the temperature and influx of this water type are predicted to increase in the future. It is thus likely that environmental conditions in Svalbard in the future will become more favourable for harbour seals.

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“…The west coast of Svalbard is one of the northernmost areas in the Atlantic to be affected by the warm Norwegian Atlantic Current (''the Gulf Stream''); this area does not experience ice-cover outside the inner parts of the fjords during winter. A satellite tracking study of harbour seals on Svalbard showed that adult animals were more or less resident throughout the year in the immediate area of Prins Karls Forland (Gjertz et al 2001). No recent data are available on population size, but surveys during the 1980s concluded that the population consisted of at least 500-600 animals (Prestrud and Gjertz 1990).…”

Section: Introductionmentioning

confidence: 99%

Growth and population parameters of the world?s northernmost harbour seals Phoca vitulina residing in Svalbard, Norway

Lydersen

Kovacs

2004

Polar Biol

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The harbour seals (Phoca vitulina) in Svalbard are the northernmost population of this species. The population size is thought to be less than 1,000 individuals; these animals reside principally within a national park on Prins Karls Forland on the west coast of Spitsbergen, Svalbard, at about 78°20¢N. The material presented in this study was collected from 367 livecaptured animals, aged based on growth layers read from stained, decalcified incisor sections (except for pups of the year). Standard length (F 1,246 =45.70, P<0.0001) and body mass (F 1,258 =25.28; P<0.0001) were both significantly influenced by sex when age was taken into account. Adult males are both longer [152.9±4.8 (SE) vs 140.1±2.0 cm, standard length] and heavier (104.0±5.0 vs 83.2±2.7 kg, body mass) than adult females in this population. Age at sexual maturity was assessed based on analyses of sex hormones. Testosterone levels in males showed an abrupt increase at 6 years of age, while estradiol levels in females increased from age 4. The reproductive rate of adult females was 0.93. The longevity of Svalbard harbour seals was short compared to harbour-seal populations from other areas. However, these seals are not exposed to terrestrial predation; there is no known mortality due to fisheries or hunting and their pollution burdens are low. Extreme seasonality and perhaps other harsh environmental conditions at the northern edge of this species' distribution may exert long-term low levels of stress that result in short life span, or there are currently unknown acute sources of mortality in this population. To our knowledge, this is the first study of population parameters on a pinniped species using cross-sectional, nonterminal sampling.

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Distribution and diving of harbour seals ( Phoca vitulina ) in Svalbard

Cited by 34 publications

References 22 publications

Status and biology of harbour seals (<i>Phoca vitulina</i>) in Svalbard

Status and biology of harbour seals (<i>Phoca vitulina</i>) in Svalbard

Harbour seal Phoca vitulina movement patterns in the high-Arctic archipelago of Svalbard, Norway

Growth and population parameters of the world?s northernmost harbour seals Phoca vitulina residing in Svalbard, Norway

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