scholarly journals Exploitation of ringed seals (Phoca hispida) in Greenland

1998 ◽  
Vol 1 ◽  
pp. 130 ◽  
Author(s):  
Jonas Teilmann ◽  
Finn O Kapel
Keyword(s):  
Great Majority ◽  
Open Water ◽  
Ringed Seal ◽  
Phoca Hispida ◽  
Age Classes ◽  
Ringed Seals ◽  
Original Culture ◽  
Term Variation ◽  
Northern Regions

The ringed seal (Phoca hispida) is the most important game for the Inuit hunters of Greenland, providing many of the basic needs in the original culture. It is distributed all around Greenland with the main distribution north of 69°N on the west coast and north of 66°N on the east coast. During 1974-76, studies were conducted in the most important ringed seal catching area, Upernavik, Northwest Greenland, and a total of 7,089 ringed seals were sampled. The methods used for catching ringed seals were categorised into five different groups. The most common hunting method used in the municipality of Upernavik during 1974-76 was netting under the ice, accounting for almost half of the total annual catch. Seals shot on the ice and seals shot at the ice edge accounted for one fifth and one tenth of the annual catch, respectively. In this region seals shot in open water made up about one fifth of the annual catch of ringed seals, while netting in open water contributed only a few percent.Of the seals sampled in Upernavik in 1974-76, 60% were males and 40% were females. In the ringed seal samples collected all around Greenland in the 1980s and 1990s the males comprised 56% and the females 44% (n=923). Similar ratios were found for all age classes and for all hunting methods suggesting either a skewed sex ratio in the ringed seal stock(s) around Greenland or a differencein availability to the hunters of male and female ringed seals. In tagging experiments a higher mobility was found for females than for males, which suggests differences in the behaviour of the two sexes.Catch and trade statistics on ringed seals are reviewed and evaluated for the period of 1954 until 1994, and the seasonal and regional variation is examined. The peak season for ringed seal hunting in Greenland as a whole is from January through May. This is particularly evident for the northern regions, where relatively few ringed seals are taken during the open water season from June to September. In the southern regions, however, the great majority of ringed seals are caught in openwater.In all regions, the catch of ringed seals showed great annual and long-term variation. The variations were not identical in all regions, but similar trends were found for Northwest and Central West, and for Southwest and South. From 1954 to 1994 there was a general, significant increase in the reported catches of ringed seals in west Greenland. For Greenland overall, the catch of ringed seals wasaround 43,000 per year in the 1950s, peaked in the late 1970s at almost 100,000 per year, but since decreased to about 70,000 in the early 1990s.

scholarly journals The numbers of ringed seals (Phoca hispida) in Baffin Bay and associated waters

1998 ◽  
Vol 1 ◽  
pp. 181 ◽  
Author(s):  
Michael C S Kingsley
Keyword(s):  
Polar Bear ◽  
Approximate Model ◽  
Ringed Seal ◽  
Phoca Hispida ◽  
Age Classes ◽  
Field Metabolic Rate ◽  
Baffin Bay ◽  
Ringed Seals ◽  
Pack Ice ◽  
Seal Population

The size of the population of ringed seals (Phoca hispida) inhabiting Baffin Bay and associated waters was estimated by two methods. An approximate model of the energetics of the polar bear (Ursus maritimus) estimated an energetic need of about 16,000 MJ/bear per year. Modelled estimates of the energetic yield of a ringed seal population showed that a stable standing population of 140-170 ringed seals per bear would be needed to provide that much energy, assuming that all mortalities were due to polar bear predation. This result was sensitive to assumptions about the Field Metabolic Rate (FMR) of the bears and the energetic yield of individual ringed seals, but less sensitive to assumptions about relative incidence of predation on different age classes of seal or the age structure of the polar bear population. Estimated sizes of polar bear populations in Baffin Bay and associated waters (total about 4,025), and of the standing population needed to support an estimated hunter kill of 100,000 yielded a population estimate of, very roughly, 1.2 million ringed seals. Estimates of ice areas and of the density of hauled out seals from aerial surveys were used to generate another approximate figure for the ringed seal population, which was about the same. The density of seals in the pack-ice area of Baffin Bay, which is imperfectly known, has a large influence on the latter estimate.

Population parameters of ringed seals (Phoca hispida Schreber, 1775) in the Svalbard area

1987 ◽  
Vol 65 (4) ◽  
pp. 1021-1027 ◽  
Author(s):  
Christian Lydersen ◽  
Ian Gjertz
Keyword(s):  
Sex Ratio ◽  
Ringed Seal ◽  
Adult Males ◽  
Population Parameters ◽  
Phoca Hispida ◽  
Age Class ◽  
Ringed Seals ◽  
Males And Females ◽  
The Mean ◽  
Sexually Mature

Samples were taken from 284 ringed seals (Phoca hispida) in the Svalbard area during April–July 1981 and March–April 1982. The age of 283 seals was determined by reading annuli in the cementum of the canine teeth. The mean age of the males was 11.3 years, and of the females, 14.9 years. Females were found to be significantly older than males. The mean length of sexually mature ringed seals was 128.9 cm for both sexes. The mean weight of adult males and females was 53.5 and 61.4 kg, respectively. Females were found to be significantly heavier than males. The sex ratio was 47.8% males and 52.2% females. Studies of microscopic sections of testis and epididymis from ringed seal males showed that 63, 75, and 80% of 5-, 6-, and 7-year-old animals, respectively, were sexually mature. The weights of testis and epididymis, diameters of tubuli, and the size of testis all showed a marked increase in the 5-year age-class. Macroscopic sections of ovaries from ringed seal females showed that 20, 60, and 80% of 3-, 4-, and 5-year-old animals, respectively, were sexually mature. The size of the ovaries showed a marked increase in the 5-year age-class. The ovulation rate of ringed seals from Svalbard was calculated to be 0.91.

Characteristics of ringed seal, Phoca hispida, subnivean structures and breeding habitat and their effects on predation

1996 ◽  
Vol 74 (5) ◽  
pp. 858-874 ◽  
Author(s):  
C. M. Furgal ◽  
K. M. Kovacs ◽  
S. Innes
Keyword(s):  
Snow Depth ◽  
Function Analysis ◽  
Ringed Seal ◽  
Breeding Habitat ◽  
Phoca Hispida ◽  
Ringed Seals ◽  
Arctic Foxes ◽  
Ridge Height ◽  
Length Width ◽  
Fast Ice

Characteristics of ringed seal (Phoca hispida) subnivean structures and breeding habitat were quantified and their potential influence on predation success by polar bears (Ursus maritimus), arctic foxes (Alopex lagopus), and humans on ringed seals was investigated in Admiralty Inlet and Strathcona Sound, Northwest Territories. A total of 237 ringed seal structures were located between April and June 1991–1993 using trained dogs. Ringed seal lairs and breathing holes were concentrated in areas of deep snow, and were associated with large, thick ice ridges. Only a small percentage of the available fast-ice habitat had sufficient snow depth for lair construction each year. A discriminant function analysis used to classify structures located in 1992, using a combination of structural and habitat measurements, correctly classified 70% of structures located in 1991 and 1993 into functional groups. The length, width, internal height, and level of "tiggak," the odour of rutting male ringed seals, associated with structures were the most important descriptors separating structure types. Seventy-three percent of structures located in the study were undisturbed by predators. The mean length and width of structures entered by predators were significantly greater than those of undisturbed structures. Polar bear success decreased as snow depth and the thickness of the roof covering the structures increased. The conditions necessary for successful arctic fox predation are unclear. Inuit hunters attacked structures close to ice ridges, and ridge height and snow depth influenced their success. All predators attacked lairs having the odour of rutting male ringed seals less often than structures with no male odour.

Lactation in the Ringed Seal (Phoca hispida)

1991 ◽  
Vol 48 (12) ◽  
pp. 2471-2476 ◽  
Author(s):  
M. O. Hammill ◽  
C. Lydersen ◽  
M. Ryg ◽  
T. G. Smith
Keyword(s):  
Growth Rate ◽  
Weight Loss ◽  
Ringed Seal ◽  
Energy Reserves ◽  
Stored Energy ◽  
Phoca Hispida ◽  
Cross Sectional ◽  
Ringed Seals ◽  
Pup Growth ◽  
Female Weight

Length of lactation, pup growth rate, and female weight loss in ringed seals (Phoca hispida) were estimated using cross-sectional data from the Canadian and Norwegian Arctic. At birth the pups had a standard length of 63.4 cm (SE = 1.3, N = 11) and weighed 5.4 kg (SE = 0.4, N = 6). Weaning occurred approximately 39 d (range 36–41 d) after birth at an estimated length of 88.4 cm (SE = 0.65, N = 96) and an estimated weight of 22.1 kg, resulting in an increase in length of 0.64 cm∙d−1 and a weight change of 0.43 kg∙d−1. Regression of female weight on the number of days after the nominal date of birth for each region indicated that the postpartum female weighed 81.2 kg and lost 0.64 kg∙d−1 (95% CI = ±0.20). During lactation, female weight declined by an estimated 32%, with much of the loss occurring from the blubber. Analyses of stomachs indicated that ringed seals supplemented stored energy reserves by feeding during lactation.

Three-dimensional movements within individual dives by ringed seals (Phoca hispida)

2001 ◽  
Vol 79 (8) ◽  
pp. 1455-1464 ◽  
Author(s):  
Michael A Simpkins ◽  
Brendan P Kelly ◽  
Douglas Wartzok
Keyword(s):  
Travel Behavior ◽  
Three Dimensional ◽  
Ringed Seal ◽  
Travel Times ◽  
Phoca Hispida ◽  
Normal Distributions ◽  
Ringed Seals ◽  
Continuous Movement

We analyzed the three-dimensional movements within individual dives of five freely swimming ringed seals (Phoca hispida). We divided dives into a series of moves, each of which represented continuous movement in one direction, and evaluated several three-dimensional movement variables to distinguish between types of movement within dives. Horizontal directionality proved to be the most useful variable, and we distinguished convoluted and directional movements by fitting a mixture of two normal distributions to the observed horizontal-directionality values. Both convoluted and directional movements occurred within each phase of most dives, suggesting that ringed seals switched between behavioral modes within dive phases. Descent and ascent phases were not simply travel behavior, nor were bottom phases equivalent to patch time, complicating the formulation of optimal diving models for ringed seals. Most ringed seal dives appeared to consist of a series of patch times separated by travel times. Travel behavior accounted for the majority of dive times.

Uptake and Clearance of Petroleum Hydrocarbons in the Ringed Seal, Phoca hispida

1977 ◽  
Vol 34 (8) ◽  
pp. 1143-1147 ◽  
Author(s):  
F. Rainer Engelhardt ◽  
Joseph R. Geraci ◽  
Thomas G. Smith
Keyword(s):  
Crude Oil ◽  
Key Words ◽  
Plasma Levels ◽  
Petroleum Hydrocarbons ◽  
Ringed Seal ◽  
Phoca Hispida ◽  
Ringed Seals ◽  
Rapid Absorption ◽  
Body Tissues

Ringed seals, Phoca hispida, showed rapid absorption of hydrocarbons from Norman Wells crude oil into body tissues and fluids when exposed by both immersion and ingestion. Relatively low but significant levels were found in tissue, blood, and plasma. Levels in bile and urine were high, indicating these to be routes of excretion. Key words: petroleum, hydrocarbons, benzene, ringed seal, immersion, ingestion, uptake, clearance

scholarly journals The ringed seal (Phoca hispida) in the western Russian Arctic

1998 ◽  
Vol 1 ◽  
pp. 63 ◽  
Author(s):  
Stanislav E Belikov ◽  
Andrei N Boltunov
Keyword(s):  
Barents Sea ◽  
White Sea ◽  
Ringed Seal ◽  
Kara Sea ◽  
Russian Arctic ◽  
The White Sea ◽  
Phoca Hispida ◽  
Ringed Seals ◽  
The Barents Sea ◽  
Fast Ice

This paper presents a review of available published and unpublished material on the ringed seal (Phoca hispida) in the western part of the Russian Arctic, including the White, Barents and Kara seas. The purpose of the review is to discuss the status of ringed seal stocks in relation to their primary habitat, the history of sealing, and a recent harvest of the species in the region. The known primary breeding habitats for this species are in the White Sea, the south-western part of the Barents Sea, and in the coastal waters of the Kara Sea, which are seasonally covered by shore-fast ice. The main sealing sites are situated in the same areas. Female ringed seals become mature by the age of 6, and males by the age of 7. In March-April a female gives birth to one pup in a breeding lair constructed in the shore-fast ice. The most important prey species for ringed seals in the western sector of the Russian Arctic are pelagic fish and crustaceans. The maximum annual sealing level for the region was registered in the first 70 years of the 20th century: the White Sea maximum (8,912 animals) was registered in 1912; the Barents Sea maximum (13,517 animals) was registered in 1962; the Kara Sea maximum (13,200 animals) was registered in 1933. Since the 1970s, the number of seals harvested has decreased considerably. There are no data available for the number of seals harvested annually by local residents for their subsistence.

Temporal variation in reproduction and body mass of polar bears in western Hudson Bay

1995 ◽  
Vol 73 (9) ◽  
pp. 1657-1665 ◽  
Author(s):  
Andrew E. Derocher ◽  
Ian Stirling
Keyword(s):  
Body Mass ◽  
Litter Production ◽  
Hudson Bay ◽  
Polar Bears ◽  
Age Classes ◽  
Study Recruitment ◽  
Term Variation ◽  
Long Term Trends ◽  
Western Hudson Bay

We studied annual and long-term variation in rates of reproduction in female polar bears (Ursus maritimus) in western Hudson Bay from 1966 to 1992. In addition, long-term trends in body mass were examined from 3146 captured polar bears. Reproduction rates declined in the late 1980s from higher levels in 1966–1984. Litter production decreased from 0.48 to 0.34 litters per female each year over the study. Recruitment to autumn declined from 0.75 to 0.52 cubs per female each year, in part because of cub mortality between spring and autumn, which increased from 25.0% in 1980–1984 to 50.9% in 1987–1992. Spring and autumn litter sizes of females with cubs did not vary annually, but litter sizes of females with yearlings varied between years. The proportion of yearlings independent of their mother in autumn dropped from 81% prior to 1980 to 34% in 1980–1992. After 1986, offspring remained with their mothers longer, resulting in the birth interval increasing from 2.1 to 2.9 years. Body mass of most age-classes of females and males declined in the 1980s. Unlike earlier studies that found reproduction rates to be higher in western Hudson Bay than in higher latitude populations, reproduction rates in 1986–1992 in western Hudson Bay were similar to those of other populations. Insufficient information was available to determine the cause of declines in reproduction and body mass.

Oxygen stores and aerobic dive limit of ringed seals (Phoca hispida)

1992 ◽  
Vol 70 (3) ◽  
pp. 458-461 ◽  
Author(s):  
Christian Lydersen ◽  
Morten Skrede Ryg ◽  
Mike Osborne Hammill ◽  
Peter James O'Brien
Keyword(s):  
Ringed Seal ◽  
Composition Analysis ◽  
Phoca Hispida ◽  
Free Living ◽  
Weddell Seals ◽  
Lung Capacity ◽  
Ringed Seals ◽  
Aerobic Dive Limit ◽  
Oxygen Stores ◽  
Average Adult

In this paper we measured total lung capacity, myoglobin content of muscle tissue, and hemoglobin content of the blood of ringed seals (Phoca hispida). Based on this information and body composition analysis we estimated the total available oxygen stores of a diving average adult ringed seal (standard length 129 cm, body mass 73.7 kg) to be 4.5 L. The aerobic dive limit for a ringed seal of this size was estimated to be 8.9 min. Diving data from previous studies show that less than 4% of the dives of adult free-living ringed seals exceed this aerobic dive limit. Based on information from the literature on maximum breathhold capacity and observed maximum dive times of ringed and Weddell seals (Leptonychotes weddellii), the maximum breathhold capacity of adult ringed seals was suggested to be 26.1 min.

scholarly journals Distribution, abundance and biology of ringed seals (Phoca hispida): an overview

1998 ◽  
Vol 1 ◽  
pp. 9 ◽  
Author(s):  
Randall R Reeves
Keyword(s):  
Polar Bear ◽  
Late Summer ◽  
Early Summer ◽  
Ringed Seal ◽  
Late Spring ◽  
Late Winter ◽  
Polar Cod ◽  
World Population ◽  
Phoca Hispida ◽  
Ringed Seals

The ringed seal (Phoca hispida) has a circumpolar Arctic distribution. Because of its great importance to northern communities and its role as the primary food of polar bears (Ursus maritimus) the ringed seal has been studied extensively in Canada, Alaska, Russia, Svalbard and Greenland as well as in the Baltic Sea and Karelian lakes. No clear-cut boundaries are known to separate ringed seal stocks in marine waters. Adult seals are thought to be relatively sedentary, but sub-adults sometimes disperse over long distances. Stable ice with good snow cover is considered the most productive habitat although production in pack ice has been little studied. Populations appear to be structured so that immature animals and young adults are consigned to sub-optimal habitat during the spring pupping and breeding season. Annual production in ringed seal populations, defined as thepup percentage in the total population after the late winter pupping season, is probably in the order of 18-24%. Most estimates of maximum sustainable yield are in the order of 7%.The world population of ringed seals is at least a few million. Methods of abundance estimation have included aerial surveys, dog searches and remote sensing of lairs and breathing holes, acoustic monitoring, correlation analysis by reference to sizes of polar bear populations, and inference from estimated energy requirements of bear populations. Aerial strip survey has been the method of choice for estimating seal densities over large areas. Adjustment factors to account for seals not hauled out at the time of the survey, for seals that dove ahead of the aircraft, and for seals on the ice within the surveyed strip but not detected by the observers, are required for estimates of absolute abundance.Male and female ringed seals are sexually mature by 5-7 years of age (earlier at Svalbard). Pupping usually occurs in March or early April and is followed by 5-7 weeks of lactation. Breeding takes place in mid to late May, and implantation is delayed for about 3 months. In at least some parts of their range, ringed seals feed mainly on schooling gadids from late autumn through early spring andon benthic crustaceans and polar cod (Boreogadus saida) from late spring through summer. Little feeding is done during the moult, which takes place in late spring and early summer. Pelagic crustaceans offshore and mysids inshore become important prey in late summer and early autumn in some areas. Ringed seals have several natural predators, the most important of which is the polar bear in most arctic regions. Arctic foxes (Alopex lagopus) kill a large percentage of pups in someareas.From a conservation perspective, the ringed seal appears to be secure. Levels of exploitation of arctic populations have usually been considered sustainable, except in the Okhotsk Sea. Large fluctuations in production of ringed seals in the Beaufort Sea and Amundsen Gulf are thought to be driven by natural variability in environmental conditions. While concern has been expressed about thepotential impacts of industrial activity and pollution on ringed seals, such impacts have been documented only in limited areas. Because of their ubiquitous occurrence and availability for sampling, ringed seals are good subjects for monitoring contaminant trends in Arctic marine food chains. 

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