Variability in the Diet of Ringed Seals, Phoca hispida, in Alaska

1980 ◽  
Vol 37 (12) ◽  
pp. 2254-2261 ◽  
Author(s):  
Lloyd F. Lowry ◽  
Kathryn J. Frost ◽  
John J. Burns
Keyword(s):  
Stomach Contents ◽  
Late Summer ◽  
Beaufort Sea ◽  
Boundary Region ◽  
Early Summer ◽  
Phoca Hispida ◽  
Arctic Cod ◽  
Ringed Seals ◽  
Saffron Cod ◽  
Crangon Septemspinosa

Analysis of stomach contents of ringed seals (Phoca hispida) collected at eight locations along the Alaskan coast showed significant seasonal and regional differences in diet. During the spring–summer period saffron cod (Eleginus gracilis) was the most important food item in the nearshore zone of the northeastern Bering and southeastern Chukchi Seas. In that period shrimps (Pandalus spp., Eualus spp., Lebbeus polaris, and Crangon septemspinosa) were the major food in the northcentral Bering Sea, hyperiid amphipods (Parathemisto libellula) in the central Beaufort Sea and euphausiids (Thysanoessa spp.) in the boundary region (Barrow area) between the Chukchi and Beaufort seas. During late summer–early autumn hyperiid amphipods were important foods in the central Beaufort and the southeastern Chukchi. The autumn diet of seals in Norton Sound included mainly saffron cod During winter–early spring Arctic cod (Boreogadus saida) predominated the diet at all localities. During spring and early summer in the northeastern Bering and southeastern Chukchi seas the amount of saffron cod consumed was directly correlated with age. In the Beaufort Sea during autumn and winter Arctic cod were eaten in similar amounts by all age-classes. An analysis of the energy value and quantities of prey consumed indicates that prey species that occur in concentrations (Arctic and saffron cods, hyperiid amphipods, euphausiids and some shrimps) are of particular importance in the annual nutrition of ringed seals. These seals may be food limited in areas and during times when these kinds of prey are not available.Key words: food habits, Phoca hispida, ringed seals, Arctic cod, saffron cod, crustaceans, Alaska

Distribution of ringed seals in the southeastern Beaufort Sea during late summer

1992 ◽  
Vol 70 (5) ◽  
pp. 891-900 ◽  
Author(s):  
Lois A. Harwood ◽  
Ian Stirling
Keyword(s):  
Relative Abundance ◽  
Late Summer ◽  
Beaufort Sea ◽  
General Area ◽  
Phoca Hispida ◽  
Sea State ◽  
Ringed Seals ◽  
Aerial Surveys ◽  
Early Fall

The distribution and relative abundance of ringed seals (Phoca hispida) in the southeastern Beaufort Sea were examined through systematic aerial surveys in August–September of 1982 and 1984–1986. All data analyzed were collected by the same observer when sea state was ≤ 2 on the Beaufort Scale and when there was no forward glare. In late summer and early fall of 1982, 1984, and 1986, ringed seals occurred singly and in groups, to an observed maximum of 21 seals. Groups of seals were clumped into large areas of aggregation which appeared to persist for several weeks. Densities in aggregation areas ranged from 121 to 326 seals/100 km2, approximately 6–13 times greater than regional mean densities. The geographic extent of aggregation areas (350–2800 km2) and the numbers (1 in 1984, 2 in 1982, 3 in 1986) and locations of aggregations varied among years. Ringed seals tended to aggregate most frequently and in greatest numbers in waters north of the Tuktoyaktuk Peninsula, in the general area where the Cape Bathurst polynya occurs in winter. The relative abundance of ringed seals varied among the years of the study, reaching a maximum in 1982 (42.20 seals/100 km2), declining through 1984 (14.73/100 km2) and 1985 (7.92/100 km2), and increasing again in 1986 (19.35/100 km2).

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. 

Ecological Studies of Arctic Cod (Boreogadus saida) in Beaufort Sea Coastal Waters, Alaska

1982 ◽  
Vol 39 (3) ◽  
pp. 395-406 ◽  
Author(s):  
P. C. Craig ◽  
W. B. Griffiths ◽  
L. Haldorson ◽  
H. McElderry
Keyword(s):  
Life History ◽  
Coastal Waters ◽  
Life History Strategy ◽  
Late Summer ◽  
Beaufort Sea ◽  
Shallow Waters ◽  
Boreogadus Saida ◽  
Arctic Cod ◽  
Arctic Fish ◽  
Slow Growing

Fish use of Beaufort Sea coastal waters was examined during summer and winter periods 1977–80. Arctic cod (Boreogadus saida) were abundant but their occurrence was highly variable. They accounted for 8–78% of all fish caught in Simpson Lagoon during two summers, and 0.4–100% of catches at various coastal sites in winter. Arctic cod increased in abundance in the lagoon during late summer and some association was noted between their numbers and higher salinities but not temperature or turbidity. Some cod remained in shallow waters in early winter but deeper areas were used through the winter, and the highest catch rate was recorded 175 km offshore. Principal foods of the cod in nearshore waters were mysids (Mysis litoralis, M. relicta), amphipods (Onisimus glacialis), and copepods. The cod caught were generally small (60–170 mm) and young (ages 1–3). Most males matured at ages 2–3 and females at age 3. These size, age, and maturity characteristics indicate a life history strategy (r-selection) unlike that typified by many other arctic fish populations, particularly the freshwater and anadromous species which tend to be slow growing, late maturing and long-lived (K-selection).Key words: Arctic cod, Boreogadus saida; Beaufort Sea, distribution, life history strategy

Factors Affecting the Observed Densities of Ringed Seals, Phoca hispida, in the Alaskan Beaufort Sea, 1996-99

ARCTIC ◽  
2004 ◽  
Vol 57 (2) ◽  
Author(s):  
Kathryn J. Frost ◽  
Lloyd F. Lowry ◽  
Grey Pendleton ◽  
Helen R. Nute
Keyword(s):  
Beaufort Sea ◽  
Phoca Hispida ◽  
Factors Affecting ◽  
Ringed Seals

Factors influencing local abundance and haulout behaviour of ringed seals (Phoca hispida) on landfast ice of the Alaskan Beaufort Sea

2002 ◽  
Vol 80 (11) ◽  
pp. 1900-1917 ◽  
Author(s):  
Valerie D Moulton ◽  
W John Richardson ◽  
Trent L McDonald ◽  
Robert E Elliott ◽  
Michael T Williams
Keyword(s):  
Beaufort Sea ◽  
Time Of Day ◽  
Intermediate Water ◽  
Phoca Hispida ◽  
Weather Factors ◽  
Industrial Activity ◽  
Ringed Seals ◽  
Landfast Ice ◽  
Local Abundance ◽  
Water Depths

This study investigates how the local abundance of ringed seals (Phoca hispida) on landfast ice of the central Alaskan Beaufort Sea is related to habitat factors and how the haulout behaviour of seals is influenced by temporal and weather factors. An understanding of these relationships is required before the potential impacts of industrial activity on ringed seals can be assessed. Intensive and replicated aerial surveys employing strip transect methodology were conducted during the springs of 1997–1999. Data were examined with χ2 tests and Poisson regression. The overall observed densities of ringed seals over water depths >3 m was 0.43, 0.39, and 0.63 seals/km2 in 1997–1999, respectively. Significantly more seals occurred over intermediate water depths, especially 10–20 m. In all years, seals were widely distributed on the landfast ice, but during breakup, higher numbers of seals occurred near the ice edge. Densities were significantly lower in areas with high ice deformation and extensive melt water. There was no consistent relationship between seal sightings and time of day within the 10:00–18:00 period with surveys. The peak period of haulout occurred around 1 and 2 June. Significantly more ringed seals were observed on warm, cloudy days. There was no indication that limited winter industrial activity, including ice roads and Vibroseis, occurring within the study area in 1997–1999 significantly affected ringed seal density in spring.

Summer diet of the narwhal (Monodon monoceros) in Pond Inlet, northern Baffin Island

1982 ◽  
Vol 60 (12) ◽  
pp. 3353-3363 ◽  
Author(s):  
K. J. Finley ◽  
E. J. Gibb
Keyword(s):  
Age Groups ◽  
Stomach Contents ◽  
Late Summer ◽  
Polar Cod ◽  
Greenland Halibut ◽  
Arctic Cod ◽  
Deep Diving ◽  
Monodon Monoceros ◽  
Measured Weight ◽  
Greenland Halibut Reinhardtius Hippoglossoides

Stomach contents of 73 narwhals (Monodon monoceros) taken in Pond Inlet during June to September 1978–1979 were examined. Arctic cod (Boreogadus saida) and Greenland halibut (Reinhardtius hippoglossoides) comprised 51% and 37%, respectively, of the diet by weight. Arctic cod contributed 57% in 1978 but only 29% in 1979. Squid (Gonatus fabricii) beaks were abundant but not representative of recent intake. Deepwater fish (halibut, redfish (Sebastes marinus), and polar cod (Arctogadus glacialis)), found primarily in male narwhals, indicate a deep diving (>500 m) capability. The largest measured weight of stomach contents was 10.1 kg and weights projected from otoliths did not exceed 19.6 kg. No selection of prey items by size was evident amongst various sex and age groups of narwhals. Feeding was most intensive at the ice edge and ice cracks but little feeding took place in the fiords during late summer. Blubber thickness declined in females but not in males during the summer. The significance of traditional summering areas appears to be related to calving requirements and not to feeding opportunities.

Arctic summer sea-ice SAR signatures, melt-season characteristics, and melt-pond fractions

Polar Record ◽  
1997 ◽  
Vol 33 (185) ◽  
pp. 101-112 ◽  
Author(s):  
M. O. Jeffries ◽  
K. Schwartz ◽  
S. Li
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Late Summer ◽  
Beaufort Sea ◽  
Early Summer ◽  
The Arctic ◽  
Late Winter ◽  
Melt Pond ◽  
Melt Ponds ◽  
The Arctic Ocean

AbstractVariations in multiyear sea-ice backscatter from the synthetic aperture radar (SAR) aboard the ERS-1 satellite are interpreted in terms of melt-season characteristics (onset of melt in spring and of freeze-up in autumn, and the duration of the snow-decay period, the melt season, and the melt-pond season) from late winter to early autumn 1992 in two regions of the Arctic Ocean: the northeastern Beaufort Sea adjacent to the Queen Elizabeth Islands in the Canadian high Arctic and the western Beaufort Sea north of Alaska. In the northeastern Beaufort Sea, the onset of melt occurs later, and the periods of snow-cover decay and the occurrence of melt ponds are shorter than in the western Beaufort Sea. These melt-season characteristics of each area are consistent with previous observations that the northeastern Beaufort Sea has one of the most severe summer climates in the Arctic Ocean. A model, which assumes that the backscatter from multiyear floes is the sum of backscatter from bare ice and melt ponds, is used to derive the melt-pond fraction during the summer. The results show that melt-pond fractions decrease from an early-summer maximum of about 60% to a late-summer minimum around 10%. The magnitude of the melt-pond fractions and their decline during the summer is consistent with previous, more qualitative data. The SAR model, which gives melt-pond fractions with lower variability and less uncertainty than previous data, offers an improved approach to the reliable estimation of the areal extent of water on ice floes. Suggestions for further improvement of the model include accounting for the consequences of wind-speed variations, summer snowfall, and freeze/thaw cycles and their effects on melt-pond and ice-surface roughness.

scholarly journals Two Configurations of the Western Arctic Shelfbreak Current in Summer

2012 ◽  
Vol 42 (3) ◽  
pp. 329-351 ◽  
Author(s):  
Wilken-Jon von Appen ◽  
Robert S. Pickart
Keyword(s):  
Late Summer ◽  
Beaufort Sea ◽  
Early Summer ◽  
Coastal Current ◽  
Mean Flow ◽  
Warm Core ◽  
The Pacific ◽  
Western Arctic ◽  
Alaskan Coastal Current ◽  
Pacific Summer Water

Abstract Data from a closely spaced array of moorings situated across the Beaufort Sea shelfbreak at 152°W are used to study the Western Arctic Shelfbreak Current, with emphasis on its configuration during the summer season. Two dynamically distinct states of the current are revealed in the absence of wind, with each lasting approximately one month. The first is a surface-intensified shelfbreak jet transporting warm and buoyant Alaskan Coastal Water in late summer. This is the eastward continuation of the Alaskan Coastal Current. It is both baroclinically and barotropically unstable and hence capable of forming the surface-intensified warm-core eddies observed in the southern Beaufort Sea. The second configuration, present during early summer, is a bottom-intensified shelfbreak current advecting weakly stratified Chukchi Summer Water. It is baroclinically unstable and likely forms the middepth warm-core eddies present in the interior basin. The mesoscale instabilities extract energy from the mean flow such that the surface-intensified jet should spin down over an e-folding distance of 300 km beyond the array site, whereas the bottom-intensified configuration should decay within 150 km. This implies that Pacific Summer Water does not extend far into the Canadian Beaufort Sea as a well-defined shelfbreak current. In contrast, the Pacific Winter Water configuration of the shelfbreak jet is estimated to decay over a much greater distance of approximately 1400 km, implying that it should reach the first entrance to the Canadian Arctic Archipelago.

Distribution and Abundance of Seals in the Eastern Beaufort Sea

1977 ◽  
Vol 34 (7) ◽  
pp. 976-988 ◽  
Author(s):  
Ian Stirling ◽  
W. Ralph Archibald ◽  
Douglas DeMaster
Keyword(s):  
Marine Ecosystem ◽  
Major Change ◽  
Beaufort Sea ◽  
Phoca Hispida ◽  
Ringed Seals ◽  
Erignathus Barbatus ◽  
Independent Observations ◽  
Baseline Information ◽  
Reproductive Rates ◽  
Bearded Seals

The objectives of this study were: (1) to design a statistically reliable method for surveying ringed seals (Phoca hispida) and bearded seals (Erignathus barbatus) that could be repeated and, (2) to obtain baseline information on the distribution, abundance, and general biology of ringed and bearded seals in relation to other mammals in the pack-ice ecosystem of the eastern Beaufort Sea.Because of the limitations encountered in aerial surveying during the period of optimum haul out, and the heterogeneous environment, we employed a stratified design incorporating a weighted linear regression model. Identical surveys, conducted from June 15 to 29, 1974 and from June 12 to 20, 1975, showed a significant decline in numbers of both seal species in 1975. This conclusion was supported by other independent observations. Observer bias in sighting and identifying the species of seals was tested for and rejected. Neither species was distributed randomly over the heterogeneous habitat but the degree of clumping was different. In general, bearded seals preferred shallower areas and ringed seals deeper ones.When the seal population declined, the reproductive rates of both species dropped markedly and young of the year virtually disappeared from the population. The reduction in numbers of seals stimulated a major change in reproductive rates of the polar bears (Ursus maritimus) and arctic foxes (Alopex lagopus) that depend upon them for food, and the bear and fox populations decreased in size.Some possible causes of the decline are discussed. This unprecedented variability in the stability of the marine ecosystem has serious management implications. Key words: census techniques, Phoca hispida, Erignathus barbatus, seals, interspecific relationships, Beaufort Sea

Sign in / Sign up

Export Citation Format

Share Document