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. 

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

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.

Distribution and abundance of ringed (Phoca hispida) and bearded seals (Erignathus barbatus) in western Hudson Bay

1997 ◽  
Vol 54 (4) ◽  
pp. 914-921 ◽  
Author(s):  
N J Lunn ◽  
I Stirling ◽  
S N Nowicki
Keyword(s):  
Polar Bear ◽  
Hudson Bay ◽  
Phoca Hispida ◽  
Current Estimate ◽  
Ringed Seals ◽  
Erignathus Barbatus ◽  
The Mean ◽  
Western Hudson Bay ◽  
The Relationship ◽  
Bearded Seals

We flew a medium-altitude, systematic, strip-transect survey for ringed (Phoca hispida) and bearded seals (Erignathus barbatus) over western Hudson Bay in early June 1994 and 1995. The mean density (per square kilometre) of ringed seals hauled out on the ice was four times higher in 1995 (1.690) than in 1994 (0.380). The 1994 survey appeared to underestimate seal abundance because it was flown too late. Ringed seals preferred high ice cover habitat (6 + /8 ice) and, within this habitat, favoured cracking ice and large floes. We found no consistent effect of either wind or cloud cover on habitat preference. We estimated a total of 1980 bearded seals and 140<|>880 ringed seals hauled out on the sea ice in June 1995. A recent review of the relationship between ringed seal and polar bear (Ursus maritimus) populations suggests that a visible population of this size should support a population of up to 1300 polar bears, which is in general agreement with the current estimate of 1250-1300 bears in western Hudson Bay.

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.

scholarly journals Compost and soil moisture effects on seasonal carbon and nitrogen dynamics, greenhouse gas fluxes and global warming potential of semi-arid soils

2019 ◽  
Vol 8 (S1) ◽  
pp. 367-376 ◽  
Author(s):  
Mavis Badu Brempong ◽  
Urszula Norton ◽  
Jay B. Norton
Keyword(s):  
Global Warming ◽  
Soil Moisture ◽  
Global Warming Potential ◽  
Carbon Dioxide Emissions ◽  
Inorganic Nitrogen ◽  
Early Summer ◽  
Late Spring ◽  
Late Winter ◽  
Normal Soil ◽  
Soil Inorganic

Abstract Purpose An 8-week incubation study was conducted to monitor soil inorganic nitrogen (N), dissolved organic carbon (DOC), greenhouse gases (GHG) [CO2, N2O and CH4] and cumulative global warming potential (GWP) in dryland soil. Methods Soil was amended with variable rates of compost (zero, 15, 30 and 45 dry Mg ha−1) and soil moistures [5% (dry), 7% (normal) and 14% (wet) water filled pore space (WFPS)] and experienced biweekly temperature transitions from 5 °C (late winter) to 10 °C (early spring) to 15 °C (late spring) to 25 °C (early summer). Results The addition of 30 and 45 Mg ha−1 compost enhanced N mineralization with 13% more soil inorganic N (7.49 and 7.72 µg Ng−1 day−1, respectively) during early summer compared with lower compost rates. Normal and wet soils had 35% more DOC in the late spring (an average of 34 µg g−1 day−1) compared to the dry WFPS, but transitioning from late spring to early summer, DOC at all soil WFPS levels increased. Highest rates of compost were not significant sources of GHG with normal soil WFPS, compared with lower compost rates. Carbon dioxide emissions increased by 59 and 15%, respectively, as soil WFPS increased from dry to normal and normal to wet. Soils with normal WFPS were the most effective CH4 sink. Conclusion One-time application of high compost rates to dryland soils leads to enhanced N and C mineralization under normal soil moisture and warmer temperature of the summer but will not pose significant global warming dangers to the environment through GHG emissions since soils are rarely wet.

The caloric value of whole ringed seals (Phoca hispida) in relation to polar bear (Ursus maritimus) ecology and hunting behavior

1975 ◽  
Vol 53 (8) ◽  
pp. 1021-1027 ◽  
Author(s):  
Ian Stirling ◽  
Eoin H. McEwan
Keyword(s):  
Total Body Water ◽  
Polar Bear ◽  
Fat Body ◽  
Ursus Maritimus ◽  
Ringed Seal ◽  
Body Water ◽  
Phoca Hispida ◽  
Hunting Behavior ◽  
Wet Weight ◽  
Total Body

Throughout its circumpolar range, the polar bear (Ursus maritimus) feeds predominantly on the ringed seal (Phoca hispida). Despite seasonal variation in availability and distribution of seals, polar bears prefer to eat mainly the fat, often leaving substantial portions of seal meat and blubber. In the present study, 12 seals were minced and analyzed for water, fat, protein, and ash contents. The percentage composition varied from 23 to 58% protein, 34 to 76% fat, 2 to 5.5% ash, and 47.4 to 69.5% total body water. The caloric values varied from 2.3 to 5.3 kcal/g wet weight. Relationships between total body water and fat (%), body water (litres) and protein (kg) are presented. These results are discussed in relation to the ecology and hunting behavior of the polar bear.

scholarly journals Fungal Decay of First-Crop and Main-Crop Figs

Plant Disease ◽  
2007 ◽  
Vol 91 (12) ◽  
pp. 1657-1662 ◽  
Author(s):  
Mark A. Doster ◽  
Themis J. Michailides
Keyword(s):  
Aspergillus Niger ◽  
Alternaria Alternata ◽  
Late Summer ◽  
Early Summer ◽  
Late Spring ◽  
Fungal Decay ◽  
Main Crop ◽  
Low Levels ◽  
Serious Disease

Fig cultivars grown in California typically have two crops, although the first crop may be unimportant commercially. The first crop, also known as the breba crop, ripens in late spring and early summer, whereas the main or second crop ripens in late summer. For both cultivars studied, Conadria and Calimyrna, the first-crop figs typically are left in the orchard unharvested. First-crop figs had relatively high levels of fungal decay and tended to have more fungal decay than main-crop figs, especially Alternaria rot (caused by Alternaria alternata and Ulocladium atrum). At least 16 different Aspergillus spp. were found decaying first-crop figs. Fig smut, a serious disease caused by Aspergillus niger and related fungi, usually was present at approximately the same level in first-crop and main-crop figs. Aspergillus spp. known to produce the mycotoxins aflatoxin or ochratoxin were found decaying first-crop figs. Aflatoxin was detected in first-crop figs at low levels similar to those detected in the main-crop figs. Because the abundant spores produced on the first-crop figs can infect main-crop figs, the fungal decay of first-crop figs might result in higher levels of decay for main-crop figs.

scholarly journals Flowering Response of Bougainvillea Cultivars to Dikegulac

HortScience ◽  
1994 ◽  
Vol 29 (4) ◽  
pp. 282-284 ◽  
Author(s):  
J.G. Norcini ◽  
J.H. Aldrich ◽  
J.M. McDowell
Keyword(s):  
Sodium Salt ◽  
Growth Habit ◽  
Foliar Spray ◽  
Late Summer ◽  
Early Summer ◽  
Late Spring ◽  
The Other ◽  
Spray Application ◽  
Flowering Response ◽  
Bougainvillea Glabra

Foliar spray application of dikegulac at 1600 mg·liter-1 during production of Bougainvillea glabra Choicy `Mauna Kea White', and Bougainvillea `Raspberry Ice', `Royal Purple', `Summer Snow', and `Temple Fire' in 4.5-liter hanging baskets (25.4 cm in diameter) was investigated in relation to flowering. The effect of foliar-applied dikegulac at 0, 400, 800, 1200, and 1600 mg·liter-1 on bracteole size of `Mauna Kea White' was also determined. Liners of `Temple Fire' pruned at transplanting (0 weeks) and sprayed with dikegulac at, 0 and 4 weeks had increased flowering and a slightly more compact, pendulous growth habit than plants that had only been pruned at 0 and 4 weeks. Dikegulac had little to no effect on flowering of the other cultivars. Under late-spring to early summer conditions (generally increasing temperatures), bracteole size of `Mauna Kea White' was reduced ≈25 % by 400 mg dikegulac/liter compared to nontreated plants; 800 to 1600 mg dikegulac/liter reduced bracteole size ≈37%. Under late-summer to mid-fall conditions when the weather was cooler and wetter, dikegulac had little to no effect on bracteole size; however, bracteoles of nontreated plants were ≈25% smaller than those of plants grown under the warmer and drier conditions of late spring to early summer. Chemical name used: sodium salt of 2,3:4,6-bis -O- (1-methylethylidene) -α-l-xylo- 2-hexulofuranosonic acid (dikegulac).

scholarly journals Status and biology of ringed seals (Phoca hispida) in Svalbard

1998 ◽  
Vol 1 ◽  
pp. 46 ◽  
Author(s):  
Christian Lydersen
Keyword(s):  
Body Mass ◽  
Dive Duration ◽  
Early Spring ◽  
Ringed Seal ◽  
The Arctic ◽  
Polar Cod ◽  
Net Energy ◽  
Adult Males ◽  
Ringed Seals ◽  
Males And Females

The ringed seal is the most abundant mammal in the Svalbard area. Annual pup production in this area is estimated to be 20,000. No systematic harvest records exist, but some few hundred seals are taken annually, mainly for dog food. The ringed seals in Svalbard are protected from hunting in the period 15 March - 15 April. Peak pupping season is the first week of April. New-born ringed seals weigh an average of 4.6 kg. They are nursed for about 39 days, and weaned at an average body mass of around 22 kg. During the period of maternal care pups consume a total of about 54 litres of milk, that is composed of approximately 38% fat and 10% protein. Asymptotic standard lengths and body masses for adult ringed seal males and females are 131.5 and 127.8 cm, and 52.6 and 59.9 kg,respectively. The maximum values recorded for lengths of males and females in Svalbard are 157 cm and 107 kg, respectively. There is marked seasonal variation in body mass in both sexes with the highest mass records being recorded in early spring before pupping occurs, and with minimum values in the summer after the breeding and moulting seasons. The observed variation in mass is mainly due to changing blubber thickness of the seals. Ringed seal males attain sexual maturity at the age of 5 - 7 years, while females reach maturity when they are 3-5 years of age. The oldest seal collected in Svalbard was aged 45. Ringed seals in the Svalbard area feed on a variety of prey organisms, the most important of which are polar cod (Boreogadus saida) and the crustaceans Parathemisto libellula, Thysanoessa inermis and Pandalus borealis. Ringed seal pups start diving during the nursing period while they are still white-coats, and spend about 50% of the time in thewater prior to weaning. They are capable of diving for up to 12min and dive to the bottom of the study areas (max. 89 m). Nursing females spend more than 80% of their time in the water. Maximum recorded dive duration for mothers was 21.2 min. In order to produce a weaned pup, the net energy expenditure for a ringed seal mother is 1,073 MJ. This energy value corresponds to the consumption of 185 kg of polar cod or 282 kg of P. libellula. The annual gross energy consumption for adult males and females is calculated to be 5,600 MJ and 7,300 MJ, respectively. The main predators of ringed seals in Svalbard are polar bears (Ursus maritimus) and Arctic foxes (Alopex lagopus). In addition, both glaucous gulls (Larus hyperboreus) and walruses (Odobenus rosmarus) are documented as predators of ringed seals in this area. Heavy predation pressure is probably the main factor explaining why pups of this species start diving at such a young age, why they have access to so many breathing holes (8.7 on average) and why they keep their white coat long after its thermoregulatory properties have vanished. Pollution levels in ringed seals from Svalbard are, generally speaking, similar to levels in other areas of the Arctic.

Seasonal changes in prevalence and intensity of Cosmocercoides dukae (Nematoda: Cosmocercoidea) in Deroceras laeve (Mollusca)

1987 ◽  
Vol 65 (7) ◽  
pp. 1662-1665 ◽  
Author(s):  
Daryl J. Vanderburgh ◽  
R. C. Anderson
Keyword(s):  
Natural Population ◽  
Seasonal Changes ◽  
Late Summer ◽  
Early Summer ◽  
Late Spring ◽  
New Host ◽  
Histological Sections ◽  
Arion Fasciatus ◽  
New Host Records

A natural population of Deroceras laeve was examined regularly for the presence of Cosmocercoides dukae (Holl, 1928) Travassos, 1931. Transmission of C. dukae in D. laeve occurred in late spring and early summer before adult slugs from the previous year died in July. Transmission to juvenile slugs (hatched from eggs laid in spring) continued in late summer and fall. Histological sections of slugs exposed experimentally to larvae of C. dukae revealed that larvae penetrate slug tissues. Arion fasciatus, Arion hortensis, and Zonitoides nitidus represent new host records for C. dukae.

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