COUNTS OF GROWTH LAYER GROUPS IN CEMENTUM AND DENTINE IN RINGED SEALS (PHOCA HISPIDA)

1996 ◽  
Vol 12 (3) ◽  
pp. 383-401 ◽  
Author(s):  
Robert E. A. Stewart ◽  
Barbara E. Stewart ◽  
Ian Stirling ◽  
Elaine Street
Keyword(s):  
Growth Layer ◽  
Phoca Hispida ◽  
Ringed Seals ◽  
Layer Groups

Assessment of claw growth-layer groups from ringed seals (Pusa hispida) as biomonitors of inter- and intra-annual Hg, δ15N, and δ13C variation

2011 ◽  
Vol 89 (9) ◽  
pp. 774-784 ◽  
Author(s):  
Elizabeth O. Ferreira ◽  
Lisa L. Loseto ◽  
Steven H. Ferguson
Keyword(s):  
Life History ◽  
Marine Mammals ◽  
Ringed Seal ◽  
The Body ◽  
Conservation Strategies ◽  
Growth Layer ◽  
Annual Variations ◽  
Ringed Seals ◽  
Pusa Hispida ◽  
Layer Groups

The ringed seal ( Pusa hispida (Schreber, 1775)) is a sentinel species of arctic marine mammals; therefore, methods to monitor its life-history changes are crucial to establish effective conservation strategies. We evaluate the potential use of claws of ringed seals as a proxy for counts of tooth growth-layer groups (age) and a biomonitor of total mercury burden (THg) and diet (stable isotope ratios expressed as δ15N and δ13C). The count of claw growth-layer groups was indicative of age up to 8 years and we infer differentiation of dark and light annuli as being associated with the spring moult. No differences of THg, δ15N, or δ13C were observed among flipper digits. The proximal claw annulus representing the most recent growth had δ13C values that were correlated to both muscle and liver δ13C, supporting the use of claws to monitor visceral δ13C. Claw log10THg from the proximate annulus was significantly correlated to liver and whisker log10THg, while significant interannual THg accumulation was observed in 18 of 32 seals ≥4 years, suggesting the claws receive and disperse Hg from active tissues of the body. Results support the use of claw tissue from ringed seal to provide a chronological record of inter- and intra-annual variations representing seal diet, contaminant load, and life history.

Haul-out behaviour and densities of ringed seals (Phoca hispida) in the Barrow Strait area, N.W.T.

1979 ◽  
Vol 57 (10) ◽  
pp. 1985-1997 ◽  
Author(s):  
Kerwin J. Finley
Keyword(s):  
Wind Speed ◽  
Early Morning ◽  
Maximum Density ◽  
Stable Population ◽  
The Sun ◽  
High Wind ◽  
Phoca Hispida ◽  
High Wind Speed ◽  
Ringed Seals ◽  
Calm Weather

Numbers of ringed seals hauled out on the ice began to increase in early June. Numbers on the ice were highest from 0900 to 1500 hours Central Standard Time and lowest (average 40–50% of peak) in early morning. Seals commonly remained on the ice for several hours, and occasionally (during calm weather) for > 48 h. Numbers on the ice were reduced on windy days and possibly also on unusually warm, bright and calm days. Seals tended to face away from the wind (particularly with high wind speed) and oriented broadside to the sun. Seals usually occurred singly (60–70% of all groups) at their holes.Numbers of seals hauled out at Freemans Cove remained relatively constant during June (maximum density 4.86/km2), whereas at Aston Bay numbers increased dramatically to a maximum density of 10.44/km2 in late June. The increase was thought to be due to an influx of seals abandoning unstable ice. The density of seal holes at Freemans Cove (5.92/km2) was much higher than at Aston Bay (2.73/km2). The ratio of holes to the maximum numbers of seals (1.12:1) at Freemans Cove represents a first estimate of this relationship in an apparently stable population.

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.

The scent of rutting male ringed seals(Phoca hispida)

1992 ◽  
Vol 226 (4) ◽  
pp. 681-689 ◽  
Author(s):  
M. Ryg ◽  
Y. Solberg ◽  
C. Lydersen ◽  
T. G. Smith
Keyword(s):  
Phoca Hispida ◽  
Ringed Seals

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.

Biotransformation of PCBs in Relation to Phase I and II Xenobiotic-Metabolizing Enzyme Activities in Ringed Seals (Phoca hispida) from Svalbard and the Baltic Sea

2008 ◽  
Vol 42 (23) ◽  
pp. 8952-8958 ◽  
Author(s):  
Heli Routti ◽  
Robert J. Letcher ◽  
Augustine Arukwe ◽  
Bert van Bavel ◽  
Nigel G. Yoccoz ◽  
...  
Keyword(s):  
Phase I ◽  
Baltic Sea ◽  
Enzyme Activities ◽  
Phoca Hispida ◽  
The Baltic Sea ◽  
Ringed Seals ◽  
Metabolizing Enzyme ◽  
The Baltic ◽  
Phase I And Ii

GROWTH LAYER GROUPS (GLGs) IN THE TEETH OF AN ADULT BELUKHA WHALE (DELPHINAPTERUS LEUCAS) OF KNOWN AGE: EVIDENCE FOR TWO ANNUAL LAYERS

1987 ◽  
Vol 3 (1) ◽  
pp. 14-21 ◽  
Author(s):  
Arthur D. Goren ◽  
Paul F. Brodie ◽  
Stephen Spotte ◽  
G. Carleton Ray ◽  
H. W. Kaufman ◽  
...  
Keyword(s):  
Delphinapterus Leucas ◽  
Growth Layer ◽  
Layer Groups

scholarly journals Variation in skull bone mineral density of ringed seals (Phoca hispida) from the Gulf of Bothnia and West Greenland between 1829 and 2019

2020 ◽  
Vol 143 ◽  
pp. 105968 ◽  
Author(s):  
Britta Schmidt ◽  
Christian Sonne ◽  
Dominik Nachtsheim ◽  
Rune Dietz ◽  
Ralf Oheim ◽  
...  
Keyword(s):  
Bone Mineral Density ◽  
Bone Mineral ◽  
Skull Bone ◽  
Phoca Hispida ◽  
Mineral Density ◽  
West Greenland ◽  
Ringed Seals ◽  
Gulf Of Bothnia

scholarly journals Growth of the skull of the bottlenose dolphin, Tursiops truncatus, in the Southwest Atlantic Ocean

10.5597/00229 ◽  
2017 ◽  
Vol 11 (1-2) ◽  
pp. 199-211 ◽  
Author(s):  
André Silva Barreto
Keyword(s):  
Bottlenose Dolphin ◽  
Tursiops Truncatus ◽  
Growth Equation ◽  
Growth Layer ◽  
Southwest Atlantic ◽  
Development Patterns ◽  
Skull Measurements ◽  
The One ◽  
Layer Groups ◽  
Mature Size

Defining the age of attainment of physical maturity is important for many studies, including identification of stocks, populations or species. In order to identify the age when the skull of the bottlenose dolphin, Tursiops truncatus, reaches maturity, skulls of fifty-three specimens found stranded along the coasts of southern Brazil, Uruguay and northern Argentina (27o35’S, 48o34’W-36o49’S, 55o19’W) were analyzed. Sixty skull measurements were taken to compare the growth rate of the different functional apparatuses. Age was estimated by counts of growth layer groups in the dentine of decalcified, stained longitudinal sections of teeth. Von Bertalanffy’s equation was applied to assess the growth and determine the age at maturity of each apparatus. Generally the maturation of skull starts at age two and stabilizes at age five, and the age of reaching the mature size varies amongst different characters. The braincase is the most precocious apparatus, while the feeding is the one that last stabilizes. The development patterns observed for the hearing, vision and breathing apparatuses were similar. Statistic analysis revealed significant differences among the ages at maturity, but not for von Bertalanffy’s growth equation parameters for each functional apparatus. For the studied population it is suggested that skulls can be considered mature in animals with more than five years. 

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