Precision of determining age in ringed seals (Phoca hispida) was examined by repeated readings of undecalcified cross sections and decalcified stained longitudinal sections of mandibular canines. There appeared to be geographical differences in repeatability although this could not be tested statistically. There was no difference in repeatability between cross and stained sections. / The effect of precision on population parameters was examined. Smoothing procedures necessary to construct life tables and to do Leslie matrix calculations obscured any differences in ages between readings. Variance between readings was found to give inconsistent notions of sexual maturity. Imprecision caused little overall difference in growth curves. / Without known age animals, accuracy cannot be evaluated directly. High correlation between ages from canines from different sides of the same animal, between dentine and cementum of teeth from the same animal, and between readers examining the same sets of teeth gave an indirect suggestion of accuracy.

No description available.

The effects of habitat features on the distribution of ringed seals (Phoca hispada) in the fast ice of Barrow Strait were examined between March and June 1984 to 1986. Breathing hole density in thirty-two, 2-4 km$ sp2$ study plots provided an index of seal abundance. Densities of seal holes were determined using a combination of trained dogs to locate the subnivean breathing holes and removal sampling. / Birth lairs were not seen before 4 April, but the incidence of these structures increased as the season progressed. Structures maintained by male seals were evident in late March, but were not found after mid-May. In 1984, densities of seal holes were correlated with ice thickness. In 1985, no relationship was detected between seal hole density and habitat. In 1986, the highest densities of subnivean structures including birth lairs, were associated with deep snow conditions located in areas of late consolidating ice. No relationship was identified between the density of male structures and any habitat variables. / The mean reproductive rate for females $>$7 years old was 0.64. Between March and June for adult males lost 204 g per day with 72% of this weight being lost from blubber. Pregnant females lost 467 g per day with 68% of the loss occurring from the blubber. In adult seals no differences in body condition were detected between sexes or between years, but juveniles collected in 1986 were in significantly better condition than juveniles collected in 1984 and 1985.

No description available.

Ringed seals (Phoca hispida) in the Canadian Arctic are subject to a variety of environmental and anthropogenic stressors that stand to potentially compromise population health and survival. Typically, animals exposed to chronic stressors initiate a stress response resulting in cortisol production, which results in physiological and behavioural changes designed to maintain homeostasis under the influence of the stressor. Cortisol extraction techniques were developed for Ringed seal blubber and fur samples. Blubber cortisol was found to be a reliable indicator of the condition factor ratio of blubber depth to core diameter. Ringed seal blubber cortisol concentration and condition was shown to alter depending on season and age class. The findings of this study are an important first step in developing an understanding of how this ice obligate species has and may respond to environmental stressors and will assist with developing conservation strategies. / October 2016

No description available.

No description available.

Ringed seal (Phoca hispida) is a major component and a major source of mercury (Hg) in the Inuit traditional diet. A high correlation between Hg and selenium (Se), as different forms of Hg-Se complex, has been reported in many species of marine mammals. The chemical form of the Hg-Se complex in ringed seals has never be characterised. In this study, Hg and Se concentrations in different seal tissues: liver, kidney, muscle and brain, were measured. The highest Hg and Se concentrations were found in the liver and a strong linear correlation was also observed between Hg and Se concentration in the seal liver. Extensive chromatographic and mass spectrometry techniques have been used to isolate and characterize the Hg and Se ligands in seal liver. Extraction of Hg and Se showed that Hg and Se were bound to ligands within the cell membranes of ringed seal liver. The Hg/Se binding protein has a MW range of about 65 kDa and Hg and Se had a 1:1 molecular ratio. The Hg/Se binding protein may contain 3 major polypeptides with MW of 6510.8, 14305.1 and 14353.1 Da. The toxicology of this Hg/Se binding protein will be studied using an animal feeding experiment.

No description available.

No description available.