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In the period 1990–94, harp seals, Phoca groenlandica, were sampled for ecological studies in various areas and seasons in the Barents Sea. Data on total body weight, standard body length, axillary and maximum girth, dorsal and ventral blubber thickness were selected from all adult seals (defined as...
| Main Authors: | , , , , , , |
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.507.3502 http://archive.nafo.int/open/studies/s26/nilssen.pdf |
| Summary: | In the period 1990–94, harp seals, Phoca groenlandica, were sampled for ecological studies in various areas and seasons in the Barents Sea. Data on total body weight, standard body length, axillary and maximum girth, dorsal and ventral blubber thickness were selected from all adult seals (defined as seals with standard body length 150 cm or more) in order to evaluate the seasonal dynamics in condition of the animals. Blubber thickness measurements and condition indices (one including length, weight and dorsal blubber thickness and the other including maximum girth and length) showed the same seasonal patterns. The seals were in poor condition in spring and early summer (May–June), the condition improved during the course of summer, and the animals were in good condition in September and in October when the mean dorsal blubber thickness was approximately 88 mm. The energy stores built up during the summer and autumn were maintained until February, whereafter the seals became thinner as the stores of blubber decreased rapidly during the breeding season (February/March). A slight increase in dorsal blubber thickness was observed in the short period between lactation and moult (late March–early April), but the stores of blubber decreased further during moult (late April–May) to a mean dorsal blubber thickness of less than 20 mm in mid-June. No significant differences were observed in blubber thickness or condition indices between the sexes in the various periods, except during April when the females were in significantly poorer condition than the males. Harp seals sampled during the seal invasions to North Norwegian coastal waters in February 1988 were in poorer condition than seals captured in the Barents Sea in February 1993. |
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