Long-term variability in the abundance of Antarctic fur seals Arctocephalus gazella at Signy Island, South Orkneys |
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Authors: | Claire M Waluda Susan Gregory Michael J Dunn |
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Institution: | (1) British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, CB3 0ET, UK |
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Abstract: | The number of Antarctic fur seals Arctocephalus gazella hauled out at Signy Island in the South Orkneys was monitored annually between 1977 and 2008. Over the study period seal
abundance showed a tenfold increase, from a minimum of 1,643 seals in 1978 to a maximum of 21,303 in 1994. The majority of
individuals observed were young adult males, likely to be migrants from South Georgia, with small numbers of female seals
and only 65 pups recorded during the survey period. Variability in counts showed a similar pattern to Laurie Island, also
in the South Orkneys archipelago, suggesting a similar annual immigration of seals to these two islands. The date of first
seal arrival was correlated with the date of fast-ice breakout at Factory Cove, Signy Island, and years in which break out
was exceptionally late (>21 December) corresponded with years of reduced seal abundance. While the presence of fast-ice during
the early breeding season may currently inhibit the establishment of a major breeding population of fur seals at Signy Island,
it is important that routine monitoring should continue, particularly in the light of current patterns of climate warming
in the Antarctic. |
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