Long term population changes of fur seals Arctocephalus gazella and Arctocephalus tropicalis on subantarctic (Crozet) and subtropical (St. Paul and Amsterdam) islands and their possible relationship to El Niño Southern Oscillation

The population trend over the last decade for subantarctic fur seals ( Arctocephalus tropicalis ) on Amsterdam and St. Paul islands and on Possession Island (Crozet Archipelago) and Antarctic fur seals ( A. gazella ) on Possession Island are analysed. At Amsterdam Island, based on pup counts, the su...

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Bibliographic Details
Published in:Antarctic Science
Main Authors: Guinet, C., Jouventin, P., Georges, J-Y.
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press (CUP) 1994
Subjects:
Geology
Ecology, Evolution, Behavior and Systematics
Oceanography
Amsterdam Island
Antarc*
Antarctic
Antarctic Fur Seal
Antarctic Fur Seals
Antarctic Science
Arctocephalus gazella
Paul Islands
Possession Island
Southern Ocean
Online Access:http://dx.doi.org/10.1017/s0954102094000714
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102094000714
Description
Summary:The population trend over the last decade for subantarctic fur seals ( Arctocephalus tropicalis ) on Amsterdam and St. Paul islands and on Possession Island (Crozet Archipelago) and Antarctic fur seals ( A. gazella ) on Possession Island are analysed. At Amsterdam Island, based on pup counts, the subantarctic fur seal population appears to have stabilized after a period of rapid growth. At Possession Island subantarctic fur seal and Antarctic fur seal, with respective annual growth rates of 19.2 and 17.4%, are reaching the maximum growth rate for the genus Arctocephalus . Annual pup censuses at Possession Island since 1978 indicate important variations from year to year with pup production for A. gazella significantly lower the year after an El Niño Southern Oscillation (ENSO) event, but with no such relationship for A. tropicalis . Several other long term demographic studies of seabirds and marine mammals at different breeding locations in the Southern Ocean indicate that the breeding success of several of these predators appears to be widely affected in years which appear to be related to the ENSO events. To clarify this, it is necessary to analyse in more detail the demographic data obtained for the different subantarctic and Antarctic locations where long term monitoring programmes are conducted.

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