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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

Published online by Cambridge University Press:  12 May 2004

C. Guinet
Affiliation:
Centre d'Etudes Biologiques de Chizé/Centre National de la Recherche Scientifique, 79 360 Villiers en Bois, France
P. Jouventin
Affiliation:
Centre d'Etudes Biologiques de Chizé/Centre National de la Recherche Scientifique, 79 360 Villiers en Bois, France
J-Y. Georges
Affiliation:
Centre d'Etudes Biologiques de Chizé/Centre National de la Recherche Scientifique, 79 360 Villiers en Bois, France

Abstract

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.

Type
Papers—Life Sciences and Oceanography
Copyright
© Antarctic Science Ltd 1994

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