Trend changes in sympatric Subantarctic and Antarctic fur seal pup populations at Marion Island, Southern Ocean

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dc.contributor.author Wege, Mia
dc.contributor.author Etienne, Marie-Pierre
dc.contributor.author Oosthuizen, W.C. (Wessel Christiaan)
dc.contributor.author Reisinger, Ryan Rudolf
dc.contributor.author Bester, Marthan Nieuwoudt
dc.contributor.author De Bruyn, P.J. Nico
dc.date.accessioned 2016-11-24T06:03:32Z
dc.date.issued 2016-07
dc.description.abstract Recent pup population estimates of sympatric Subantarctic (Arctocephalus tropicalis) and Antarctic fur seals (A. gazella) at Marion Island are presented. Published pup population estimates of A. tropicalis (1995 and 2004) with an unpublished total island count in 2013, and annual counts on subsets of rookeries (2007–2015) were analyzed using a hierarchical Bayesian model. The pup population declined by 46% (95% credible interval CI: 43%–48%) between 2004 (mean = 15,260, CI: 14,447– 16,169 pups) and 2013 (mean = 8,312, CI: 7,983–8,697), mirrored by a 58%–60% decline at rookeries counted annually (2007–2015). Population decline was highest at high-density west and north coast rookeries, despite negligible change in female attendance patterns, pup mortality or median pupping date over the previous 25 yr. A better understanding of foraging behavior and its effects on reproductive success and survival in this A. tropicalis population is needed before we can attribute population decline to any external factors. In contrast, total island counts of A. gazella pups in 2007, 2010, and 2013, suggest that this population is still increasing although the annual intrinsic rate of population growth decreased from 17.0% (1995–2004, 744 pups) to 4.0% (2010–2013, 1,553 pups). The slowed growth of A. gazella is likely the result of saturation at the main rookery en_ZA
dc.description.department Mammal Research Institute en_ZA
dc.description.department Zoology and Entomology en_ZA
dc.description.embargo 2017-07-31
dc.description.librarian hb2016 en_ZA
dc.description.sponsorship The Department of Science and Technology, through the National Research Foundation (NRF), in support of the Marion Island Marine Mammal Programme of the MRI. en_ZA
dc.description.uri http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1748-7692 en_ZA
dc.identifier.citation Wege, M, Etienne, MP, Oosthuizen, WC, Reisinger, RR, Bester, MN & De Bruyn, PJN 2016, 'Trend changes in sympatric Subantarctic and Antarctic fur seal pup populations at Marion Island, Southern Ocean', Marine Mammal Science, vol. 32, no. 3, pp. 960-982. en_ZA
dc.identifier.issn 0824-0469 (print)
dc.identifier.issn 1748-7692 (online)
dc.identifier.other 10.1111/mms.12306
dc.identifier.uri http://hdl.handle.net/2263/58268
dc.language.iso en en_ZA
dc.publisher Wiley en_ZA
dc.rights © 2016 Society for Marine Mammalogy. This is the pre-peer reviewed version of the following article : Trend changes in sympatric Subantarctic and Antarctic fur seal pup populations at Marion Island, Southern Ocean, Marine Mammal Science, vol. 32, no. 3, pp. 960-982, 2016. doi : 10.1111/mms.12306. The definite version is available at : http://onlinelibrary.wiley.comjournal/10.1111/(ISSN)1748-7692. en_ZA
dc.subject Arctocephalus en_ZA
dc.subject Subantarctic fur seal en_ZA
dc.subject Antarctic fur seal en_ZA
dc.subject Population estimate en_ZA
dc.subject Marion Island en_ZA
dc.subject Hierarchical Bayesian model en_ZA
dc.subject Detection probability en_ZA
dc.subject Sympatry en_ZA
dc.subject Density en_ZA
dc.subject Count en_ZA
dc.title Trend changes in sympatric Subantarctic and Antarctic fur seal pup populations at Marion Island, Southern Ocean en_ZA
dc.type Postprint Article en_ZA


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