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

dc.contributor.authorWege, Mia
dc.contributor.authorEtienne, Marie-Pierre
dc.contributor.authorOosthuizen, Wessel Christiaan
dc.contributor.authorReisinger, Ryan Rudolf
dc.contributor.authorBester, Marthan Nieuwoudt
dc.contributor.authorDe Bruyn, P.J. Nico
dc.contributor.emailmwege@zoology.up.ac.zaen_ZA
dc.date.accessioned2016-11-24T06:03:32Z
dc.date.issued2016-07
dc.description.abstractRecent 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 Published pup population estimates of A. tropicalis (1995 and 2004) with an unpublished total island count in 2013, and annual counts on subsets of rookeries (2007–2015) were analyzed using a hierarchical Bayesian model.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 rookeryen_ZA
dc.description.departmentMammal Research Instituteen_ZA
dc.description.departmentZoology and Entomologyen_ZA
dc.description.embargo2017-07-31
dc.description.librarianhb2016en_ZA
dc.description.sponsorshipThe 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.urihttp://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1748-7692en_ZA
dc.identifier.citationWege, 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.issn0824-0469 (print)
dc.identifier.issn1748-7692 (online)
dc.identifier.other10.1111/mms.12306
dc.identifier.urihttp://hdl.handle.net/2263/58268
dc.language.isoenen_ZA
dc.publisherWileyen_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.subjectArctocephalusen_ZA
dc.subjectSubantarctic fur sealen_ZA
dc.subjectAntarctic fur sealen_ZA
dc.subjectPopulation estimateen_ZA
dc.subjectMarion Islanden_ZA
dc.subjectHierarchical Bayesian modelen_ZA
dc.subjectDetection probabilityen_ZA
dc.subjectSympatryen_ZA
dc.subjectDensityen_ZA
dc.subjectCounten_ZA
dc.titleTrend changes in sympatric Subantarctic and Antarctic fur seal pup populations at Marion Island, Southern Oceanen_ZA
dc.typePostprint Articleen_ZA

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