Gauging the threat: the first population estimate for white sharks in South Africa using photo identification and automated software

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dc.contributor.authorTowner, Alison Ven_ZA
dc.contributor.authorWcisel, Michelle Aen_ZA
dc.contributor.authorReisinger, Ryan Ren_ZA
dc.contributor.authorEdwards, Daviden_ZA
dc.contributor.authorJewell, Oliver J Den_ZA
dc.date.accessioned2015-11-16T04:14:11Z
dc.date.available2015-11-16T04:14:11Z
dc.date.issued2013en_ZA
dc.description.abstractSouth Africa is reputed to host the world’s largest remaining population of white sharks, yet no studies have accurately determined a population estimate based on mark-recapture of live individuals. We used dorsal fin photographs (fin IDs) to identify white sharks in Gansbaai, South Africa, from January 2007 - December 2011. We used the computer programme DARWIN to catalogue and match fin IDs of individuals; this is the first study to successfully use the software for white shark identification. The programme performed well despite a number of individual fins showing drastic changes in dorsal fin shape over time. Of 1682 fin IDs used, 532 unique individuals were identified. We estimated population size using the open-population POPAN parameterisation in Program MARK, which estimated the superpopulation size at 908 (95% confidence interval 808-1008). This estimated population size is considerably larger than those described at other aggregation areas of the species and is comparable to a previous South African population estimate conducted 16 years prior. Our assessment suggests the species has not made a marked recovery since being nationally protected in 1991. As such, additional international protection may prove vital for the long-term conservation of this threatened species.en_ZA
dc.identifier.apacitationTowner, A. V., Wcisel, M. A., Reisinger, R. R., Edwards, D., & Jewell, O. J. D. (2013). Gauging the threat: the first population estimate for white sharks in South Africa using photo identification and automated software. <i>PLoS One</i>, http://hdl.handle.net/11427/15032en_ZA
dc.identifier.chicagocitationTowner, Alison V, Michelle A Wcisel, Ryan R Reisinger, David Edwards, and Oliver J D Jewell "Gauging the threat: the first population estimate for white sharks in South Africa using photo identification and automated software." <i>PLoS One</i> (2013) http://hdl.handle.net/11427/15032en_ZA
dc.identifier.citationTowner, A. V., Wcisel, M. A., Reisinger, R. R., Edwards, D., & Jewell, O. J. (2012). Gauging the threat: the first population estimate for white sharks in South Africa using photo identification and automated software. PloS one, 8(6), e66035-e66035. doi:10.1371/journal.pone.0066035en_ZA
dc.identifier.ris TY - Journal Article AU - Towner, Alison V AU - Wcisel, Michelle A AU - Reisinger, Ryan R AU - Edwards, David AU - Jewell, Oliver J D AB - South Africa is reputed to host the world’s largest remaining population of white sharks, yet no studies have accurately determined a population estimate based on mark-recapture of live individuals. We used dorsal fin photographs (fin IDs) to identify white sharks in Gansbaai, South Africa, from January 2007 - December 2011. We used the computer programme DARWIN to catalogue and match fin IDs of individuals; this is the first study to successfully use the software for white shark identification. The programme performed well despite a number of individual fins showing drastic changes in dorsal fin shape over time. Of 1682 fin IDs used, 532 unique individuals were identified. We estimated population size using the open-population POPAN parameterisation in Program MARK, which estimated the superpopulation size at 908 (95% confidence interval 808-1008). This estimated population size is considerably larger than those described at other aggregation areas of the species and is comparable to a previous South African population estimate conducted 16 years prior. Our assessment suggests the species has not made a marked recovery since being nationally protected in 1991. As such, additional international protection may prove vital for the long-term conservation of this threatened species. DA - 2013 DB - OpenUCT DO - 10.1371/journal.pone.0066035 DP - University of Cape Town J1 - PLoS One LK - https://open.uct.ac.za PB - University of Cape Town PY - 2013 T1 - Gauging the threat: the first population estimate for white sharks in South Africa using photo identification and automated software TI - Gauging the threat: the first population estimate for white sharks in South Africa using photo identification and automated software UR - http://hdl.handle.net/11427/15032 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/15032
dc.identifier.urihttp://dx.doi.org/10.1371/journal.pone.0066035
dc.identifier.vancouvercitationTowner AV, Wcisel MA, Reisinger RR, Edwards D, Jewell OJD. Gauging the threat: the first population estimate for white sharks in South Africa using photo identification and automated software. PLoS One. 2013; http://hdl.handle.net/11427/15032.en_ZA
dc.language.isoengen_ZA
dc.publisherPublic Library of Scienceen_ZA
dc.publisher.departmentDepartment of Biological Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.rightsThis is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.en_ZA
dc.rights.holder© 2013 Towner et alen_ZA
dc.rights.urihttp://creativecommons.org/licenses/by/4.0en_ZA
dc.sourcePLoS Oneen_ZA
dc.source.urihttp://journals.plos.org/plosoneen_ZA
dc.subject.otherSharksen_ZA
dc.subject.otherComputer applicationsen_ZA
dc.subject.otherComputer softwareen_ZA
dc.subject.otherMarine fishen_ZA
dc.subject.otherSouth Africaen_ZA
dc.subject.otherConfidence intervalsen_ZA
dc.subject.otherEyesen_ZA
dc.subject.otherMarine environmentsen_ZA
dc.titleGauging the threat: the first population estimate for white sharks in South Africa using photo identification and automated softwareen_ZA
dc.typeJournal Articleen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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