The influence of environmental variables on the presence of white sharks, Carcharodon carcharias at two popular Cape Town bathing beaches: A generalized additive mixed model

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dc.contributor.authorWeltz, Kayen_ZA
dc.contributor.authorKock, Alison Aen_ZA
dc.contributor.authorWinker, Henningen_ZA
dc.contributor.authorAttwood, Colinen_ZA
dc.contributor.authorSikweyiya, Monwabisien_ZA
dc.date.accessioned2016-01-02T05:06:48Z
dc.date.available2016-01-02T05:06:48Z
dc.date.issued2013en_ZA
dc.description.abstractShark attacks on humans are high profile events which can significantly influence policies related to the coastal zone. A shark warning system in South Africa, Shark Spotters , recorded 378 white shark ( Carcharodon carcharias ) sightings at two popular beaches, Fish Hoek and Muizenberg, during 3690 six-hour long spotting shifts, during the months September to May 2006 to 2011. The probabilities of shark sightings were related to environmental variables using Binomial Generalized Additive Mixed Models (GAMMs). Sea surface temperature was significant, with the probability of shark sightings increasing rapidly as SST exceeded 14°C and approached a maximum at 18°C, whereafter it remains high. An 8 times (Muizenberg) and 5 times (Fish Hoek) greater likelihood of sighting a shark was predicted at 18°C than at 14°C. Lunar phase was also significant with a prediction of 1.5 times (Muizenberg) and 4 times (Fish Hoek) greater likelihood of a shark sighting at new moon than at full moon. At Fish Hoek, the probability of sighting a shark was 1.6 times higher during the afternoon shift compared to the morning shift, but no diel effect was found at Muizenberg. A significant increase in the number of shark sightings was identified over the last three years, highlighting the need for ongoing research into shark attack mitigation. These patterns will be incorporated into shark awareness and bather safety campaigns in Cape Town.en_ZA
dc.identifier.apacitationWeltz, K., Kock, A. A., Winker, H., Attwood, C., & Sikweyiya, M. (2013). The influence of environmental variables on the presence of white sharks, Carcharodon carcharias at two popular Cape Town bathing beaches: A generalized additive mixed model. <i>PLoS One</i>, http://hdl.handle.net/11427/16171en_ZA
dc.identifier.chicagocitationWeltz, Kay, Alison A Kock, Henning Winker, Colin Attwood, and Monwabisi Sikweyiya "The influence of environmental variables on the presence of white sharks, Carcharodon carcharias at two popular Cape Town bathing beaches: A generalized additive mixed model." <i>PLoS One</i> (2013) http://hdl.handle.net/11427/16171en_ZA
dc.identifier.citationWeltz, K., Kock, A. A., Winker, H., Attwood, C., & Sikweyiya, M. (2013). The influence of environmental variables on the presence of white sharks, Carcharodon carcharias at two popular Cape Town bathing beaches: A generalized additive mixed model. PloS one, 8(7), e68554. doi:10.1371/journal.pone.0068554en_ZA
dc.identifier.ris TY - Journal Article AU - Weltz, Kay AU - Kock, Alison A AU - Winker, Henning AU - Attwood, Colin AU - Sikweyiya, Monwabisi AB - Shark attacks on humans are high profile events which can significantly influence policies related to the coastal zone. A shark warning system in South Africa, Shark Spotters , recorded 378 white shark ( Carcharodon carcharias ) sightings at two popular beaches, Fish Hoek and Muizenberg, during 3690 six-hour long spotting shifts, during the months September to May 2006 to 2011. The probabilities of shark sightings were related to environmental variables using Binomial Generalized Additive Mixed Models (GAMMs). Sea surface temperature was significant, with the probability of shark sightings increasing rapidly as SST exceeded 14°C and approached a maximum at 18°C, whereafter it remains high. An 8 times (Muizenberg) and 5 times (Fish Hoek) greater likelihood of sighting a shark was predicted at 18°C than at 14°C. Lunar phase was also significant with a prediction of 1.5 times (Muizenberg) and 4 times (Fish Hoek) greater likelihood of a shark sighting at new moon than at full moon. At Fish Hoek, the probability of sighting a shark was 1.6 times higher during the afternoon shift compared to the morning shift, but no diel effect was found at Muizenberg. A significant increase in the number of shark sightings was identified over the last three years, highlighting the need for ongoing research into shark attack mitigation. These patterns will be incorporated into shark awareness and bather safety campaigns in Cape Town. DA - 2013 DB - OpenUCT DO - 10.1371/journal.pone.0068554 DP - University of Cape Town J1 - PLoS One LK - https://open.uct.ac.za PB - University of Cape Town PY - 2013 T1 - The influence of environmental variables on the presence of white sharks, Carcharodon carcharias at two popular Cape Town bathing beaches: A generalized additive mixed model TI - The influence of environmental variables on the presence of white sharks, Carcharodon carcharias at two popular Cape Town bathing beaches: A generalized additive mixed model UR - http://hdl.handle.net/11427/16171 ER - en_ZA
dc.identifier.urihttp://dx.doi.org/10.1371/journal.pone.0068554en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/16171
dc.identifier.vancouvercitationWeltz K, Kock AA, Winker H, Attwood C, Sikweyiya M. The influence of environmental variables on the presence of white sharks, Carcharodon carcharias at two popular Cape Town bathing beaches: A generalized additive mixed model. PLoS One. 2013; http://hdl.handle.net/11427/16171.en_ZA
dc.language.isoengen_ZA
dc.publisherPublic Library of Scienceen_ZA
dc.publisher.departmentMarine Research (MA-RE) Instituteen_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 Weltz 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.otherWinden_ZA
dc.subject.otherBeachesen_ZA
dc.subject.otherBinomialsen_ZA
dc.subject.otherConservation scienceen_ZA
dc.subject.otherPredationen_ZA
dc.subject.otherMarine conservationen_ZA
dc.subject.otherSurface temperatureen_ZA
dc.titleThe influence of environmental variables on the presence of white sharks, Carcharodon carcharias at two popular Cape Town bathing beaches: A generalized additive mixed modelen_ZA
dc.typeJournal Articleen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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