Identifying the "demon whale-biter": Patterns of scarring on large whales attributed to a cookie-cutter shark Isistius sp

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dc.contributor.authorBest, Peter Ben_ZA
dc.contributor.authorPhotopoulou, Theonien_ZA
dc.date.accessioned2016-04-13T12:37:38Z
dc.date.available2016-04-13T12:37:38Z
dc.date.issued2016en_ZA
dc.description.abstractThe presence of crater-like wounds on cetaceans and other large marine vertebrates and invertebrates has been attributed to various organisms. We review the evidence for the identity of the biting agent responsible for crater wounds on large whales, using data collected from sei ( Balaenoptera borealis ), fin ( B . physalus ), inshore and offshore Bryde's ( B . brydeii sp) and sperm whales ( Physeter macrocephalus ) examined at the Donkergat whaling station, Saldanha Bay, South Africa between March and October 1963. We then analyse the intensity and trends in its predation on large whales. Despite the scarcity of local records, we conclude that a cookie-cutter shark Isistius sp is the most likely candidate. We make inferences about the trends in (1) total counts of unhealed bitemarks, and (2) the proportion of unhealed bitemarks that were recent. We use day of the year; reproductive class, social grouping or sex; depth interval and body length as candidate covariates. The models with highest support for total counts of unhealed bitemarks involve the day of the year in all species. Depth was an important predictor in all species except offshore Bryde's whales. Models for the proportion of recent bites were only informative for sei and fin whales. We conclude that temporal scarring patterns support what is currently hypothesized about the distribution and movements of these whale species, given that Isistius does not occur in the Antarctic and has an oceanic habitat. The incidence of fresh bites confirms the presence of Isistius in the region. The lower numbers of unhealed bites on medium-sized sperm whales suggests that this group spends more time outside the area in which bites are incurred, providing a clue to one of the biggest gaps in our understanding of the movements of mature and maturing sperm males.en_ZA
dc.identifier.apacitationBest, P. B., & Photopoulou, T. (2016). Identifying the "demon whale-biter": Patterns of scarring on large whales attributed to a cookie-cutter shark Isistius sp. <i>PLoS One</i>, http://hdl.handle.net/11427/18858en_ZA
dc.identifier.chicagocitationBest, Peter B, and Theoni Photopoulou "Identifying the "demon whale-biter": Patterns of scarring on large whales attributed to a cookie-cutter shark Isistius sp." <i>PLoS One</i> (2016) http://hdl.handle.net/11427/18858en_ZA
dc.identifier.citationBest, P. B., & Photopoulou, T. (2016). Identifying the "demon whale-biter": Patterns of scarring on large whales attributed to a cookie-cutter shark Isistius sp. PLOS ONE, 11(4), e0152643. doi:10.1371/journal.pone.0152643en_ZA
dc.identifier.ris TY - Journal Article AU - Best, Peter B AU - Photopoulou, Theoni AB - The presence of crater-like wounds on cetaceans and other large marine vertebrates and invertebrates has been attributed to various organisms. We review the evidence for the identity of the biting agent responsible for crater wounds on large whales, using data collected from sei ( Balaenoptera borealis ), fin ( B . physalus ), inshore and offshore Bryde's ( B . brydeii sp) and sperm whales ( Physeter macrocephalus ) examined at the Donkergat whaling station, Saldanha Bay, South Africa between March and October 1963. We then analyse the intensity and trends in its predation on large whales. Despite the scarcity of local records, we conclude that a cookie-cutter shark Isistius sp is the most likely candidate. We make inferences about the trends in (1) total counts of unhealed bitemarks, and (2) the proportion of unhealed bitemarks that were recent. We use day of the year; reproductive class, social grouping or sex; depth interval and body length as candidate covariates. The models with highest support for total counts of unhealed bitemarks involve the day of the year in all species. Depth was an important predictor in all species except offshore Bryde's whales. Models for the proportion of recent bites were only informative for sei and fin whales. We conclude that temporal scarring patterns support what is currently hypothesized about the distribution and movements of these whale species, given that Isistius does not occur in the Antarctic and has an oceanic habitat. The incidence of fresh bites confirms the presence of Isistius in the region. The lower numbers of unhealed bites on medium-sized sperm whales suggests that this group spends more time outside the area in which bites are incurred, providing a clue to one of the biggest gaps in our understanding of the movements of mature and maturing sperm males. DA - 2016 DB - OpenUCT DO - 10.1371/journal.pone.0152643 DP - University of Cape Town J1 - PLoS One LK - https://open.uct.ac.za PB - University of Cape Town PY - 2016 T1 - Identifying the "demon whale-biter": Patterns of scarring on large whales attributed to a cookie-cutter shark Isistius sp TI - Identifying the "demon whale-biter": Patterns of scarring on large whales attributed to a cookie-cutter shark Isistius sp UR - http://hdl.handle.net/11427/18858 ER - en_ZA
dc.identifier.urihttp://dx.doi.org/10.1371/journal.pone.0152643en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/18858
dc.identifier.vancouvercitationBest PB, Photopoulou T. Identifying the "demon whale-biter": Patterns of scarring on large whales attributed to a cookie-cutter shark Isistius sp. PLoS One. 2016; http://hdl.handle.net/11427/18858.en_ZA
dc.language.isoengen_ZA
dc.publisherPublic Library of Scienceen_ZA
dc.publisher.departmentDepartment of Statistical 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© 2016 Best, Photopoulouen_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.otherSperm whalesen_ZA
dc.subject.otherWhalesen_ZA
dc.subject.otherPredationen_ZA
dc.subject.otherSharksen_ZA
dc.subject.otherSperm headen_ZA
dc.subject.otherLatitudeen_ZA
dc.subject.otherKiller whalesen_ZA
dc.subject.otherStomachen_ZA
dc.titleIdentifying the "demon whale-biter": Patterns of scarring on large whales attributed to a cookie-cutter shark Isistius spen_ZA
dc.typeJournal Articleen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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