Sightings of killer whales Orcinus orca from longline vessels in South African waters, and consideration of the regional conservation status

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dc.contributor.authorWilliams, A J
dc.contributor.authorPetersen, S L
dc.contributor.authorGoren, M
dc.contributor.authorWatkins, B P
dc.date.accessioned2016-02-25T11:40:28Z
dc.date.available2016-02-25T11:40:28Z
dc.date.issued2009
dc.date.updated2016-01-19T08:24:02Z
dc.description.abstractKiller whales Orcinus orca are seldom reported from South African nearshore waters but, allowing for the bias of vessel attraction, observations from longline vessels suggest there is a resident offshore population of fish-eating killer whales. We present reports of killer whales made by observers on pelagic longline vessels fishing for tuna Thunnus spp., swordfish Xiphias gladius and sharks off South Africa, and on demersal longline vessels fishing for Patagonian toothfish Dissostichus eleginoides off the Subantarctic Prince Edward Islands. Off South Africa, observers reported 689 occurrences of killer whales during the period January 2002 to December 2006. Observations off South Africa peaked in January and were minimal in April–May. Most killer whale pods comprised 1–4 individuals and few were more than six. Observations were largely over the shelf edge between the Agulhas Bank and Port Elizabeth on the south-east coast of South Africa. In all, 1 843 line sets, using 3.8 million hooks, were monitored and killer whales occurred at an overall rate of 0.18 per 1 000 hooks. Killer whales depredated at an overall rate of 0.5% of the total catch. A small (maximum 12 individuals) population was recorded at longline vessels off the Prince Edward Islands, but observations were limited to August–September, October–November and May–June. We consider the conservation status of killer whales in southern African waters to be 'vulnerable', because the populations are very small and are subject to both short- and long-term impacts from the longline fisheries.en_ZA
dc.identifierhttp://dx.doi.org/10.2989/AJMS.2009.31.1.7.778
dc.identifier.apacitationWilliams, A. J., Petersen, S. L., Goren, M., & Watkins, B. P. (2009). Sightings of killer whales Orcinus orca from longline vessels in South African waters, and consideration of the regional conservation status. <i>African Journal of Marine Science</i>, http://hdl.handle.net/11427/17258en_ZA
dc.identifier.chicagocitationWilliams, A J, S L Petersen, M Goren, and B P Watkins "Sightings of killer whales Orcinus orca from longline vessels in South African waters, and consideration of the regional conservation status." <i>African Journal of Marine Science</i> (2009) http://hdl.handle.net/11427/17258en_ZA
dc.identifier.citationWilliams, A. J., Petersen, S. L., Goren, M., & Watkins, B. P. (2009). Sightings of killer whales Orcinus orca from longline vessels in South African waters, and consideration of the regional conservation status. African Journal of Marine Science, 31(1), 81-86.en_ZA
dc.identifier.issn1814-232Xen_ZA
dc.identifier.ris TY - Journal Article AU - Williams, A J AU - Petersen, S L AU - Goren, M AU - Watkins, B P AB - Killer whales Orcinus orca are seldom reported from South African nearshore waters but, allowing for the bias of vessel attraction, observations from longline vessels suggest there is a resident offshore population of fish-eating killer whales. We present reports of killer whales made by observers on pelagic longline vessels fishing for tuna Thunnus spp., swordfish Xiphias gladius and sharks off South Africa, and on demersal longline vessels fishing for Patagonian toothfish Dissostichus eleginoides off the Subantarctic Prince Edward Islands. Off South Africa, observers reported 689 occurrences of killer whales during the period January 2002 to December 2006. Observations off South Africa peaked in January and were minimal in April–May. Most killer whale pods comprised 1–4 individuals and few were more than six. Observations were largely over the shelf edge between the Agulhas Bank and Port Elizabeth on the south-east coast of South Africa. In all, 1 843 line sets, using 3.8 million hooks, were monitored and killer whales occurred at an overall rate of 0.18 per 1 000 hooks. Killer whales depredated at an overall rate of 0.5% of the total catch. A small (maximum 12 individuals) population was recorded at longline vessels off the Prince Edward Islands, but observations were limited to August–September, October–November and May–June. We consider the conservation status of killer whales in southern African waters to be 'vulnerable', because the populations are very small and are subject to both short- and long-term impacts from the longline fisheries. DA - 2009 DB - OpenUCT DP - University of Cape Town J1 - African Journal of Marine Science LK - https://open.uct.ac.za PB - University of Cape Town PY - 2009 SM - 1814-232X T1 - Sightings of killer whales Orcinus orca from longline vessels in South African waters, and consideration of the regional conservation status TI - Sightings of killer whales Orcinus orca from longline vessels in South African waters, and consideration of the regional conservation status UR - http://hdl.handle.net/11427/17258 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/17258
dc.identifier.vancouvercitationWilliams AJ, Petersen SL, Goren M, Watkins BP. Sightings of killer whales Orcinus orca from longline vessels in South African waters, and consideration of the regional conservation status. African Journal of Marine Science. 2009; http://hdl.handle.net/11427/17258.en_ZA
dc.languageengen_ZA
dc.publisherTaylor & Francisen_ZA
dc.publisher.departmentMarine Resource Assessment and Management Groupen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.sourceAfrican Journal of Marine Scienceen_ZA
dc.source.urihttp://www.tandfonline.com/doi/abs/10.2989/AJMS.2009.31.1.7.778
dc.subject.otherConservation
dc.subject.otherKiller Whale
dc.subject.otherLong-Line Fishery
dc.subject.otherOrcinus Orca
dc.subject.otherThunnus
dc.subject.otherXiphias
dc.titleSightings of killer whales Orcinus orca from longline vessels in South African waters, and consideration of the regional conservation statusen_ZA
dc.typeJournal Articleen_ZA
uct.subject.keywordsconservationen_ZA
uct.subject.keywordskiller whaleen_ZA
uct.subject.keywordslong-line fisheryen_ZA
uct.subject.keywordsorcinus orcaen_ZA
uct.subject.keywordsthunnusen_ZA
uct.subject.keywordsxiphiasen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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