Humpback whale abundance south of 60°S from three complete circumpolar sets of surveys

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dc.contributor.authorBranch, Trevor A
dc.date.accessioned2016-02-25T10:33:18Z
dc.date.available2016-02-25T10:33:18Z
dc.date.issued2011
dc.date.updated2016-02-25T10:19:41Z
dc.description.abstractAustral summer estimates of abundance are obtained for humpback whales (Megaptera novaeangliae) in the Southern Ocean from the IWC’s IDCR and SOWER circumpolar programmes. These surveys have encircled the Antarctic three times: 1978/79–1983/84 (CPI), 1985/86–1990/91 (CPII) and 1991/92–2003/04 (CPIII), criss-crossing strata totalling respectively 64.3%, 79.5% and 99.7% of the open-ocean area south of 60°S. Humpback whales were absent from the Ross Sea, but were sighted in all other regions, and in particularly high densities around the Antarctic Peninsula, in Management Area IV and north of the Ross Sea. Abundance estimates are presented for each CP, for Management Areas, and for assumed summer feeding regions of each Breeding Stock. Abundance estimates are negatively biased because some whales on the trackline are missed and because some humpback whales are outside the survey region. Circumpolar estimates with approximate midpoints of 1980/81, 1987/88 and 1997/98 are 7,100 (CV = 0.36), 10,200 (CV = 0.30) and 41,500 (CV = 0.11). When these are adjusted simply for unsurveyed northern areas, the estimated annual rate of increase is 9.6% (95% CI 5.8–13.4%). All Breeding Stocks are estimated to be increasing but increase rates are significantly greater than zero only for those on the eastern and western coasts of Australia. Given the observed rates of increase, the current total Southern Hemisphere abundance is greater than 55,000, which is similar to the summed northern breeding ground estimates (~60,000 from 1999–2008). Some breeding ground abundance estimates are far greater, and others far lower, than the corresponding IDCR/SOWER estimates, in a pattern apparently related to the latitudinal position of the Antarctic Polar Front.en_ZA
dc.identifier.apacitationBranch, T. A. (2011). Humpback whale abundance south of 60°S from three complete circumpolar sets of surveys. <i>Journal of Cetacean Research and Management (Special Issue)</i>, http://hdl.handle.net/11427/17255en_ZA
dc.identifier.chicagocitationBranch, Trevor A "Humpback whale abundance south of 60°S from three complete circumpolar sets of surveys." <i>Journal of Cetacean Research and Management (Special Issue)</i> (2011) http://hdl.handle.net/11427/17255en_ZA
dc.identifier.citationBranch, T. A. (2011). Humpback whale abundance south of 60°S from three complete circumpolar sets of surveys. Journal of Cetacean Research and Management (special issue), 3, 53-69.en_ZA
dc.identifier.issn1561-0713en_ZA
dc.identifier.ris TY - Journal Article AU - Branch, Trevor A AB - Austral summer estimates of abundance are obtained for humpback whales (Megaptera novaeangliae) in the Southern Ocean from the IWC’s IDCR and SOWER circumpolar programmes. These surveys have encircled the Antarctic three times: 1978/79–1983/84 (CPI), 1985/86–1990/91 (CPII) and 1991/92–2003/04 (CPIII), criss-crossing strata totalling respectively 64.3%, 79.5% and 99.7% of the open-ocean area south of 60°S. Humpback whales were absent from the Ross Sea, but were sighted in all other regions, and in particularly high densities around the Antarctic Peninsula, in Management Area IV and north of the Ross Sea. Abundance estimates are presented for each CP, for Management Areas, and for assumed summer feeding regions of each Breeding Stock. Abundance estimates are negatively biased because some whales on the trackline are missed and because some humpback whales are outside the survey region. Circumpolar estimates with approximate midpoints of 1980/81, 1987/88 and 1997/98 are 7,100 (CV = 0.36), 10,200 (CV = 0.30) and 41,500 (CV = 0.11). When these are adjusted simply for unsurveyed northern areas, the estimated annual rate of increase is 9.6% (95% CI 5.8–13.4%). All Breeding Stocks are estimated to be increasing but increase rates are significantly greater than zero only for those on the eastern and western coasts of Australia. Given the observed rates of increase, the current total Southern Hemisphere abundance is greater than 55,000, which is similar to the summed northern breeding ground estimates (~60,000 from 1999–2008). Some breeding ground abundance estimates are far greater, and others far lower, than the corresponding IDCR/SOWER estimates, in a pattern apparently related to the latitudinal position of the Antarctic Polar Front. DA - 2011 DB - OpenUCT DP - University of Cape Town J1 - Journal of Cetacean Research and Management (Special Issue) LK - https://open.uct.ac.za PB - University of Cape Town PY - 2011 SM - 1561-0713 T1 - Humpback whale abundance south of 60°S from three complete circumpolar sets of surveys TI - Humpback whale abundance south of 60°S from three complete circumpolar sets of surveys UR - http://hdl.handle.net/11427/17255 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/17255
dc.identifier.vancouvercitationBranch TA. Humpback whale abundance south of 60°S from three complete circumpolar sets of surveys. Journal of Cetacean Research and Management (Special Issue). 2011; http://hdl.handle.net/11427/17255.en_ZA
dc.languageengen_ZA
dc.publisherInternational Whaling Commissionen_ZA
dc.publisher.departmentMarine Resource Assessment and Management Groupen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.sourceJournal of Cetacean Research and Management (Special Issue)en_ZA
dc.source.urihttps://iwc.int/journalspecial
dc.subject.otherabundance estimate
dc.subject.otherAntarctic
dc.subject.otherbreeding grounds
dc.subject.otherdistribution
dc.subject.otherfeeding grounds
dc.subject.othermonitoring
dc.titleHumpback whale abundance south of 60°S from three complete circumpolar sets of surveysen_ZA
dc.typeJournal Articleen_ZA
uct.subject.keywordsabundance estimateen_ZA
uct.subject.keywordsAntarcticen_ZA
uct.subject.keywordsbreeding groundsen_ZA
uct.subject.keywordsdistributionen_ZA
uct.subject.keywordsfeeding groundsen_ZA
uct.subject.keywordsmonitoringen_ZA
uct.subject.keywordssouthern hemisphereen_ZA
uct.subject.keywordssouthern oceanen_ZA
uct.subject.keywordssoweren_ZA
uct.subject.keywordssurvey–vesselen_ZA
uct.subject.keywordstrendsen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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