Abundance of Antarctic blue whales south of 60°S from three complete circumpolar sets of surveys

Simple item page
dc.contributor.authorBranch, Trevor A
dc.date.accessioned2016-02-25T12:49:06Z
dc.date.available2016-02-25T12:49:06Z
dc.date.issued2007
dc.date.updated2016-02-25T09:48:17Z
dc.description.abstractSightings from the IDCR/SOWER austral summer surveys are analysed to provide abundance estimates for Antarctic (true) blue whales (Balaenoptera musculus intermedia) south of 60°S. The IDCR/SOWER ship-borne surveys have completely circled the Antarctic three times: 1978/79-1983/84 (CPI); 1985/86-1990/91 (CPII); and 1991/92-2003/04 (CPIII), covering strata totalling 64.3%, 79.5% and 99.7% of the ocean surface between the pack ice and 60°S. During the surveys, blue whale sightings were rare but were recorded in all regions. Raw sighting rates (schools per 1,000 n.mile of primary search effort) were 0.44 (CPI), 0.67 (CPII) and 1.48 (CPIII). Respective circumpolar abundance estimates were 453 (CV=0.40), 559 (CV=0.47) and 2,280 (CV=0.36), with corresponding mid-years of 1981, 1988 and 1998. The CPIII estimates are the most complete and recent for this subspecies. When adjusted for unsurveyed regions in a simple way, the estimated circumpolar rate of increase is 8.2% (95% CI=1.6–14.8%) per year; nevertheless, Antarctic blue whales still number far less than the estimated 202,000-311,000 that existed before exploitation. These abundance estimates are negatively biased because some Antarctic blue whales may have been north of 60°S or in the pack ice at the time of the surveys and because a small number of blue whales on the trackline were probably missed. Furthermore, a small proportion of pygmy blue whales, probably less than 1%, may have been included in the sightings.en_ZA
dc.identifier.apacitationBranch, T. A. (2007). Abundance of Antarctic blue whales south of 60°S from three complete circumpolar sets of surveys. <i>Journal of Cetacean Research and Management</i>, http://hdl.handle.net/11427/17261en_ZA
dc.identifier.chicagocitationBranch, Trevor A "Abundance of Antarctic blue whales south of 60°S from three complete circumpolar sets of surveys." <i>Journal of Cetacean Research and Management</i> (2007) http://hdl.handle.net/11427/17261en_ZA
dc.identifier.citationBranch, T. A. (2007). 253 Abundance of Antarctic blue whales south of 60 S from three complete circumpolar sets of surveys. J. Cetacean Res. Manage, 9(3), 253-262.en_ZA
dc.identifier.issn1561-0713en_ZA
dc.identifier.ris TY - Journal Article AU - Branch, Trevor A AB - Sightings from the IDCR/SOWER austral summer surveys are analysed to provide abundance estimates for Antarctic (true) blue whales (Balaenoptera musculus intermedia) south of 60°S. The IDCR/SOWER ship-borne surveys have completely circled the Antarctic three times: 1978/79-1983/84 (CPI); 1985/86-1990/91 (CPII); and 1991/92-2003/04 (CPIII), covering strata totalling 64.3%, 79.5% and 99.7% of the ocean surface between the pack ice and 60°S. During the surveys, blue whale sightings were rare but were recorded in all regions. Raw sighting rates (schools per 1,000 n.mile of primary search effort) were 0.44 (CPI), 0.67 (CPII) and 1.48 (CPIII). Respective circumpolar abundance estimates were 453 (CV=0.40), 559 (CV=0.47) and 2,280 (CV=0.36), with corresponding mid-years of 1981, 1988 and 1998. The CPIII estimates are the most complete and recent for this subspecies. When adjusted for unsurveyed regions in a simple way, the estimated circumpolar rate of increase is 8.2% (95% CI=1.6–14.8%) per year; nevertheless, Antarctic blue whales still number far less than the estimated 202,000-311,000 that existed before exploitation. These abundance estimates are negatively biased because some Antarctic blue whales may have been north of 60°S or in the pack ice at the time of the surveys and because a small number of blue whales on the trackline were probably missed. Furthermore, a small proportion of pygmy blue whales, probably less than 1%, may have been included in the sightings. DA - 2007 DB - OpenUCT DP - University of Cape Town J1 - Journal of Cetacean Research and Management LK - https://open.uct.ac.za PB - University of Cape Town PY - 2007 SM - 1561-0713 T1 - Abundance of Antarctic blue whales south of 60°S from three complete circumpolar sets of surveys TI - Abundance of Antarctic blue whales south of 60°S from three complete circumpolar sets of surveys UR - http://hdl.handle.net/11427/17261 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/17261
dc.identifier.vancouvercitationBranch TA. Abundance of Antarctic blue whales south of 60°S from three complete circumpolar sets of surveys. Journal of Cetacean Research and Management. 2007; http://hdl.handle.net/11427/17261.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 Managementen_ZA
dc.source.urihttps://iwc.int/jcrm
dc.subject.otherblue whale
dc.subject.othersower
dc.subject.otherwhaling-historical
dc.subject.otherAntarctic
dc.subject.othersouthern hemisphere
dc.subject.othersurvey-vessel
dc.subject.otherabundance estimate
dc.titleAbundance of Antarctic blue whales south of 60°S from three complete circumpolar sets of surveysen_ZA
dc.typeJournal Articleen_ZA
uct.subject.keywordsblue whaleen_ZA
uct.subject.keywordssoweren_ZA
uct.subject.keywordswhaling-historicalen_ZA
uct.subject.keywordsAntarcticen_ZA
uct.subject.keywordssouthern hemisphereen_ZA
uct.subject.keywordssurvey-vesselen_ZA
uct.subject.keywordsabundance estimateen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
Branch_Abundance_Antarctic_blue_2007.pdf
Size:
2.21 MB
Format:
Adobe Portable Document Format
Description:
Download
License bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
license.txt
Size:
1.72 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
Journal Articles