Separating southern blue whale subspecies based on length frequencies of sexually mature females

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dc.contributor.authorBranch, Trevor A
dc.contributor.authorAbubaker, E M N
dc.contributor.authorMkango, S
dc.contributor.authorButterworth, Doug S
dc.date.accessioned2016-02-26T07:51:17Z
dc.date.available2016-02-26T07:51:17Z
dc.date.issued2007
dc.date.updated2016-02-25T09:05:30Z
dc.description.abstractWhen sexually mature, Antarctic (true) blue whales are substantially longer than pygmy blue whales. To estimate the proportions of these two subspecies in various regions, Bayesian mixture models were fitted to catch length frequencies of sexually mature females. The extent of rounding to 5-ft intervals was also estimated. Antarctic blue whales dominated (99.2%) pelagic catches south of 52°S, whereas pygmy blue whales dominated (99.9%) north of 52°S and in 35°–180°E. South of 60°S, only 0.7% (95% credibility interval 0.5%–1.0%) were pygmy blue whales, lower than the 7% upper bound currently assumed. Shore-based catches from SW Africa and those before 1937 from South Georgia and the South Shetlands were estimated to contain 90%–92% Antarctic blue whales. Actual proportions were probably higher, but these data show evidence of rounding (up to 19% of records), poor length-estimation methods, and other problems. The mean length of sexually mature female Chilean blue whales (77.1 ft, 23.5 m) was intermediate between pygmy (68.9 ft, 21.0 m) and Antarctic blue whales (83.4–86.3 ft, 25.4–26.6 m). A good fit to these data was obtained only by assuming that the Chilean whales are a separate subspecies or distinctive population. This finding is also consistent with their discrete distribution, and genetic and call type differences, compared to Antarctic and pygmy blue whales.en_ZA
dc.identifierhttp://dx.doi.org/10.1111/j.1748-7692.2007.00137.x
dc.identifier.apacitationBranch, T. A., Abubaker, E. M. N., Mkango, S., & Butterworth, D. S. (2007). Separating southern blue whale subspecies based on length frequencies of sexually mature females. <i>Marine Mammal Science</i>, http://hdl.handle.net/11427/17290en_ZA
dc.identifier.chicagocitationBranch, Trevor A, E M N Abubaker, S Mkango, and Doug S Butterworth "Separating southern blue whale subspecies based on length frequencies of sexually mature females." <i>Marine Mammal Science</i> (2007) http://hdl.handle.net/11427/17290en_ZA
dc.identifier.citationBranch, T. A., Abubaker, E. M. N., Mkango, S., & Butterworth, D. S. (2007). Separating southern blue whale subspecies based on length frequencies of sexually mature females. Marine Mammal Science, 23(4), 803-833.en_ZA
dc.identifier.issn0824-0469en_ZA
dc.identifier.ris TY - Journal Article AU - Branch, Trevor A AU - Abubaker, E M N AU - Mkango, S AU - Butterworth, Doug S AB - When sexually mature, Antarctic (true) blue whales are substantially longer than pygmy blue whales. To estimate the proportions of these two subspecies in various regions, Bayesian mixture models were fitted to catch length frequencies of sexually mature females. The extent of rounding to 5-ft intervals was also estimated. Antarctic blue whales dominated (99.2%) pelagic catches south of 52°S, whereas pygmy blue whales dominated (99.9%) north of 52°S and in 35°–180°E. South of 60°S, only 0.7% (95% credibility interval 0.5%–1.0%) were pygmy blue whales, lower than the 7% upper bound currently assumed. Shore-based catches from SW Africa and those before 1937 from South Georgia and the South Shetlands were estimated to contain 90%–92% Antarctic blue whales. Actual proportions were probably higher, but these data show evidence of rounding (up to 19% of records), poor length-estimation methods, and other problems. The mean length of sexually mature female Chilean blue whales (77.1 ft, 23.5 m) was intermediate between pygmy (68.9 ft, 21.0 m) and Antarctic blue whales (83.4–86.3 ft, 25.4–26.6 m). A good fit to these data was obtained only by assuming that the Chilean whales are a separate subspecies or distinctive population. This finding is also consistent with their discrete distribution, and genetic and call type differences, compared to Antarctic and pygmy blue whales. DA - 2007 DB - OpenUCT DP - University of Cape Town J1 - Marine Mammal Science LK - https://open.uct.ac.za PB - University of Cape Town PY - 2007 SM - 0824-0469 T1 - Separating southern blue whale subspecies based on length frequencies of sexually mature females TI - Separating southern blue whale subspecies based on length frequencies of sexually mature females UR - http://hdl.handle.net/11427/17290 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/17290
dc.identifier.vancouvercitationBranch TA, Abubaker EMN, Mkango S, Butterworth DS. Separating southern blue whale subspecies based on length frequencies of sexually mature females. Marine Mammal Science. 2007; http://hdl.handle.net/11427/17290.en_ZA
dc.languageengen_ZA
dc.publisherWileyen_ZA
dc.publisher.departmentMarine Resource Assessment and Management Groupen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.sourceMarine Mammal Scienceen_ZA
dc.source.urihttp://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1748-7692
dc.subject.otherbalaenoptera musculus intermedia
dc.subject.otherB. m. brevicauda
dc.subject.otherblue whale
dc.subject.othermixture models
dc.subject.otherBayesian
dc.titleSeparating southern blue whale subspecies based on length frequencies of sexually mature femalesen_ZA
dc.typeJournal Articleen_ZA
uct.subject.keywordsBalaenoptera musculus intermediaen_ZA
uct.subject.keywordsB. m. brevicaudaen_ZA
uct.subject.keywordsBlue whaleen_ZA
uct.subject.keywordsMixture modelsen_ZA
uct.subject.keywordsBayesianen_ZA
uct.subject.keywordsLength frequenciesen_ZA
uct.subject.keywordsJackknife analysisen_ZA
uct.subject.keywordsSubspeciesen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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