Female length at sexual maturity for pygmy and Antarctic blue whales based on Soviet ovarian corpora, 1961-72

dc.contributor.authorBranch, Trevor A
dc.contributor.authorMikhalev, Y A
dc.date.accessioned2016-04-20T11:39:24Z
dc.date.available2016-04-20T11:39:24Z
dc.date.issued2007
dc.date.updated2016-04-13T07:02:01Z
dc.description.abstractFemale blue whale ovarian corpora data were translated and encoded from the USSR’s Slava (1961/62–1965/66) and Sovietskaya Ukraina (1961/62–1971/72) expeditions. Complete ovarian data were available for 1,425 blue whales (1,272 pygmy, 153 Antarctic). Catches north of 52°S were assumed to be pygmy blue whales (Balaenoptera musculus brevicauda), while those south of 56°S were assumed to be Antarctic (true) blue whales (B. m. intermedia), although there was some evidence for a small proportion (<1%) of both Antarctic blue whales north of 52°S and pygmy blue whales south of 56°S. A small proportion of lengths were rounded to the nearest metre, and many whales shorter than 18.0 were recorded as 18.0 m or greater (whale stretching). A Bayesian logistic model fitted to the data provided estimates of L50 and L95 (the lengths at which 50% and 95% of females are sexually mature). For pygmy blue whales L50 was 19.2 m (95% interval 19.1–19.3 m) and L95 was 20.5 m (95% interval 20.4–20.7 m). These estimates are more precise than those from Japanese data because the Soviet vessels recorded 32 times more pygmy blue whales shorter than the legal minimum length (21.3 m). Among small areas, L50 varied from 18.4 to 19.9 m for pygmy blue whales; all estimates were much shorter than the 23.4 m from the Antarctic. The status of northern Indian Ocean pygmy blue whales is unclear: L50 for these blue whales was statistically significantly shorter than L50 for both the southern Indian Ocean and around Australia, but the magnitude of the differences was small: 0.5–0.6 m.en_ZA
dc.identifier.apacitationBranch, T. A., & Mikhalev, Y. A. (2007). <i>Female length at sexual maturity for pygmy and Antarctic blue whales based on Soviet ovarian corpora, 1961-72</i> University of Cape Town ,Faculty of Science ,Marine Resource Assessment and Management Group. Retrieved from http://hdl.handle.net/11427/19010en_ZA
dc.identifier.chicagocitationBranch, Trevor A, and Y A Mikhalev <i>Female length at sexual maturity for pygmy and Antarctic blue whales based on Soviet ovarian corpora, 1961-72.</i> University of Cape Town ,Faculty of Science ,Marine Resource Assessment and Management Group, 2007. http://hdl.handle.net/11427/19010en_ZA
dc.identifier.citationBranch, T., & Mikhalev, Y. (2007). Female length at sexual maturity for pygmy and Antarctic blue whales based on Soviet ovarian corpora, 1961–72. IWC Doucuments.SC/59/SH7en_ZA
dc.identifier.ris TY - Working Paper AU - Branch, Trevor A AU - Mikhalev, Y A AB - Female blue whale ovarian corpora data were translated and encoded from the USSR’s Slava (1961/62–1965/66) and Sovietskaya Ukraina (1961/62–1971/72) expeditions. Complete ovarian data were available for 1,425 blue whales (1,272 pygmy, 153 Antarctic). Catches north of 52°S were assumed to be pygmy blue whales (Balaenoptera musculus brevicauda), while those south of 56°S were assumed to be Antarctic (true) blue whales (B. m. intermedia), although there was some evidence for a small proportion (<1%) of both Antarctic blue whales north of 52°S and pygmy blue whales south of 56°S. A small proportion of lengths were rounded to the nearest metre, and many whales shorter than 18.0 were recorded as 18.0 m or greater (whale stretching). A Bayesian logistic model fitted to the data provided estimates of L50 and L95 (the lengths at which 50% and 95% of females are sexually mature). For pygmy blue whales L50 was 19.2 m (95% interval 19.1–19.3 m) and L95 was 20.5 m (95% interval 20.4–20.7 m). These estimates are more precise than those from Japanese data because the Soviet vessels recorded 32 times more pygmy blue whales shorter than the legal minimum length (21.3 m). Among small areas, L50 varied from 18.4 to 19.9 m for pygmy blue whales; all estimates were much shorter than the 23.4 m from the Antarctic. The status of northern Indian Ocean pygmy blue whales is unclear: L50 for these blue whales was statistically significantly shorter than L50 for both the southern Indian Ocean and around Australia, but the magnitude of the differences was small: 0.5–0.6 m. DA - 2007 DB - OpenUCT DP - University of Cape Town J1 - International Whaling Commission LK - https://open.uct.ac.za PB - University of Cape Town PY - 2007 T1 - Female length at sexual maturity for pygmy and Antarctic blue whales based on Soviet ovarian corpora, 1961-72 TI - Female length at sexual maturity for pygmy and Antarctic blue whales based on Soviet ovarian corpora, 1961-72 UR - http://hdl.handle.net/11427/19010 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/19010
dc.identifier.vancouvercitationBranch TA, Mikhalev YA. Female length at sexual maturity for pygmy and Antarctic blue whales based on Soviet ovarian corpora, 1961-72. 2007 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/19010en_ZA
dc.languageengen_ZA
dc.publisher.departmentMarine Resource Assessment and Management Groupen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.sourceInternational Whaling Commission
dc.titleFemale length at sexual maturity for pygmy and Antarctic blue whales based on Soviet ovarian corpora, 1961-72en_ZA
dc.typeWorking Paperen_ZA
uct.type.filetypeText
uct.type.publicationResearchen_ZA
uct.type.resourceResearch paperen_ZA
Files
Original bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
Branch_Female_length_at_sexual_2007.pdf
Size:
351.42 KB
Format:
Adobe Portable Document Format
Description:
License bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
license.txt
Size:
1.72 KB
Format:
Item-specific license agreed upon to submission
Description:
Collections