Humpback whale abundance south of 60°S from three complete circumpolar sets of surveys
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...
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ftunivcapetownir:oai:localhost:11427/17255 2023-05-15T13:32:17+02:00 Humpback whale abundance south of 60°S from three complete circumpolar sets of surveys Branch, Trevor A 2011 application/pdf http://hdl.handle.net/11427/17255 https://open.uct.ac.za/bitstream/11427/17255/1/Branch_Humpback_whale_abundance_2011.pdf eng eng International Whaling Commission University of Cape Town Faculty of Science Marine Resource Assessment and Management Group http://hdl.handle.net/11427/17255 https://open.uct.ac.za/bitstream/11427/17255/1/Branch_Humpback_whale_abundance_2011.pdf Journal of Cetacean Research and Management (Special Issue) https://iwc.int/journalspecial abundance estimate Antarctic breeding grounds distribution feeding grounds monitoring Journal Article 2011 ftunivcapetownir 2022-09-13T05:54:02Z 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. Article in Journal/Newspaper Antarc* Antarctic Antarctic Peninsula Humpback Whale Megaptera novaeangliae Ross Sea Southern Ocean University of Cape Town: OpenUCT Antarctic Antarctic Peninsula Austral Ross Sea Southern Ocean The Antarctic |
institution |
Open Polar |
collection |
University of Cape Town: OpenUCT |
op_collection_id |
ftunivcapetownir |
language |
English |
topic |
abundance estimate Antarctic breeding grounds distribution feeding grounds monitoring |
spellingShingle |
abundance estimate Antarctic breeding grounds distribution feeding grounds monitoring Branch, Trevor A Humpback whale abundance south of 60°S from three complete circumpolar sets of surveys |
topic_facet |
abundance estimate Antarctic breeding grounds distribution feeding grounds monitoring |
description |
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. |
format |
Article in Journal/Newspaper |
author |
Branch, Trevor A |
author_facet |
Branch, Trevor A |
author_sort |
Branch, Trevor A |
title |
Humpback whale abundance south of 60°S from three complete circumpolar sets of surveys |
title_short |
Humpback whale abundance south of 60°S from three complete circumpolar sets of surveys |
title_full |
Humpback whale abundance south of 60°S from three complete circumpolar sets of surveys |
title_fullStr |
Humpback whale abundance south of 60°S from three complete circumpolar sets of surveys |
title_full_unstemmed |
Humpback whale abundance south of 60°S from three complete circumpolar sets of surveys |
title_sort |
humpback whale abundance south of 60°s from three complete circumpolar sets of surveys |
publisher |
International Whaling Commission |
publishDate |
2011 |
url |
http://hdl.handle.net/11427/17255 https://open.uct.ac.za/bitstream/11427/17255/1/Branch_Humpback_whale_abundance_2011.pdf |
geographic |
Antarctic Antarctic Peninsula Austral Ross Sea Southern Ocean The Antarctic |
geographic_facet |
Antarctic Antarctic Peninsula Austral Ross Sea Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Antarctic Peninsula Humpback Whale Megaptera novaeangliae Ross Sea Southern Ocean |
genre_facet |
Antarc* Antarctic Antarctic Peninsula Humpback Whale Megaptera novaeangliae Ross Sea Southern Ocean |
op_source |
Journal of Cetacean Research and Management (Special Issue) https://iwc.int/journalspecial |
op_relation |
http://hdl.handle.net/11427/17255 https://open.uct.ac.za/bitstream/11427/17255/1/Branch_Humpback_whale_abundance_2011.pdf |
_version_ |
1766025665162772480 |