Observer experience and minke whale sighting ability in the IWC/IDCR-SOWER surveys
The relationship between observer experience and the number of minke whale schools sighted on International Whaling Commission/International Decade of Cetacean Research-Southern Ocean Whale and Ecosystem Research (IWC/IDCR-SOWER) surveys from 1993/94 to 1998/99 is investigated for Independent Observ...
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Journal of Cetacean Research and Management
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ftunivcapetownir:oai:localhost:11427/18582 2023-05-15T13:46:03+02:00 Observer experience and minke whale sighting ability in the IWC/IDCR-SOWER surveys Mori, Mitsuyo Butterworth, Doug S Brandão, Anabela Rademeyer, Rebecca A Okamura, Hiroshi Hiroyuki, Matsuda 2003 application/pdf http://hdl.handle.net/11427/18582 https://open.uct.ac.za/bitstream/11427/18582/1/Mori_Observer_2003.pdf eng eng Journal of Cetacean Research and Management University of Cape Town Faculty of Science Marine Resource Assessment and Management Group http://hdl.handle.net/11427/18582 https://open.uct.ac.za/bitstream/11427/18582/1/Mori_Observer_2003.pdf MARAM, University of Cape Town Antarctic minke whale trend g(0) surveys-vessel southern hemisphere sightings surveys abundance estimates methodology Journal Article 2003 ftunivcapetownir 2022-09-13T05:58:16Z The relationship between observer experience and the number of minke whale schools sighted on International Whaling Commission/International Decade of Cetacean Research-Southern Ocean Whale and Ecosystem Research (IWC/IDCR-SOWER) surveys from 1993/94 to 1998/99 is investigated for Independent Observer (IO) mode survey. Observer experience is defined as the number of past sightings surveys in which the observer participated. During the third circumpolar set of surveys (from 1991/92 onwards), about half of the observers had participated in fewer than five previous sightings surveys. Based upon the QAIC model selection criterion, the observers are classified into two groups depending on their experience: ‘Beginners’ (0-4 surveys) and ‘Experts’ ( > 4). The sighting rate for minke whale schools by Beginners is estimated to be 42% lower than that by Expert observers. Furthermore, perpendicular distances to the sightings do not show significant differences in relation to observer experience. These results jointly indicate that the probability of detection on the trackline, g(0), may be less than one when Beginners are amongst those observing. Abundance estimation for minke whales in IO mode involves the sightings made by triple observer combinations, with two observers in the barrel and one observer in the Independent Observer Platform (IOP) all searching simultaneously. Surprisingly, given the result above, no significant trend in sighting rate with the combined experience of this three-observer combination is detected. This might be an artifact of small sample size for some observer combinations, such as Experts in all platforms. When observer combinations in the barrel are pooled across, the estimated trend in the sighting rate with combined observer experience becomes steeper. Furthermore, when like-minke sightings are also taken into account, the trend becomes steeper still. In this case, when observations are pooled across observer combinations in the barrel, a model for sighting rate that includes an observer ... Article in Journal/Newspaper Antarc* Antarctic Antarctic Minke whale minke whale Southern Ocean University of Cape Town: OpenUCT Antarctic Southern Ocean |
institution |
Open Polar |
collection |
University of Cape Town: OpenUCT |
op_collection_id |
ftunivcapetownir |
language |
English |
topic |
Antarctic minke whale trend g(0) surveys-vessel southern hemisphere sightings surveys abundance estimates methodology |
spellingShingle |
Antarctic minke whale trend g(0) surveys-vessel southern hemisphere sightings surveys abundance estimates methodology Mori, Mitsuyo Butterworth, Doug S Brandão, Anabela Rademeyer, Rebecca A Okamura, Hiroshi Hiroyuki, Matsuda Observer experience and minke whale sighting ability in the IWC/IDCR-SOWER surveys |
topic_facet |
Antarctic minke whale trend g(0) surveys-vessel southern hemisphere sightings surveys abundance estimates methodology |
description |
The relationship between observer experience and the number of minke whale schools sighted on International Whaling Commission/International Decade of Cetacean Research-Southern Ocean Whale and Ecosystem Research (IWC/IDCR-SOWER) surveys from 1993/94 to 1998/99 is investigated for Independent Observer (IO) mode survey. Observer experience is defined as the number of past sightings surveys in which the observer participated. During the third circumpolar set of surveys (from 1991/92 onwards), about half of the observers had participated in fewer than five previous sightings surveys. Based upon the QAIC model selection criterion, the observers are classified into two groups depending on their experience: ‘Beginners’ (0-4 surveys) and ‘Experts’ ( > 4). The sighting rate for minke whale schools by Beginners is estimated to be 42% lower than that by Expert observers. Furthermore, perpendicular distances to the sightings do not show significant differences in relation to observer experience. These results jointly indicate that the probability of detection on the trackline, g(0), may be less than one when Beginners are amongst those observing. Abundance estimation for minke whales in IO mode involves the sightings made by triple observer combinations, with two observers in the barrel and one observer in the Independent Observer Platform (IOP) all searching simultaneously. Surprisingly, given the result above, no significant trend in sighting rate with the combined experience of this three-observer combination is detected. This might be an artifact of small sample size for some observer combinations, such as Experts in all platforms. When observer combinations in the barrel are pooled across, the estimated trend in the sighting rate with combined observer experience becomes steeper. Furthermore, when like-minke sightings are also taken into account, the trend becomes steeper still. In this case, when observations are pooled across observer combinations in the barrel, a model for sighting rate that includes an observer ... |
format |
Article in Journal/Newspaper |
author |
Mori, Mitsuyo Butterworth, Doug S Brandão, Anabela Rademeyer, Rebecca A Okamura, Hiroshi Hiroyuki, Matsuda |
author_facet |
Mori, Mitsuyo Butterworth, Doug S Brandão, Anabela Rademeyer, Rebecca A Okamura, Hiroshi Hiroyuki, Matsuda |
author_sort |
Mori, Mitsuyo |
title |
Observer experience and minke whale sighting ability in the IWC/IDCR-SOWER surveys |
title_short |
Observer experience and minke whale sighting ability in the IWC/IDCR-SOWER surveys |
title_full |
Observer experience and minke whale sighting ability in the IWC/IDCR-SOWER surveys |
title_fullStr |
Observer experience and minke whale sighting ability in the IWC/IDCR-SOWER surveys |
title_full_unstemmed |
Observer experience and minke whale sighting ability in the IWC/IDCR-SOWER surveys |
title_sort |
observer experience and minke whale sighting ability in the iwc/idcr-sower surveys |
publisher |
Journal of Cetacean Research and Management |
publishDate |
2003 |
url |
http://hdl.handle.net/11427/18582 https://open.uct.ac.za/bitstream/11427/18582/1/Mori_Observer_2003.pdf |
geographic |
Antarctic Southern Ocean |
geographic_facet |
Antarctic Southern Ocean |
genre |
Antarc* Antarctic Antarctic Minke whale minke whale Southern Ocean |
genre_facet |
Antarc* Antarctic Antarctic Minke whale minke whale Southern Ocean |
op_source |
MARAM, University of Cape Town |
op_relation |
http://hdl.handle.net/11427/18582 https://open.uct.ac.za/bitstream/11427/18582/1/Mori_Observer_2003.pdf |
_version_ |
1766235387563343872 |