Killer whales (Orcinus orca) at Marion Island, Southern Ocean
Killer whales (Orcinus orca) were studied using data obtained on an opportunistic basis between 1973 and 1996 at Marion Island (46°54’S, 37°45’E) in the Southern Indian Ocean. A clear seasonal pattern of occurrence with the main peak between October and December was evident. Most killer whales were...
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ftjafricanj:oai:ojs.ajol.info:article/155357 2023-05-15T17:10:19+02:00 Killer whales (Orcinus orca) at Marion Island, Southern Ocean Keith, M. Bester, M.N. Bartlett, P.A. Baker, D. 2017-04-26 application/pdf https://www.ajol.info/index.php/az/article/view/155357 eng eng NISC (Pty) Ltd https://www.ajol.info/index.php/az/article/view/155357/144982 https://www.ajol.info/index.php/az/article/view/155357 The copyright belongs to the Zoological Society of Southern Africa. African Zoology; Vol 36, No 2 (2001); 163–175 2224-073X 1562-7020 population structure seasonal patterns photogrammetry info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Peer-reviewed Article 2017 ftjafricanj 2017-04-29T23:57:25Z Killer whales (Orcinus orca) were studied using data obtained on an opportunistic basis between 1973 and 1996 at Marion Island (46°54’S, 37°45’E) in the Southern Indian Ocean. A clear seasonal pattern of occurrence with the main peak between October and December was evident. Most killer whales were observed within 5 m of the shore and adult males typically occurred further offshore than adult females. The distribution of killer whales around the island was not uniform and more than 80 % of all sightings occurred close to the base station. This was probably due to a concentration of search effort in the vicinity of the base station and to an uneven distribution of prey species. Killer whales occurred in groups with an average of 3.56 individuals and a maximum of 28 animals per group; females predominated throughout the study. Dawn-to-dusk surveys of killer whales in the near-shore waters during 1986, 1989 and 1990 showed small, statistically non-significant peaks of sightings in the early morning and late afternoon. Twenty-six killer whales were individually identified from photographs, eleven of which recurred at Marion Island. Modified photogrammetric methods may improve current photogrammetric analysis of cetacean dorsal fins.Key words: population structure; seasonal patterns, photogrammetry. Article in Journal/Newspaper Marion Island Orca Orcinus orca Southern Ocean AJOL - African Journals Online Southern Ocean Indian |
institution |
Open Polar |
collection |
AJOL - African Journals Online |
op_collection_id |
ftjafricanj |
language |
English |
topic |
population structure seasonal patterns photogrammetry |
spellingShingle |
population structure seasonal patterns photogrammetry Keith, M. Bester, M.N. Bartlett, P.A. Baker, D. Killer whales (Orcinus orca) at Marion Island, Southern Ocean |
topic_facet |
population structure seasonal patterns photogrammetry |
description |
Killer whales (Orcinus orca) were studied using data obtained on an opportunistic basis between 1973 and 1996 at Marion Island (46°54’S, 37°45’E) in the Southern Indian Ocean. A clear seasonal pattern of occurrence with the main peak between October and December was evident. Most killer whales were observed within 5 m of the shore and adult males typically occurred further offshore than adult females. The distribution of killer whales around the island was not uniform and more than 80 % of all sightings occurred close to the base station. This was probably due to a concentration of search effort in the vicinity of the base station and to an uneven distribution of prey species. Killer whales occurred in groups with an average of 3.56 individuals and a maximum of 28 animals per group; females predominated throughout the study. Dawn-to-dusk surveys of killer whales in the near-shore waters during 1986, 1989 and 1990 showed small, statistically non-significant peaks of sightings in the early morning and late afternoon. Twenty-six killer whales were individually identified from photographs, eleven of which recurred at Marion Island. Modified photogrammetric methods may improve current photogrammetric analysis of cetacean dorsal fins.Key words: population structure; seasonal patterns, photogrammetry. |
format |
Article in Journal/Newspaper |
author |
Keith, M. Bester, M.N. Bartlett, P.A. Baker, D. |
author_facet |
Keith, M. Bester, M.N. Bartlett, P.A. Baker, D. |
author_sort |
Keith, M. |
title |
Killer whales (Orcinus orca) at Marion Island, Southern Ocean |
title_short |
Killer whales (Orcinus orca) at Marion Island, Southern Ocean |
title_full |
Killer whales (Orcinus orca) at Marion Island, Southern Ocean |
title_fullStr |
Killer whales (Orcinus orca) at Marion Island, Southern Ocean |
title_full_unstemmed |
Killer whales (Orcinus orca) at Marion Island, Southern Ocean |
title_sort |
killer whales (orcinus orca) at marion island, southern ocean |
publisher |
NISC (Pty) Ltd |
publishDate |
2017 |
url |
https://www.ajol.info/index.php/az/article/view/155357 |
geographic |
Southern Ocean Indian |
geographic_facet |
Southern Ocean Indian |
genre |
Marion Island Orca Orcinus orca Southern Ocean |
genre_facet |
Marion Island Orca Orcinus orca Southern Ocean |
op_source |
African Zoology; Vol 36, No 2 (2001); 163–175 2224-073X 1562-7020 |
op_relation |
https://www.ajol.info/index.php/az/article/view/155357/144982 https://www.ajol.info/index.php/az/article/view/155357 |
op_rights |
The copyright belongs to the Zoological Society of Southern Africa. |
_version_ |
1766066910903926784 |