Long-term trends in cetacean occurrence during the annual sardine run off the Wild Coast, South Africa
During the austral winter, cetaceans and other apex predators follow the annual northeastward movement of shoaling sardines, known as the sardine run, along the southeast coast of South Africa, including a 400-km stretch called the Wild Coast. In total, 131 opportunistic aerial surveys were conducte...
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ftjafricanj:oai:ojs.ajol.info:article/159049 2023-05-15T16:36:09+02:00 Long-term trends in cetacean occurrence during the annual sardine run off the Wild Coast, South Africa Caputo, M Froneman, PW du Preez, D Thompson, G Plön, S 2017-07-21 application/pdf https://www.ajol.info/index.php/ajms/article/view/159049 eng eng NISC https://www.ajol.info/index.php/ajms/article/view/159049/148671 https://www.ajol.info/index.php/ajms/article/view/159049 Copyright for articles published in this journal is retained by the publisher. African Journal of Marine Science; Vol 39, No 1 (2017); 83-94 1814-232X aerial survey Balaenoptera edeni Delphinus capensis Eubalaena australis Megaptera novaeangliae mysticetes Transkei region Tursiops aduncus spatial and temporal distribution info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Peer-reviewed Article 2017 ftjafricanj 2017-07-22T23:57:57Z During the austral winter, cetaceans and other apex predators follow the annual northeastward movement of shoaling sardines, known as the sardine run, along the southeast coast of South Africa, including a 400-km stretch called the Wild Coast. In total, 131 opportunistic aerial surveys were conducted between May and July, from 1996 to 2014, to monitor sardine movement. Cetacean-sighting data from these surveys were analysed, focusing on long-term trends in frequencies of the cetaceans. In total, 630 sightings involving five cetacean species were recorded: 268 (approximately 32 400 individuals) of Indo-Pacific bottlenose dolphin Tursiops aduncus, 108 (approximately 79 400 individuals) of long-beaked common dolphin Delphinus capensis, 242 (approximately 670 individuals) of humpback whale Megaptera novaeangliae, 1 (two individuals) of southern right whale Eubalaena australis, and 11 (16 individuals) of Bryde’s whale Balaenoptera edeni. The occurrence of common dolphins, typically associated with sardines, decreased significantly in average group size over the study period (p = 0.0343); bottlenose dolphins, considered generalist feeders, demonstrated no such trend (p = 0.916). Humpback whales were most frequently sighted between 2010 and 2014, and with significantly larger groups observed towards the end of the study period (p = 0.0121). For all these species, more sightings were made inside than outside of marine protected areas (>70% of the dolphin species, and >65% of the humpback whales), both pre- and post-2005 (from 2005 the size of the survey area increased). The results indicate that movements of the common dolphin may be employed as a proxy for sardine occurrence. Long-term trends evident in the data also demonstrate the importance of this coastal region for bottlenose dolphins as well as use as a migratory corridor for humpback whales.Keywords: aerial survey, Balaenoptera edeni, Delphinus capensis, Eubalaena australis, Megaptera novaeangliae, mysticetes, Transkei region, Tursiops aduncus, spatial and temporal distribution Article in Journal/Newspaper Humpback Whale Megaptera novaeangliae Southern Right Whale AJOL - African Journals Online Austral Pacific |
institution |
Open Polar |
collection |
AJOL - African Journals Online |
op_collection_id |
ftjafricanj |
language |
English |
topic |
aerial survey Balaenoptera edeni Delphinus capensis Eubalaena australis Megaptera novaeangliae mysticetes Transkei region Tursiops aduncus spatial and temporal distribution |
spellingShingle |
aerial survey Balaenoptera edeni Delphinus capensis Eubalaena australis Megaptera novaeangliae mysticetes Transkei region Tursiops aduncus spatial and temporal distribution Caputo, M Froneman, PW du Preez, D Thompson, G Plön, S Long-term trends in cetacean occurrence during the annual sardine run off the Wild Coast, South Africa |
topic_facet |
aerial survey Balaenoptera edeni Delphinus capensis Eubalaena australis Megaptera novaeangliae mysticetes Transkei region Tursiops aduncus spatial and temporal distribution |
description |
During the austral winter, cetaceans and other apex predators follow the annual northeastward movement of shoaling sardines, known as the sardine run, along the southeast coast of South Africa, including a 400-km stretch called the Wild Coast. In total, 131 opportunistic aerial surveys were conducted between May and July, from 1996 to 2014, to monitor sardine movement. Cetacean-sighting data from these surveys were analysed, focusing on long-term trends in frequencies of the cetaceans. In total, 630 sightings involving five cetacean species were recorded: 268 (approximately 32 400 individuals) of Indo-Pacific bottlenose dolphin Tursiops aduncus, 108 (approximately 79 400 individuals) of long-beaked common dolphin Delphinus capensis, 242 (approximately 670 individuals) of humpback whale Megaptera novaeangliae, 1 (two individuals) of southern right whale Eubalaena australis, and 11 (16 individuals) of Bryde’s whale Balaenoptera edeni. The occurrence of common dolphins, typically associated with sardines, decreased significantly in average group size over the study period (p = 0.0343); bottlenose dolphins, considered generalist feeders, demonstrated no such trend (p = 0.916). Humpback whales were most frequently sighted between 2010 and 2014, and with significantly larger groups observed towards the end of the study period (p = 0.0121). For all these species, more sightings were made inside than outside of marine protected areas (>70% of the dolphin species, and >65% of the humpback whales), both pre- and post-2005 (from 2005 the size of the survey area increased). The results indicate that movements of the common dolphin may be employed as a proxy for sardine occurrence. Long-term trends evident in the data also demonstrate the importance of this coastal region for bottlenose dolphins as well as use as a migratory corridor for humpback whales.Keywords: aerial survey, Balaenoptera edeni, Delphinus capensis, Eubalaena australis, Megaptera novaeangliae, mysticetes, Transkei region, Tursiops aduncus, spatial and temporal distribution |
format |
Article in Journal/Newspaper |
author |
Caputo, M Froneman, PW du Preez, D Thompson, G Plön, S |
author_facet |
Caputo, M Froneman, PW du Preez, D Thompson, G Plön, S |
author_sort |
Caputo, M |
title |
Long-term trends in cetacean occurrence during the annual sardine run off the Wild Coast, South Africa |
title_short |
Long-term trends in cetacean occurrence during the annual sardine run off the Wild Coast, South Africa |
title_full |
Long-term trends in cetacean occurrence during the annual sardine run off the Wild Coast, South Africa |
title_fullStr |
Long-term trends in cetacean occurrence during the annual sardine run off the Wild Coast, South Africa |
title_full_unstemmed |
Long-term trends in cetacean occurrence during the annual sardine run off the Wild Coast, South Africa |
title_sort |
long-term trends in cetacean occurrence during the annual sardine run off the wild coast, south africa |
publisher |
NISC |
publishDate |
2017 |
url |
https://www.ajol.info/index.php/ajms/article/view/159049 |
geographic |
Austral Pacific |
geographic_facet |
Austral Pacific |
genre |
Humpback Whale Megaptera novaeangliae Southern Right Whale |
genre_facet |
Humpback Whale Megaptera novaeangliae Southern Right Whale |
op_source |
African Journal of Marine Science; Vol 39, No 1 (2017); 83-94 1814-232X |
op_relation |
https://www.ajol.info/index.php/ajms/article/view/159049/148671 https://www.ajol.info/index.php/ajms/article/view/159049 |
op_rights |
Copyright for articles published in this journal is retained by the publisher. |
_version_ |
1766026461878157312 |