Observations on the near-surface behaviour of sardinella schools in Angolan waters
The schooling dynamics and swimming behaviour of sardinella Sardinella maderensis and S. aurita schooling near the surface in Angolan waters were recorded visually, using a calibrated echo integration system and a 95kHz high resolution sonar on board RV Dr Fridtjof Nansen during three cruises; July...
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ftjafricanj:oai:ojs.ajol.info:article/33210 2023-05-15T16:18:27+02:00 Observations on the near-surface behaviour of sardinella schools in Angolan waters Misund, O A Luyeye, N Boyer, D Coetzee, J Cloete, R Dalen, J Oechslin, G 2005-06-30 application/pdf http://www.ajol.info/index.php/ajms/article/view/33210 eng eng NISC http://www.ajol.info/index.php/ajms/article/view/33210/24191 http://www.ajol.info/index.php/ajms/article/view/33210 Copyright for articles published in this journal is retained by the publisher. African Journal of Marine Science; Vol 27, No 1 (2005); 169-176 1814-232X behaviour sardinella schooling sightings sonar info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Peer-reviewed Article 2005 ftjafricanj 2017-03-05T06:32:21Z The schooling dynamics and swimming behaviour of sardinella Sardinella maderensis and S. aurita schooling near the surface in Angolan waters were recorded visually, using a calibrated echo integration system and a 95kHz high resolution sonar on board RV Dr Fridtjof Nansen during three cruises; July 1996, May 1997 and May 1998. The mean packing density of the sardinella schools was about 3 fish m–3, but this figure varied by two orders of magnitude among the schools. There was a linear relationship between the area and the biomass of the schools, which can be used in future surveys to convert recordings of school area by camera, lidar or sonar to school biomass. The sardinella schools swam at an average horizontal speed of 1.24m s–1, mostly towards or away from the coast. The schools seemed to be feeding near the surface and behaved rather dynamically. Intra-school events such as change of shape, reorganisation, splitting and leaving occurred every 2.4 minutes on average. Inter-school events such as approach and join was every 14.2 minutes on average. The schools were visible on the surface in the morning and in the afternoon, but seemed remarkably undisturbed by predating birds, fish and seals during the day. It is suggested that the low predation activity near the surface enables the sardinella to exploit plankton prey that is concentrated at surface fronts of internal waves and along the convergence lines of coastal and oceanic currents. African Journal of Marine Science 2005, 27(1): 169–176 Article in Journal/Newspaper Fridtjof Nansen AJOL - African Journals Online Fridtjof ENVELOPE(-56.717,-56.717,-63.567,-63.567) |
institution |
Open Polar |
collection |
AJOL - African Journals Online |
op_collection_id |
ftjafricanj |
language |
English |
topic |
behaviour sardinella schooling sightings sonar |
spellingShingle |
behaviour sardinella schooling sightings sonar Misund, O A Luyeye, N Boyer, D Coetzee, J Cloete, R Dalen, J Oechslin, G Observations on the near-surface behaviour of sardinella schools in Angolan waters |
topic_facet |
behaviour sardinella schooling sightings sonar |
description |
The schooling dynamics and swimming behaviour of sardinella Sardinella maderensis and S. aurita schooling near the surface in Angolan waters were recorded visually, using a calibrated echo integration system and a 95kHz high resolution sonar on board RV Dr Fridtjof Nansen during three cruises; July 1996, May 1997 and May 1998. The mean packing density of the sardinella schools was about 3 fish m–3, but this figure varied by two orders of magnitude among the schools. There was a linear relationship between the area and the biomass of the schools, which can be used in future surveys to convert recordings of school area by camera, lidar or sonar to school biomass. The sardinella schools swam at an average horizontal speed of 1.24m s–1, mostly towards or away from the coast. The schools seemed to be feeding near the surface and behaved rather dynamically. Intra-school events such as change of shape, reorganisation, splitting and leaving occurred every 2.4 minutes on average. Inter-school events such as approach and join was every 14.2 minutes on average. The schools were visible on the surface in the morning and in the afternoon, but seemed remarkably undisturbed by predating birds, fish and seals during the day. It is suggested that the low predation activity near the surface enables the sardinella to exploit plankton prey that is concentrated at surface fronts of internal waves and along the convergence lines of coastal and oceanic currents. African Journal of Marine Science 2005, 27(1): 169–176 |
format |
Article in Journal/Newspaper |
author |
Misund, O A Luyeye, N Boyer, D Coetzee, J Cloete, R Dalen, J Oechslin, G |
author_facet |
Misund, O A Luyeye, N Boyer, D Coetzee, J Cloete, R Dalen, J Oechslin, G |
author_sort |
Misund, O A |
title |
Observations on the near-surface behaviour of sardinella schools in Angolan waters |
title_short |
Observations on the near-surface behaviour of sardinella schools in Angolan waters |
title_full |
Observations on the near-surface behaviour of sardinella schools in Angolan waters |
title_fullStr |
Observations on the near-surface behaviour of sardinella schools in Angolan waters |
title_full_unstemmed |
Observations on the near-surface behaviour of sardinella schools in Angolan waters |
title_sort |
observations on the near-surface behaviour of sardinella schools in angolan waters |
publisher |
NISC |
publishDate |
2005 |
url |
http://www.ajol.info/index.php/ajms/article/view/33210 |
long_lat |
ENVELOPE(-56.717,-56.717,-63.567,-63.567) |
geographic |
Fridtjof |
geographic_facet |
Fridtjof |
genre |
Fridtjof Nansen |
genre_facet |
Fridtjof Nansen |
op_source |
African Journal of Marine Science; Vol 27, No 1 (2005); 169-176 1814-232X |
op_relation |
http://www.ajol.info/index.php/ajms/article/view/33210/24191 http://www.ajol.info/index.php/ajms/article/view/33210 |
op_rights |
Copyright for articles published in this journal is retained by the publisher. |
_version_ |
1766004621892911104 |