Pelagic Fish Behaviour During Trawl Sampling Off Angola
Large sardinella (Sardinella maderensis and Sardinella aurita) in warm waters off the coast of Africa are known to be a challenge for pelagic trawl sampling, for example during acoustic surveys for abundance estimation. We observed the swimming behaviour of sardinella mixed with other pelagic specie...
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Online Access: | http://hdl.handle.net/11250/109288 https://doi.org/10.2174/1874252101105010022 |
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ftimr:oai:imr.brage.unit.no:11250/109288 2023-05-15T16:18:27+02:00 Pelagic Fish Behaviour During Trawl Sampling Off Angola Haugland, Eli Kyrkjebø Misund, Ole Arve 2011-12-16 application/pdf http://hdl.handle.net/11250/109288 https://doi.org/10.2174/1874252101105010022 eng eng Bentham Open http://benthamscience.com/open/openaccess.php?tooceaj/articles/V005/22TOOCEAJ.htm urn:issn:1874-2521 http://hdl.handle.net/11250/109288 https://doi.org/10.2174/1874252101105010022 8 s. 5 The Open Oceanography Journal 1 pelagic trawl Sardinella underwater video-recording fish behaviour fish escapes VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Aquaculture: 922 Journal article Peer reviewed 2011 ftimr https://doi.org/10.2174/1874252101105010022 2021-09-23T20:14:48Z Large sardinella (Sardinella maderensis and Sardinella aurita) in warm waters off the coast of Africa are known to be a challenge for pelagic trawl sampling, for example during acoustic surveys for abundance estimation. We observed the swimming behaviour of sardinella mixed with other pelagic species, mainly Cunene horse mackerel (Trachurus trecae), during sampling with a pelagic trawl in the course of a study of swimming behaviour and endurance in the trawl belly and escape behaviour during hauling. The study consisted of two pelagic trawl surveys with R/V “Dr. Fridtjof Nansen” off the coast of Angola. We observed the fish with a trawl sonde in the trawl mouth, from a towed vehicle with sonar and camera positioned above the trawl belly or the trawl mouth, and finally with a camera with video recorder in the trawl belly. The behaviour of the fish was quantified from the video recordings by observing the swimming speed of the fish relative to the trawl and by recording the frequency of different behaviours. Two different reactions of schools were observed. We defined a “fright” reaction as a sudden reaction, where individuals swam in different directions and the collective school organisation collapsed for a few seconds. The second type of school reaction, the “adjust” reaction, did not cause the school organisation to disintegrate, but caused the whole school to gradually change its swimming direction by moving closer to one of the sides or the bottom of the trawl. The fish were also observed to swim along within the trawl for tens of minutes, possibly for up to around an hour. The main conclusion of this study is that pelagic species in warm water have the potential to actively swim forward in the trawl and escape during hauling. This could have substantial consequences for trawl sampling during surveys in terms of species- and sizedependent selectivity. Article in Journal/Newspaper Fridtjof Nansen Institute for Marine Research: Brage IMR Fridtjof ENVELOPE(-56.717,-56.717,-63.567,-63.567) The Open Oceanography Journal 5 1 22 29 |
institution |
Open Polar |
collection |
Institute for Marine Research: Brage IMR |
op_collection_id |
ftimr |
language |
English |
topic |
pelagic trawl Sardinella underwater video-recording fish behaviour fish escapes VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Aquaculture: 922 |
spellingShingle |
pelagic trawl Sardinella underwater video-recording fish behaviour fish escapes VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Aquaculture: 922 Haugland, Eli Kyrkjebø Misund, Ole Arve Pelagic Fish Behaviour During Trawl Sampling Off Angola |
topic_facet |
pelagic trawl Sardinella underwater video-recording fish behaviour fish escapes VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Aquaculture: 922 |
description |
Large sardinella (Sardinella maderensis and Sardinella aurita) in warm waters off the coast of Africa are known to be a challenge for pelagic trawl sampling, for example during acoustic surveys for abundance estimation. We observed the swimming behaviour of sardinella mixed with other pelagic species, mainly Cunene horse mackerel (Trachurus trecae), during sampling with a pelagic trawl in the course of a study of swimming behaviour and endurance in the trawl belly and escape behaviour during hauling. The study consisted of two pelagic trawl surveys with R/V “Dr. Fridtjof Nansen” off the coast of Angola. We observed the fish with a trawl sonde in the trawl mouth, from a towed vehicle with sonar and camera positioned above the trawl belly or the trawl mouth, and finally with a camera with video recorder in the trawl belly. The behaviour of the fish was quantified from the video recordings by observing the swimming speed of the fish relative to the trawl and by recording the frequency of different behaviours. Two different reactions of schools were observed. We defined a “fright” reaction as a sudden reaction, where individuals swam in different directions and the collective school organisation collapsed for a few seconds. The second type of school reaction, the “adjust” reaction, did not cause the school organisation to disintegrate, but caused the whole school to gradually change its swimming direction by moving closer to one of the sides or the bottom of the trawl. The fish were also observed to swim along within the trawl for tens of minutes, possibly for up to around an hour. The main conclusion of this study is that pelagic species in warm water have the potential to actively swim forward in the trawl and escape during hauling. This could have substantial consequences for trawl sampling during surveys in terms of species- and sizedependent selectivity. |
format |
Article in Journal/Newspaper |
author |
Haugland, Eli Kyrkjebø Misund, Ole Arve |
author_facet |
Haugland, Eli Kyrkjebø Misund, Ole Arve |
author_sort |
Haugland, Eli Kyrkjebø |
title |
Pelagic Fish Behaviour During Trawl Sampling Off Angola |
title_short |
Pelagic Fish Behaviour During Trawl Sampling Off Angola |
title_full |
Pelagic Fish Behaviour During Trawl Sampling Off Angola |
title_fullStr |
Pelagic Fish Behaviour During Trawl Sampling Off Angola |
title_full_unstemmed |
Pelagic Fish Behaviour During Trawl Sampling Off Angola |
title_sort |
pelagic fish behaviour during trawl sampling off angola |
publisher |
Bentham Open |
publishDate |
2011 |
url |
http://hdl.handle.net/11250/109288 https://doi.org/10.2174/1874252101105010022 |
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 |
8 s. 5 The Open Oceanography Journal 1 |
op_relation |
http://benthamscience.com/open/openaccess.php?tooceaj/articles/V005/22TOOCEAJ.htm urn:issn:1874-2521 http://hdl.handle.net/11250/109288 https://doi.org/10.2174/1874252101105010022 |
op_doi |
https://doi.org/10.2174/1874252101105010022 |
container_title |
The Open Oceanography Journal |
container_volume |
5 |
container_issue |
1 |
container_start_page |
22 |
op_container_end_page |
29 |
_version_ |
1766004628908933120 |