A three level pelagic trawl for near surface sampling of juvenile fish
In the northeast Atlantic Ocean catch rates of juvenile fish from pelagic trawls are used to calculate indices of relative abundance which are applied as a first indication of year class strength. A major constraint for a reliable time series of these indices may arise from a varying vertical fish d...
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ftimr:oai:imr.brage.unit.no:11250/105127 2023-05-15T17:41:23+02:00 A three level pelagic trawl for near surface sampling of juvenile fish Godø, Olav Rune Valdemarsen, John Willy 1993 application/pdf http://hdl.handle.net/11250/105127 eng eng ICES ICES CM Documents;1993/B:19 This report is not to be cited without prior reference to the authors http://hdl.handle.net/11250/105127 10 s. pelagic trawl pelagisk trål sampling prøvetaking juveniles yngel VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Catch: 925 Working paper 1993 ftimr 2021-09-23T20:16:05Z In the northeast Atlantic Ocean catch rates of juvenile fish from pelagic trawls are used to calculate indices of relative abundance which are applied as a first indication of year class strength. A major constraint for a reliable time series of these indices may arise from a varying vertical fish distribution, particularly near the surface due to sampling gear behaviour. In this paper a new three level trawl, which samples three separate depths simultaneously, is described in detail and catches are compared with catches from a standard juvenile survey trawl. The new trawl was highly more efficient in catching small juveniles in the near surface layers than the standard trawl. We concluded that changes in densities in this layer could significantly affect the reliability of the catch data from the standard trawl. Report Northeast Atlantic Institute for Marine Research: Brage IMR |
institution |
Open Polar |
collection |
Institute for Marine Research: Brage IMR |
op_collection_id |
ftimr |
language |
English |
topic |
pelagic trawl pelagisk trål sampling prøvetaking juveniles yngel VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Catch: 925 |
spellingShingle |
pelagic trawl pelagisk trål sampling prøvetaking juveniles yngel VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Catch: 925 Godø, Olav Rune Valdemarsen, John Willy A three level pelagic trawl for near surface sampling of juvenile fish |
topic_facet |
pelagic trawl pelagisk trål sampling prøvetaking juveniles yngel VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Catch: 925 |
description |
In the northeast Atlantic Ocean catch rates of juvenile fish from pelagic trawls are used to calculate indices of relative abundance which are applied as a first indication of year class strength. A major constraint for a reliable time series of these indices may arise from a varying vertical fish distribution, particularly near the surface due to sampling gear behaviour. In this paper a new three level trawl, which samples three separate depths simultaneously, is described in detail and catches are compared with catches from a standard juvenile survey trawl. The new trawl was highly more efficient in catching small juveniles in the near surface layers than the standard trawl. We concluded that changes in densities in this layer could significantly affect the reliability of the catch data from the standard trawl. |
format |
Report |
author |
Godø, Olav Rune Valdemarsen, John Willy |
author_facet |
Godø, Olav Rune Valdemarsen, John Willy |
author_sort |
Godø, Olav Rune |
title |
A three level pelagic trawl for near surface sampling of juvenile fish |
title_short |
A three level pelagic trawl for near surface sampling of juvenile fish |
title_full |
A three level pelagic trawl for near surface sampling of juvenile fish |
title_fullStr |
A three level pelagic trawl for near surface sampling of juvenile fish |
title_full_unstemmed |
A three level pelagic trawl for near surface sampling of juvenile fish |
title_sort |
three level pelagic trawl for near surface sampling of juvenile fish |
publisher |
ICES |
publishDate |
1993 |
url |
http://hdl.handle.net/11250/105127 |
genre |
Northeast Atlantic |
genre_facet |
Northeast Atlantic |
op_source |
10 s. |
op_relation |
ICES CM Documents;1993/B:19 This report is not to be cited without prior reference to the authors http://hdl.handle.net/11250/105127 |
_version_ |
1766142898678530048 |