Corrections of indices of abundance of 0-group fish in the Barents Sea for varying capture efficiency
Each year since 1965 "The International 0-group Survey in the Barents Sea and Adjacent Waters" has provided indices of abundance of 0-group fish. During the 30 years of operation of the survey large improvements in capture efficiency have been introduced including larger trawls, instrument...
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ftimr:oai:imr.brage.unit.no:11250/100331 2023-05-15T15:38:40+02:00 Corrections of indices of abundance of 0-group fish in the Barents Sea for varying capture efficiency Nakken, Odd Raknes, Askjell 1996 417175 bytes application/pdf http://hdl.handle.net/11250/100331 eng eng ICES ICES CM documents 1996/G:12 This report is not to be quoted without prior consultation with the General Secretary. http://hdl.handle.net/11250/100331 10 s. 0-gruppe 0-group VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920 Working paper 1996 ftimr 2021-09-23T20:15:38Z Each year since 1965 "The International 0-group Survey in the Barents Sea and Adjacent Waters" has provided indices of abundance of 0-group fish. During the 30 years of operation of the survey large improvements in capture efficiency have been introduced including larger trawls, instrumentation for monitoring trawl depth and geometry and larger and better equipped vessels. The time series of survey indices indicate an increasing trend throughout the period and thus it seemed reasonable that the improvements have effected the level of the abundance indices. The present work is an attempt to correct the indices of abundance so that the comparability of indices from different parts of the time series is maintained. Corrections were made following two lines of approach: 1. Assuming that the annual average capture efficiency had increased proportional to the increase of the average area ofthe trawl mouth (opening). 2. Assuming that the main trend in the sum of indices of cod, haddock and redfish reflects the trend in overall capture efficiency. Both methods generated a substantial increase in the indices for the early part of the time series. Report Barents Sea Institute for Marine Research: Brage IMR Barents Sea |
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Open Polar |
collection |
Institute for Marine Research: Brage IMR |
op_collection_id |
ftimr |
language |
English |
topic |
0-gruppe 0-group VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920 |
spellingShingle |
0-gruppe 0-group VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920 Nakken, Odd Raknes, Askjell Corrections of indices of abundance of 0-group fish in the Barents Sea for varying capture efficiency |
topic_facet |
0-gruppe 0-group VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920 |
description |
Each year since 1965 "The International 0-group Survey in the Barents Sea and Adjacent Waters" has provided indices of abundance of 0-group fish. During the 30 years of operation of the survey large improvements in capture efficiency have been introduced including larger trawls, instrumentation for monitoring trawl depth and geometry and larger and better equipped vessels. The time series of survey indices indicate an increasing trend throughout the period and thus it seemed reasonable that the improvements have effected the level of the abundance indices. The present work is an attempt to correct the indices of abundance so that the comparability of indices from different parts of the time series is maintained. Corrections were made following two lines of approach: 1. Assuming that the annual average capture efficiency had increased proportional to the increase of the average area ofthe trawl mouth (opening). 2. Assuming that the main trend in the sum of indices of cod, haddock and redfish reflects the trend in overall capture efficiency. Both methods generated a substantial increase in the indices for the early part of the time series. |
format |
Report |
author |
Nakken, Odd Raknes, Askjell |
author_facet |
Nakken, Odd Raknes, Askjell |
author_sort |
Nakken, Odd |
title |
Corrections of indices of abundance of 0-group fish in the Barents Sea for varying capture efficiency |
title_short |
Corrections of indices of abundance of 0-group fish in the Barents Sea for varying capture efficiency |
title_full |
Corrections of indices of abundance of 0-group fish in the Barents Sea for varying capture efficiency |
title_fullStr |
Corrections of indices of abundance of 0-group fish in the Barents Sea for varying capture efficiency |
title_full_unstemmed |
Corrections of indices of abundance of 0-group fish in the Barents Sea for varying capture efficiency |
title_sort |
corrections of indices of abundance of 0-group fish in the barents sea for varying capture efficiency |
publisher |
ICES |
publishDate |
1996 |
url |
http://hdl.handle.net/11250/100331 |
geographic |
Barents Sea |
geographic_facet |
Barents Sea |
genre |
Barents Sea |
genre_facet |
Barents Sea |
op_source |
10 s. |
op_relation |
ICES CM documents 1996/G:12 This report is not to be quoted without prior consultation with the General Secretary. http://hdl.handle.net/11250/100331 |
_version_ |
1766369893084561408 |