Assessing trawl-survey estimates of frequency distributions
Marine trawl surveys catch a cluster of fish at each station and fish caught together tend to have more similar characteristics, such as length, age, stomach contents etc., than those in the entire population. When this is the case, the effective sample size of estimates of the frequency distributio...
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ftimr:oai:imr.brage.unit.no:11250/106087 2023-05-15T15:38:57+02:00 Assessing trawl-survey estimates of frequency distributions Pennington, Michael Burmeister, Liza-Mare Hjellvik, Vidar 2000 application/pdf http://hdl.handle.net/11250/106087 eng eng ICES ICES CM Documents;2000/K:23 This report is not to be cited without prior reference to the authors http://hdl.handle.net/11250/106087 14 s. trawl trål sampling prøvetaking distribution utbredelse VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fisheries technology: 924 VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452 VDP::Mathematics and natural science: 400::Mathematics: 410::Analysis: 411 Working paper 2000 ftimr 2021-09-23T20:16:10Z Marine trawl surveys catch a cluster of fish at each station and fish caught together tend to have more similar characteristics, such as length, age, stomach contents etc., than those in the entire population. When this is the case, the effective sample size of estimates of the frequency distribution of a population characteristic can be much smaller than the number of fish sampled during a survey. As examples, it is shown that the effective sample size for estimates of length-frequency distributions generated by trawl surveys conducted in the Barents Sea, off Namibia and off South Africa is on average approximately one fish per tow. It is concluded that many more fish than necessary are measured at each station and that one way to increase the effective sample size for these surveys and, hence, increase the precision of the length-frequency estimates, is to reduce tow duration and use the time saved to collect samples at more stations. Report Barents Sea Institute for Marine Research: Brage IMR Barents Sea |
institution |
Open Polar |
collection |
Institute for Marine Research: Brage IMR |
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ftimr |
language |
English |
topic |
trawl trål sampling prøvetaking distribution utbredelse VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fisheries technology: 924 VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452 VDP::Mathematics and natural science: 400::Mathematics: 410::Analysis: 411 |
spellingShingle |
trawl trål sampling prøvetaking distribution utbredelse VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fisheries technology: 924 VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452 VDP::Mathematics and natural science: 400::Mathematics: 410::Analysis: 411 Pennington, Michael Burmeister, Liza-Mare Hjellvik, Vidar Assessing trawl-survey estimates of frequency distributions |
topic_facet |
trawl trål sampling prøvetaking distribution utbredelse VDP::Agriculture and fishery disciplines: 900::Fisheries science: 920::Fisheries technology: 924 VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452 VDP::Mathematics and natural science: 400::Mathematics: 410::Analysis: 411 |
description |
Marine trawl surveys catch a cluster of fish at each station and fish caught together tend to have more similar characteristics, such as length, age, stomach contents etc., than those in the entire population. When this is the case, the effective sample size of estimates of the frequency distribution of a population characteristic can be much smaller than the number of fish sampled during a survey. As examples, it is shown that the effective sample size for estimates of length-frequency distributions generated by trawl surveys conducted in the Barents Sea, off Namibia and off South Africa is on average approximately one fish per tow. It is concluded that many more fish than necessary are measured at each station and that one way to increase the effective sample size for these surveys and, hence, increase the precision of the length-frequency estimates, is to reduce tow duration and use the time saved to collect samples at more stations. |
format |
Report |
author |
Pennington, Michael Burmeister, Liza-Mare Hjellvik, Vidar |
author_facet |
Pennington, Michael Burmeister, Liza-Mare Hjellvik, Vidar |
author_sort |
Pennington, Michael |
title |
Assessing trawl-survey estimates of frequency distributions |
title_short |
Assessing trawl-survey estimates of frequency distributions |
title_full |
Assessing trawl-survey estimates of frequency distributions |
title_fullStr |
Assessing trawl-survey estimates of frequency distributions |
title_full_unstemmed |
Assessing trawl-survey estimates of frequency distributions |
title_sort |
assessing trawl-survey estimates of frequency distributions |
publisher |
ICES |
publishDate |
2000 |
url |
http://hdl.handle.net/11250/106087 |
geographic |
Barents Sea |
geographic_facet |
Barents Sea |
genre |
Barents Sea |
genre_facet |
Barents Sea |
op_source |
14 s. |
op_relation |
ICES CM Documents;2000/K:23 This report is not to be cited without prior reference to the authors http://hdl.handle.net/11250/106087 |
_version_ |
1766370390930620416 |