Assessing the precision of frequency distributions estimated from trawl-survey samples
In trawl surveys a cluster of fish are caught 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 for estimates of the frequency distribu...
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ftoceandocs:oai:aquadocs.org:1834/31044 2023-05-15T15:38:55+02:00 Assessing the precision of frequency distributions estimated from trawl-survey samples Pennington, Michael Burmeister, Liza-Mare Hjellvik, Vidar 2002 application/pdf 74-80 http://hdl.handle.net/1834/31044 en eng http://fishbull.noaa.gov/1001/pen.pdf 0090-0656 http://hdl.handle.net/1834/31044 http://aquaticcommons.org/id/eprint/15191 403 2014-05-30 07:10:53 15191 United States National Marine Fisheries Service Fisheries Management article TRUE 2002 ftoceandocs 2023-04-06T17:04:19Z In trawl surveys a cluster of fish are caught 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 for estimates of the frequency distribution of a population characteristic can, therefore, 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. Thus many more fish than necessary are measured at each station (location). 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. Article in Journal/Newspaper Barents Sea IODE-UNESCO: OceanDocs - E-Repository of Ocean Publications Barents Sea |
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Open Polar |
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IODE-UNESCO: OceanDocs - E-Repository of Ocean Publications |
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ftoceandocs |
language |
English |
topic |
Fisheries Management |
spellingShingle |
Fisheries Management Pennington, Michael Burmeister, Liza-Mare Hjellvik, Vidar Assessing the precision of frequency distributions estimated from trawl-survey samples |
topic_facet |
Fisheries Management |
description |
In trawl surveys a cluster of fish are caught 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 for estimates of the frequency distribution of a population characteristic can, therefore, 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. Thus many more fish than necessary are measured at each station (location). 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 |
Article in Journal/Newspaper |
author |
Pennington, Michael Burmeister, Liza-Mare Hjellvik, Vidar |
author_facet |
Pennington, Michael Burmeister, Liza-Mare Hjellvik, Vidar |
author_sort |
Pennington, Michael |
title |
Assessing the precision of frequency distributions estimated from trawl-survey samples |
title_short |
Assessing the precision of frequency distributions estimated from trawl-survey samples |
title_full |
Assessing the precision of frequency distributions estimated from trawl-survey samples |
title_fullStr |
Assessing the precision of frequency distributions estimated from trawl-survey samples |
title_full_unstemmed |
Assessing the precision of frequency distributions estimated from trawl-survey samples |
title_sort |
assessing the precision of frequency distributions estimated from trawl-survey samples |
publishDate |
2002 |
url |
http://hdl.handle.net/1834/31044 |
geographic |
Barents Sea |
geographic_facet |
Barents Sea |
genre |
Barents Sea |
genre_facet |
Barents Sea |
op_source |
http://aquaticcommons.org/id/eprint/15191 403 2014-05-30 07:10:53 15191 United States National Marine Fisheries Service |
op_relation |
http://fishbull.noaa.gov/1001/pen.pdf 0090-0656 http://hdl.handle.net/1834/31044 |
_version_ |
1766370327016767488 |