Gillnet selectivity for North Sea Atlantic cod ( Gadus morhua): model ambiguity and data quality are related
Gillnet selectivity curves for North Sea Atlantic cod (Gadus morhua) were fitted to catch data obtained with six different mesh sizes. The selectivity curves investigated included frequently used selectivity models following the normal, lognormal, and gamma distributions. Another group of selectivit...
Published in: | Canadian Journal of Fisheries and Aquatic Sciences |
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1999
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Online Access: | http://dx.doi.org/10.1139/f99-070 http://www.nrcresearchpress.com/doi/pdf/10.1139/f99-070 |
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crcansciencepubl:10.1139/f99-070 2024-05-19T07:37:06+00:00 Gillnet selectivity for North Sea Atlantic cod ( Gadus morhua): model ambiguity and data quality are related Hovgård, Holger Lassen, Hans Madsen, Niels Poulsen, Thomas Moth Wileman, David 1999 http://dx.doi.org/10.1139/f99-070 http://www.nrcresearchpress.com/doi/pdf/10.1139/f99-070 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Fisheries and Aquatic Sciences volume 56, issue 7, page 1307-1316 ISSN 0706-652X 1205-7533 journal-article 1999 crcansciencepubl https://doi.org/10.1139/f99-070 2024-05-02T06:51:25Z Gillnet selectivity curves for North Sea Atlantic cod (Gadus morhua) were fitted to catch data obtained with six different mesh sizes. The selectivity curves investigated included frequently used selectivity models following the normal, lognormal, and gamma distributions. Another group of selectivity models that take the method of capture (gilled, maxillae, or "randomly" enmeshed) into consideration was also included. The best description of the selection data was found for the latter models. Therefore, the capture processes and girth measurements should be recorded as a matter of routine and such data used when constructing and evaluating gillnet selectivity models. The shape of the selectivity curve for those size intervals where there were satisfactory catch information was well defined, while the selection curve was ambiguous outside the interval with adequate data. Ambiguities in the shape of the selectivity curve can be diminished by choosing an appropriate range in mesh sizes and ensuring that the mesh sizes match the size distribution of the population fished. It is furthermore suggested that the estimated length distribution of the fish encountering the nets be robust to misspecification of the selectivity model. Article in Journal/Newspaper atlantic cod Gadus morhua Canadian Science Publishing Canadian Journal of Fisheries and Aquatic Sciences 56 7 1307 1316 |
institution |
Open Polar |
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Canadian Science Publishing |
op_collection_id |
crcansciencepubl |
language |
English |
description |
Gillnet selectivity curves for North Sea Atlantic cod (Gadus morhua) were fitted to catch data obtained with six different mesh sizes. The selectivity curves investigated included frequently used selectivity models following the normal, lognormal, and gamma distributions. Another group of selectivity models that take the method of capture (gilled, maxillae, or "randomly" enmeshed) into consideration was also included. The best description of the selection data was found for the latter models. Therefore, the capture processes and girth measurements should be recorded as a matter of routine and such data used when constructing and evaluating gillnet selectivity models. The shape of the selectivity curve for those size intervals where there were satisfactory catch information was well defined, while the selection curve was ambiguous outside the interval with adequate data. Ambiguities in the shape of the selectivity curve can be diminished by choosing an appropriate range in mesh sizes and ensuring that the mesh sizes match the size distribution of the population fished. It is furthermore suggested that the estimated length distribution of the fish encountering the nets be robust to misspecification of the selectivity model. |
format |
Article in Journal/Newspaper |
author |
Hovgård, Holger Lassen, Hans Madsen, Niels Poulsen, Thomas Moth Wileman, David |
spellingShingle |
Hovgård, Holger Lassen, Hans Madsen, Niels Poulsen, Thomas Moth Wileman, David Gillnet selectivity for North Sea Atlantic cod ( Gadus morhua): model ambiguity and data quality are related |
author_facet |
Hovgård, Holger Lassen, Hans Madsen, Niels Poulsen, Thomas Moth Wileman, David |
author_sort |
Hovgård, Holger |
title |
Gillnet selectivity for North Sea Atlantic cod ( Gadus morhua): model ambiguity and data quality are related |
title_short |
Gillnet selectivity for North Sea Atlantic cod ( Gadus morhua): model ambiguity and data quality are related |
title_full |
Gillnet selectivity for North Sea Atlantic cod ( Gadus morhua): model ambiguity and data quality are related |
title_fullStr |
Gillnet selectivity for North Sea Atlantic cod ( Gadus morhua): model ambiguity and data quality are related |
title_full_unstemmed |
Gillnet selectivity for North Sea Atlantic cod ( Gadus morhua): model ambiguity and data quality are related |
title_sort |
gillnet selectivity for north sea atlantic cod ( gadus morhua): model ambiguity and data quality are related |
publisher |
Canadian Science Publishing |
publishDate |
1999 |
url |
http://dx.doi.org/10.1139/f99-070 http://www.nrcresearchpress.com/doi/pdf/10.1139/f99-070 |
genre |
atlantic cod Gadus morhua |
genre_facet |
atlantic cod Gadus morhua |
op_source |
Canadian Journal of Fisheries and Aquatic Sciences volume 56, issue 7, page 1307-1316 ISSN 0706-652X 1205-7533 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/f99-070 |
container_title |
Canadian Journal of Fisheries and Aquatic Sciences |
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56 |
container_issue |
7 |
container_start_page |
1307 |
op_container_end_page |
1316 |
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1799476337616879616 |