How Many Fish Need to Be Measured to Effectively Evaluate Trawl Selectivity?
The aim of this study was to provide practitioners working with trawl selectivity with general and easily understandable guidelines regarding the fish sampling effort necessary during sea trials. In particular, we focused on how many fish would need to be caught and length measured in a trawl haul i...
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ftrepec:oai:RePEc:plo:pone00:0161512 2023-05-15T15:39:06+02:00 How Many Fish Need to Be Measured to Effectively Evaluate Trawl Selectivity? Bent Herrmann Manu Sistiaga Juan Santos Antonello Sala https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0161512 https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0161512&type=printable unknown https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0161512 https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0161512&type=printable article ftrepec 2020-12-04T13:35:35Z The aim of this study was to provide practitioners working with trawl selectivity with general and easily understandable guidelines regarding the fish sampling effort necessary during sea trials. In particular, we focused on how many fish would need to be caught and length measured in a trawl haul in order to assess the selectivity parameters of the trawl at a designated uncertainty level. We also investigated the dependency of this uncertainty level on the experimental method used to collect data and on the potential effects of factors such as the size structure in the catch relative to the size selection of the gear. We based this study on simulated data created from two different fisheries: the Barents Sea cod (Gadus morhua) trawl fishery and the Mediterranean Sea multispecies trawl fishery represented by red mullet (Mullus barbatus). We used these two completely different fisheries to obtain results that can be used as general guidelines for other fisheries. We found that the uncertainty in the selection parameters decreased with increasing number of fish measured and that this relationship could be described by a power model. The sampling effort needed to achieve a specific uncertainty level for the selection parameters was always lower for the covered codend method compared to the paired-gear method. In many cases, the number of fish that would need to be measured to maintain a specific uncertainty level was around 10 times higher for the paired-gear method than for the covered codend method. The trends observed for the effect of sampling effort in the two fishery cases investigated were similar; therefore the guidelines presented herein should be applicable to other fisheries. Article in Journal/Newspaper Barents Sea Gadus morhua RePEc (Research Papers in Economics) Barents Sea |
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The aim of this study was to provide practitioners working with trawl selectivity with general and easily understandable guidelines regarding the fish sampling effort necessary during sea trials. In particular, we focused on how many fish would need to be caught and length measured in a trawl haul in order to assess the selectivity parameters of the trawl at a designated uncertainty level. We also investigated the dependency of this uncertainty level on the experimental method used to collect data and on the potential effects of factors such as the size structure in the catch relative to the size selection of the gear. We based this study on simulated data created from two different fisheries: the Barents Sea cod (Gadus morhua) trawl fishery and the Mediterranean Sea multispecies trawl fishery represented by red mullet (Mullus barbatus). We used these two completely different fisheries to obtain results that can be used as general guidelines for other fisheries. We found that the uncertainty in the selection parameters decreased with increasing number of fish measured and that this relationship could be described by a power model. The sampling effort needed to achieve a specific uncertainty level for the selection parameters was always lower for the covered codend method compared to the paired-gear method. In many cases, the number of fish that would need to be measured to maintain a specific uncertainty level was around 10 times higher for the paired-gear method than for the covered codend method. The trends observed for the effect of sampling effort in the two fishery cases investigated were similar; therefore the guidelines presented herein should be applicable to other fisheries. |
format |
Article in Journal/Newspaper |
author |
Bent Herrmann Manu Sistiaga Juan Santos Antonello Sala |
spellingShingle |
Bent Herrmann Manu Sistiaga Juan Santos Antonello Sala How Many Fish Need to Be Measured to Effectively Evaluate Trawl Selectivity? |
author_facet |
Bent Herrmann Manu Sistiaga Juan Santos Antonello Sala |
author_sort |
Bent Herrmann |
title |
How Many Fish Need to Be Measured to Effectively Evaluate Trawl Selectivity? |
title_short |
How Many Fish Need to Be Measured to Effectively Evaluate Trawl Selectivity? |
title_full |
How Many Fish Need to Be Measured to Effectively Evaluate Trawl Selectivity? |
title_fullStr |
How Many Fish Need to Be Measured to Effectively Evaluate Trawl Selectivity? |
title_full_unstemmed |
How Many Fish Need to Be Measured to Effectively Evaluate Trawl Selectivity? |
title_sort |
how many fish need to be measured to effectively evaluate trawl selectivity? |
url |
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0161512 https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0161512&type=printable |
geographic |
Barents Sea |
geographic_facet |
Barents Sea |
genre |
Barents Sea Gadus morhua |
genre_facet |
Barents Sea Gadus morhua |
op_relation |
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0161512 https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0161512&type=printable |
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1766370544836411392 |