Inclusion of discards in stock assessment models
Abstract A large portion of the catch in many stocks may comprise discards which need to be accounted for in assessments in order to avoid bias in estimates of fishing mortality, stock biomass and reference points. In age‐structured assessment models, discards are sometimes treated as a separate fle...
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crwiley:10.1111/faf.12408 2024-09-15T18:25:23+00:00 Inclusion of discards in stock assessment models Cook, Robin M. H2020 Societal Challenges 2019 http://dx.doi.org/10.1111/faf.12408 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Ffaf.12408 https://onlinelibrary.wiley.com/doi/pdf/10.1111/faf.12408 https://onlinelibrary.wiley.com/doi/full-xml/10.1111/faf.12408 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Fish and Fisheries volume 20, issue 6, page 1232-1245 ISSN 1467-2960 1467-2979 journal-article 2019 crwiley https://doi.org/10.1111/faf.12408 2024-08-09T04:26:54Z Abstract A large portion of the catch in many stocks may comprise discards which need to be accounted for in assessments in order to avoid bias in estimates of fishing mortality, stock biomass and reference points. In age‐structured assessment models, discards are sometimes treated as a separate fleet or are added to the landings before fitting so that information about discard behaviour and sampling error is lost. In this paper, an assessment model is developed to describe the discard process with size as a covariate while retaining age‐structured population dynamics. Discard size selection, high grading and bulk dumping of fish at sea are modelled so that the temporal dynamics of the process can be quantified within the assessment. The model is used to show that discarding practices have changed over time in a range of Northeast Atlantic demersal fish. In some stocks, there is a substantial increase in high grading and evidence for bulk discarding which can be related to regulatory measures. The model offers a means of identifying transient effects in the discard process that should be removed from both short‐term forecasts and equilibrium reference point calculations. Article in Journal/Newspaper Northeast Atlantic Wiley Online Library Fish and Fisheries 20 6 1232 1245 |
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Abstract A large portion of the catch in many stocks may comprise discards which need to be accounted for in assessments in order to avoid bias in estimates of fishing mortality, stock biomass and reference points. In age‐structured assessment models, discards are sometimes treated as a separate fleet or are added to the landings before fitting so that information about discard behaviour and sampling error is lost. In this paper, an assessment model is developed to describe the discard process with size as a covariate while retaining age‐structured population dynamics. Discard size selection, high grading and bulk dumping of fish at sea are modelled so that the temporal dynamics of the process can be quantified within the assessment. The model is used to show that discarding practices have changed over time in a range of Northeast Atlantic demersal fish. In some stocks, there is a substantial increase in high grading and evidence for bulk discarding which can be related to regulatory measures. The model offers a means of identifying transient effects in the discard process that should be removed from both short‐term forecasts and equilibrium reference point calculations. |
author2 |
H2020 Societal Challenges |
format |
Article in Journal/Newspaper |
author |
Cook, Robin M. |
spellingShingle |
Cook, Robin M. Inclusion of discards in stock assessment models |
author_facet |
Cook, Robin M. |
author_sort |
Cook, Robin M. |
title |
Inclusion of discards in stock assessment models |
title_short |
Inclusion of discards in stock assessment models |
title_full |
Inclusion of discards in stock assessment models |
title_fullStr |
Inclusion of discards in stock assessment models |
title_full_unstemmed |
Inclusion of discards in stock assessment models |
title_sort |
inclusion of discards in stock assessment models |
publisher |
Wiley |
publishDate |
2019 |
url |
http://dx.doi.org/10.1111/faf.12408 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Ffaf.12408 https://onlinelibrary.wiley.com/doi/pdf/10.1111/faf.12408 https://onlinelibrary.wiley.com/doi/full-xml/10.1111/faf.12408 |
genre |
Northeast Atlantic |
genre_facet |
Northeast Atlantic |
op_source |
Fish and Fisheries volume 20, issue 6, page 1232-1245 ISSN 1467-2960 1467-2979 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/faf.12408 |
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Fish and Fisheries |
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20 |
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6 |
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1232 |
op_container_end_page |
1245 |
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1810465899750096896 |