Spatial age-length key modelling using continuation ratio logits
Many fish stock assessments are based on numbers at age from research sampling programmes and samples from commercial catches. However, only a small fraction of the catch is typically analyzed for age as this is a costly and time-consuming process. Larger samples of the length distribution and a so-...
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2012
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ftdtupubl:oai:pure.atira.dk:publications/9c29206c-0232-4fdf-9ab7-83185a678f38 2024-09-09T19:40:54+00:00 Spatial age-length key modelling using continuation ratio logits Berg, Casper W. Kristensen, Kasper 2012 application/pdf https://orbit.dtu.dk/en/publications/9c29206c-0232-4fdf-9ab7-83185a678f38 https://doi.org/10.1016/j.fishres.2012.06.016 https://backend.orbit.dtu.dk/ws/files/10214559/836C3d01.pdf eng eng https://orbit.dtu.dk/en/publications/9c29206c-0232-4fdf-9ab7-83185a678f38 info:eu-repo/semantics/openAccess Berg , C W & Kristensen , K 2012 , ' Spatial age-length key modelling using continuation ratio logits ' , Fisheries Research , vol. 129-130 , pp. 119-126 . https://doi.org/10.1016/j.fishres.2012.06.016 Age length key comparison Continuation ratio logits Generalized Additive Models article 2012 ftdtupubl https://doi.org/10.1016/j.fishres.2012.06.016 2024-06-18T14:38:05Z Many fish stock assessments are based on numbers at age from research sampling programmes and samples from commercial catches. However, only a small fraction of the catch is typically analyzed for age as this is a costly and time-consuming process. Larger samples of the length distribution and a so-called age-length key (ALK) is then used to obtain the age distribution. Regional differences in ALKs are not uncommon, but stratification is often problematic due to a small number of samples. Here, we combine generalized additive modelling with continuation ratio logits to model the probability of age given length and spatial coordinates to overcome these issues. The method is applied to data gathered on North Sea haddock (Melanogrammus aeglefinus), cod (Gadus morhua), whiting (Merlangius merlangus) and herring (Clupea harengus) and its implications for a simple age-based survey index of abundance are examined. The spatial varying ALK outperforms simpler approaches with respect to AIC and BIC, and the survey indices created using the spatial varying ALK displays better internal and external consistency indicating improved precision. Article in Journal/Newspaper Gadus morhua Technical University of Denmark: DTU Orbit Fisheries Research 129-130 119 126 |
institution |
Open Polar |
collection |
Technical University of Denmark: DTU Orbit |
op_collection_id |
ftdtupubl |
language |
English |
topic |
Age length key comparison Continuation ratio logits Generalized Additive Models |
spellingShingle |
Age length key comparison Continuation ratio logits Generalized Additive Models Berg, Casper W. Kristensen, Kasper Spatial age-length key modelling using continuation ratio logits |
topic_facet |
Age length key comparison Continuation ratio logits Generalized Additive Models |
description |
Many fish stock assessments are based on numbers at age from research sampling programmes and samples from commercial catches. However, only a small fraction of the catch is typically analyzed for age as this is a costly and time-consuming process. Larger samples of the length distribution and a so-called age-length key (ALK) is then used to obtain the age distribution. Regional differences in ALKs are not uncommon, but stratification is often problematic due to a small number of samples. Here, we combine generalized additive modelling with continuation ratio logits to model the probability of age given length and spatial coordinates to overcome these issues. The method is applied to data gathered on North Sea haddock (Melanogrammus aeglefinus), cod (Gadus morhua), whiting (Merlangius merlangus) and herring (Clupea harengus) and its implications for a simple age-based survey index of abundance are examined. The spatial varying ALK outperforms simpler approaches with respect to AIC and BIC, and the survey indices created using the spatial varying ALK displays better internal and external consistency indicating improved precision. |
format |
Article in Journal/Newspaper |
author |
Berg, Casper W. Kristensen, Kasper |
author_facet |
Berg, Casper W. Kristensen, Kasper |
author_sort |
Berg, Casper W. |
title |
Spatial age-length key modelling using continuation ratio logits |
title_short |
Spatial age-length key modelling using continuation ratio logits |
title_full |
Spatial age-length key modelling using continuation ratio logits |
title_fullStr |
Spatial age-length key modelling using continuation ratio logits |
title_full_unstemmed |
Spatial age-length key modelling using continuation ratio logits |
title_sort |
spatial age-length key modelling using continuation ratio logits |
publishDate |
2012 |
url |
https://orbit.dtu.dk/en/publications/9c29206c-0232-4fdf-9ab7-83185a678f38 https://doi.org/10.1016/j.fishres.2012.06.016 https://backend.orbit.dtu.dk/ws/files/10214559/836C3d01.pdf |
genre |
Gadus morhua |
genre_facet |
Gadus morhua |
op_source |
Berg , C W & Kristensen , K 2012 , ' Spatial age-length key modelling using continuation ratio logits ' , Fisheries Research , vol. 129-130 , pp. 119-126 . https://doi.org/10.1016/j.fishres.2012.06.016 |
op_relation |
https://orbit.dtu.dk/en/publications/9c29206c-0232-4fdf-9ab7-83185a678f38 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1016/j.fishres.2012.06.016 |
container_title |
Fisheries Research |
container_volume |
129-130 |
container_start_page |
119 |
op_container_end_page |
126 |
_version_ |
1809910391338172416 |