Challenging ICES age estimation protocols: lessons learned from the eastern Baltic cod stock

Karin Hüssy, Krzysztof Radtke, Maris Plikshs, Rainer Oeberst, Tatjana Baranova, Uwe Krumme, Rajlie Sjöberg, Yvonne Walther, Henrik Mosegaard

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Over the recent decades, the International Council for the Exploration of the Sea (ICES) has set guidelines for best practise quality control of age estimation procedures. The applicability of these guidelines is assessed by reviewing the ageing issues of eastern Baltic cod (EBC) as a case study. Since the implementation of an age-based assessment of EBC in the beginning of the 1970s, the assessment has been hampered by the quality of the age composition data, in recent years to a degree that age-based assessment is no longer used. The reason for the age reading problems is the low visual contrast between growth zones in the otoliths which seems to be the result of complex interactions of the hydrography in the Baltic Sea with the cod’s biology and behaviour. Over the last 40 years, various expert groups have struggled to document and improve the agreement of age estimation between national otolith readers, standardize methods and age estimations through repeated exchanges and reference collections as well as an internationally agreed manual. Despite these initiatives the precision of the age estimations
based on traditional ageing did not improve, with significant bias persisting between and within readers. Additionally, a wide range of alternative
methods for deriving the age information necessary for stock assessment and for validation of the true age have been tested. However, these methods did not produce unbiased age estimates over the entire size and age range of the EBC stock. An age-validation is urgently needed. Deviations from the ICES guidelines identified are as follows: (i) the lack of rigorous quality control, particularly the auditing of national trends in age precision over the years using a reference collection and (ii) the implementation of an age error matrix in the stock assessment
Original languageEnglish
JournalICES Journal of Marine Science
Volume73
Issue number9
Pages (from-to)2138-2149
ISSN1054-3139
DOIs
Publication statusPublished - 2016

Cite this

Hüssy, Karin ; Radtke, Krzysztof ; Plikshs, Maris ; Oeberst, Rainer ; Baranova, Tatjana ; Krumme, Uwe ; Sjöberg, Rajlie ; Walther, Yvonne ; Mosegaard, Henrik. / Challenging ICES age estimation protocols: lessons learned from the eastern Baltic cod stock. In: ICES Journal of Marine Science. 2016 ; Vol. 73, No. 9. pp. 2138-2149.
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abstract = "Over the recent decades, the International Council for the Exploration of the Sea (ICES) has set guidelines for best practise quality control of age estimation procedures. The applicability of these guidelines is assessed by reviewing the ageing issues of eastern Baltic cod (EBC) as a case study. Since the implementation of an age-based assessment of EBC in the beginning of the 1970s, the assessment has been hampered by the quality of the age composition data, in recent years to a degree that age-based assessment is no longer used. The reason for the age reading problems is the low visual contrast between growth zones in the otoliths which seems to be the result of complex interactions of the hydrography in the Baltic Sea with the cod’s biology and behaviour. Over the last 40 years, various expert groups have struggled to document and improve the agreement of age estimation between national otolith readers, standardize methods and age estimations through repeated exchanges and reference collections as well as an internationally agreed manual. Despite these initiatives the precision of the age estimationsbased on traditional ageing did not improve, with significant bias persisting between and within readers. Additionally, a wide range of alternativemethods for deriving the age information necessary for stock assessment and for validation of the true age have been tested. However, these methods did not produce unbiased age estimates over the entire size and age range of the EBC stock. An age-validation is urgently needed. Deviations from the ICES guidelines identified are as follows: (i) the lack of rigorous quality control, particularly the auditing of national trends in age precision over the years using a reference collection and (ii) the implementation of an age error matrix in the stock assessment",
author = "Karin H{\"u}ssy and Krzysztof Radtke and Maris Plikshs and Rainer Oeberst and Tatjana Baranova and Uwe Krumme and Rajlie Sj{\"o}berg and Yvonne Walther and Henrik Mosegaard",
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Hüssy, K, Radtke, K, Plikshs, M, Oeberst, R, Baranova, T, Krumme, U, Sjöberg, R, Walther, Y & Mosegaard, H 2016, 'Challenging ICES age estimation protocols: lessons learned from the eastern Baltic cod stock', ICES Journal of Marine Science, vol. 73, no. 9, pp. 2138-2149. https://doi.org/10.1093/icesjms/fsw107

Challenging ICES age estimation protocols: lessons learned from the eastern Baltic cod stock. / Hüssy, Karin; Radtke, Krzysztof; Plikshs, Maris; Oeberst, Rainer; Baranova, Tatjana; Krumme, Uwe; Sjöberg, Rajlie; Walther, Yvonne; Mosegaard, Henrik.

In: ICES Journal of Marine Science, Vol. 73, No. 9, 2016, p. 2138-2149.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Challenging ICES age estimation protocols: lessons learned from the eastern Baltic cod stock

AU - Hüssy, Karin

AU - Radtke, Krzysztof

AU - Plikshs, Maris

AU - Oeberst, Rainer

AU - Baranova, Tatjana

AU - Krumme, Uwe

AU - Sjöberg, Rajlie

AU - Walther, Yvonne

AU - Mosegaard, Henrik

PY - 2016

Y1 - 2016

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AB - Over the recent decades, the International Council for the Exploration of the Sea (ICES) has set guidelines for best practise quality control of age estimation procedures. The applicability of these guidelines is assessed by reviewing the ageing issues of eastern Baltic cod (EBC) as a case study. Since the implementation of an age-based assessment of EBC in the beginning of the 1970s, the assessment has been hampered by the quality of the age composition data, in recent years to a degree that age-based assessment is no longer used. The reason for the age reading problems is the low visual contrast between growth zones in the otoliths which seems to be the result of complex interactions of the hydrography in the Baltic Sea with the cod’s biology and behaviour. Over the last 40 years, various expert groups have struggled to document and improve the agreement of age estimation between national otolith readers, standardize methods and age estimations through repeated exchanges and reference collections as well as an internationally agreed manual. Despite these initiatives the precision of the age estimationsbased on traditional ageing did not improve, with significant bias persisting between and within readers. Additionally, a wide range of alternativemethods for deriving the age information necessary for stock assessment and for validation of the true age have been tested. However, these methods did not produce unbiased age estimates over the entire size and age range of the EBC stock. An age-validation is urgently needed. Deviations from the ICES guidelines identified are as follows: (i) the lack of rigorous quality control, particularly the auditing of national trends in age precision over the years using a reference collection and (ii) the implementation of an age error matrix in the stock assessment

U2 - 10.1093/icesjms/fsw107

DO - 10.1093/icesjms/fsw107

M3 - Journal article

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SP - 2138

EP - 2149

JO - I C E S Journal of Marine Science

JF - I C E S Journal of Marine Science

SN - 1054-3139

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ER -