Evaluation of otolith shape as a tool for stock discrimination in marine fishes using Baltic Sea cod as a case study

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Abstract

In the Western Baltic Sea two genetically distinct cod stocks “Eastern Baltic cod” and “Western Balticcod” occur with considerable mixing of stocks. In this study we evaluated the applicability of otolithshape analysis for classification of individuals caught in the mixed stock cod fishery, using SNP (singlenucleotide polymorphism) based genetic assignment of otolith shape baselines. We further developeda management aimed approach for mixed stock assignment by robust stochastic baseline selection andposterior bias correction by individual reassignment of the least likely classifications into the alternatestock. Classification criteria selected by Monte Carlo runs of Linear Discriminant Analysis were capturedby otolith area and 20 Elliptic Fourier Descriptors of primarily low frequency harmonics. Classificationsuccess was considerably lower when using a baseline of spawning individuals only, compared to thebetter spatial coverage of a combined baseline also including genotyped individuals from the mixed stockarea. Furthermore, the inclusion of genotyped individuals balanced the baseline size composition and toa large extent removed a strong size related bias in classification success. These results demonstrate theinterplay of environmental, ontogenetic and genetic influences on otolith shape, which complicates theapplication of otolith shape for stock discrimination in mixed-stock scenarios. Rigours genetic validationand further studies on the temporal dynamics of shape formation are necessary.
Original languageEnglish
JournalFisheries Research
Volume174
Pages (from-to)210-218
ISSN0165-7836
DOIs
Publication statusPublished - 2016

Cite this

@article{2a93105fce01417cbe1f9f22cb60e51f,
title = "Evaluation of otolith shape as a tool for stock discrimination in marine fishes using Baltic Sea cod as a case study",
abstract = "In the Western Baltic Sea two genetically distinct cod stocks “Eastern Baltic cod” and “Western Balticcod” occur with considerable mixing of stocks. In this study we evaluated the applicability of otolithshape analysis for classification of individuals caught in the mixed stock cod fishery, using SNP (singlenucleotide polymorphism) based genetic assignment of otolith shape baselines. We further developeda management aimed approach for mixed stock assignment by robust stochastic baseline selection andposterior bias correction by individual reassignment of the least likely classifications into the alternatestock. Classification criteria selected by Monte Carlo runs of Linear Discriminant Analysis were capturedby otolith area and 20 Elliptic Fourier Descriptors of primarily low frequency harmonics. Classificationsuccess was considerably lower when using a baseline of spawning individuals only, compared to thebetter spatial coverage of a combined baseline also including genotyped individuals from the mixed stockarea. Furthermore, the inclusion of genotyped individuals balanced the baseline size composition and toa large extent removed a strong size related bias in classification success. These results demonstrate theinterplay of environmental, ontogenetic and genetic influences on otolith shape, which complicates theapplication of otolith shape for stock discrimination in mixed-stock scenarios. Rigours genetic validationand further studies on the temporal dynamics of shape formation are necessary.",
author = "Karin H{\"u}ssy and Henrik Mosegaard and Albertsen, {Christoffer Moesgaard} and {Eg Nielsen}, Einar and Hansen, {Jakob Hemmer} and Margit Eero",
year = "2016",
doi = "10.1016/j.fishres.2015.10.010",
language = "English",
volume = "174",
pages = "210--218",
journal = "Fisheries Research",
issn = "0165-7836",
publisher = "Elsevier",

}

TY - JOUR

T1 - Evaluation of otolith shape as a tool for stock discrimination in marine fishes using Baltic Sea cod as a case study

AU - Hüssy, Karin

AU - Mosegaard, Henrik

AU - Albertsen, Christoffer Moesgaard

AU - Eg Nielsen, Einar

AU - Hansen, Jakob Hemmer

AU - Eero, Margit

PY - 2016

Y1 - 2016

N2 - In the Western Baltic Sea two genetically distinct cod stocks “Eastern Baltic cod” and “Western Balticcod” occur with considerable mixing of stocks. In this study we evaluated the applicability of otolithshape analysis for classification of individuals caught in the mixed stock cod fishery, using SNP (singlenucleotide polymorphism) based genetic assignment of otolith shape baselines. We further developeda management aimed approach for mixed stock assignment by robust stochastic baseline selection andposterior bias correction by individual reassignment of the least likely classifications into the alternatestock. Classification criteria selected by Monte Carlo runs of Linear Discriminant Analysis were capturedby otolith area and 20 Elliptic Fourier Descriptors of primarily low frequency harmonics. Classificationsuccess was considerably lower when using a baseline of spawning individuals only, compared to thebetter spatial coverage of a combined baseline also including genotyped individuals from the mixed stockarea. Furthermore, the inclusion of genotyped individuals balanced the baseline size composition and toa large extent removed a strong size related bias in classification success. These results demonstrate theinterplay of environmental, ontogenetic and genetic influences on otolith shape, which complicates theapplication of otolith shape for stock discrimination in mixed-stock scenarios. Rigours genetic validationand further studies on the temporal dynamics of shape formation are necessary.

AB - In the Western Baltic Sea two genetically distinct cod stocks “Eastern Baltic cod” and “Western Balticcod” occur with considerable mixing of stocks. In this study we evaluated the applicability of otolithshape analysis for classification of individuals caught in the mixed stock cod fishery, using SNP (singlenucleotide polymorphism) based genetic assignment of otolith shape baselines. We further developeda management aimed approach for mixed stock assignment by robust stochastic baseline selection andposterior bias correction by individual reassignment of the least likely classifications into the alternatestock. Classification criteria selected by Monte Carlo runs of Linear Discriminant Analysis were capturedby otolith area and 20 Elliptic Fourier Descriptors of primarily low frequency harmonics. Classificationsuccess was considerably lower when using a baseline of spawning individuals only, compared to thebetter spatial coverage of a combined baseline also including genotyped individuals from the mixed stockarea. Furthermore, the inclusion of genotyped individuals balanced the baseline size composition and toa large extent removed a strong size related bias in classification success. These results demonstrate theinterplay of environmental, ontogenetic and genetic influences on otolith shape, which complicates theapplication of otolith shape for stock discrimination in mixed-stock scenarios. Rigours genetic validationand further studies on the temporal dynamics of shape formation are necessary.

U2 - 10.1016/j.fishres.2015.10.010

DO - 10.1016/j.fishres.2015.10.010

M3 - Journal article

VL - 174

SP - 210

EP - 218

JO - Fisheries Research

JF - Fisheries Research

SN - 0165-7836

ER -