Ageing bias and precision for deep-water snappers

Evaluating nascent otolith preparation methods using novel multivariate comparisons among readers and growth parameter estimates

Corey B. Wakefield, Joseph M. O'Malley, Ashley J. Williams, Brett M. Taylor, Ryan S. Nichols, Tuikolongahau Halafihi, Robert L. Humphreys, Jeremie Kaltavara, Simon J. Nicol, Stephen J. Newman

    Research output: Contribution to journalArticle

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    Abstract

    Tropical deep-water snappers (Etelinae) support valuable fisheries across the Indo-Pacific, with stock assessments reliant on age-based information in the absence of reliable catch and effort statistics. These long-lived species have been considered notoriously difficult to age. However, nascent developments in ageing protocols, particularly thinner transverse sections of otoliths (∼180-200 μm), are providing improvements in growth zone clarity, interpretation and repeatability of annuli counts. At a recent international workshop, thin sectioned otoliths from three deep-water snappers were read under reflected light by eight fisheries scientists from across the Indo-Pacific, with various levels of fish-ageing experience. Precision and bias were assessed using traditional ageing precision metrics (index of average percent error, IAPE; and coefficient of variation, CV), and a novel approach using multivariate analyses (metric multidimensional scaling, mMDS) based on Euclidean dissimilarity among readers' counts and subsequent von Bertalanffy (vB) growth parameter estimates. Annuli counts between the primary reader and all other readers were within two for 80% of estimates, with uniform variation across a wide age range for Etelis carbunculus (intraclass correlation coefficient (ICC) = 0.924, n = 20, 3-25 annuli) and Etelis sp. (ICC = 0.933, n = 15, 2-27 annuli). In contrast, annuli counts for Pristipomoides filamentosus (n = 14, 4-49) were less precise (i.e. ICC = 0.835, 66% of counts within two of primary reader) with a bias toward greater variation in younger, pre-maturational life stages (≤5 annuli). Traditionally accepted ageing precision (IAPE ≤ 5.5%, CV ≤ 7.6%) was achieved for each species, but was commensurate with reader experience. The multivariate mMDS ordination was more informative in identifying both distance (i.e. dissimilarity) and direction (i.e. form) of variations in annuli counts and vB growth parameter estimates among readers. The acceptable level of ageing precision and bias achieved among most readers indicated that deep-water snappers can be aged precisely when appropriate otolith preparation methods are used. This study contributes towards ageing protocols that can be used to (i) interrogate bias and precision of age data for stock assessments, and (ii) standardise comparisons of age-based life history characteristics across a species range.

    Original languageEnglish
    Pages (from-to)193-203
    Number of pages11
    JournalICES Journal of Marine Science
    Volume74
    Issue number1
    DOIs
    Publication statusPublished - 1 Jan 2017

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    snapper
    otolith
    otoliths
    deep water
    stock assessment
    water
    fisheries
    methodology
    fishery
    repeatability
    ordination
    statistics
    life history
    parameter
    comparison
    method
    fish

    Cite this

    Wakefield, Corey B. ; O'Malley, Joseph M. ; Williams, Ashley J. ; Taylor, Brett M. ; Nichols, Ryan S. ; Halafihi, Tuikolongahau ; Humphreys, Robert L. ; Kaltavara, Jeremie ; Nicol, Simon J. ; Newman, Stephen J. / Ageing bias and precision for deep-water snappers : Evaluating nascent otolith preparation methods using novel multivariate comparisons among readers and growth parameter estimates. In: ICES Journal of Marine Science. 2017 ; Vol. 74, No. 1. pp. 193-203.
    @article{49d15167aeae405796bda1b17a23563d,
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    abstract = "Tropical deep-water snappers (Etelinae) support valuable fisheries across the Indo-Pacific, with stock assessments reliant on age-based information in the absence of reliable catch and effort statistics. These long-lived species have been considered notoriously difficult to age. However, nascent developments in ageing protocols, particularly thinner transverse sections of otoliths (∼180-200 μm), are providing improvements in growth zone clarity, interpretation and repeatability of annuli counts. At a recent international workshop, thin sectioned otoliths from three deep-water snappers were read under reflected light by eight fisheries scientists from across the Indo-Pacific, with various levels of fish-ageing experience. Precision and bias were assessed using traditional ageing precision metrics (index of average percent error, IAPE; and coefficient of variation, CV), and a novel approach using multivariate analyses (metric multidimensional scaling, mMDS) based on Euclidean dissimilarity among readers' counts and subsequent von Bertalanffy (vB) growth parameter estimates. Annuli counts between the primary reader and all other readers were within two for 80{\%} of estimates, with uniform variation across a wide age range for Etelis carbunculus (intraclass correlation coefficient (ICC) = 0.924, n = 20, 3-25 annuli) and Etelis sp. (ICC = 0.933, n = 15, 2-27 annuli). In contrast, annuli counts for Pristipomoides filamentosus (n = 14, 4-49) were less precise (i.e. ICC = 0.835, 66{\%} of counts within two of primary reader) with a bias toward greater variation in younger, pre-maturational life stages (≤5 annuli). Traditionally accepted ageing precision (IAPE ≤ 5.5{\%}, CV ≤ 7.6{\%}) was achieved for each species, but was commensurate with reader experience. The multivariate mMDS ordination was more informative in identifying both distance (i.e. dissimilarity) and direction (i.e. form) of variations in annuli counts and vB growth parameter estimates among readers. The acceptable level of ageing precision and bias achieved among most readers indicated that deep-water snappers can be aged precisely when appropriate otolith preparation methods are used. This study contributes towards ageing protocols that can be used to (i) interrogate bias and precision of age data for stock assessments, and (ii) standardise comparisons of age-based life history characteristics across a species range.",
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    author = "Wakefield, {Corey B.} and O'Malley, {Joseph M.} and Williams, {Ashley J.} and Taylor, {Brett M.} and Nichols, {Ryan S.} and Tuikolongahau Halafihi and Humphreys, {Robert L.} and Jeremie Kaltavara and Nicol, {Simon J.} and Newman, {Stephen J.}",
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    Wakefield, CB, O'Malley, JM, Williams, AJ, Taylor, BM, Nichols, RS, Halafihi, T, Humphreys, RL, Kaltavara, J, Nicol, SJ & Newman, SJ 2017, 'Ageing bias and precision for deep-water snappers: Evaluating nascent otolith preparation methods using novel multivariate comparisons among readers and growth parameter estimates', ICES Journal of Marine Science, vol. 74, no. 1, pp. 193-203. https://doi.org/10.1093/icesjms/fsw162

    Ageing bias and precision for deep-water snappers : Evaluating nascent otolith preparation methods using novel multivariate comparisons among readers and growth parameter estimates. / Wakefield, Corey B.; O'Malley, Joseph M.; Williams, Ashley J.; Taylor, Brett M.; Nichols, Ryan S.; Halafihi, Tuikolongahau; Humphreys, Robert L.; Kaltavara, Jeremie; Nicol, Simon J.; Newman, Stephen J.

    In: ICES Journal of Marine Science, Vol. 74, No. 1, 01.01.2017, p. 193-203.

    Research output: Contribution to journalArticle

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    T1 - Ageing bias and precision for deep-water snappers

    T2 - Evaluating nascent otolith preparation methods using novel multivariate comparisons among readers and growth parameter estimates

    AU - Wakefield, Corey B.

    AU - O'Malley, Joseph M.

    AU - Williams, Ashley J.

    AU - Taylor, Brett M.

    AU - Nichols, Ryan S.

    AU - Halafihi, Tuikolongahau

    AU - Humphreys, Robert L.

    AU - Kaltavara, Jeremie

    AU - Nicol, Simon J.

    AU - Newman, Stephen J.

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    N2 - Tropical deep-water snappers (Etelinae) support valuable fisheries across the Indo-Pacific, with stock assessments reliant on age-based information in the absence of reliable catch and effort statistics. These long-lived species have been considered notoriously difficult to age. However, nascent developments in ageing protocols, particularly thinner transverse sections of otoliths (∼180-200 μm), are providing improvements in growth zone clarity, interpretation and repeatability of annuli counts. At a recent international workshop, thin sectioned otoliths from three deep-water snappers were read under reflected light by eight fisheries scientists from across the Indo-Pacific, with various levels of fish-ageing experience. Precision and bias were assessed using traditional ageing precision metrics (index of average percent error, IAPE; and coefficient of variation, CV), and a novel approach using multivariate analyses (metric multidimensional scaling, mMDS) based on Euclidean dissimilarity among readers' counts and subsequent von Bertalanffy (vB) growth parameter estimates. Annuli counts between the primary reader and all other readers were within two for 80% of estimates, with uniform variation across a wide age range for Etelis carbunculus (intraclass correlation coefficient (ICC) = 0.924, n = 20, 3-25 annuli) and Etelis sp. (ICC = 0.933, n = 15, 2-27 annuli). In contrast, annuli counts for Pristipomoides filamentosus (n = 14, 4-49) were less precise (i.e. ICC = 0.835, 66% of counts within two of primary reader) with a bias toward greater variation in younger, pre-maturational life stages (≤5 annuli). Traditionally accepted ageing precision (IAPE ≤ 5.5%, CV ≤ 7.6%) was achieved for each species, but was commensurate with reader experience. The multivariate mMDS ordination was more informative in identifying both distance (i.e. dissimilarity) and direction (i.e. form) of variations in annuli counts and vB growth parameter estimates among readers. The acceptable level of ageing precision and bias achieved among most readers indicated that deep-water snappers can be aged precisely when appropriate otolith preparation methods are used. This study contributes towards ageing protocols that can be used to (i) interrogate bias and precision of age data for stock assessments, and (ii) standardise comparisons of age-based life history characteristics across a species range.

    AB - Tropical deep-water snappers (Etelinae) support valuable fisheries across the Indo-Pacific, with stock assessments reliant on age-based information in the absence of reliable catch and effort statistics. These long-lived species have been considered notoriously difficult to age. However, nascent developments in ageing protocols, particularly thinner transverse sections of otoliths (∼180-200 μm), are providing improvements in growth zone clarity, interpretation and repeatability of annuli counts. At a recent international workshop, thin sectioned otoliths from three deep-water snappers were read under reflected light by eight fisheries scientists from across the Indo-Pacific, with various levels of fish-ageing experience. Precision and bias were assessed using traditional ageing precision metrics (index of average percent error, IAPE; and coefficient of variation, CV), and a novel approach using multivariate analyses (metric multidimensional scaling, mMDS) based on Euclidean dissimilarity among readers' counts and subsequent von Bertalanffy (vB) growth parameter estimates. Annuli counts between the primary reader and all other readers were within two for 80% of estimates, with uniform variation across a wide age range for Etelis carbunculus (intraclass correlation coefficient (ICC) = 0.924, n = 20, 3-25 annuli) and Etelis sp. (ICC = 0.933, n = 15, 2-27 annuli). In contrast, annuli counts for Pristipomoides filamentosus (n = 14, 4-49) were less precise (i.e. ICC = 0.835, 66% of counts within two of primary reader) with a bias toward greater variation in younger, pre-maturational life stages (≤5 annuli). Traditionally accepted ageing precision (IAPE ≤ 5.5%, CV ≤ 7.6%) was achieved for each species, but was commensurate with reader experience. The multivariate mMDS ordination was more informative in identifying both distance (i.e. dissimilarity) and direction (i.e. form) of variations in annuli counts and vB growth parameter estimates among readers. The acceptable level of ageing precision and bias achieved among most readers indicated that deep-water snappers can be aged precisely when appropriate otolith preparation methods are used. This study contributes towards ageing protocols that can be used to (i) interrogate bias and precision of age data for stock assessments, and (ii) standardise comparisons of age-based life history characteristics across a species range.

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