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  • 1
    Online Resource
    Online Resource
    Understanding transboundary stocks’ availability by combining multiple fisheries-independent surveys and oceanographic conditions in spatiotemporal models
    Oxford University Press (OUP) ; 2022
    In:  ICES Journal of Marine Science Vol. 79, No. 4 ( 2022-05-23), p. 1063-1074
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 79, No. 4 ( 2022-05-23), p. 1063-1074
    Abstract: Shifts in the distribution of groundfish species as oceans warm can complicate management efforts if species distributions expand beyond the extent of existing scientific surveys, changing the proportion of groundfish available to any one survey each year. We developed the first-ever model-based biomass estimates for three Bering Sea groundfishes (walleye pollock (Gadus chalcogrammus), Pacific cod (Gadus macrocephalus), and Alaska plaice (Pleuronectes quadrituberculatus)) by combining fishery-independent bottom trawl data from the U.S. and Russia in a spatiotemporal framework using Vector Autoregressive Spatio-Temporal (VAST) models. We estimated a fishing-power correction to calibrate disparate data sets and the effect of an annual oceanographic index to explain variation in groundfish spatiotemporal density. Groundfish densities shifted northward relative to historical densities, and high-density areas spanned the international border, particularly in years warmer than the long-term average. In the final year of comprehensive survey data (2017), 49%, 65%, 47% of biomass was in the western and northern Bering Sea for pollock, cod, and plaice, respectively, suggesting that availability of groundfish to the more regular eastern Bering Sea survey is declining. We conclude that international partnerships to combine past data and coordinate future data collection are necessary to track fish as they shift beyond historical survey areas.
    Type of Medium: Online Resource
    ISSN: 1054-3139 , 1095-9289
    URL: Article
    DOI: 10.1093/icesjms/fsac046
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2022
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    SSG: 12
    SSG: 21,3
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    The benefits and risks of incorporating climate-driven growth variation into stock assessment models, with application to Splitnose Rockfish (Sebastes diploproa)
    Oxford University Press (OUP) ; 2018
    In:  ICES Journal of Marine Science Vol. 75, No. 1 ( 2018-01-01), p. 245-256
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 75, No. 1 ( 2018-01-01), p. 245-256
    Type of Medium: Online Resource
    ISSN: 1054-3139 , 1095-9289
    URL: Article
    DOI: 10.1093/icesjms/fsx147
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2018
    detail.hit.zdb_id: 2463178-4
    detail.hit.zdb_id: 1468003-8
    detail.hit.zdb_id: 29056-7
    SSG: 12
    SSG: 21,3
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    Developing spatio-temporal models using multiple data types for evaluating population trends and habitat usage
    Oxford University Press (OUP) ; 2019
    In:  ICES Journal of Marine Science Vol. 76, No. 6 ( 2019-12-01), p. 1748-1761
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 76, No. 6 ( 2019-12-01), p. 1748-1761
    Abstract: Spatio-temporal models have become key tools for evaluating population trends and habitat usage. We developed a spatio-temporal modelling framework employing a combination of encounter/non-encounter, count, and biomass data collected by different monitoring programs (“combined data”). The three data types are predicted using a computationally efficient approximation to a compound Poisson-gamma process. We fitted spatio-temporal models to combined data for Gulf of Mexico (GOM) red snapper (Lutjanus campechanus) for 2006–2014. These spatio-temporal models provided insights into GOM red snapper spatial distribution patterns, which we corroborated by comparing to past predictions generated using only encounter/non-encounter data. However, relying on biomass and count data in addition to encounter/non-encounter data also allowed us to reconstruct biomass trends for GOM red snapper and to examine patterns of distribution shifts and range expansion/contraction for this population for the first time. Moreover, combining multiple data types improved the precision of reconstructed population trends and some variables quantifying habitat usage. Finally, scenarios and simulation experiments conditioned upon red snapper data showed that the improvement in fitting to combined data is greater when biomass data for the study population are lacking for an entire subregion and, to a lesser extent, for an entire time period (e.g. in early years).
    Type of Medium: Online Resource
    ISSN: 1054-3139 , 1095-9289
    URL: Article
    DOI: 10.1093/icesjms/fsz075
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2019
    detail.hit.zdb_id: 2463178-4
    detail.hit.zdb_id: 1468003-8
    detail.hit.zdb_id: 29056-7
    SSG: 12
    SSG: 21,3
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    Online Resource
  • 4
    Online Resource
    Online Resource
    A spatial statistical approach for identifying population structuring of marine fish species: European sprat as a case study
    Oxford University Press (OUP) ; 2022
    In:  ICES Journal of Marine Science Vol. 79, No. 2 ( 2022-03-10), p. 423-434
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 79, No. 2 ( 2022-03-10), p. 423-434
    Abstract: Many marine fish species are widely distributed over large areas. Failing to acknowledge that such species may be composed of distinct populations may result in overestimation of the stock's true harvest potential. To avoid overexploitation, ways to identify population structuring are therefore needed. In this study, we developed and applied a statistical approach to identify biologically relevant population boundaries for a widely distributed marine fish species, European sprat (Sprattus sprattus). Specifically, we compiled and standardized multiple trawl-survey data sets and used a range of statistical tools to assess whether the current management boundaries adequately account for potential population structuring. Our results demonstrate regional differences in spatial abundance patterns, temporal dynamics and population demographics. These findings are in line with recent genetic studies of sprat, indicating reproductive isolation between the Baltic Sea/Kattegat and a larger cluster containing the North-, Irish-, Celtic Sea, and Bay of Biscay. Since relying on routinely collected survey data, our statistical approach can be a cost-effective complement to population genetic methods for detecting population structuring. These can be used to guide spatial management efforts and ensure sustainable exploitation, especially under climate change and the expected changes in species distributions across current management borders.
    Type of Medium: Online Resource
    ISSN: 1054-3139 , 1095-9289
    URL: Article
    DOI: 10.1093/icesjms/fsac007
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2022
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    detail.hit.zdb_id: 1468003-8
    detail.hit.zdb_id: 29056-7
    SSG: 12
    SSG: 21,3
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    Online Resource
  • 5
    Online Resource
    Online Resource
    The multivariate-Tweedie: a self-weighting likelihood for age and length composition data arising from hierarchical sampling designs
    Oxford University Press (OUP) ; 2022
    In:  ICES Journal of Marine Science ( 2022-09-21)
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), ( 2022-09-21)
    Abstract: Weighting data appropriately in stock assessment models is necessary to diagnose model mis-specification, estimate uncertainty, and when combining data sets. Age- and length-composition data are often fitted using a multinomial distribution and then reweighted iteratively, and the Dirichlet-multinomial (“DM”) likelihood provides a model-based alternative that estimates an additional parameter and thereby “self-weights” data. However, the DM likelihood requires specifying an input sample size (ninput), which is often unavailable and results are sensitive to ninput. We therefore introduce the multivariate-Tweedie (MVTW) as alternative with three benefits: (1) it can identify both overdispersion (downweighting) or underdispersion (upweighting) relative to the ninput; (2) proportional changes in ninput are exactly offset by parameters; and (3) it arises naturally when expanding data arising from a hierarchical sampling design. We use an age-structured simulation to show that the MVTW (1) can be more precise than the DM in estimating data weights, and (2) can appropriately upweight data when needed. We then use a real-world state-space assessment to show that the MVTW can easily be adapted to other software. We recommend that stock assessments explore the sensitivity to specifying DM, MVTW, and logistic-normal likelihoods, particularly when the DM estimates an effective sample size approaching ninput.
    Type of Medium: Online Resource
    ISSN: 1054-3139 , 1095-9289
    URL: Article
    DOI: 10.1093/icesjms/fsac159
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2022
    detail.hit.zdb_id: 2463178-4
    detail.hit.zdb_id: 1468003-8
    detail.hit.zdb_id: 29056-7
    SSG: 12
    SSG: 21,3
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
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