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  • Marandel, Florianne  (5)
  • 1
    In: Aquatic Living Resources, EDP Sciences, Vol. 29, No. 2 ( 2016-4), p. 209-
    Type of Medium: Online Resource
    ISSN: 0990-7440 , 1765-2952
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2016
    detail.hit.zdb_id: 2019083-9
    detail.hit.zdb_id: 291280-6
    SSG: 12
    SSG: 21,3
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  • 2
    In: Fish and Fisheries, Wiley, Vol. 20, No. 1 ( 2019-01), p. 189-198
    Abstract: Sustainable exploitation of marine populations is a challenging task relying on information about their current and past abundance. Fisheries‐related data can be scarce and unreliable making them unsuitable for quantitative modelling. One fishery independent method that has attracted attention in this context consists in estimating the effective population size ( N e ), a concept founded in population genetics. We reviewed recent empirical studies on N e and carried out a simulation study to evaluate the feasibility of estimating N e in large fish populations with the currently available methods. The detailed review of 26 studies found that published empirical N e values were very similar despite differences in species and total population sizes ( N ). Genetic simulations for an age‐structured fish population were carried out for a range of population and samples sizes, and N e was estimated using the Linkage Disequilibrium method. The results showed that already for medium‐sized populations (1 million individuals) and common sample sizes (50 individuals), negative estimates were likely to occur which for real applications is commonly interpreted as indicating very large (infinite) N e . Moreover, on average, N e estimates were negatively biased. The simulations further indicated that around 1% of the total number of individuals might have to be sampled to ensure sufficiently precise estimates of N e . For large marine populations, this implies rather large samples (several thousands to millions of individuals). If however such large samples were to be collected, many more population parameters than only N e could be estimated.
    Type of Medium: Online Resource
    ISSN: 1467-2960 , 1467-2979
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 2024569-5
    SSG: 21,3
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    Wiley ; 2019
    In:  Fisheries Management and Ecology Vol. 26, No. 4 ( 2019-08), p. 365-373
    In: Fisheries Management and Ecology, Wiley, Vol. 26, No. 4 ( 2019-08), p. 365-373
    Abstract: Sustainable fisheries management requires assessment of exploited populations and communities. Traditional fisheries stock assessment methods need species‐specific input data, which for skates have only recently become available in Europe. To overcome this limitation, a Bayesian multispecies biomass production model was developed. In addition to aggregated landings, input data are short time series with species‐specific information (landings and biomass indices). Applying the approach to four main skate species and a group of two skate species, all managed together in the Bay of Biscay (Northeast Atlantic), long‐term changes in the skate assemblage composition were identified. Since the 1990s, Leucoraja naevus became increasingly dominant, while the contributions of the other three species ( Raja brachyura , Raja clavata and Raja montagui ) declined. The abundance of the grouped Leucoraja fullonica and L. circularis has also strongly decreased, suggesting long‐term overexploitation. All species except this species group are expected to increase over the next decade under current harvest rates. Currently, the species considered here are managed under a single fishing quota making it unlikely that the group of the two most depleted species will recover soon. The multispecies modelling approach bears promise for other harvested assemblages for which only grouped harvest information is available for certain periods.
    Type of Medium: Online Resource
    ISSN: 0969-997X , 1365-2400
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 1193882-1
    detail.hit.zdb_id: 2020299-4
    SSG: 21,3
    SSG: 12
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  • 4
    In: Ecology and Evolution, Wiley, Vol. 10, No. 4 ( 2020-02), p. 1929-1937
    Abstract: Effective population size ( N e ) is a key parameter of population genetics. However, N e remains challenging to estimate for natural populations as several factors are likely to bias estimates. These factors include sampling design, sequencing method, and data filtering. One issue inherent to the restriction site‐associated DNA sequencing (RADseq) protocol is missing data and SNP selection criteria (e.g., minimum minor allele frequency, number of SNPs). To evaluate the potential impact of SNP selection criteria on N e estimates (Linkage Disequilibrium method) we used RADseq data for a nonmodel species, the thornback ray. In this data set, the inbreeding coefficient F IS was positively correlated with the amount of missing data, implying data were missing nonrandomly. The precision of N e estimates decreased with the number of SNPs. Mean N e estimates (averaged across 50 random data sets with2000 SNPs) ranged between 237 and 1784. Increasing the percentage of missing data from 25% to 50% increased N e estimates between 82% and 120%, while increasing the minor allele frequency (MAF) threshold from 0.01 to 0.1 decreased estimates between 71% and 75%. Considering these effects is important when interpreting RADseq data‐derived estimates of effective population size in empirical studies.
    Type of Medium: Online Resource
    ISSN: 2045-7758 , 2045-7758
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 2635675-2
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  • 5
    Online Resource
    Online Resource
    Canadian Science Publishing ; 2018
    In:  Canadian Journal of Fisheries and Aquatic Sciences Vol. 75, No. 8 ( 2018-08), p. 1291-1302
    In: Canadian Journal of Fisheries and Aquatic Sciences, Canadian Science Publishing, Vol. 75, No. 8 ( 2018-08), p. 1291-1302
    Abstract: Studying demographic and genetic connectivity can help assess marine metapopulation structure. Rays and skates have no larval phase; hence, population connectivity can only result from active movement of individuals. Using thornback ray (Raja clavata) in European waters as a case study, demographic and genetic connectivity were studied for 11 putative populations with unequal population abundances and two hypotheses of dispersal rates. Genetic simulation results highlighted three large metapopulations: in the Mediterranean, around the Azores, and on the Northeast Atlantic shelf. Demographic results highlighted a finer population structure indicating that several pairs of putative populations might be demographically linked. Results were highly sensitive to dispersal assumptions and relative population abundances, which provided insights into the potential magnitude of genetic and demographic connectivity differences. Accounting for demographic connectivity appears to be crucial for managing and conserving rays and skates, while genetic connectivity provides a longer-term perspective and less subtle spatial structures. Moreover, accounting for heterogeneity in population abundances is a key factor for determining or interpreting metapopulation connectivity.
    Type of Medium: Online Resource
    ISSN: 0706-652X , 1205-7533
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2018
    detail.hit.zdb_id: 7966-2
    detail.hit.zdb_id: 1473089-3
    SSG: 21,3
    SSG: 12
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