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| Registros recuperados: 10 | |
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| Marandel, Florianne; Lorance, Pascal; Trenkel, Verena M.. |
| The thornback ray (Raja clavata) in the Bay of Biscay is presumed to have declined during the 20th Century. To evaluate this decline and estimate biomass trajectories, a hypothetical catch time series was created for the period 1903-2013. A Bayesian state-space biomass production model with a Schaefer production function was fitted to the hypothetical catch time series and to a shorter research vessel Catch Per Unit Eeffort (CPUE) time series (1973-2013, with missing years). A censored likelihood made it possible to obtain biomass estimates without a CPUE time series or only with an estimate of biomass depletion. A simulation-estimation approach showed a high sensitivity of results to the prior for the intrinsic growth rate. The model provided biomass... |
| Tipo: Text |
Palavras-chave: Population dynamics; Stock assessment; Data poor; Censored data; Bayes; Thornback ray; State-space model. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00359/47032/46947.pdf |
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| Nicolaus, E. E. Manuel; Barry, Jon; Bolam, Thi P. C.; Lorance, Pascal; Marandel, Florianne; Phillips, Sophy R. Mccully; Neville, Suzanna; Ellis, Jim R.. |
| Trace metal concentrations in muscle and liver tissues from two offshore species of skate were examined. Concentrations of mercury in muscle of Leucoraja circularis (n = 20; 23–110.5 cm total length, 157–490 m water depth) and L. fullonica (n = 24; 28.5–100 cm total length, 130–426 m water depth) were 0.02–1.8 and 0.04–0.61 mg kg− 1, respectively. Concentrations of both As and Hg increased with total length. Only the largest specimen had a concentration of Hg in muscle > 1.0 mg kg− 1. Data were limited for specimens > 90 cm long, and further studies on contaminants in larger-bodied skates could usefully be undertaken. |
| Tipo: Text |
Palavras-chave: Trace metals; Sandy ray; Shagreen ray; Bay of Biscay; Celtic Sea. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00397/50829/51592.pdf |
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| Marandel, Florianne; Lorance, Pascal; Trenkel, Verena. |
| 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... |
| Tipo: Text |
Palavras-chave: Community changes; Fishing impacts; Multispecies management; Multispecies model; Rajiformes; Species composition; Vulnerable skates. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00589/70088/68138.pdf |
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| Trenkel, Verena; Marandel, Florianne; Lorance, Pascal. |
| Sustainable fisheries management requires the evaluation of the status of exploited populations and communities. Certain bycatch species such as rays are managed together which has led to overexploitation and conservations concerns for the most vulnerable ones. Traditional fisheries stock evaluation methods need species-specific input data while for ray species-specific landings have become available only recently in Europe. To overcome data limitations caused by grouped landings we developed a Bayesian multispecies biomass production model. In addition to the grouped landings the input data are shorter time series with species-specific information (landings and scientific biomass indices). Life history traits are used to define informative priors for... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00470/58214/60718.pdf |
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| Marandel, Florianne; Charrier, Gregory; Lamy, Jean-baptiste; Le Cam, Sabrina; Lorance, Pascal; Trenkel, Verena. |
| Effective population size (Ne) is a key parameter of population genetics. However, Ne 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 Ne estimates (Linkage Disequilibrium method) we used RADseq data for a nonmodel species, the thornback ray. In this data set, the inbreeding coefficient FIS was positively correlated with the amount of missing data, implying data were missing... |
| Tipo: Text |
Palavras-chave: Effective population size; Linkage disequilibrium; NeEstimator; RADseq; Skates and rays. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00607/71934/70628.pdf |
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| Marandel, Florianne. |
| During the 20th century, several skates and rays species in European waters declined because of fishing. Conservation of these species is a major objective of the management of marine resources. The thornback ray (Raja clavata) is the most widespread species of the North-Est Atlantic. Its management is based on a nonspecific quota and lay on observations only as no stock assessment is available. Thus this thesis aims to compare the available stock assessments methods for this species and to apply them to empiric data. Two types of methods are investigated: methods based on population demography and methods based on population genetics. The thesis is separated in three parts: 1) assessment of management units; 2) assessment of the state of the thornback ray... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00471/58268/60788.pdf |
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| Marandel, Florianne; Biais, Gerard; Bidault, Adeline; Charrier, Grégory; Cornette, Florence; Lapegue, Sylvie; Laroche, Jean; Le Cam, Sabrina; Stephan, Eric; Trenkel, Verena; Lorance, Pascal. |
| At the ecosystem level, sustainable exploitation of fisheries resources depends not only on the status of target species but also on that of bycatch species, some of which are even more sensitive to exploitation. This is the case for a number of elasmobranchs (skates, rays and sharks) species whose abundance declined during the 20th century. Further, the biology of elamobranchs is still poorly known and traditional fisheries stock assessment methods using fisheries catches and scientific survey data for estimating abundance are expensive or even inapplicable due to the small numbers observed. The GenoPopTaille project attempts to apply to the case of the thornback ray (Raja clavata) recent genetic-based methods for absolute population abundance estimation... |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00343/45439/44960.pdf |
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| Marandel, Florianne; Lorance, Pascal; Andrello, Marco; Charrier, Gregory; Le Cam, Sabrina; Lehuta, Sigrid; Trenkel, Verena. |
| Studying demographic and genetic connectivity can help assessing marine meta-population 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 for unequal population abundances and two hypotheses of dispersal rates. Genetic simulation results highlighted three large meta-populations: 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... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00404/51535/52125.pdf |
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| Marandel, Florianne. |
| In this literature review, some fundamental aspects of population genetics are presented to introduce the notion of effective population size. Estimation methods, ecological processes affecting it, and its use in fishery research are also discussed. The definition of population used is the genetic one (but see glossary). |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00472/58360/60921.pdf |
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| Registros recuperados: 10 | |
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