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| Registros recuperados: 27 | |
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| Royer, Francois; Fromentin, Jean-marc. |
| We present a methodology for the non-linear analysis of long-term ecological time series. Using a time-delay embedding procedure, we investigated the complexity of 1-dimensional signals and compared their structure to their stochastic counterparts. Recurrence-based statistics and surrogate testing were used for this purpose. The method was first tested on elementary models for illustrative purposes and its potentialities and limits reviewed. We then investigated the time structure of 6 Mediterranean bluefin tuna trap catches known to display long-term fluctuations. These time series showed significantly more determinism than linear stochastic processes, displaying more recurring patterns/states than stochastic surrogates. The short term structure of these... |
| Tipo: Text |
Palavras-chave: Embedding; Surrogate testing; Density dependence; Recurrence; Thunnus thynnus. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1982.pdf |
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| Kell, L. T.; Fromentin, Jean-marc. |
| This paper presents an example of Management Strategy Evaluation (MSE) for Mediterranean and East Atlantic bluefin tuna using the FLR open source framework. Scenarios corresponding to alternative plausible hypotheses about the stock dynamics were used to evaluate alternative management strategies and to test their robustness to implementation error e.g. catch mis-reporting. The strategies evaluated correspond to i) harvest control rule (HCR) based upon F0.1 (a proxy for FMSY ) with an objective of restoring the stock to a level that would “ permit the maximum sustainable catch” and ii) a reduction of fishing mortality on immature fish. The main conclusions were that the F0.1 HCR alone would not result in the recovery of the stock in the next 15 years and... |
| Tipo: Text |
Palavras-chave: Thunnus thynnus; Management plans; Management strategy evaluation; Simulation model. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00194/30477/28884.pdf |
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| Fromentin, Jean-marc; Bonhommeau, Sylvain; Kell, Laurence; Restrepo, Victor. |
| Estimating the productivity of an exploited marine species is not an easy or a trivial task. In the case of Atlantic bluefin tuna, the productivity can hardly be estimated from the natural mortality rates or the stock recruitment relationships because the former have never been estimated for this species from scientific data, but only “guesstimated”, while the latter remain highly uncertain for both the eastern stock (BFTE) and the western stock (BFTW). To get a better idea of bluefin tuna productivity, we thus applied the approach by Jennings et al. (1998) who proposed a surrogate of r, r’, named the potential rate of population increase. We compared this parameter and age-at-maturity (and to some extent the individual growth curves) of 25 species... |
| Tipo: Text |
Palavras-chave: Thunnus thynnus; Population growth rate; Fecundity; Maturity; CITES criteria. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00192/30293/28777.pdf |
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| Hattour, A.; Moussa, A.. |
| An analysis of data from a Tunisian farm during the months of June to November of the year 2008 is presented. These data were broken down into two sets the first concern sampled fish while towing them to farm (wild set), the second set concern sampled specimen at the end of fattening process (fattening set). The wild group comprised specimens ranging from 90 to 276 cm fork length, and the fattened group included specimens from 105 to 310 сm. Juvenile proportion (Lf<130 сm) in fattened specimen (15.7%) was considerably smaller compared to the proportion in wild specimens (61,8%). The distribution of individual weights of slaughtered BFT shows the prevalence 31-50 kg specimen class (60.4%). The L-W relationships were determined for each of these sets.... |
| Tipo: Journal Contribution |
Palavras-chave: Thunnus thynnus; Tuna fisheries; Length-weight relationships; Fish farms; Tuna; Fattening. |
| Ano: 2012 |
URL: http://hdl.handle.net/1834/5315 |
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| Hattour, A. |
| L'objectif de ce document est d’améliorer notre connaissance au sujet des activités de la plus performante des madragues tunisiennes en l’occurrence celle de Sidi Daoud. Notre intérêt va porter particulièrement sur les prises saisonnières de la principale espèce, le thon rouge ainsi que les prises accessoires. Les données proviennent des débarquements commerciaux et des observations des échantillonneurs sur place enregistrés au cours de notre suivi de cette madrague. Nous avons également fait recours aux différentes données historiques de plusieurs auteurs ayant noté les prises saisonnières des différentes madragues tunisiennes. |
| Tipo: Journal Contribution |
Palavras-chave: Catching methods; Fishing nets; Trap nets; Tuna fisheries; Thunnus thynnus; Fishing nets. |
| Ano: 2005 |
URL: http://hdl.handle.net/1834/3690 |
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| Registros recuperados: 27 | |
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