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| Registros recuperados: 96 | |
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| Rochet, Marie-joelle; Rice, Jake C.. |
| Simulation-based management strategy evaluations are increasingly developed and used for science advice in support of fisheries management, along with risk evaluation and decision analysis. These methods tackle the problem of uncertainty in fisheries systems and data by modelling uncertainty in two ways. For quantities that are difficult to measure accurately or are inherently variable, variables are replaced by probability distributions, and system dynamics are simulated by Monte Carlo simulations, drawing numbers from these distributions. For processes that are not fully understood, arrays of model formulations that might underlie the observed patterns are developed, each is assumed successively, and the results of the corresponding arrays of model... |
| Tipo: Text |
Palavras-chave: Uncertainty; Risk estimates; Monte Carlo simulation; Management strategy evaluation. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6361.pdf |
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| Guerineau, Lise; Rochet, Marie-joelle; Peronnet, Isabelle. |
| Ce document présente un panorama des rejets dans les pêches françaises, établi à partir des données d’échantillonnage à bord des navires de pêche de 2003 à 2009, et des statistiques de pêche de 2003 à 2008. Le taux d’échantillonnage, faible en début de période, ainsi que la qualité des données, empêchent dans la plupart des cas d’obtenir des estimations fiables, aussi seules des gammes de variation des quantités rejetées sont présentées. Cependant les résultats obtenus permettent toutefois d’identifier les espèces faisant l’objet des rejets les plus importants. Ainsi, sur l’ensemble des zones examinées, le chinchard fait l’objet de rejets importants, même quand une partie de la capture est débarquée. En Manche-mer du Nord, trois métiers ont pu être... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00001/11232/7753.pdf |
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| Trenkel, Verena; Rochet, Marie-joelle; Mesnil, Benoit. |
| Traditional advice for fisheries management, especially in the ICES world, focuses on short-term stock projections relative to reference points. Primarily, two numbers, spawning-stock biomass and fishing mortality rate, are considered in the advice, although a range of biological processes are included in the stock assessment models. We propose an alternative form of final advice that would not rely on stock predictions and only two numbers, but on a suite of indicators that are combined to provide stock assessment and management advice. For a single stock, the approach consists of monitoring a set of indicators of population state and fishing pressure. Stock reference status at some time in the past is assessed, based on these indicators and/or other... |
| Tipo: Text |
Palavras-chave: Scientific advice; Indicators; Fisheries management. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2619.pdf |
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| Cornou, Anne Sophie; Goascoz, Nicolas; Scavinner, Marion; Prioul, Francois; Sabbio, Andrea; Dubroca, Laurent; Renaud, Florent; Rochet, Marie-joelle. |
| Ce document est une synthèse des informations collectées en 2017 à bord des navires de pêche professionnelle dans le cadre de l'action ObsMer. Cette action vise à observer in situ l’activité de pêche et l'ensemble de la capture, particulièrement la partie non retenue, en identifiant les espèces capturées, les tonnages par espèce et en prenant des mesures de tailles. Ce travail s'inscrit dans le cadre d'un partenariat entre le Comite National des Pêches Maritimes et des Élevages Marins (CNPMEM), la Direction des Pêches Maritimes et de l'Aquaculture (DPMA) du Ministère de l’Agriculture et de l'Alimentation, et l'Ifremer. |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00461/57314/59410.pdf |
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| Rochet, Marie-joelle. |
| Density dependence means that exploited fish populations exhibit earlier maturity, a faster growth rate, increased fecundity and reduced egg size. Here, the consequences of these effects on population dynamics, the estimation of spawning biomass per recruit and associated biological reference points are examined by a simulation model. The model is a self-regenerating model in which the population parameters (age at maturity, growth, fecundity, egg size) vary according to three classes of population abundance. Early life stages are characterized by a size-dependent growth and mortality model. It is concluded that spawning per recruit is an ambiguous concept because, if density dependence occurs in the adult population, the spawning biomass of a cohort is... |
| Tipo: Text |
Palavras-chave: Teleost fishes; Population dynamics; Life history; Density dependence; Biological reference points. |
| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/2000/publication-485.pdf |
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| Nielsen, J. Rasmus; Bastardie, Francois; Buhl-mortensen, Lene; Eigaard, Ole; Gümüs, Aysun; Hintzen, Niels T.; Kavadas, Stefanos; Laffargue, Pascal; Mehault, Sonia; Notti, Emilio; Papadoupoulou, Nadia; Polet, Hans; Reid, David; Rijnsdorp, Adriaan D.; Rochet, Marie-joelle; Robert, Alexandre; Sala, Antonello; Smith, Chris; Virgili, Massimo; Zengin, Mustafa. |
| Baltic Sea Benthic ecosystem impacts from demersal fishery in the western Baltic is assumed to come mainly from Nephrops trawling in the central and southern Kattegat, mussel dredging in the Belt Sea, and mixed cod trawling in the western Baltic Sea.These fisheries both impact the seabed, as well as produce substantial amounts of discards. The western Baltic Sea offer a unique opportunity to analyse the benthic effects of fishingthanks to the closure of Øresund to towed gears since the 1920s, and the introduction of the Kattegat MPA in2009 (including cod closure) and the western Baltic Sea Natura-2000 areas. Furthermore an extensive benthic nationalmonitoring and data collection effort has taken place in the area over a number of years, which can be usedto... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00310/42142/41453.pdf |
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| Benoit, Eric; Rochet, Marie-joelle. |
| A new time-dependent continuous model of biomass size spectra is developed. In this model, predation is the single process governing the energy flow in the ecosystem, as it causes both growth and mortality. The ratio of predator to prey is assumed to be distributed: predators may feed on a range of prey sizes. Under these assumptions, it is shown that linear size spectra are stationary solutions of the model. Exploited fish communities are simulated by adding fishing mortality to the model: it is found that realistic fishing should affect the curvature and stability of the size spectrum rather than its slope. |
| Tipo: Text |
Palavras-chave: Predation; Mortality; Growth; Biomass size spectrum; Allometry. |
| Ano: 2004 |
URL: http://archimer.ifremer.fr/doc/2004/publication-665.pdf |
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| Mesnil, Benoit; Rochet, Marie-joelle. |
| With political commitment to restore stocks to levels where they can produce maximum sustainable yield (MSY), fisheries managers request evaluations of management plans that include options for an FMSY policy. The procedure to estimate FMSY with dynamic-pool, stock assessment models is well established for common stock-recruitment relationships (S-RR). In this paper, we extend this capacity to another S-RR, a piecewise function known as the hockey stick, which is frequently assumed when the data do not support more elaborate functions. However, the hockey stick is not continuous, which makes it problematic for this application, where differentiable functions are required. The bent-hyperbola model proves to be an adequate continuous equivalent to the hockey... |
| Tipo: Text |
Palavras-chave: Bent hyperbola; F-MSY; Hockey stick; MSY; Stock-recruitment. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00016/12735/9667.pdf |
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| Cornou, Anne-sophie; Dimeet, Joel; Goascoz, Nicolas; Scavinner, Marion; Rochet, Marie-joelle. |
| Ce document est une synthèse des informations collectées en 2015 à bord des navires de pêche professionnelle dans le cadre de l'action ObsMer. Cette action vise à observer in situ l’activité de pêche et l'ensemble de la capture, particulièrement la partie non retenue, en identifiant les espèces capturées, les tonnages par espèce et en prenant des mesures de tailles. Ce travail s'inscrit dans le cadre d'un partenariat entre le Comite National des Pêches Maritimes et des Élevages Marins (CNPMEM), la Direction des Pêches Maritimes et de l'Aquaculture (DPMA) du Ministère de l’Écologie, du Développement Durable et de l’Énergie, et l'Ifremer. |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00353/46441/46185.pdf |
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| Lassalle, Geraldine; Pasqual, Jean-sebastien Nelva; Boet, Philippe; Rochet, Marie-joelle; Trenkel, Verena; Niquil, Nathalie. |
| To develop and implement ecosystem-based management, it is critical to monitor foodweb components or functional groups which are robust to uncertainty in ecosystem structure and functioning yet sensitive to changes. To select such functional groups for the Bay of Biscay continental shelf, both quantitative and qualitative foodweb models were developed. First, functional groups for which predictions of directions of change following an increase in primary productivity, prey or predators, or in fishing activities were identical across alternative qualitative model structures were identified. Second, the robustness to model type was assessed by comparing qualitative predictions with quantitative Ecopath model results. The demersal fish community was... |
| Tipo: Text |
Palavras-chave: Comparative studies; Ecosystem management; Foodweb; Loop analysis; Northeast Atlantic continental shelf. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00173/28427/26852.pdf |
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| Rochet, Marie-joelle; Prigent, M; Bertrand, Jacques; Carpentier, Andre; Coppin, Franck; Delpech, Jean-paul; Fontenelle, G; Foucher, Eric; Mahe, Kelig; Rostiaux, Emilie; Trenkel, Verena. |
| The results of a survey on fishers' perceptions of recent changes in the eastern English Channel ecosystem carried out in 2006 were compared with fishery and bottom-trawl survey data. A hypothesis-testing framework was used, testing the null hypothesis that fishers' statements were true, which permitted evaluation of both agreement and disagreement. Overall good agreement between fishers' statements and scientific data was found, and both sources suggested that the fish community in the Channel is undergoing large changes, among which are decreases in some commercially important species; in addition, a number of human pressures impact the ecosystem. Fishers had an accurate perception of changes and their time-frames, but not necessarily of their causes.... |
| Tipo: Text |
Palavras-chave: Stakeholder interview; Hypothesis testing; Fisher knowledge; Ecosystem approach to fisheries management; Eastern English Channel. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4474.pdf |
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| Trenkel, Verena; Pinnegar, John; Rochet, Marie-joelle; Rackham, Brian. |
| Choice of sampling method and survey period can have an important impact on the perception of the structure and dynamics of an ecological community. For the Celtic Sea fish assemblage we compared data obtained by three different trawl surveys: an autumn groundfish survey with a GOV trawl, and a spring and an autumn groundfish survey, both carried out with a Portuguese high-headline trawl. Time-series of abundance estimates were not consistent among surveys for all species and were generally very noisy. An analysis of variance components showed that the sampling method contributed more to the variance in abundance estimates compared to survey period, interannual variability, or even sampling variance. Overall community assessments based on indicators such... |
| Tipo: Text |
Palavras-chave: Trawl; Survey; Species diversity; Size spectrum; Celtic Sea; Abundance. |
| Ano: 2004 |
URL: https://archimer.ifremer.fr/doc/2004/publication-899.pdf |
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| Catchpole, T. L.; Feekings, J. P.; Madsen, N.; Palialexis, A.; Vassilopoulou, V.; Valeiras, J.; Garcia, T.; Nikolic, Natacha; Rochet, Marie-joelle. |
| Discards refer to the part of the catch not retained on board during commercial fishing operations, but returned to the sea. The proposed European Union Common Fisheries Policy reform, to be implemented in 2014, sets out a gradual elimination of discards by reducing unwanted catches and ensuring that all catches are landed. To develop successful discard mitigation measures, it is necessary to identify the reasons for discarding. Here, we have developed a simple model that can be applied to data from observer programmes (ObsPs) to establish the contribution of different drivers of discarding behaviour. The analysis makes inferences on the causes of discarding by partitioning discards into four categories based on the length of the fish and the associated... |
| Tipo: Text |
Palavras-chave: CFP; Discards; Fishers market; Quota. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00159/27030/26202.pdf |
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| Trenkel, Verena; Berthele, Olivier; Lorance, Pascal; Bertrand, Jacques; Brind'Amour, Anik; Cochard, Marie-laure; Coppin, Franck; Leaute, Jean-pierre; Mahe, Jean-claude; Morin, Jocelyne; Rochet, Marie-joelle; Salaun, Michele; Souplet, Arnauld; Verin, Yves. |
| Depuis une vingtaine d'années, l'Ifremer organise des campagnes de pêche scientifique en mer du Nord, Manche, Atlantique et Méditerranée concernant les ressources pélagiques, démersales et benthiques. L'objectif prioritaire est de produire des indices d'abondance des principales espèces commerciales. Elles recueillent également des données sur les espèces capturées non commerciales. Les campagnes sont réalisées selon des plans d'échantillonnage standardisés. L'engin de pêche et son gréement, la position des stations, le tri des captures, les prélèvements biologiques suivent des protocoles fixés. Chaque zone étudiée est découpée en fonction de la profondeur, de la latitude ou d'autres critères. L'échantillonnage prévoit un nombre de traits de chalut... |
| Tipo: Text |
Palavras-chave: Populations; Halieutique; Bulletin; Méditerranée; Golfe de Gascogne; Manche; Mer du Nord; France; Pêche; Campagnes à la mer; Atlas; Survey; Mediterranean Sea; Bay of Biscay; English Channel; North Sea; France; Populations; Fishery science; Bulletin; Atlas. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/rapport-6976.pdf |
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| Rochet, Marie-joelle; Collie, Jeremy S.; Trenkel, Verena. |
| Competition and predation can play different roles in mediating the influence of external pressures, such as fishing or environmental variations, on marine communities. Pressure effects propagate through food webs along predation links. These predator-prey interactions may result in trophic cascades, but they can be buffered by competitive interactions. We investigated these mechanisms by taking a functional-group approach. Are functional groups affected by external pressures in a predictable way? Within functional groups, do all species respond in the same way, or does competitive release allow for compensation among species? We constructed a simple community model, with functional groups connected by predation links. Loop analysis was used to make... |
| Tipo: Text |
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| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00154/26492/25465.pdf |
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| Battaglia, Andre; Trenkel, Verena; Rochet, Marie-joelle. |
| The end effect in trawl catches is defined as the proportion of the fish catch taken during shooting and hauling of the net, a period excluded from that nominally referred to as haul duration. If important, this effect will lead to biased abundance estimates, because the swept area will be underestimated. An experimental survey was carried out to compare catch numbers obtained in standard research 30-min hauls with those from 0-min hauls, the latter referring to the trawl being hauled as soon as the trawl geometry stabilized on the seabed. Average catch ratios (0-min/30-min hauls) ranged from 0.05 (s.d. 0.06) for sole to 0.34 (s.d. 0.64) for hake, indicating that the end effect might be more important and more variable for highly mobile species. As a... |
| Tipo: Text |
Palavras-chave: Trawl survey; Bias; Abundance index. |
| Ano: 2006 |
URL: https://archimer.ifremer.fr/doc/2006/publication-1686.pdf |
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| Registros recuperados: 96 | |
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