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| Registros recuperados: 21 | |
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| Mesnil, Benoit. |
| The Catch-Survey Analysis (CSA) method of assessment aims at estimating stock abundance from relative indices by filtering measurement error in the latter through a simple two-stage population dynamics model. The method is not widely used and the associated literature is still limited. The objective of this work is to improve current understanding of the properties of the method, using data generated from a known fully age-structured population. A sensitivity analysis confirms that CSA is capable of providing reliable information about general stock trends. However, absolute estimates are sensitive to the parameter relating survey catchabilities of the two stages, which needs to be estimated externally with methods that warrant further validation. Biased... |
| Tipo: Text |
Palavras-chave: Data limited environments; Collie Sissenwine model; Catch Survey Analysis; Stock assessment. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/2003/publication-439.pdf |
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| Catanzano, Joseph; Mesnil, Benoit. |
| Fisheries can be characterized as a network of interactions between natural and social systems, and thus should be viewed as complex, dynamic systems. Due to the multiplicity of components and processes, the involvement of various disciplines is required to understand the inter-relationships within and between the systems, and more so to adequately address management issues that typically affect several elements in the systems. To be successful, multidisciplinary approaches require mutual understanding of the perspectives, concepts, vocabulary and methods held by various disciplines, and agreement on the objects to be studied in common. In that spirit, at framework is suggested whereby fisheries systems are decomposed into related sub-systems that can be... |
| Tipo: Text |
Palavras-chave: Système halieutique; Systèmes naturels et sociaux; Multidisciplinarité; Gestion des pêcheries; Risque; Production; Incertitude.; FISHERIES SYSTEM; NATURAL AND SOCIAL SYSTEMS; MULTIDISCIPLINARY APPROACHES; FISHERIES MANAGEMENT; RISK; PRODUCTION; UNCERTAINTY. |
| Ano: 1995 |
URL: http://archimer.ifremer.fr/doc/00179/29033/27467.pdf |
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| Mesnil, Benoit; Petitgas, Pierre. |
| Statistical Process Control (SPC) methods are extensively used in manufacturing contexts to monitor production processes. This article illustrates their potential utility for monitoring the state of marine ecosystems, using survey indicators. We exemplify the use of one SPC tool, the cumulative sum (CUSUM) control chart, to detect persistent changes in the state of a system as new observations are collected, using simulated and real data. Practical guidelines are given on how the chart parameters can be tuned to achieve an acceptable compromise between the ability to detect anomalies quickly and keeping the risk of false alarms low. The common performance measures associated with control charts depend on some key assumptions being met, and the potential... |
| Tipo: Text |
Palavras-chave: Aquatic resource monitoring; CUSUM; Statistical process control. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6689.pdf |
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| Biseau, Alain; Mesnil, Benoit. |
| Formellement, le Rendement Maximum Soutenable (RMS, ou RMD pour ‘rendement maximum durable, plus généralement connu sous le sigle anglais MSY pour "Maximum Sustainable Yield") est la plus grande quantité de biomasse que l'on peut en moyenne extraire continûment d'un stock, dans les conditions environnementales existantes (ou moyennes), sans affecter (sensiblement) le processus de reproduction. Le RMS est exprimé en terme de capture, généralement pondérale. Cette capture est le produit d’une biomasse (totale ou de reproducteurs) particulière du stock notée BMSY et d’une mortalité par pêche (ou taux de capture) spécifique notée FMSY. A efficacité de pêche donnée, il correspond à FMSY un effort de pêche EMSY. Ainsi, "les niveaux permettant d'obtenir le RMS"... |
| Tipo: Text |
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| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/00069/18058/15600.pdf |
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| Mesnil, Benoit. |
| Foreword: Sequential analysis of the demographic structures revealed by catches is currently the method most used, in particular by work groups working together within the framework of the C.I.E.M., to assess the characteristic parameters of exploited marine populations. The reasons for its success are due to a simple analytical definition, the absence of restrictive hypotheses, and especially a singular property thanks to which the results converge towards the parameters' true values. Due to its quasi-systematic use at the outset of the process leading to exploitation regulations, it is particularly important to take in the method's advantages, limits and rules of usage. This study is, in part, a review of the principal work performed on and around cohort... |
| Tipo: Text |
Palavras-chave: Methodology; Sequential Analysis; Fishing Captures. |
| Ano: 1980 |
URL: https://archimer.ifremer.fr/doc/1980/publication-1949.pdf |
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| Cotter, A; Mesnil, Benoit; Piet, G. |
| A year-class curve is a plot of log cpue (catch per unit effort) over age for a single year class of a species (in contrast to the better known catch curve, fitted to multiple year classes at one time). When linear, the intercept and slope estimate the log cpue at age 0 and the average rate of total mortality, Z, respectively. Here, we suggest methodological refinements within a linear least squares framework. Candidate models may include a selectivity term, fleet-specific parameters, and polynomials in year to allow for gradual variations of Z. An iterative weighting method allows for differing precisions among the different fleets, and a forward (one-step ahead) validation procedure tests predicted cpue against observed values. Choice of the best... |
| Tipo: Text |
Palavras-chave: Year class curve; Plaice; North Sea; Iteratively weighted least squares; Forward validation; Fish stock assessment; Cpue; Analysis of relative residual variance. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2776.pdf |
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| Cotter, John; Petitgas, Pierre; Abella, Alvaro; Apostolaki, Panayiota; Mesnil, Benoit; Politou, Chrissi-yianna; Rivoirard, Jacques; Rochet, Marie-joelle; Spedicato, Maria Teresa; Trenkel, Verena; Woillez, Mathieu. |
| Ideas and considerations are put forward for managing fisheries and marine populations using primarily trawl surveys to supply biological and spatial indicators of the state of stocks, and to permit catch per unit effort (CPUE)-based assessments. Trawl surveys seldom allow absolute estimates of fish population sizes but, if appropriately located, timed, and designed, can provide a broad range of information about catchable fish species and the ecosystem that supports them. This information may be more conducive to sustainable management of fisheries than the traditional focus on the abundances of selected stocks. The paper first briefly proposes how survey-based methods might supplement existing fishery-dependent stock assessments, as would be necessary... |
| Tipo: Text |
Palavras-chave: Fishing effort indicator; Fisheries independent assessment; Survey based stock assessment; Spatial indicator; State indicator; Trawl survey; Fisheries management. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6691.pdf |
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| Mesnil, Benoit. |
| Pour analyser un stock exploité, et plus encore pour prévoir en termes quantitatifs les conséquences de mesures envisagées pour sa gestion, le recours à des représentations explicites des phénomènes régissant les états de ce stock s'impose. Dans un premier temps, les statistiques associées aux facteurs élémentaires, sont étudiées et leurs variations figurées sous un format approprié. La modélisation consiste en la recherche de la loi mathématique ou fonction dont la courbe caractéristique s'ajuste de la façon la plus étroite aux diagrammes des variations observées Ce faisant, on réduit considérablement le volume des données : les quelques coefficients de la fonction retenue en assurent la synthèse et suffisent à représenter les phénomènes quand des valeurs... |
| Tipo: Text |
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| Ano: 1980 |
URL: http://archimer.ifremer.fr/doc/00046/15690/13092.pdf |
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| Cotter, John; Mesnil, Benoit; Witthames, Peter; Parker-humphreys, Matt. |
| This paper reviews a selection of nine indicators for assessing the biological state of a fish population monitored only by using trawl surveys in which catchability is assumed constant from time to time and place to place. The intention is to inform or remind of the range of possibilities and of associated practical and statistical issues. The indicators, grouped according to relationships with abundance, length, age, weight, and reproduction, are documented in a standard format covering estimation, interpretability, sensitivity, considerations for reference points where possible, and an example of their application. Lastly, selected indicators together with year-class curves fitted to abundance indices-at-age are applied to the North Sea cod to... |
| Tipo: Text |
Palavras-chave: Ecosystem approach to fisheries management; Year class curves; Weight index; Maturity stage; Age composition; Length based indicators; Biological indicators. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6901.pdf |
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| Kell, L; Pilling, G; Kirkwood, G; Pastoors, M; Mesnil, Benoit; Korsbrekke, K; Abaunza, P; Aps, R; Biseau, Alain; Kunzlik, P; Needle, C; Roel, B; Ulrich, Clara. |
| Current scientific management objectives for ICES roundfish stocks are to ensure conservation of the biological resource and do not explicitly consider economic or social objectives. For example, there are currently no objectives to maximize the sustainable yield or to reduce variability in total allowable catches (TACs). This is despite the fact that the current system can result in wide annual fluctuations in TAC, limiting the ability of the fishing industry to plan for the future. Therefore, this study evaluated management strategies that stabilized catches by setting bounds on the interannual variability in TACs. An integrated modelling framework was used, which simulated both the real and observed systems and the interactions between system... |
| Tipo: Text |
Palavras-chave: Whiting; TAC; Simulation; Saithe; Population modelling; North Sea; Management; Limiting variations; Harvest strategies; Hake; Haddock; Evaluation; Cod; Bounds. |
| Ano: 2006 |
URL: https://archimer.ifremer.fr/doc/2006/publication-3694.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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| Chevalier, R.; Gondeaux, E.; Koutsikopoulos, C.; Mesnil, Benoit. |
| Thè present document is a compilation of the topics presented during an introductory course to sampling techniques held in the IFREMER center of Nantes (17-21 October 1988). The purpose of this course was a presentation of some basic elements of the sampling theory followed by a description and practice of the principal sampling techniques. After an introoduction th the sampling theory the floowing sampling techniques were presented : simple Random Sampming, Ratio estimator, Stratified sampling, Cluster Sampling and Multistages Sampling. Two supplments with the basic mathematical and statistical notions used in this document are also included. |
| Tipo: Text |
Palavras-chave: Teechniques de sondage; Sampling techniques. |
| Ano: 1988 |
URL: http://archimer.ifremer.fr/doc/00450/56177/57725.pdf |
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| Chevalier, R.; Mesnil, Benoit. |
| Sorne problems encountered in estimating the age structure of landings from fish market samplinq are reviewed in this document. Being perequisite to the definition of on optimal sampling strategy, the selection of a sampling scheme and the choice of the estimators are discussed. The definition of an objective function to optimize is also critical. We have used an average of instantaneous fishing mortality rates obtained from a (pseudo- ) cohort analysis. More elaborate functions can be envisaoed. |
| Tipo: Text |
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| Ano: 1986 |
URL: https://archimer.ifremer.fr/doc/00503/61478/65258.pdf |
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| Mesnil, Benoit; Guichet, Roger. |
| Due to difficulties in routinely ageing European hake, assessments of the stock have hitherto been carried out using length-based methods, and were thus restricted to pseudo-cohort analyses and long-term equilibrium projections under steady state assomptions. However, given the availability of numerical length-to-age conversion methods, it seems feasible to consider age-based assessments using the methodology of regular ICES working groups. In this paper, attempts are made to derive a time series of catches at age from the length compositions of international catches assembled by the ICES Hake Working Group for the period 1978-1990. The age-length key which is reconstructed in each year is also applied to the length composition of catches by selected... |
| Tipo: Text |
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| Ano: 1991 |
URL: https://archimer.ifremer.fr/doc/00394/50568/51259.pdf |
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| Mesnil, Benoit. |
| According to the media the French fishing industry has been in permanent state of crisis for the last 40 years. This paper recounts the events surrounding three major episodes of crises (late 1970s, mid-1990s, and early 2000s), and the measures taken by governments to resolve them. Invariably, these involved the distribution of sizeable amounts of public aids, in different forms, to the fishing sector. The efficacy of the subsidy programmes is discussed with reference to the goals stated by their proponents, regarding trade balance, competitiveness, profitability, employment and safety. Overall, the massive aids granted to the sector (comparable with the gross value of landings, annually) have not achieved the stated objectives and, paradoxically, have... |
| Tipo: Text |
Palavras-chave: France; Subsidies; Fisheries policies. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4538.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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| Registros recuperados: 21 | |
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