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  • Oxford University Press (OUP)  (10)
  • 2005-2009  (10)
  • 1
    Online Resource
    Online Resource
    Simulation-based management strategy evaluation: ignorance disguised as mathematics?
    Oxford University Press (OUP) ; 2009
    In:  ICES Journal of Marine Science Vol. 66, No. 4 ( 2009-05-01), p. 754-762
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 66, No. 4 ( 2009-05-01), p. 754-762
    Abstract: Rochet, M-J. and Rice, J. C. 2009. Simulation-based management strategy evaluation: ignorance disguised as mathematics? – ICES Journal of Marine Science, 66: 754–762. 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 results are then combined. We argue that these approaches have several paradoxical features. Stochastic modelling of uncertainty is paradoxical, because it implies knowing more than deterministic approaches: to know the distribution of a quantity requires more information than only estimating its expected value. To combine the results of Monte Carlo simulations with different model formulations may be paradoxical if outcomes of concern are unlikely under some formulations but very likely under others, whereas the reported uncertainty from combined results may produce a risk level that does not occur under any plausible assumed formulation. Moreover, risk estimates of the probability of undesirable outcomes are often statements about likelihood of events that were seldom observed and lie in the tails of the simulated distributions, where the results of Monte Carlo simulation are the least reliable. These potential paradoxes lead us to suggest that greater attention be given to alternative methods to evaluate risks or management strategies, such as qualitative methods and empirical post hoc analyses.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsp023
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2009
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  • 2
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    A framework for selecting a suite of indicators for fisheries management
    Oxford University Press (OUP) ; 2005
    In:  ICES Journal of Marine Science Vol. 62, No. 3 ( 2005-01-01), p. 516-527
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 62, No. 3 ( 2005-01-01), p. 516-527
    Abstract: We develop a framework for the objective selection of a suite of indicators for use in fisheries management. The framework encompasses eight steps, and provides guidance on pitfalls to be avoided at each step. Step 1 identifies user groups and their needs, featuring the setting of operational objectives, and Step 2 identifies a corresponding list of candidate indicators. Step 3 assigns weights to nine screening criteria for the candidate indicators: concreteness, theoretical basis, public awareness, cost, measurement, historic data, sensitivity, responsiveness, and specificity. Step 4 scores the indicators against the criteria, and Step 5 summarizes the results. Steps 3–5 offer technical aspects on which guidance is provided, including scoring standards for criteria and a generalized method for applying the standards when scoring individual indicators. Multi-criterion summarization methods are recommended for most applications. Steps 6 and 7 are concerned with deciding how many indicators are needed, and making the final selection of complementary suites of indicators. Ordinarily, these steps are done interactively with the users of the indicators, thus providing guidance on process rather than technical approach. Step 8 is the clear presentation to all users of the information contained. The discussion also includes the special case in which indicators are used in formal decision rules.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1016/j.icesjms.2005.01.003
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2005
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  • 3
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    Evaluating potential indicators for an ecosystem approach to fishery management in European waters
    Oxford University Press (OUP) ; 2008
    In:  ICES Journal of Marine Science Vol. 65, No. 8 ( 2008-11-01), p. 1449-1455
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 65, No. 8 ( 2008-11-01), p. 1449-1455
    Abstract: Piet, G. J., Jansen, H. M., and Rochet, M-J. 2008. Evaluating potential indicators for an ecosystem approach to fishery management in European waters. – ICES Journal of Marine Science, 65: 1449–1455. This study describes the process of evaluating potential indicators for an ecosystem approach to fishery management in European waters by evaluating these indicators against existing criteria using questionnaires completed by experts. We (i) compare the use of a longer list of simple criteria with a shorter list of elaborate ones; (ii) compare evaluation results when screening criteria are applied to specific indicators vs. high-level headline indicators; and (iii) examine whether detailed questionnaires, with elaborate indicators and elaborate criteria, result in ranked scores that are less influenced by familiarity with the indicators. The results show that the ranked scores of indicators are affected by the level of detail, both in terms of criteria and indicators, provided in the questionnaires. It appears that adding detail to the questionnaires makes the scoring process more transparent and provides better founded scores; at a certain point, however, more-detailed indicators and/or more-detailed criteria result in decreased performance of the scoring process, reflecting mostly factors that do not determine the suitability of the indicator (e.g. the level of familiarity), while giving the false impression of a more thorough analysis.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsn124
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2008
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  • 4
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    Do explicit criteria help in selecting indicators for ecosystem-based fisheries management?
    Oxford University Press (OUP) ; 2005
    In:  ICES Journal of Marine Science Vol. 62, No. 3 ( 2005-01-01), p. 528-539
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 62, No. 3 ( 2005-01-01), p. 528-539
    Abstract: An evaluation framework developed to help select an appropriate suite of indicators to support an ecosystem approach to fisheries management was tested experimentally by asking independent experts to weight the selection criteria provided and to score indicators against those criteria in several ecological settings. The steps in selecting indicators proved to be prone to subjectivity and value judgement, and differences in scores between experts were the main factor contributing to variability in evaluation results. Having to justify scores in a written document did not improve consistency among the experts. The framework, however, did enhance transparency by explicitly stating each issue to be addressed in the selection process, and by giving experts or stakeholders the opportunity to present their values explicitly. For example, using a longer list of simpler selection criteria appeared to provide less controversial results than a shorter list of more complex ones.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1016/j.icesjms.2005.01.007
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2005
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    detail.hit.zdb_id: 29056-7
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    SSG: 21,3
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  • 5
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    Online Resource
    From model-based prescriptive advice to indicator-based interactive advice
    Oxford University Press (OUP) ; 2007
    In:  ICES Journal of Marine Science Vol. 64, No. 4 ( 2007-05-01), p. 768-774
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 64, No. 4 ( 2007-05-01), p. 768-774
    Abstract: Trenkel, V. M., Rochet, M-J., and Mesnil, B. 2007. From model-based prescriptive advice to indicator-based interactive advice. – ICES Journal of Marine Science, 64: 768–774. 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 available information. Changes in indicator values after this reference time are then estimated, interpreted, and finally combined into a diagnostic that highlights possible causes of the changes observed. After considering management objectives, appropriate management actions can then be proposed. The proposed approach is illustrated for anglerfish stocks in the Celtic Sea and the Bay of Biscay.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsm006
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2007
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    detail.hit.zdb_id: 29056-7
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  • 6
    Online Resource
    Online Resource
    Ecosystem trends: evidence for agreement between fishers' perceptions and scientific information
    Oxford University Press (OUP) ; 2008
    In:  ICES Journal of Marine Science Vol. 65, No. 6 ( 2008-09-01), p. 1057-1068
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 65, No. 6 ( 2008-09-01), p. 1057-1068
    Abstract: Rochet, M-J., Prigent, M., Bertrand, J. A., Carpentier, A., Coppin, F., Delpech, J-P., Fontenelle, G., Foucher, E., Mahé, K., Rostiaux, E., and Trenkel, V. M. 2008. Ecosystem trends: evidence for agreement between fishers' perceptions and scientific information. – ICES Journal of Marine Science, 65: 1057–1068. 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. They had a greater power than survey data to detect recent changes, showing that fishers' perceptions have great potential as early warning signals.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsn062
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2008
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    detail.hit.zdb_id: 1468003-8
    detail.hit.zdb_id: 29056-7
    SSG: 12
    SSG: 21,3
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  • 7
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    Online Resource
    Using size-based indicators to evaluate the ecosystem effects of fishing
    Oxford University Press (OUP) ; 2005
    In:  ICES Journal of Marine Science Vol. 62, No. 3 ( 2005-01-01), p. 384-396
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 62, No. 3 ( 2005-01-01), p. 384-396
    Abstract: The usefulness and relevance of size-based indicators (SBIs) to an ecosystem approach to fisheries (EAF) are assessed through a review of empirical and modelling studies. SBIs are tabulated along with their definitions, data requirements, potential biases, availability of time-series, and expected directions of change in response to fishing pressure. They include mean length in a population, mean length in a community, mean maximum length in a community, and the slope and intercept of size spectra. Most SBIs can be derived from fairly standard survey data on length frequencies, without the need for elaborate models. Possible fishing- and environment-induced effects are analysed to distinguish between the two causes, and hypothetical cases of reference directions of change are tabulated. We conclude that no single SBI can serve as an effective overall indicator of heavy fishing pressure. Rather, suites of SBI should be selected, and reference directions may be more useful than reference points. Further modelling and worldwide comparative studies are needed to provide better understanding of SBIs and the factors affecting them. The slow response to fishing pressure reflects the complexity of community interactions and ecosystem responses, and prohibits their application in the context of short-term (annual) tactical fisheries management. However, movement towards longer-term (5–10 years) strategic management in EAF should facilitate their use.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1016/j.icesjms.2005.01.004
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2005
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  • 8
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    Estimating end effects in trawl catches
    Oxford University Press (OUP) ; 2006
    In:  ICES Journal of Marine Science Vol. 63, No. 5 ( 2006-01-01), p. 956-959
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 63, No. 5 ( 2006-01-01), p. 956-959
    Abstract: 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 consequence, the bias in abundance indices derived from swept area estimates that ignore end effects will be species-dependent.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1016/j.icesjms.2006.03.002
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2006
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    SSG: 21,3
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  • 9
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    Is a management framework based on spawning-stock biomass indicators sustainable? A viability approach
    Oxford University Press (OUP) ; 2007
    In:  ICES Journal of Marine Science Vol. 64, No. 4 ( 2007-05-01), p. 761-767
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 64, No. 4 ( 2007-05-01), p. 761-767
    Abstract: De Lara, M., Doyen, L., Guilbaud, Th., and Rochet, M-J. 2007. Is a management framework based on spawning-stock biomass indicators sustainable? A viability approach. – ICES Journal of Marine Science, 64: 761–767: 000–000. Fisheries management agencies have to drive resources on sustainable paths, i.e. within defined boundaries for an indefinite time. The viable-control approach is proposed as a relevant method to deal with sustainability. We analyse the ICES precautionary approach (PA) by means of the notion of viability domain, and provide a mathematical test for sustainability. It is found that the PA based on spawning-stock biomass (SSB) and fishing mortality (F) indicators is sustainable only when recruits make a significant contribution to SSB. In this case, advice based upon SSB, with an appropriate reference point, is sufficient to ensure sustainability. In all other cases, SSB is not a sufficient metric of stock productivity and must be complemented with other management indicators to ensure sustainability. The approach is illustrated with numerical applications to the northern hake and Bay of Biscay anchovy.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1093/icesjms/fsm024
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2007
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    detail.hit.zdb_id: 1468003-8
    detail.hit.zdb_id: 29056-7
    SSG: 12
    SSG: 21,3
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  • 10
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    Combining indicator trends to assess ongoing changes in exploited fish communities: diagnostic of communities off the coasts of France
    Oxford University Press (OUP) ; 2005
    In:  ICES Journal of Marine Science Vol. 62, No. 8 ( 2005-01-01), p. 1647-1664
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 62, No. 8 ( 2005-01-01), p. 1647-1664
    Abstract: We present a method for combining individual indicator results into a comprehensive diagnostic of fishing impacts on fish populations and communities. A conceptual framework for interpreting combined trends in a set of simple indicators is proposed, relying beforehand on qualitative expectations anchored in ecological theory. The initial state of the community is first assessed using published information. Which combinations of trends are acceptable or undesirable is decided, depending on the initial status. The indicators are then calculated from a time-series and their time trends are estimated as the slopes of linear models. Finally, the test results are combined within the predefined framework, providing a diagnostic on the dynamics of fishing impacts on populations and communities. The method is demonstrated for nine coastal and shelf-sea fish communities monitored by French surveys. Most communities were persistently or increasingly impacted by fishing. In addition, climate change seems to have contributed to changes in East Atlantic communities. Cet article propose une méthode utilisant des indicateurs pour élaborer un diagnostic sur les effets de la pêche sur les populations et les peuplements de poissons. Un cadre conceptuel permet d'interpréter les tendances conjointes d'indicateurs à partir de la théorie écologique. L'état initial du peuplement est d'abord évalué sur la base d'informations publiées. En fonction de l'état initial et des objectifs de gestion, les combinaisons des tendances sont qualifiées d'indésirables ou satisfaisantes. Les indicateurs sont ensuite estimés à partir de données de campagnes de pêches scientifiques: abondance et longueur moyenne d'une sélection de populations, nombre, biomasse totale, poids moyen et longueur moyenne dans le peuplement, et la pente du spectre de taille multispécifique. Les tendances temporelles de ces indicateurs sont testées au moyen d'un modèle linéaire, et les résultats des tests sont combinés en un diagnostic final. La méthode est mise en œuvre pour neuf peuplements de poissons côtiers et du plateau continental, suivis par des campagnes françaises. Il en résulte que la plupart de ces peuplements sont affectés par la pêche de manière stationnaire ou croissante. Par ailleurs, les changements climatiques dans l'Atlantique Nord-Est contribuent aussi à des modifications dans les peuplements de poissons de cette région.
    Type of Medium: Online Resource
    ISSN: 1095-9289 , 1054-3139
    URL: Article
    DOI: 10.1016/j.icesjms.2005.06.009
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2005
    detail.hit.zdb_id: 2463178-4
    detail.hit.zdb_id: 1468003-8
    detail.hit.zdb_id: 29056-7
    SSG: 12
    SSG: 21,3
    Location Call Number Limitation Availability
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    Online Resource
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