Browsing by Author "Kell, Laurence T"

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    Performance review of simple management procedures
    (International Council for the Exploration of the Sea, 2015) Carruthers, Thomas R; Kell, Laurence T; Butterworth, Doug S; Maunder, Mark N; Geromont, Helena F; Walters, Carl; McAllister, Murdoch K; Hillary, Richard; Levontin, Polina; Kitakado, Toshihide; Davies, Campbell R
    Using a management strategy evaluation approach, we compare a range of new and established management procedures (MPs) for setting catch-limits in fisheries. Performance is evaluated with respect to fish life history type, level of stock depletion, data quality, and autocorrelation in recruitment strength. We quantify the robustness of each MP with respect to the various observation processes. Methods using observations of absolute biomass or stock depletion offer the best overall performance and this is consistent across life history types, data qualities, and stock depletion levels. Simple MPs can outperform conventional data-limited methods and data-rich assessments that use time-series of catch and effort data. MP performance is most sensitive to biases in catch data. Our results indicate that often tuning MPs for specific stocks is important, though this may not be viable in data-poor assessment scenarios because of insufficient data and analysis resources.
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    Purported flaws in management strategy evaluation:basic problems or misinterpretations?
    (National Inquiry Services Centre (NISC), 2010) Butterworth, Doug S; Bentley, Nokome; De Oliveira, Jose´ A A; Donovan, Gregory P; Kell, Laurence T; Parma, Ana M; Punt, Andre´ E; Sainsbury, Keith J; Smith, Anthony D M; Stokes, Kevin T
    Rochet and Rice, while recognizing management strategy evaluation (MSE) as an important step forward in fisheries management, level a number of criticisms at its implementation. Some of their points are sound, such as the need for care in representing uncertainties and for thorough documentation of the process. However, others evidence important misunderstandings. Although the difficulties in estimating tail probabilities and risks, as discussed by Rochet and Rice, are well known, their arguments that Efron's non-parametric bootstrap re-sampling method underestimates the probabilities of low values are flawed. In any case, though, the focus of MSEs is primarily on comparing performance and robustness across alternative management procedures (MPs), rather than on estimating absolute levels of risk. Qualitative methods can augment MSE, but their limitations also need to be recognized. Intelligence certainly needs to play a role in fisheries management, but not at the level of tinkering in the provision of annual advice, which Rochet and Rice apparently advocate, inter alia because this runs the risk of advice following noise rather than signal. Instead, intelligence should come into play in the exercise of oversight through the process of multiannual reviews of MSE and associated MPs. A number of examples are given of the process of interaction with stakeholders which should characterize MSE.