Browsing by Author "Parma, Ana M"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Restricted
    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.
  • Thumbnail Image
    Item
    Restricted
    A scientific alternative to moratoria for rebuilding depleted international tuna stocks
    (Wiley, 2015) Hillary, Richard M; Preece, Ann L; Davies, Campbell R; Kurota, Hiroyuki; Sakai, Osamu; Itoh, Tomoyuki; Parma, Ana M; Butterworth, Doug S; Ianelli, James; Branch, Trevor A
    There is considerable international concern and scientific debate about the current state and future of tuna stocks worldwide and the capacity of Regional Fisheries Management Organisations to manage the associated fisheries effectively. In some cases, this concern has extended to predictions of imminent collapse with minimal chances of recovery, even under a commercial catch moratorium. As a viable alternative to a full fishery closure, the Commission for the Conservation of Southern Bluefin Tuna (CCSBT) has adopted a scientifically tested, adaptive rebuilding strategy for the depleted southern bluefin tuna (Thunnus maccoyii) stock. The management procedure (MP) adopted involves a harvest control rule that fully specifies the total allowable catch as a function of key indicators of stock status, adjusting future harvest levels every three years so as to meet the rebuilding targets agreed by CCSBT. It was chosen from a subset of candidate MPs selected following extensive simulation testing. This involved first selecting a wide range of plausible scenarios for stock status and input data, ranging from pessimistic to optimistic, against which the alternative candidate MPs were tested to ensure that they were robust to important uncertainties. This is the first time that a comprehensively evaluated MP has been adopted for an internationally managed tuna stock. Both the process and the outcomes have broad applicability to other internationallymanaged stocks.