Browsing by Subject "operating model"

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    Conditioning of the SBT operating model to inform projection specifications
    (University of Cape Town, 2011) Sakai, Osamu; Kurota, Hiroyuki; Takahashi, Norio; Butterworth, Doug S
    The effects of updates on the operating model are examined. Because of the new growth schedule and the most recent two years’ data, the operating model prefers somewhat higher steepness compared to the previous version. This difference has little influence on the historical trajectories of spawning stock biomass, but it leads to more optimistic projection results.
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    Making management procedures operational—innovations implemented in South Africa
    (Oxford University Press, 2007) Plagányi, Éva E; Rademeyer, Rebecca A; Butterworth, Doug S; Cunningham, Carryn L; Johnston, Susan J
    Operational management procedures (OMPs) have become an indispensable fisheries management tool in South Africa in light of their ability to consider the consequences of the main sources of assessment uncertainty. An overview is provided of the MP approaches applied to the major South African fisheries for hake, sardine and anchovy, and west coast rock lobster. As these are among the first OMPs to be implemented worldwide, some for periods longer than 10 y, they provide useful examples of some of the successes and problems encountered with the approach. Particular emphasis is given to some recent innovations and adaptations. These include moves to (i) joint two-species OMPs for the hake and sardine/anchovy resources; (ii) a reference set of weighted operating models for primary testing and tuning in preference to a single model; (iii) consideration of a “research-conditional” approach for hake to allow greater catches in the short term, conditional on research being implemented to resolve a key uncertainty; and (iv) incorporation of some ecosystem considerations by developing appropriate robustness tests (which link with moves towards an ecosystem approach to fisheries). Key lessons gained from experience over the past decade of OMP implementation in South Africa are summarized.