Changes between Version 1 and Version 2 of EwEugFishingPolicySearch


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Timestamp:
2010-02-07 22:55:39 (9 years ago)
Author:
varunr
Comment:

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  • EwEugFishingPolicySearch

    v1 v2  
    1010These approaches can be used in combination, e.g. by doing a formal optimization search then ‘reshaping’ the fishing rate estimates from this search in order to meet other objectives besides those recognized during the search process. 
    1111 
    12 The first of these approaches has been implemented in Ecosim since its first version, and has been widely applied for exploring ecosystem effects of changes in fishing effort (see [wiki:EwEugEcosimBasics Ecosim basic] and the help topic for the Run Ecosim form). The second is ‘open loop’ policy exploration simulation that acknowledges that policy may be defined as an approach towards reaching a broadly defined goal, that fisheries policies are often implemented via TACs that are recalculated annually, and through regulation that affects fleet structure and deployment. 
     12The first of these approaches has been implemented in Ecosim since its first version, and has been widely applied for exploring ecosystem effects of changes in fishing effort (see [wiki:EwEugEcosimBasics Ecosim basic] and the help topic for the Run Ecosim form). The second is ‘open loop’ policy exploration simulation that acknowledges that policy may be defined as an approach towards reaching a broadly defined goal, that fisheries policies are often implemented via TACs that are recalculated annually, and through regulation that affects fleet structure and deployment. 
    1313 
    14 Two very different approaches can be taken to the identification of optimum levels of fishing efforts for multiple fleets that may each harvest multiple species from an ecosystem.  The first or ‘sole owner’ approach is to identify a single, overall performance measure for combined value from all fishing operations, then vary the by-fleet efforts so as to try and maximize this performance measure.  The sole owner approach has been used extensively in past Ecosim optimization exercises, using performance measures ranging from total profit from fishing (sum over fleets of incomes minus costs) to total employment (sum of catches times employment per catch) to [wiki:EwEugImplementingPolicyOptimization risk-averse utility measures] that favour a balanced ‘investment portfolio’ of fishing activities.  A fundamental problem with this approach is the implicit assumption of value and cost pooling; supposedly ‘optimum’ solutions often involve operating one or more fleets at uneconomic levels, essentially using these fleets to cull some fish species so as to increase production from other, more valued species. 
     14Two very different approaches can be taken to the identification of optimum levels of fishing efforts for multiple fleets that may each harvest multiple species from an ecosystem.  The first or ‘sole owner’ approach is to identify a single, overall performance measure for combined value from all fishing operations, then vary the by-fleet efforts so as to try and maximize this performance measure.  The sole owner approach has been used extensively in past Ecosim optimization exercises, using performance measures ranging from total profit from fishing (sum over fleets of incomes minus costs) to total employment (sum of catches times employment per catch) to [wiki:EwEugImplementingPolicyOptimizationInEcosim risk-averse utility measures] that favour a balanced ‘investment portfolio’ of fishing activities.  A fundamental problem with this approach is the implicit assumption of value and cost pooling; supposedly ‘optimum’ solutions often involve operating one or more fleets at uneconomic levels, essentially using these fleets to cull some fish species so as to increase production from other, more valued species. 
    1515 
    1616The second or ‘multiple fishing rights’ approach is to treat each fishing fleet (and perhaps non-consumptive stakeholder or user groups as well) as a separate economic industry with some legal right or entitlement to harvest, then seek a level for each fleet that optimizes a fleet-specific performance criterion such as total profits or growth until profitability (ratio of profits to income or cost) falls to a typical or reasonable level for economic industries in the economy as a whole. 
    1717 
    18 See [wiki:EwEugImplementingPolicyOptimization Implementing policy optimization] in Ecosim for help with implementing these two approaches in Ecosim. 
     18See [wiki:EwEugImplementingPolicyOptimizationInEcosim Implementing policy optimization] in Ecosim for help with implementing these two approaches in Ecosim. 
    1919 
    2020==== Policy objectives ====