Management strategy evaluation results and discussion for Australias North West Shelf

Brief description

The management strategy evaluation (MSE) framework has been developed for scientific support of regional multiple-use management of marine and coastal resources. The MSE approach was used in the North West Shelf Joint Environmental Management Study to demonstrate the variation in possible outcomes from prospective and existing management strategies and development scenarios. In this report we provide an evaluation of the results of computer simulations designed to demonstrate the utility of the MSE framework. Relevant background and further elaboration can be found in three companion reports Gray et al. (2006), Fulton et al. (2006b) and Hatfield et al. (2006). The key message from the simulations is that patterns in indicator variables under the integrated management strategy are clearly distinguishable from those under both the status quo and enhanced management strategies. Notwithstanding a few notable exceptions, this outcome is consistent across a range of uncertainties, including those treated explicitly in the alternative model specifications and development scenarios, and those treated as random variables in separate computer simulations. The outcome is consistent because the integrated strategy balances impacts across a range of sectoral activities that impact not only the sector itself, but also other sectors, or the human population and ecosystem as a whole. In contrast, the sectorally-based management strategies (i.e. the status quo and enhanced strategies) invoke broadly similar (to each other) patterns in the indicator variables, although the enhanced strategy has differential impacts on some conservation and social variables. The integrated management strategy outcomes improves upon those from the sectorbased strategies because it actively manages the region from a multiple-use perspective and simultaneously monitors, and responds to, indicator variables that represent social, environmental conservation, economic and safety considerations. With the exception of cases where uncertainty dominates the simulation results (notably prawn biomass and regional habitat coverage), the integrated management strategy (compared to the other, sector-based, management strategies) leads to: significant increases in the stocks and catch rates of high-value fish species; increased recreational fishing catch; improved abundance of species of high conservation value (particularly turtles, though the magnitude of this can be dependent on model type and assumptions); improved biodiversity; a reduction in commercial fishing effort; a reduction in commercial fishery gross margins; a decline in contaminant impact; and a decrease in the risk of ship collisions and catastrophic spills. The two sector-based management strategies perform differently from each other according to only four indicator variables. The enhanced strategy leads to increased commercial catch and CPUE of high-value target species and greater recreational catch, as compared to the status quo management strategy. Enhanced management also leads to lower habitat fragmentation at local scales than status quo management. 2 These results provide a limited number of examples to demonstrate how alternative management strategies can alter natural resource use in a multiple-use setting. What they also demonstrate, however, is that the MSE framework is now developed sufficiently to provide robust evaluations of alternate management strategies, model specifications and development scenarios. Scientists and managers now have available powerful simulation tools that can assist in evaluating potential strategies, scenarios and model specification to help achieve better ecosystem level and sectoral outcomes and to guide scientific research and data collection, to best serve regional natural resource management. The calibration of the model software using real-world data allows easy identification of shortcomings in both the model

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Statement: Original record compiled for the Western Australian Marine Science Institution (WAMSI), Project 3.8, 2008.

Notes

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R. Little

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E. Fulton

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R. Gray

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D. Hayes

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V. Lyne

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R. Scott

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K. Sainsbury

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D. McDonald