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Designing marine reserves for biodiversity and sustainable fisheries

Designing marine reserves for biodiversity and sustainable fisheries. R. Quentin Grafton and Tom Kompas Crawford School of Economics and Government CERF Project/CERF Hub Presentation 20 May 2008 Acknowledgement: DEWHA. Motivation.

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Designing marine reserves for biodiversity and sustainable fisheries

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  1. Designing marine reserves for biodiversity and sustainable fisheries R. Quentin Grafton and Tom Kompas Crawford School of Economics and Government CERF Project/CERF Hub Presentation 20 May 2008 Acknowledgement: DEWHA

  2. Motivation • Marine reserves as a management tool are receiving increasing attention in response to growth, recruitment and economic over-harvesting and mismanagement of marine resources. • In response to perceived problems in fisheries management, fisheries scientists increasingly argue for an ecosystem-based approach to fisheries that includes the increased use of marine reserves. • Despite potential benefits (population persistence, biodiversity and habitat protection, age structure & spillovers), many fishers oppose reserves and claim they do not generate an economic payoff (rather, losses in GVP and profits).

  3. Preliminary Results • Reserves have positive economic value under environmental uncertainty (i.e., increase profitability), even if harvesting is optimal and probability and occurrence of negative shocks known in advance. • Payoff arises from spillovers that increase harvest immediately after a shock and reduced recovery time – a ‘resilience effect’. • Resource rents (compared to no reserve case) are increasing in size and frequency of negative shocks. • Reserves are valuable because they act as buffers following a negative shock that allows additional harvesting because of transfers from reserve.

  4. What is the Optimal Reserve Size? • The answer will vary across populations and potential biodiversity and environmental benefits-- requires a bioeconomic model to explicitly account for uncertainty. • Results from two examples (economic profitability only): • BC Halibut Fishery • Northern Cod Fishery

  5. BC Halibut (resilience effect)

  6. BC Halibut (resilience effect)

  7. Northern Cod (sustainability)

  8. Future CERF work • Apply to several Australian Fisheries (NPF and SETF) • Show how the loss in GVP exaggerates ‘damages’ from MPAs, by not measuring increased profitability in response to negative shocks. • Construct spatial models of MPAs • Measure the added benefits of marine biodiversity

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