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Are MPAs more effective than Traditional Stock Management in Conserving Fishery Resources ?

Are MPAs more effective than Traditional Stock Management in Conserving Fishery Resources ?. Vidar G. Wespestad. Chief Scientist Pacific Whiting Conservation Cooperative Science Consultant American Fishermen's Research Foundation. Primary reason we are here is because there is a

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Are MPAs more effective than Traditional Stock Management in Conserving Fishery Resources ?

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  1. Are MPAs more effective than Traditional Stock Management in Conserving Fishery Resources ? Vidar G. Wespestad Chief Scientist Pacific Whiting Conservation Cooperative Science Consultant American Fishermen's Research Foundation

  2. Primary reason we are here is because there is a sentiment that Fisheries Science has failed to maintain sustainable fisheries.

  3. I’m not very engaged in this topic, but I feel the overall goal of MPA’s is not very clear or rigorously stated. It’s unclear whether the goal is habitat and “biodiversity” preservation, or enhancing and maintaining fisheries production. Personally, I find it interesting that we are meeting on the subject of conservation vs. preservation about 100 years after issue was first raised in the Sierras with the Hetch- Hetchy Dam controversy.

  4. In the area of protecting unique habitat preserving associated unfished populations of marine biota Marine Reserves have shown great success. Examples- Hanama Bay, Florida Keys, Puget Sound reefs Most MPA examples in the literature are for areas that are natural aggregating areas, and for species that are highly habitat linked. However, for most exploited species the range is large, and MPAs hold little value compared to traditional stock management methods.

  5. In traditional Fisheries Management MPAs are a subset of tools in which population control is exercised through either effort or catch regulation. Y = a • b • f • Biomass Where: Y = Yield Controls - examples a = selectivity gear and/or size limits b = availability area/time closures f = effort inefficiencies – vessel size, hp, days, buybacks?

  6. Control through Yield Regulation Method Data Needs CPUE monitoring Low – catch data Size – Sex Limits Medium Quota High One of the reasons for fisheries failure is the inability to invest in data collection.

  7. R G M The Control Parameters of Fish Abundance Biomass as a balloon F R= Recruitment G= Growth M= Natural Mortality F= Fishing Mortality

  8. Control on Population Parameters R – Can regulate to some degree by maintaining spawning stock G – Can regulate some if density dependent M – Can regulate via fishery if pred-prey interaction F – Main Point of Regulation

  9. Logistic Growth and Production Theory B0 Unfished

  10. Adaptive management ?

  11. Most fisheries can be adequately managed using traditional management. Past failures primarily due to lack of data and/or political will to restrain fisheries. I’m not sure, but I sense a drift toward weakest stock management which limits harvest of more abundant species. PFMC- Canary rockfish Perhaps MPAs could be utilized to protect the core area of weak stocks that have defined habitat. Initiation of ecosystem based management could achieve similar results.

  12. Needed Species Area Species Interactions Benefit

  13. Don’t say MPA will benefit fishermen ! It wouldn’t. An MPA is basically another inefficiency in effort. Better to tell fishermen they can’t fish.

  14. Would fisheries in the US that are overfished have not been overfished had there been MPAs in place? Most examples are in highly localized areas or habitats. I don’t think it has been demonstrated that MPAs will foster stock recovery and sustainability better than current efforts directed toward harvest control. It is not clear that all the problems are do to fishing – I.e. if global warming responsible for coral reef destruction and loss of habit then there is little value in controlling fishing to preserve diversity if habitat is lost. In the long run – habitat reserves likely more important, especially in coastal nursery areas.

  15. Conclusions Role of MPAs ambiguous: preserve, habitat, reduce fish, establish some defined community structure? Spatial – temporal management has been used in fisheries management. What is new in MPA management is application of permanent closures over broad areas in place of active management techniques. Need to determine how MPAs are shaped into a management tool. Will it be a club, a knife, or a scalpel? Lastly, one aspect of MPAs that does not seem to have received much review is enforcement. This may be very difficult if there is no acceptance of the system.

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