Benefits of MPA's to Conservation and Fisheries

BENEFITS OF MPA'S TO CONSERVATION conservation of biodiversity  - critical habitats and threatened species Protection of genetic diversity of heavily exploited populations - if well designed and conserve species well Reference sites for monitoring natural changes vs human induced change - better site of reference than exploited areas A refuge for intensely exploited species Preservation of ecosystem function - should be most important

Fisheries are managed with set TAC's - often not adhered to.Failed to prevent many managed stocks from collapsing e.g., Gadhus morhua in North Sea  - probably could have prevented this if advice followedEAFM - Ecological Approach to Fisheries Management becoming more widespread - have to manage prey populations of predator you want to catchBenefits of MPA's to fisheries still debated but this is often because scientific advice is not followed.BENEFITS INCLUDE Increase in biomass, abundance and average size of exploited populations in no take zone (protection less for migratory species) Evidence see in Merrit Island National Wildlife Refuge - 40km2. Near Cape Kennedy space centre, protected since 1960's. Bohnsack (reported in Roberts et al. 2001) looked at area within 200km of coast around reserve- evidence of improved fish stocks in areas adjacent to reserves Overspill from MPA, restocking of population More and larger fish result in increased egg production - larger fish are more fecund Possible mitigation against ecosystem effects of fisheries - protection of lower trophic level fish means these organisms can support the rest of the food web and commercial species higher up the chain Example: Georges Bank, Gulf of Maine USA Very important fishing ground, Cod stock collapse in 1990's - huge economic losses Set protection from all bottom contact gear Increase in all stocks within the area within 5 years Anecdotal evidence from fisherman - best catches are from the edge of MPA's - fishing the line Closed areas, also reduced fishing effort at the same time Improvements down to MPA or less fishing?

 MPA's often protect habitat specific systems such as coral reefs on which many organisms are sessile/territorial/non-migratory - can data from these areas really be used as evidence of the efficacy of MPA's for other habitats? MPA's often small scale Shifting baselines - what state are you trying to recover the habitat - previous and concurrent fishing history Genetic bottle necks stock collapse Compliance - hard to get fishers to adhere to the rules of MPAs? Highly mobile species are not afforded much protection Activity displacement - fishing effort moved to another area, many socio - economic problems associated with this Climate change - changing distributions MPA's are a tool for managent but perhaps not a panacea for fisheries issues.Unlikely to be successful in isolation - need to work with other management

Conservation

Fisheries

Criticisms and Counter-arguements