Predicting the ecological success of a closure merely by looking at how large or old it is, is a bit like judging a book by it’s cover. There is more to it.

A new study conducted by centre researcher Tim Daw together with researchers from Australia and the US highlights the importance of also considering socioeconomic conditions in the surrounding area, such as human population density and how much people respect the rules. These were more closely related to a reserve’s ability to increase the amount of fish.

The study analysed the success rate of 17 fisheries closures from Kenya, Tanzania, Madagascar, Mauritius and Seychelles were analysed. Daw and his colleagues looked beyond the classic physical design features and included variables such as population size, community infrastructure and to what extent people respect fishing restrictions  to see which of these seem to affect the ecological success of the closures.

A critical determinant for success
“It is increasingly recognised that marine protected areas are social-ecological systems that can be influenced by socioeconomic conditions and not just physical aspects of age, size and area-based configurations,” Tim Daw says.

“Our results raise important questions about what determines the success of a fishery closure. They imply a greater need to consider social dimensions in addition to the design dimensions”.

Daw and his colleagues also critically assessed the performance of a reserve by looking at how much fish was inside it (an absolute value), and by comparing the amount of fish inside with the surrounding areas (a relative value).

“We found that absolute and relative indicators of success gave quite different results. The relative measure of success was most pronounced in areas with high population density, but the absolute measure was not related to human population density, and depended more on the levels of compliance by neighbouring communities.”

Put differently, comparative studies should also look at absolute amounts of fish inside because the amount of fish inside the reserves are affected by heavy fishing outside a reserve.

Look beyond the borders of the closure
Daw and his colleagues underline the importance of not looking blindly at what happens inside the closure but also in its surrounding seascape.

A large concentration of fish within the closure might at first glance indicate a successfully managed area, but if the surrounding areas are depleted for fish and coral cover alarm bells should be ringing. A thriving closure is a short-lived comfort if the area around it is deteriorating.

“An assessment that neglects relations and conditions inside and outside closures can lead to spurious indications of “success” or “failure” of closures that have little to do with the reality of things,” Daw warns.

In fact, both locally managed closures and national parks improved the amount of fish compared to neighbouring areas, but did not make a consistent impact on coral cover, which seems to be driven more by large-scale processes such as coral bleaching.

Source:  T. Daw, T. M., J. E. Cinner, T. R. McClanahan, N. A. J. Graham, and S. K. Wilson. 2011. Design factors and socioeconomic variables associated with ecological responses to fishery closures in the western Indian Ocean. Coastal Management 39:412-424.

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