The political target of setting aside 20% of ocean habitats as no-take zones by the year 2020, or earlier, has recently found its way into several MPA-related policies in the Western Hemisphere. Since January, government organizations in the Galápagos Islands (MPA News 1:7) and the US (1:6) have adopted a 20% closure figure as a target for protecting their coastal waters and coral reefs, respectively. A science panel advising the Bahamian government on its upcoming national reserve system recommended that the eventual network close at least 20% of the Bahamas' shelf edge (1:5). The target has appeared, too, in discussions on California's MPA system (1:3) and in a recommendation offered by several scientists and NGOs for the protection of US marine waters (1:6).
The 20% closure figure has clearly emerged as a tool in MPA negotiations and policymaking, at least in the Americas. Where did this target come from, and when is it useful?