Periodic Harvests


Tess Croner/Solutions

Many studies have shown that permanently closed marine protected areas conserve fish populations and fisheries, and there have been several ambitious calls to establish these areas and reserve networks in order to meet global biodiversity targets. Yet it is notoriously difficult to gain community support for permanent marine reserves, especially in areas that have been fished for generations. Even where large parks have been established, some areas have been left open for extraction, and enforcement has been poor, especially in Asia and the Pacific islands.

Christopher Bartlett and colleagues’ research on developing island nations in the Pacific shows that periodic harvest can be a valuable management tool—both flexible and effective. When areas are closed to harvest for extended periods each year, the abundance and biomass of fish increase to levels that resemble permanently closed areas. This management scheme is especially promising in coastal communities of Vanuatu and other island nations of the South Pacific, where taboo systems already exist. It turns out that some villages have been practicing a form of periodic harvest for centuries—traditional management that consisted of infrequent, short-term harvests in the common properties of the ocean.

Periodic harvest will not necessarily work everywhere or for every species: rotational strategies in Hawaii have been ineffective, perhaps because the reserves were open for too long. And for species that are large bodied and easy to collect, this solution will not work in isolation: giant clams and top shell snails, for example, may require additional management strategies—such as extended closures and a network of permanent reserves.