According to NOAA, recent analysis of data has shown that eight percent of U.S. waters are currently designated as marine protected areas (MPAs), with the vast majority of these areas open to fishing and other activities.
The eight percent figure does not include MPAs specifically established to sustain fisheries production, which often have specific restrictions on fishing gear over large ocean areas. Other inventory analyses including these fishery MPAs, however, show that 92 percent of the area within U.S. MPAs allows some type of activity, and 85 percent is open to fishing.
The analysis also showed that more than two-thirds of all U.S. MPAs were created, at least in part, to conserve natural heritage values, such as biodiversity, ecosystems, or protected species.
About a quarter of sites focus on sustainable production, such as those established to recover overfished stocks, protect species readily taken as bycatch, or preserve essential fish habitats, while the remaining approximately ten percent were established to conserve the nation’s cultural heritage.
NOAA defines Marine Protected Areas as "areas where natural and/or cultural resources are given greater protection than the surrounding waters".
MPAs are conservation areas that include the marine environment, such as some national parks and national wildlife refuges, national marine sanctuaries and similar areas managed by state, local and tribal governments. They protect natural and cultural marine resources, and many allow a variety of activities such as fishing, recreation, and research.
The agency has also updated its online MPA Inventory. Developed with extensive input from state and federal MPA programs and drawn from other publically available data, the MPA inventory contains information on more than 1,700 sites and is the only such comprehensive dataset in the nation. Information in the inventory is current as of March 2012.