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Inside the MPA Component

What is an MPA?

Marine protected areas (MPAs) have become one of the most widely-used conservation tools to protect marine resources. MPAs are geographically defined spaces where human activities are regulated so that resources can be managed 'to achieve the long-term conservation of nature with associated ecosystem services and cultural values (International Union for the Conservation of Nature). MPAs come in all sizes, from hundreds of thousands of square kilometers down to just a few and may include zones that prohibit (or permit) specific activities, such as commercial fishing, recreational fishing, tourism, mineral exploitation or others. By reducing such human pressures, populations within MPAs are better able to resist other stresses such as sea temperature ris from global warming, ocean acidification and pollution.

 The Success of MPAs

MPAS are most frequently used as a defense against overuse of living resources. By controlling how much fish or other marine plants and animals is harvested, MPAs have been successful in restoring many populations that have been overexploited. In general, studies have found that MPAs can increase the richness (number of species), abundance, and size of many marine animals, particularly fish (4) (5) within their boundaries. They can also have indirect benefits to other organisms like corals (12) by helping to restore more natural food webs. In addition, MPAs can help to increase the overall resilience of marine ecosystems to disturbances (7) (6). Perhaps most importantly, MPAs can be used to help sustain fisheries that are adjacent to them by spillover of both adult and juvenile fish (9) (10). Healthy coastal fisheries support local economies and the food security and livelihoods of billions of people worldwide (11).  

As one example, Cabo Pulmo National Park in the Gulf of California, Mexico, was established in 1995, and was the only well-enforced no-take area in the region at the time. Thanks to strong community leadership and effective enforcement, by 2009, total fish biomass had increased by 463%, and biomass of top predators and carnivores had increased by 11 and 4 times, respectively.  The increase brought economic benefits and tourism-related employment to the nearby community's approximately 100 residents, where 30 employees in five tourist-based businesses generated nearly US$540,000 in 2006, yielding per capita incomes significantly greater than the average for Mexico (2).

We still have a lot to learn about how best to configure and manage networks of MPAs so that they function most effectively, and achieving the reference point of 30% protection for all representative marine ecosystems is still a far-off goal. However, the steady growth in the number and size of MPAs is encouraging.

Why and how MPAs are assessed in the Index

MPAs are included in the Ocean Health Index because of their essential role in helping to maintain healthy marine ecosystems. MPAs were used as a measure of resilience --the "social, institutional, and ecological factors that positively affect the ability of a goal to be delivered to people"-- for every goal of the Index except Coastal LIvelihoods & Economies, Tourism & Recreation, and Clean Waters. Because MPAs can positively impact goals in the future, their effect is manifested in the calculation of "likely future state," or where we expect the goal to be in the next five years. An increase in the extent of MPAs has a positive effect on the seven goal scores in which they factor. 

The United Nations Environment Programme's World Conservation Monitoring Centre (UNEP-WCMC) maintains the most complete dataset on terrestrial and marine-protected area boundaries, a large task considering there are now more than 6500 designated MPAs worldwide. Currently the database does not include any locally-managed MPAs, which are difficult to track. Depending on the goal model, we used those data to determine what percentage of the marine area was protected either in the entire Exclusive Economic Zone (EEZ) being evaluated or only within three nautical miles from the coast.

For Index goals like Biodiversity and sub-goals like Fisheries and Iconic Species, we looked at the degree of protection across the entire EEZ. For goals where benefits occur mainly within the near-shore coastal zone (i.e. Artisanal Fishing Opportunities, Natural Products, Carbon Storage, and Coastal Protection), we looked at the percentage of protection within three nautical miles of shore.  In both cases we set our reference point to be 30% protection, which is an accepted rough estimate for how much area needs to be protected in order to sustain marine populations and habitats (1) (3). For the Lasting Special Places sub-goal, we used MPAs and other protected areas within three nautical miles of shore plus terrestrial protected areas within one kilometer of the coastline as indicators of status rather than resilience, allowing us to roughly estimate the percentage of the area that was protected for aesthetic, spiritual, cultural, recreational or existence value purposes.

Ayau-Asia MPA in the Bird's Head Seascape

MPAs as a Critical Tool

Because MPAs are so important to the sustainable management of the benefits that our oceans provide, they are pervasive throughout the OHI calculations. As we engage in broader marine spatial planning and ocean zoning efforts, MPAs are a critical piece of the puzzle. However, there are also many other resource management tools, including more traditional fisheries management (e.g. gear restrictions, effort controls) and policies like those aimed at reducing the greenhouse gas emissions that cause global warming that are also important. Together, effective use of these management tools can help ensure a healthy flow of ocean benefits to us and future generations.


(1)  Airame S., Dugan J.E., Lafferty K.D., Leslie H., McARdle D.A. & Warner R.R. (2003). Applying ecological criteria to marine reserve design:  A case study from the California Channel islands.  Ecological Applications, 13, S170-S184

(2)  Aburto-Oropeza O., B. Erisman, G.R. Galland, I. Mascarenas-Osario, E. Sala, et al.  (2011)  Large recovery of fish biomass in a no-take marine reserve.  PloS ONE 6(8):  e23601.  doi:10.1371/journal.pone.0023601.

(3)  Fernandes L., Day J., Lewis A., Slegers S., Kerrigan B., Breen D., Cameron D, Jago B., Hall J., Lowe D., Innes J., Tanzer J., Cahdwick V., Thompson L., Gorman K., Simmons M., Barnett B., Sampsopn K., De'ath G., Mapstone B., Marsh H., Possingham H., Ball I., Ward T., Dobbgs K., Aumend J., Slater D. & Stapleton K. (2005) Establishing representative no-take areas in the Great Barrier Reef: Large-scale implementation of theory on marine protected areas.  Conservation Biology, 19, 1733-1744.

(4)  Halpern B.S. (2003) The impact of marine reserves: do reserves work and does reserve size matter?  Ecological Applications, 13, S117-S137.

(5)  Lester S.E., Halpern B.S., Grorud-Colvert K., Lubchenco J., Ruttenberg B.I., Gaines S.D., Airame S. & Warner R.R. (2009) Biological effects within no-take marine reserves: a global synthesis. Marine Ecology-Progress Series, 384, 33-46.

(6)  Micheli F., Saenz-Arroyo A., Greenley A., Vazquez L., Espinoza Montes J.A., Rossetta M. & De Leo G. A. (2012) Evidence That Marine Reserves Enhance Resilience to Climactic Impacts. PLoS ONE, 7, e40832

(7)  Mumby P.J. & Harborne A.R. (2010) Marine reserves enhance the recovery of corals on Caribbean reefs, PLoS ONE, 5.

(8)  Peic R.A., Warner R.R., Gaines S.D. & Paris C.B. (2010) Detecting larval export from marine reserves.  Proceedings of the National Academy of Sciences, 107, 18266-18271.

(9)  Roberts C.M., Bohnsack J.A., Gell F. Hawkins J.P. & Goodridge R. (2001) Effects of marine reserves on adjacent fisheries.  Science, 294, 1920-1923.

(10)  Russ G.R., Alcala A.C., Maypa A.P., Calumpong H.P. & White A.T. (2004) Marine reserve benefits local fisheries.  Ecologtical Applications, 14, 597-606.

(11)  Samonte G., Karrer L. & Orbach M. (2010) People and oceans: managing marine areas for human well-being.  Conservation International, Arlington, VA.

(12)  Selig E.R. & Bruno J.F.  (2010) A global analysis of the effectiveness of marine protected areas in preventing coral loss.  PLoS ONE, 5, e9278.