The Importance of Marine Protected Areas (MPAs)

The Importance of Marine Protected Areas (MPAs)

A marine protected area (MPA) is a section of the ocean where a government has placed limits on human activity. Many MPAs allow people to use the area in ways that do not damage the environment.


9 - 12


Biology, Ecology, Earth Science, Oceanography, Geography, Physical Geography

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Morgan Stanley

This resource is also available in Spanish.

A marine protected area (MPA) is a section of the ocean where a government has placed limits on human activity. Many MPAs allow people to use the area in ways that do not damage the environment. Some ban fishing. A few do not allow people to enter the area at all.

MPAs have been established because the ocean and the things that live in it face many dangers. Threats to the ocean include overfishing, litter, water pollution, and global climate change. These threats have caused a decline in the population of many fish, marine mammals, and other sea creatures.

Marine protected areas can have many different names, including marine parks, marine conservation zones, marine reserves, marine sanctuaries, and no-take zones. More than 5,000 MPAs have been established around the world. Together, they cover a little more than 8 percent of the ocean as of 2023.

Marine protected areas can be established in a variety of aquatic habitats. Some MPAs are in the open ocean. Many MPAs protect coastlines. Others cover estuaries, places where rivers enter the sea. In estuaries, freshwater and saltwater mix. Some freshwater habitats, including protected areas in the Great Lakes, are also considered MPAs.

Goals of MPAs

Different MPAs have different goals. The main focus of many MPAs is to protect marine habitats and the variety of life that they support. For example, the Galápagos Marine Reserve, which lies about 1,000 kilometers (600 miles) off the west coast of South America, protects a series of small islands and the surrounding waters. This reserve includes a tremendous variety of habitats, from coral reefs to cold ocean currents to mangrove swamps, where trees grow directly in salty seawater. The waters around the Galápagos are home to 3,000 different plant and animal species, including unusual species such as the marine iguana (Amblyrhynchus cristatus), the world’s only seagoing lizard.

Some MPAs focus on conserving historic sites such as shipwrecks. The USS Monitor was a warship that sank in a storm off the coast of North Carolina during the United States Civil War in the 1860s. In 1975, the USS Monitor National Marine Sanctuary was established to protect the remains of the ship. It was the nation’s first national marine sanctuary.

Other MPAs are established in order to ensure that resources are sustainable—that they will not run out. By having limits that prevent overfishing, these MPAs ensure that fish can reproduce and maintain healthy populations. This enables people to fish year after year, maintaining their way of life. Georges Bank, off the coast of New England (a region in the northeast of the U.S.) and Nova Scotia, Canada, was once one of the world’s greatest fisheries. But it was heavily fished for centuries, and populations of cod, haddock (Melanogrammus aeglefinus), flounder, and other species plummeted. After several MPAs were established by the United States and Canada, fish populations began to increase, and fishing improved.

Levels of Protection

Different MPAs provide different levels of protection. The strictest type of MPA allows no human entry at all. This not only prevents people from fishing, but also prevents people from disturbing delicate habitats. No-entry MPAs tend to be small and are often used for research. Parts of the vast Seaflower Reserve off Colombia’s Caribbean coast ban all human access.

Other MPAs are less strict. In a no-take MPA, fishing and collecting are not allowed, but people can travel through the area and use it for recreation, such as snorkeling or swimming. All of Laughing Bird Caye National Park, which protects a small island 18 kilometers (11 miles) off the coast of Belize in Central America, is a no-take MPA.

In multiple-use MPAs, the area is protected, but some fishing is allowed. Many national parks, such as Acadia National Park in the U.S. state of Maine, are multiple-use MPAs.

Many MPAs are divided up into different zones. In some zones, fishing is allowed, while in other zones, people might not be permitted entry at all. Australia’s Great Barrier Reef is the site of one of the world’s largest MPAs. The Great Barrier Reef Marine Park is divided into zones. Some of these zones allow recreational and commercial fishing. About one-third of the park has strict rules against fishing. Since these zones were put in place, the numbers of fish and corals have increased.

Establishing an MPA

National governments establish many MPAs. State, local, and tribal governments also establish MPAs. For example, the U.S. state of California has established the Point Lobos State Marine Reserve to protect underwater canyons and kelp forests. The Quileute Tribe of the U.S. state of Washington works with the federal government to keep the Olympic Coast National Marine Sanctuary a sustainable fishery.

Sometimes, national governments work together to establish an MPA that crosses borders. Italy, France, and Monaco together established the Pelagos Sanctuary for Mediterranean Marine Mammals. It covers parts of sea that is in the nations’ own territories as well as international waters.

At some MPAs, the level of protection remains the same year-round. At others, people are only barred from an area during certain seasons, often when vital species are breeding. For example, in the Irish Sea, fishing is controlled during cod spawning season, when the fish produce and fertilize eggs. This helps conserve the cod population.

Fast Fact

The world's largest MPA is Phoenix Islands Protected Area. Part of the tiny nation of Kiribati, it lies in a remote part of the Pacific Ocean. The Phoenix Islands Protected Area stretches across 410,500 square kilometers (158,453 square miles), an area the size of the U.S. state of California. The MPA includes eight small islands, two coral reef systems, and large swaths of deep ocean. Only a handful of people live on the islands, so it is a nearly pristine habitat for teeming populations of birds, fish, and other marine life.
The world's smallest MPA is Echo Bay Marine Provincial Park in British Columbia, Canada. It covers just 0.4 hectares (1 acre) and is a popular spot for ocean kayakers to pull ashore.

Fast Fact

According to the National Oceanic and Atmospheric Administration (NOAA), 53 U.S. MPAs are in the proximity of the 2010 Deepwater Horizon oil spill in the Gulf of Mexico.

Media Credits

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Kim Rutledge
Melissa McDaniel
Santani Teng
Hilary Hall
Tara Ramroop
Erin Sprout
Jeff Hunt
Diane Boudreau
Hilary Costa
Mary Crooks, National Geographic Society
Tim Gunther
Jeannie Evers, Emdash Editing, Emdash Editing
Kara West
Educator Reviewer
Nancy Wynne
National Geographic Society
Last Updated

April 10, 2024

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