A marine reserve is a type of marine protected area (MPA). An MPA is a section of the ocean where a government has placed limits on human activity. A marine reserve is a marine protected area in which removing or destroying natural or cultural resources is prohibited. In the United States, marine reserves may also be "no-take MPAs,” which strictly forbid all extractive activities, such as fishing and kelp harvesting.

Marine reserves are rare in the United States, making up less than one percent of U.S. waters. Marine reserves are often located within larger, multiple-use MPAs. Some zones of multiple-use MPAs, also called marine sanctuaries, permit extractive activities. Marine reserves are sometimes located on the coastal boundary of a multiple-use MPA.

Marine reserves are created for a variety of purposes. Many reserves protect the spawning grounds of species such as salmon. Others serve as outdoor laboratories that allow scientists to compare the undisturbed areas of a reserve to those impacted by human activities. Through these experiments, scientists are better able to understand how human activities affect the marine environment.

Sitka Pinnacles Marine Reserve, Alaska
Located off the coast of of the U.S. city of Cape Edgecumbe, Alaska, Sitka Pinnacles Marine Reserve covers almost eight square kilometers (three square miles) of the northern Pacific Ocean. This marine reserve includes two underwater volcanic peaks, or pinnacles. Established in 1999, Sitka Pinnacles is the first no-take zone in Alaska.

The pinnacles provide fish species with both shallow and deep-water habitats. Fish like halibut occupy the deeper ocean floor, while lingcod and rockfish inhabit shallower water. The pinnacles are also home to cold-water corals.

The abundance of lingcod and rockfish initially attracted commercial fishermen to the area. By the 1990s, however, fishing significantly reduced their populations. Increased sport fishing activities further contributed to this population decline. The North Pacific Fishery Management Council created the reserve to provide complete protection for lingcod, rockfish, and halibut species.

Although small in size, Sitka Pinnacles Marine Reserve is one of the few no-take reserves in the world that is independent of a larger MPA.

Chagos Islands Marine Reserve
On April 1, 2010, the British government announced the creation of the world’s largest marine reserve in an area surrounding the Chagos Islands in the Indian Ocean.

The new reserve covers about 543,900 square kilometers (210,000 square miles)—an area larger than the U.S. state of California. Its establishment roughly doubles the global coverage of the world’s oceans under protection, from two-tenths to more than three-tenths of one percent.

The Chagos Islands are a group of seven coral atolls. An atoll is a low-lying, ring-shaped coral island. The atolls of the Chagos Islands are home to coral reefs, several species of endangered sea turtles, and 175,000 pairs of breeding seabirds.

The Chagos Island Marine Reserve will shelter at least 76 species classified as endangered by the International Union for the Conservation of Nature (IUCN). Some of these organisms include birds such as the Maldivan pond heron, more than 200 species of coral, sea turtles, sharks, and more than a thousand species of reef fish. The large tuna fishery in the area was responsible for the accidental bycatch of more than 60,000 sharks every year.

To protect the delicate coral reef ecosystems, all extractive activity is prohibited in the reserve. No commercial fishing, sport fishing, mining, drilling, coral collection, or treasure-hunting is allowed.

The Chagos Islands are currently uninhabited by people. Native Chagossians were forced to relocate in the late 20th century as the United States and the United Kingdom developed a nearby military base, Diego Garcia. The Diego Garcia military base is still in use by the U.S. and the U.K., and the British government has not allowed Chagossians to return to the islands.

Many Chagossians oppose the marine reserve. They want to return to their native islands, and say that their traditional way of life depends on fishing. Some Chagossians support altering the rules of the reserve to allow zones for sustainable fishing.