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Marine Protected Areas

Federal Marine Protected Areas

Ecologically protected areas of Guam (Map: Ken Buja/ NOAA)
Ecologically protected areas of Guam (Image: NOAA/Ken Buja) (Click on the map for large view)

In 1993, the Federal government established the Guam National Wildlife Refuge at the northern tip of the island to help endangered and threatened species populations recover, protect habitat, control non-native species - with emphasis on the brown tree snake, protect cultural resources, and provide recreational and educational opportunities to the public. The Refuge includes the Ritidian Unit in northern Guam and two overlay units: Anderson Air Force Base in northern Guam and the Navy Unit. The refuge is composed of 771 acres, of which approximately 400 are coral reef areas and deep water habitats backed by 321 acres of high limestone cliffs and limestone forests. The refuge at Ritidian Point was one of the last areas on Guam to lose native forest birds to the brown tree snake but has retained nesting green sea turtles and foraging fruit bats.

The Ritidian Unit includes a densely vegetated coastal plain bounded on one side by limestone cliffs reaching approximately 200 feet (61 meters) above sea level. Native vegetation on the Unit includes coastal strand, backstrand, and limestone forest communities, a sandy beach, and nearshore marine habitats to depths of 98 feet (30 meters). The coastal waters of the Ritidian Unit feature sandy areas, platform reefs, and coral habitats that support a diversity of fishes, invertebrates, and algae. These also provide foraging habitat for the endangered hawksbill and green sea turtles.

Other federally protected areas include the Haputo Ecological Reserve Area on the northwest coast, the Orote Point Ecological Reserve on the southern coast of the Orote Peninsula, the War in the Pacific National Historic Park - Agat Unit on the west coast of Guam (bordering the village of Agat, south of the Orote Peninsula), and the War in the Pacific National Historic Park - Asan Unit on the west coast of Guam (bordering the village of Asan). Broad coral reef formations, up to 1,500 feet (457 meters) wide parallel the shorelines of both units and provide habitat to a wide variety of marine life. Water depths inside the reefs vary from 1-4 feet (0.3-1.2 meters). During low tide, some of the reef is exposed.

Territory Marine Protected Areas

In 1997, Guam's territorial government established five marine preserves to restore Guam's fisheries resources. The function of the preserves was later expanded to include the protection and preservation of aquatic life, habitat, and marine communities and ecosystems. Protection of resources within the preserves was strengthened by making all forms of fishing and the taking or altering of aquatic life or any other resources unlawful unless specifically permitted by the Guam Division of Aquatic and Wildlife Resources (DAWR). Guam DAWR is responsible for management of and enforcement within the preserves.

Guam's marine preserves
Guam's marine preserves: Pati Point (PP); Tumon Bay (T); Piti Bomb Holes (PB); Sasa Bay (S); and Achang Reef Flat (A). (Image courtesy of Guampedia)

The preserves vary in size from 1.2-7.7 square miles (3-20 km2) and protect a variety of habitats from 33 feet (10 meters) above mean high tide to the 600 feet (183 meters) depth contour, including a mangrove area in Sasa Bay.

The Achang Reef Flat Marine Preserve is located in the southern tip of the island.  It consists of inner and outer reef flats, which are exposed at low tide and are separated by a depressed middle-reef flat and a low-tide moat. Mangroves and sea­grass beds are also present on the site.

Pati Point Marine Preserve is located on Anderson Air Force Base (AFB), along the perimeter of the AFB property, in northeastern Guam. It contains a diversity of habitats, with seagrasses and shallow and deeper water coral ecosystems predominating, and is rich in coastal fish species. The outer reef has a very diverse coral fauna, with more than 45 species living within a 656 feet (200 meters) transect.

Piti Bomb Holes Marine Preserve is located in Piti Bay on the west coast of Guam, just north of Apra Harbor. It is a shallow lagoon complex that resembles a barrier reef system. Fringing reefs surrounding Piti Bay keep the water very calm. The Piti Bay habitat is unique in Guam and one of the most diverse in all of Micronesia. Within the preserve, percolation pits are found at depths of about 25 feet (7.6 meters) where freshwater enters the reef flat. Several underwater canyons, white sand-filled depressions, and healthy hard coral colonies can be seen starting in 6 feet (1.8 meters) of water. There are sea-grass beds in shallow water that provide habitat for juvenile fishes. Colonies of soft corals and sea anemones can be observed at depths as shallow as 3-4 feet (0.9-1.22 meters). Sea turtles and marine mammals are also found within the shallows of the preserve.

Piti Bay is famous for its "bomb-holes", which are  sinkholes created by collapsed caves. These holes have filled with seawater and sand over time and have become populated by fishes, corals, and other marine invertebrates. The largest sinkhole, Piti Bomb-Hole, is a very popular dive and snorkeling spot home to about 200 species of fishes and a variety of marine invertebrates.

Jacks in Piti Bay
Jacks in Piti Bay (Photo: Lets Dive

The Sasa Bay Marine Preserve is located in Piti Bay and contains a mangrove swamp that skirts the coastline in a narrow band. Sasa Bay is a Hawksbill Turtle foraging area and provides habitat for a number of oyster and clam species. Four to five strings of patch reef also can be found within the deeper waters of the embayment.

Tumon Bay Marine Preserve is a two-mile-long, 1,450 feet-wide (442 meters), arc-shaped reef plat­form stretching from Ypao Point in the southwest of Guam to Gun Point in the northeast. Many hotels, restaurants, and bars are situated along Tumon Bay's beach, which is a popular site for swimming, wind-surfing, snorkeling, kayaking, and other water activities.