Mariana Archipelago: Protected Species

Protected species listed under the Endangered Species Act and known to occur in waters around the Mariana Archipelago include green, hawksbill, and leatherback sea turtles, humpback, sei and sperm whales, dugongs and the Newell’s shearwater. Blue whales, fin whales, and sei whales are known to occur in the Western Pacific region but have not been observed around the Mariana Archipelago. Other marine mammals known to occur include several types of dolphins and whales, other seabirds known to occur include shearwaters, petrels, boobies, tropicbirds and other species.

Green Sea Turtles (Chelonia mydas) [top]

Based on nearshore surveys conducted jointly between the CNMI–DFW and the NMFS around the Southern Islands an estimated 1,000 to 2,000 green sea turtles forage in these areas. The green sea turtle is a traditional food of the native population and although harvesting them is illegal, divers have been known to take them at sea and others have been taken as nesting females. Turtle eggs are also harvested in the CNMI. Nesting beaches and seagrass beds on Tinian and Rota are in good condition but beaches and seagrass beds on Saipan have been impacted by hotels, golf courses and general tourist activities. Nesting surveys for green sea turtles have been done on Guam since 1973 with the most consistent data collected since 1990. There have been up to 60 nesting females observed annually, with a generally increasing trend over the past 12 years. Aerial surveys done in 1999–2000 also found an increase in green sea turtle sightings around Guam.

Hawksbill Sea Turtles (Eretmochelys imbricata) [top]

Although hawksbill turtles have occasionally been sighted in the past around the CNMI they were not observed in a detailed assessment conducted in 1999, nor were they observed in 10 aquatic surveys along the shores of Tinian in 1995. According to the 1998 Pacific Sea Turtle Recovery Team Recovery Plan for the hawksbill turtle there are no reports of nesting in the CNMI. This does not rule out the possibility of a few hawksbill nests, as nesting surveys on small pocket beaches in remote areas of CNMI have never been done. A single hawksbill sighting occurred in 1996 during the detonation of an unexploded ordinance off of Rota. The turtle was recovered near the explosion sight and subsequently died, apparently from internal injuries incurred from the blast. One hawksbill sea turtle nest was found in November 1991 on Guam; however this was highly unusual as nesting individuals are otherwise virtually unknown on Guam.

Leatherback Sea Turtles (Dermochelys coriacea) [top]

There have been occasional sightings of leatherback turtles around Guam however, to what extent (i.e. preferred location, abundance, seasonality) leatherback turtles are present around Guam and CNMI is unknown.

Humpback Whales (Megaptera novaeangliae) [top]

Humpback whales winter in shallow nearshore waters of usually 100 fathoms or less. Mature females are believed to conceive on the breeding grounds one winter and give birth the following winter. In the North Pacific, there are at least three relatively separate populations of humpback whales that migrate between their respective summer/fall feeding areas to winter/spring calving and mating areas, with an estimated population of just under 20,000. Humpback whales that have been sighted around Guam and CNMI are believed to be part of this North Pacific stock, although the number of whales that winter in the Mariana Archipelago each year is unknown. In addition to the North Pacific stock, at least six well-defined breeding stocks of humpback whales occur in the Southern Hemisphere.

Sei Whales (Balaenoptera borealis) [top]

Two sei whales were tagged in the vicinity of the Northern Mariana Islands. The International Whaling Commission considers there to be one stock of sei whales in the North Pacific, but some evidence exists for multiple populations. In the southern Pacific most observations have been south of 30°.

Sperm Whales (Physeter macrocephalus) [top]

Sperm whales are found in tropical to polar waters throughout the world. They are among the most abundant large cetaceans in the region. Sightings of sperm whales were made during May–July in the 1980s around Guam, and in recent years stranding of dwarf and pygmy sperm whales have been reported on Guam.

Dugongs (Dugon dugong) [top]

A single dugong was observed in Cocos Lagoon, Guam in 1975. . Dugongs are members of the Sirenia order, which include sea cows and manatees, and have a distribution from the east African coast to islands in the southwestern Pacific. Several sightings were reported in 1985 on the southeastern side of Guam. Since that time, however no reports of dugong sightings have been made. No observations of dugongs have been reported around the CNMI.

Other Marine Mammals [top]

Non-ESA Listed Marine Mammals`

Newell’s Shearwater (Puffinus auricularis) [top]

Newell’s shearwaters occasionally visit the CNMI. Shearwaters are most active in the day and skim the ocean surface while foraging. Shearwaters also tend to be gregarious at sea, and the Newell’s shearwater is known to occasionally follow ships. Shearwaters feed by surface seizing and pursuit plunging. Often shearwaters will dip their heads under the water to sight their prey before submerging. Shearwaters are believed to breed only in Hawaii.

Micronesian Megapode (Megapodius laperouse) [top]

The Micronesian megapode is a land bird that formerly occurred on all of the islands in the Marianas Archipelago but was extirpated from Guam, Rota and Saipan in the 19^th and early 20^th centuries via human overexploitation and habitat degradation. Megapodes are now believed to live on 12 islands and the most recent archipelagic assessment (1997) estimated the population to total 1,440 to 1,975 individuals.

Other Seabirds [top]

The following seabirds are considered residents of the NMI: wedge-tailed shearwater (Puffinus pacificus), white-tailed tropicbird (Phaethon lepturus), red-tailed tropicbird (Phaethon lepturus), masked booby (Sula dactylatra), brown booby (Sula leucogaster), red-footed booby (Sula sula), white tern (Gygis alba), sooty tern (Sterna fuscata), brown noddy (Anous stolidus), black noddy (Anous minutus), and the great frigatebird (Fregata minor).

The following seabirds have been sighted and are considered visitors (some more common than others) to CNMI; short-tailed shearwater (Puffinus tenuirostris; common visitor), Newell’s shearwater (Puffinus auricularis; rare visitor), Audobon’s shearwater (Puffinus iherminieri), Leach’s storm-petral (Oceanodroma leucorhoa), Matsudaira’s storm-petral (Oceanodroma matsudairae), and the red-footed booby (Sula sula). There have been no sightings of the endangered short-tailed albatross (Diomedea albatrus) in the Mariana Archipelago although it is within the range of the only breeding colony at Tora Shima, Japan.

The only resident seabirds on Guam are the brown noddy and the white tern. Common visitors to Guam include the black noddy and the short-tailed shearwater. Other less common or rare visitors include: brown and red-footed boobies, wedge-tailed shearwater, Matsudaira’s storm-petral, white-tailed and red-tailed tropicbirds, great frigatebird, gulls, and terns.

Following consultations under section 7 of the ESA, NMFS has determined that the bottomfish, crustaceans, coral reef, and precious coral fisheries in the Exclusive Economic Zone around the Mariana Archipelago will not adversely affect any ESA-listed species or critical habitat.

NMFS has also concluded that the commercial fisheries in the Mariana Archipelago will not affect marine mammals in any manner not considered or authorized under the Marine Mammal Protection Act.

Following a consultation under section 7 of the ESA, the U.S. Fish and Wildlife Service concluded that military bombing maneuvers on FDM could extirpate the FDM population of megapodes (estimated at less than 10 individuals) but that this would not threaten the overall stability of the population of the species in the archipelago.