Marine Resources Assessment for the Marianas Operating ... - SPREP

AUGUST 2005 FINAL REPORT
and two pairs of claws on their flippers. The carapace of this species is often brown or amber with
irregularly radiating streaks of yellow, orange, black, and reddish-brown (NMFS and USFWS 1998b).
Status—Hawksbill turtles are classified as endangered under the ESA and are second only to the
Kemp’s ridley turtle in terms of endangerment (Bass 1994; NMFS and USFWS 1998b). In U.S.
waters, hawksbill populations are noted as neither declining nor showing indications of recovery
(Plotkin 1995). Only five regional populations worldwide remain with more than 1,000 females nesting
annually (Seychelles, the Mexican Atlantic, Indonesia, and two in Australia) (Meylan and Donnelly
1999). A lack of regular quantitative surveys for hawksbill turtles in the Pacific Ocean and the discrete
nature of this species’ nesting have made it extremely difficult for scientists to assess the distribution
and population status of hawksbills in the region (NMFS and USFWS 1998b; Seminoff et al. 2003).
The status of the hawksbill is clearly of a higher concern for the Pacific due to the serious depletion of
the species caused by international harvest and habitat destruction (NMFS and USWFS 1998b).
Habitat Preferences—In the Atlantic Ocean and Caribbean Sea, early juveniles are known to inhabit
oceanic waters, where they are sometimes associated with drift lines and floating patches of
Sargassum (Parker 1995). In the Pacific Ocean, the oceanic whereabouts of this early life stage is
unknown (NMFS and USFWS 1998b). However, it is likely that they would occur in similar areas of
advection where flotsam accumulates (HDLNR 2002).
It is believed that hawksbill turtles migrate to benthic foraging grounds when they reach 20 to 25 cm
in length (Meylan 1988). Late juvenile and adult hawksbill turtles forage around coral reefs,
mangroves, and other hard-bottom habitats in open bays and coastal zones throughout the tropical
Pacific Ocean, with adults occupying somewhat deeper waters (to 24 m) than late juveniles (to 12 m)
due to their ability to make deeper dives (Eckert 1993).
Distribution—Hawksbill turtles are circumtropical in distribution, generally occurring from 30°N to
30°S latitude within the Atlantic, Pacific, and Indian Ocean basins (NMFS and USFWS 1998b).
Although they exhibit similar habitat and water temperature preferences, hawksbills are generally less
common than green turtles around insular habitats of the North Pacific Ocean, with the exception of
the waters surrounding Palau (NMFS 1998).
Hawksbills were originally thought to be a non-migratory species because of the close proximity of
their nesting beaches to their coral reef feeding habitats and the high rates of local recapture.
Hawksbills are now known to travel long distances over the course of their lives (Meylan 1999). Tag
return, genetic, and telemetry studies have indicated that hawksbill turtles utilize multiple
developmental habitats as they age. However, within a given life stage, such as the late juvenile
stage, some hawksbills may remain at a specific developmental habitat for a long period of time
(Meylan 1999). Foraging hawksbills at Guam and the CNMI likely come from natal beaches located a
good distance away from the Marianas archipelago, such as those in Palau, the Philippines, and
possibly southern Japan (NMFS 1998; NMFS and USFWS 1998b).
Hawksbill nesting in the North Pacific Ocean is widespread and occurs at scattered locations in very
small numbers (Eckert 1993). The NMFS and USFWS (1998b) note that the nesting picture for
hawksbills throughout Micronesia appears grim. The nesting population of hawksbills at Palau is the
largest of all Micronesian islands located north of the equator (Eckert 1993). Pritchard (1995)
indicates that hawksbills nest sporadically in Guam and rarely, if ever, in the CNMI. If Palau
represents the highest hawksbill nesting activity known in the region, with conceivably as few as 20
nesting females per year, then all of Micronesia, with its thousands of islands and atolls, may not
support collectively more than a few hundred nesting females per year (NMFS and USFWS 1998b).
Information Specific to Marianas MRA Study Area―Although there are only a few recent
hawksbill occurrence records in the study area and vicinity (DoN 2004; Michael 2004), historical
records indicate a likely presence of this species in the coastal waters surrounding the islands of
the southern Marianas arc (i.e., from FDM south to Guam) (Wiles et al. 1989, 1990, 1995;
Kolinski 2001; Gutierrez 2004). As a result, hawksbill turtles are expected to occur in all study
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