Hawaii FEP - Western Pacific Fishery Council

Green turtles in Hawaii are considered genetically distinct and geographically isolated, althougha nesting population at Islas Revillagigedos in Mexico appears to share the mtDNA haplotypethat commonly occurs in Hawaii. In Hawaii, green turtles nest on six small sand islands atFrench Frigate Shoals, a crescent-shaped atoll situated in the middle of the Hawaii Archipelago(Northwestern Hawaiian Islands; Balazs et al. 1995). Ninety to 95 percent of the nesting andbreeding activity occurs at the French Frigate Shoals, and at least 50 percent of that nesting takesplace on East Island, a 12-acre island. Long-term monitoring of the population shows that thereis strong island fidelity within the regional rookery. Low-level nesting also occurs at LaysanIsland, Lisianski Island, and on Pearl and Hermes Reef (NMFS 1998).Since the establishment of the ESA in 1973, and following years of exploitation, the nestingpopulation of Hawaiian green turtles has shown a gradual but definite increase (Balazs 1996;Balazs and Chaloupka 2004). In three decades, the number of nesting females at East Islandincreased from 67 nesting females in 1973 to 467 nesting females in 2002. Nester abundanceincreased rapidly at this rookery during the early 1980s, leveled off during the early 1990s, andagain increased rapidly during the late 1990s to the present. This trend is very similar to theunderlying trend in the recovery of the much larger green turtle population that nests atTortuguero Costa Rica (Bjorndal et al. 1999). The stepwise increase of the long-term nester trendsince the mid-1980s is suggestive, but not conclusive, of a density-dependent adjustment processaffecting sea turtle abundance at the foraging grounds (Balazs and Chaloupka 2004; Bjorndal etal. 2000;). Balazs and Chaloupka (2004) concluded that the Hawaiian green sea turtle stock iswell on the way to recovery following 25 years of protection. This increase is attributed toincreased female survivorship since the harvesting of turtles was prohibited in addition to thecessation of habitat damage at the nesting beaches since the early 1950s (Balazs and Chaloupka2004).Hawksbill Sea TurtlesHawksbill sea turtles (Eretmochelys imbricata) are circumtropical in distribution, generallyoccurring from latitudes 30° N to 30° S within the Atlantic, Pacific, and Indian Oceans andassociated bodies of water (NMFS 1998). While data are somewhat limited on their diet in thePacific, it is well documented that in the Caribbean hawksbill turtles are selective spongivores,preferring particular sponge species over others (Dam and Diez 1997b). Foraging dive durationsare often a function of turtle size, with larger turtles diving deeper and longer. At a study site alsoin the northern Caribbean, foraging dives were made only during the day and dive durationsranged from 19 to 26 minutes at depths of 8–10 meters. At night, resting dives ranged from 35 to47 minutes in duration (Dam and Diez 1997a).As a hawksbill turtle grows from a juvenile to an adult, data suggest that the turtle switchesforaging behaviors from pelagic surface feeding to benthic reef feeding (Limpus 1992). Withinthe Great Barrier Reef of Australia, hawksbills move from a pelagic existence to a “neritic” lifeon the reef at a minimum CCL of 35 centimeters. The maturing turtle establishes foragingterritory and will remain in this territory until it is displaced (Limpus 1992). As with other seaturtles, hawksbills will make long reproductive migrations between foraging and nesting areas(Meylan 1999), but otherwise they remain within coastal reef habitats. In Australia, juvenile75