Hawaii FEP - Western Pacific Fishery Council

Loggerheads in the North Pacific are opportunistic feeders that target items floating at or near thesurface, and if high densities of prey are present, they will actively forage at depth (Parker et al.2002). As they age, loggerheads begin to move into shallower waters, where, as adults, theyforage over a variety of benthic hard- and soft-bottom habitats (reviewed in Dodd, 1988).Subadults and adults are found in nearshore benthic habitats around southern Japan, as well as inthe East China Sea and the South China Sea (e.g., Philippines, Taiwan, Vietnam).The loggerhead sea turtle is listed as threatened under the ESA throughout its range, primarilydue to direct take, incidental capture in various fisheries, and the alteration and destruction of itshabitat. In general, during the last 50 years, North Pacific loggerhead nesting populations havedeclined 50–90 percent (Kamezaki et al. 2003). From nesting data collected by the Sea TurtleAssociation of Japan since 1990, the latest estimates of the number of nesting females in almostall of the rookeries are as follows: 1998 −2,479 nests, 1999 −2,255 nests, and 2000 −2,589nests. 12In the South Pacific, Limpus (1982) reported an estimated 3,000 loggerheads nesting annually inQueensland, Australia during the late 1970s. However, long-term trend data from Queenslandindicate a 50 percent decline in nesting by 1988–89 due to incidental mortality of turtles in thecoastal trawl fishery. This decline is corroborated by studies of breeding females at adjacentfeeding grounds (Limpus and Reimer 1994). Currently, approximately 300 females nest annuallyin Queensland, mainly on offshore islands (Capricorn-Bunker Islands, Sandy Cape, SwainsHead; Dobbs 2001). In southern Great Barrier Reef waters, nesting loggerheads have declinedapproximately 8 percent per year since the mid-1980s (Heron Island), while the foraging groundpopulation has declined 3 percent and comprised less than 40 adults by 1992. Researchersattribute the declines to recruitment failure due to fox predation of eggs in the 1960s andmortality of pelagic juveniles from incidental capture in longline fisheries since the 1970s(Chaloupka and Limpus 2001).Green Sea TurtlesGreen turtles (Chelonia mydas) are distinguished from other sea turtles by their smooth carapacewith four pairs of lateral “scutes,” a single pair of prefrontal scutes, and a lower jaw edge that iscoarsely serrated. Adult green turtles have a light to dark brown carapace, sometimes shadedwith olive, and can exceed 1 meter in carapace length and 100 kilograms in body mass. Femalesnesting in Hawaii averaged 92 centimeters in straight carapace length (SCL), while at OlimaraoAtoll in Yap, females averaged 104 centimeters in curved carapace length and approximately140 kilograms in body mass. In the rookeries of Michoacán, Mexico, females averaged 82centimeters in CCL, while males averaged 77 centimeters in CCL (NMFS and USFWS 1998c ).Based on growth rates observed in wild green turtles, skeletochronological studies, and capture–recapture studies, all in Hawaii, it is estimated that an average of at least 25 years would beneeded to achieve sexual maturity (Eckert 1993).Although most adult green turtles appear to have a nearly exclusively herbivorous diet,consisting primarily of seagrass and algae (Wetherall 1993), those along the east Pacific coast12 In the 2001, 2002, and 2003 nesting seasons, a total of 3,122, 4,035 and 4,519 loggerhead nests, respectively,were recorded on Japanese beaches (Matsuzawa, March 2005, final report to the WPRFMC).73