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Fishery Bulletin 103(1) 



the heteropod Carinaria cithara. Okutani (1961) first 

 recorded sea turtles consuming Carinaria (including 

 Carinaria cithara, Benson 1835), in the western North 

 Pacific. Heteropods are found in the upper photic zone 

 (within 100 m of the surface) but are not typically 

 a neustonic or floating species. Recorded heteropod 

 densities in the Pacific are variable (<1/1000 m 3 to 

 150/1000 m 3 , Seapy, 1974, cited in Lalli and Gilmer, 

 1989). Although these densities seem very low, it is 

 clear that in this area of the central North Pacific 

 heteropods are numerous enough within diving depths 

 of loggerhead sea turtles to make this an attractive 

 prey item for the turtles. 



Conclusion — Interactions with fisheries 



The bycatch of nontargeted species in different fisher- 

 ies has been an issue for many years (Wetherall et al., 

 1993; Wetherall, 1996; Gardner and Nichols, 2001; 

 Suganuma 4 ). Bycatch of sea turtles has also been an 

 issue for the conservation management of most sea 

 turtle species. Sea turtle mortalities have occurred in 

 nearly all fisheries (gillnet, driftnet, trawl, and long- 

 line). During their transpacific migrations loggerhead 

 sea turtles move through areas of multinational long- 

 line fishing (Lewison et al., 2004). Mortalities of sea 

 turtles after longline fishery interactions have been 

 estimated between 28% and 50% by both U.S. and Japa- 

 nese researchers (Nishemura and Nakahigashi, 1990; 

 Kleiber, 5 McCracken'M and loggerhead sea turtles com- 

 prise a large percentage of the sea turtle interactions 

 in longline fisheries, as high as 59% of sea turtles cap- 

 tured in the Hawaii-based longline fleet. The longline 

 fishery as well as various other fisheries in the Pacific 

 (Gardner and Nichols, 2001) have been implicated as 

 part of the reason for recent declines in the loggerhead 

 sea turtle populations both in Japan (Kamezaki and 

 Matsui, 1997; Sato et al., 1997; Suganuma 4 ) and also 

 in Australia, and southern nesting areas (Limpus and 

 Couper, 1994; Limpus and Reimer 7 ). Research on feed- 

 ing behavior may help with the mitigation of fisheries 

 interactions. 



4 Suganuma, H. 2002. Population trends and mortality of 

 Japanese loggerhead turtles, Caretta caretta, in Japan. In 

 Proc. Western Pacific Sea Turtle Coop. Res. and Mgmt. 

 Workshop (I. Kinan, ed.). p. 74-77. Western Pacific Regional 

 Fishery Management Council, 1164 Bishop Street, Suite 

 1400, Honolulu, HI 96813. 



5 Kleiber, P. 1998. Estimating annual takes and kills of 

 sea turtles by the Hawaiian longline fishery, 1991-1997, 

 from observer program and logbook data. Administrative 

 report H-98-08, 21 p. Southwest Fisheries Science Center, 

 Nat. Mar. Fish. Serv., NOAA, 2570 Dole St., Honolulu, HI 

 96822. 



6 McCracken, M. L. 2000. Estimation of sea turtle take and 

 mortality in the Hawaiian longline fisheries. Administrative 

 report H-00-06, 29 p. Southwest Fisheries Science Center, 

 Nat. Mar. Fish. Serv., NOAA, 2570 Dole St., Honolulu. HI 

 96822. 



Learning more about the life history of loggerhead 

 sea turtles and understanding more about the move- 

 ments, foraging behavior, and prey of these turtles 

 are important for making well-informed management 

 decisions because foraging behavior may change as 

 seasons change and as these turtles move through dif- 

 ferent habitats (Bjorndal, 1997). Although our study 

 indicates that these turtles forage mainly on floating 

 or near-surface prey in the open ocean, studies in dif- 

 ferent areas show different feeding habits. The oceanic, 

 near-surface feeding behavior of loggerhead sea turtles 

 is likely one reason for the numerous longline fishery 

 interactions in the central North Pacific. The recorded 

 dive data for these turtles indicate that they spend a 

 large percentage of their time near the surface — as 

 much as 78% of their time is spent within 10 m of the 

 surface (Polovina et al., 2003b). Juvenile loggerhead sea 

 turtles are rarely found in the waters adjacent to Japan 

 (Uchida, 1973); the juvenile turtles are thought to use 

 the Kuroshiro Current to move out into the Pacific and 

 the southern edge of the Subartic Gyre during their 

 eastward movement toward foraging grounds in the 

 Eastern Pacific (Bowen et al., 1995). In the Atlantic, 

 however, small neonate loggerhead sea turtles have 

 been found associated with drifts of floating material, 

 especially Sargassum rafts (Witherington, 2002), and 

 although large, regular drifts of floating material are 

 rare in the Pacific, small loggerhead sea turtles may 

 also be associated with floatsam (Pitman, 1990). 



Studies have indicated that foraging changes through- 

 out the lifecycle of loggerhead sea turtles (van Nierop 

 and den Hartog, 1984; Plotkin et al., 1993; Godley et 

 al., 1997; Tomas et al., 2001). In the Pacific, oceanic 

 immature turtles (present study) forage on different 

 prey from that foraged by subadults in the pelagic and 

 neritic areas off Baja California (Nichols et al., 2000; 

 Peckham and Nichols, 2003; Seminoff et al., 2004), 

 and adults in benthic neritic habitats, in turn, forage 

 on different prey near Japan and China (Hitase et al., 

 2002). Japanese loggerhead sea turtles foraging in the 

 Eastern Pacific target Pleuroncodes planipes, the pelagic 

 red crab, which occurs year round off Baja California. 

 These turtles interact with the artisanal fisheries in 

 the area which are both pelagic and benthic fisheries 

 (Gomez-Gutierrez and Sanchez-Ortiz, 1997; Bartlett, 

 1998; Gomez-Gutierrez et al., 2000; Peckham and Nich- 

 ols, 2003). Loggerhead sea turtles have also been found 

 on the Gulf of California side of Baja California, likely 

 foraging on the large abundance of invertebrate fauna 

 found there (Brusca, 1980), and these turtles face fish- 

 ing pressure from the artisanal gillnet fishery in this 

 area (Seminoff et al., 2004). 



7 Limpus, C. J., and D. Reimer. 1994. The loggerhead turtle, 

 Caretta caretta, in Queensland: a population in decline. In 

 Proceedings of the Australian marine turtle conservation 

 workshop iR. James, compiler), p. 39-59. Queensland Dep. 

 Environ and Heritage and Aust. Nat. Conserv. Agency, GPO 

 Box 787, Canberra ACT 2601, Australia. 



