142 



Abstract — Diet analysis of 52 log- 

 gerhead sea turtles (Caretta caretta) 

 collected as bycatch from 1990 to 1992 

 in the high-seas driftnet fishery oper- 

 ating between lat. 29.5°N and 43°N 

 and between long. 150°E and 154°W 

 demonstrated that these turtles fed 

 predominately at the surface; few 

 deeper water prey items were pres- 

 ent in their stomachs. The turtles 

 ranged in size from 13.5 to 74.0 cm 

 curved carapace length. Whole tur- 

 tles (n = 10) and excised stomachs 

 (n = 42) were frozen and transported 

 to a laboratory for analysis of major 

 faunal components. Neustonic species 

 accounted for four of the five most 

 common prey taxa. The most common 

 prey items were Janthina spp. (Gas- 

 tropoda); Carinaria cithara Benson 

 1835 (Heteropoda); a chondrophore, 

 Velella velella (Hydrodia); Lepas spp. 

 (Cirripedia), Planes spp. (Decapoda: 

 Grapsidae), and pyrosomas (Pyrosoma 

 spp.). 



Diet of oceanic loggerhead sea turtles 

 (Caretta caretta) in the central North Pacific 



Denise M. Parker 



Joint Institute for Marine and Atmospheric Research 



8604 La Jolla Shores Drive 



La Jolla, California 92037 



Present address: Northwest Fisheries Science Center 



National Marine Fisheries Service, NOAA 

 Newport, Oregon 97365-5275 



E-mail address Denise Parkers noaa gov 



William J. Cooke 



AECOS, Inc. 



970 N. Kalaheo Avenue, Suite C311 



Kailua. Hawaii 96734 



George H. Balazs 



Pacific Islands Fisheries Science Center, Honolulu Laboratory 



National Marine Fisheries Service 



2570 Dole Street 



Honolulu, Hawaii 96822-2396 



Manuscript submitted 15 July 2003 

 to the Scientific Editor's Office. 



Manuscript approved for publication 

 8 July 2004 by the Scientific Editor. 



Fish. Bull. 103:142-152 12005). 



Loggerhead sea turtles are circum- 

 global, inhabiting temperate, sub- 

 tropical, and tropical waters of the 

 Atlantic, Pacific, and Indian Oceans. 

 In the Pacific, loggerhead sea turtles 

 have been found in nearshore waters 

 of China, Taiwan, Japan, Australia, 

 and New Zealand and are seen in off- 

 shore waters of Washington, Califor- 

 nia, and northwestern Mexico (Dodd, 

 1988; Pitman, 1990). Nesting in the 

 North Pacific Ocean occurs in Japan; 

 there is no known nesting in the east- 

 ern North Pacific (Marquez and Vil- 

 lanueva, 1982; Frazier, 1985; Bartlett, 

 1989). Trans-Pacific migrations of 

 juveniles have been documented from 

 mitochondrial DNA analyses of indi- 

 viduals found feeding off Baja Cali- 

 fornia. Bowen et al. (1995) identified 

 these Baja sea turtles as originating 

 from Japanese rookeries, although a 

 a small percentage come from Aus- 

 tralia. Recent research indicates that 

 all loggerhead sea turtles found in the 

 oceanic realm of the central North 

 Pacific Ocean are of Japanese stock 

 (Dutton et al., 1998). Tagging studies 

 in Japan and the Eastern Pacific also 

 demonstrate transpacific migrations 

 of loggerhead sea turtles between the 



east and west Pacific (Balazs, 1989; 

 Resendiz et al., 1998; Uchida and 

 Teruya 1 ). 



Recent oceanic satellite tracking 

 studies of loggerhead sea turtles in- 

 dicate that they are active in their 

 oceanic movements. These turtles 

 follow subtropical fronts as they 

 travel toward Japan from east to 

 west across the Pacific Ocean, often 

 swimming against weak geostrophic 

 currents (Polovina et al., 2000; Po- 

 lovina et al., 2004). One hypothesis 

 discussed in Polovina et al. (2000; 

 2004) suggests that this species ob- 

 tains prey items from the subtropi- 

 cal fronts along which they travel. A 

 sharp gradient in surface chlorophyll 

 is observed along the main frontal 

 area where these turtles are com- 

 monly encountered. This frontal area, 

 the transition zone chlorophyll front 



Uchida, S., and H. Teruya. 1991. A) 

 Transpacific migration of a tagged log- 

 gerhead, Caretta caretta. B) Tag-return 

 result of loggerhead released from Oki- 

 nawa Islands, Japan. In International 

 symposium on sea turtles '88 in Japan 

 (I. Uchida, ed.), p. 169-182. Himeji City 

 Aquarium, Tegarayama 440 Nishinobu- 

 sue, Himeji-shi, Hyoyo 670, Japan. 



