Suganuma, Hiroyuki 



The Green Turtle (Chelonia mydas) 

 in Oqasavara Islands. Japan 



J,. Ogasawara Marine Center 



Ogasawara, Tokyo, Japan 



Ogasawara Islands are located about 1,000 km south of Tokyo, 

 Japan. Green turtles breed in Ogasawara Island, one of the most 

 northern rookeries of this species in the western Pacific Ocean. 



Green turtles are caught by fishermen during mating season 

 (March-May) , and the annual catch records suggest 100-200 turtles 

 were taken in the past ten years. More than 90% of the catch 

 comes from Hahajima Island, although this population is expected 

 to diminish in the near future. Fishing for green turtles is 

 closed during June and July. Egg collection and capture of 

 turtles smaller than 75 cm (curved carapace length) are 

 prohibited. 



An experimental hatchery program was conducted from 1910 to 

 1939, and 38,971 hatchlings were released in those 30 years. In 

 1975, the hatchery program was started again, and 114,534 

 hatchlings have been released during the last 12 years. 



A tagging study of green turtles has been carried out for 

 the last 14 years. Recapture rates are: 1.3% for headstarted 

 turtles released as yearlings, 10.1% for headstarted turtles 

 released as 2-year-olds, 16.7% for headstarted turtles released 

 as 3-year-olds turtles, 13.4% for subadults, 9.9% for adults on 

 the feeding ground, and 10.7% for adults on the nesting ground 

 (remigration) . The feeding ground is located along the Pacific 

 coast of Japan, ranging from 26 N to 38 N latitude. However, it 

 may extend to the East China Sea and near Taiwan. 



The period of remigration ranges from 2 to 7 years. A 4- 

 year interval accounts for 42.5% of the remigration records, and 

 25.0% with a 3-year interval. 



Japan removed the green turtle from its reservation list at 

 the 1987 CITES meeting. A report about the situation will be 

 made after the enforcement of the regulations. 



344 



