Dispersal processes of head-started hawksbill turtles (Eretmochelys imbricate) in the Yaeyama Islands waters, Okinawa, Japan

Abstract

Behaviors of five head-started hawksbill turtles (Eretmochelys imbricata) attached with ultrasonic transmitters were monitored using 12 ultrasonic receivers set up along the reef edge. The head-started turtles were reared for two years in the Yaeyama Station, National Center for Stock Enhancement. Four of five head-started turtles moved out of the monitoring area, but their movements are not linearly. The duration the four head-started ones stayed in the monitoring area ranged from 4 to 14 days. All of the head-started turtles had a circadian rhythm to their behaviors. The other head-started turtle stayed around the release point for 88 days until it was recaptured by a fisherman. There was not much difference in diving depth between the head-started and the wild turtles reported by other sites. These results indicate that the head-started turtles tend to wander aimlessly in the natural environment, although they have natures of a circadian rhythm and diving technique.