Estimation of Migration Route of the Loggerhead Turtle Caretta caretta around the Nesting Ground

Abstract

The adult loggerhead turtles Caretta caretta use the sandy beaches of Japanese Islands as their nesting place. A female went to sea after her first spawning and 20 days later she returned again to the same beach to make a second spawning. Her migration route during this interval was estimated using time series water temperature data directly obtained from the female C. caretta by TTR, and oceanographic survey data. She was thought to arrive at the Kuroshio zone at first and to be drifting for several days in the current. After drifting, she would begin to swim toward the nesting beach, seemingly selecting the direction to arrive at the nesting ground. Therefore any random swimming motion could not be found on her estimated swimming trajectories.