Ontogeny of the dispersal migration of green turtle (Chelonia mydas) hatchlings

The purpose of this study was to determine the ontogenic change in offshore dispersal movement of sea turtles from the shore during frenzy to the post-frenzy periods. Migration and wave orientation behaviors that affect the dispersal of green turtles (Chelonia mydas) from the shore were investigated at 1, 7, and 28-56 days of age. The effect of ocean currents on dispersal migration was also measured. Our results indicate that migration velocity decreased as turtles aged. Wave orientation behavior was not significantly different between growth stages, but the directional preferences of individuals toward waves tended to decrease with age, producing winding migration trajectories in the older age groups. Ocean currents affect dispersal migrations of turtles in all age groups, although no significant differences among growth stages were observed. These results indicate a significant decrease in migration distance between turtles in the 1-day and 28-56-day-old age groups; additionally, ocean currents influenced the slower-swimming 28-56-day-old turtles for longer periods of time. These observations suggest that turtles reared for some period of time have a decreased probability of experiencing the same migration route as wild frenzied hatchlings. Thus, sea turtle hatchlings should be released as soon as possible to increase their survival and facilitate natural migration.