Movement ability of cultured hawksbill turtle in the open sea determined by satellite

Abstract

Sea turtle tagging and releasing program in the Gulf of Thailand is one of the activities for conservation and management conducted by Mannai Sea Turtle Conservation Station, Department of Fisheries, Thailand. Many turtles are cultured and kept in captivity for reproduction and release to the wild. In 2001, satellite telemetry was employed to study on movement ability of cultured hawksbill turtles after release. Four juvenile and sub-adult hawksbill turtles aged 4-12 years old were fitted with Platform Transmitter Terminals (PTTs) on their carapace. Signal data obtained showed that all hawksbills moved randomly along the coastline in the northern part of the Gulf of Thailand within water depths of 20 m, probably to search for suitable feeding areas. The movements to many areas without any oriented directions throughout the 2-3 months of tracking seemed to indicate that juvenile hawksbills could not decide to stay in any fixed habitats while sub-adult turtles appeared to show a more directed search for feeding areas. Swimming speed which was estimated from location fixes of high accuracy (LC 1-3) ranged from 0.45-0.57 km hr-1. Since the movements of the hawksbills appeared disorderly and complex, it was not possible to make conclusions on their behavior in the open sea.