Behavior of Hatchling Sea Turtles During Their Off-Shore Migration

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Sea turtles are large marine reptiles, which are an important source of protein in many third-world countries. All species of sea turtles are either threatened or endangered. This unfortunate situation comes about because of overfishing of adult stocks, nest destruction and poaching of eggs, and because the pristine oceanic beaches chosen as nest sites are now prime areas for human recreation and land development. A major conservation thrust involves the protection of the most vulnerable sea turtles--the small and virtually defenseless hatchlings--by rearing them for about a year in large tanks before releasing them into the sea. Under natural conditions, hatchlings emerge from nests at night, crawl down-beach, and migrate out to sea. Hatchlings released at sea are deprived of this experience. In many migratory animals, such as birds and salmonid fishes, cues perceived by young as they migrate are used later by individuals as adults to find suitable breeding sites. If sea turtles behave similarly, hatchlings deprived of their off-beach migration may survive but, as adults, be unable to locate appropriate beaches in which to nest. The long-term goal of the present research project is also to promote hatchling survival, but Drs. Salmon and Wyneken believe that sound conservation practices must be based upon a thorough understanding of how hatchlings migrate and when, during their journey, they are most vulnerable to predators. Thus, Drs. Salmon and Wyneken will attempt to determine how loggerhead sea turtles complete their 30-km migration between the East coast of Florida and their goal, the Sargassum matts of the Gulf Stream. Drs. Salmon and Wyneken will follow hatchlings bearing radio transmitters to determine how long the trip takes, will do experiments to determine what cues guide them, and will determine what predators take hatchlings at various portions of their journey. Armed with this understanding, Drs. Salmon and Wyneken should be able to specify under what conditions hatchlings might be released into the sea at locations where predators are least likely to capture them, and under conditions that are ideal for the completion of their migration. The potential benefits are several: reestablishment of sufficient stocks for intelligent harvesting; insights into the migratory behavior and ecology of a fascinating and magnificent marine animal; and the implementation of sound conservation practices based upon a thorough knowledge of the animal's biology.