To determine whether turtle hatchlings that have been previously misoriented by artificial lighting (attracted landward instead of seaward) can later recover from that experience, and orient normally to find the sea and swim away from the shore from a dark beach. This is needed because misoriented or disoriented hatchlings are sometimes found alive on the beach, either late at night or the morning after failing to locate the sea and some guidelines (in this case, Florida Fish and Wildlife Conservation Commission guidelines) recommend that these hatchlings should be moved closer to the water, or released in shallow water near the shore.
Type of Study:
A brief (2 min) exposure and attraction landward to lights had no effect on hatchlings subsequently finding the sea andswimming away from shore as long as surface waves were present. In a calm sea they failed to swim offshore. A long (2 h) exposure and attraction toward a landward light source, however, impaired the ability of the turtles to crawl on straight paths to the sea, and lengthened the time taken to reach the surf zone. The results demonstrated that orientation landward toward artificial light sources compromises the ability of hatchlings to respond naturally to the cues normally used to locate the sea.
They recommend changes to the guidelines for rescuing previously misoriented hatchlings: they need time to respond appropriately to natural orientation cues and this should be achieved by releasing them 13 m from the surf zone rather than at the surf zone, but they should not be released when surface waves are absent. Any hatchlings that fail to depart should be recaptured, brought to a rehabilitation centre fortreatment and later release. Releases should be done at different places on the beach to ensure that predators do not cue in and predation risk in increased.
Lorne J. K. & Salmon M. (2007) Effects of exposure to artificial lighting on orientation of hatchling sea turtles on the beach and in the ocean. Endangered Species Research 3, 23-30.