Behavioral responses of leatherback juveniles (Dermochelys coriacea L) to lights used in the longline fishery

The pelagic longline fishery is responsible for significant mortality to sea turtles as a result of foul hooking, entanglement in the lines, and internal injury after consuming the baited hook. Bait, gear and lights (used to attract the target fishes to the baits at night) are three variables that could also attract sea turtles to the lines. This study tests the role of the lights in attracting Leatherback (Dermochelys coriacea ) turtles and compares their behavior to the loggerhead ( Caretta caretta), shown in previous studies to orient toward both lightsticks and battery powered LEDs used in the fishery. The same lights were used in experiments done on leatherbacks reared at Florida Atlantic University's Marine Laboratory. The leatherbacks were exposed to the lights at night when they were between 5 and 42 days old. The results show that leatherbacks, unlike loggerheads, either do not orient toward the lights or orient away from them at an angle that enabled the turtles to keep the light in their peripheral meld of view. Thus, the capture of leatherbacks in longlines is probably a consequence of other factors (such as attraction to the odor of the baits, or to natural prey located near the lines) that need to be investigated through future research. The results also show that efforts to reduce the incidental capture and injury of marine turtles in longlines must be based upon a firm understanding of the similarities, as well as the differences, between turtle species.