Swim speed and movement patterns of gravid leatherback sea turtles (Dermochelys coriacea) at St Croix, US Virgin Islands.

Swim speed, dive behavior and movements were recorded for seven female leatherback sea turtles (Dermochelys coriacea Vandelli 1761) during a single internesting interval near St Croix in the US Virgin Islands. Modal speeds ranged from 0.56 to 0.84 m s(-1), maximum speed range 1.9-2.8 m s(-1). Turtles swam continuously throughout the day and night. There were two swim-speed patterns; the most common was slightly U-shaped, with high speeds at the initiation and conclusion of the dive, and the less common was continuous high-speed swimming. The U-shaped speed patterns were coincident with vertical diving by the turtles, while the second pattern occurred most frequently during the daytime, with the turtle swimming within 2 m of the surface. This latter swim behavior appeared to be designed to maximize efficiency for long-distance travel. The hypothesis that leatherbacks rest or bask at midday during their internesting interval is refuted by this study.