Using a remotely operated vehicle (ROV) to observe loggerhead sea turtle (Caretta caretta) behavior on foraging grounds off the mid-Atlantic United States

Abstract

This study represents the first documented use of a remotely operated vehicle (ROV) to actively track sea turtles in situ. From 2008 to 2014, an ROV was deployed to track the at-sea behavior of loggerhead turtles in the Northwest Atlantic Ocean. Seventy turtles were tracked, totaling 44.7h of direct turtle footage. For all attempts, usable video with a turtle retained in view for a minimum of 30s, was produced at a rate of 43.5% of effort. Turtles were first spotted from the boat, and then when the turtle was within ~50m of the boat, the ROV was deployed to track the turtle for as long as possible. Tracking durations reached up to 426.1min. Tracked turtles often remained within ~10m of the surface; however loggerheads were tracked to the seafloor on 12 occasions. Turtles were filmed foraging both pelagically and benthically, even though bottom temperatures reached as low as 7.1°C. A range of inter- and intra-species interactions were also captured. Several varieties of fish remained associated with individual turtles for extended periods of time, even during benthic foraging dives. Additionally, a variety of social interactions between loggerheads were documented. Generally these interactions were filmed occurring near the ocean surface. Overall, using the ROV provided great insight into loggerhead at-sea behavior, otherwise unattainable using previously established techniques.