Human vs robot: Comparing the viability and utility of autonomous underwater vehicles for the acoustic telemetry tracking of marine organisms

•An autonomous underwater vehicle was retrofitted to track acoustically tagged marine animals•The AUV tracked stationary objects with comparable accuracy with a human•The AUV was more accurate than a human when tracking moving objects•The AUV always produced more locations than a human tracker

Currently, individual animal movement data can be obtained using a variety of methods, but each methodology is limited in either temporal or spatial resolution. A new method of active tracking was developed which utilizes autonomous underwater vehicles (AUV) equipped with stereo-hydrophones that can accurately estimate the position of a moving acoustic tag, while remaining at a distance. This technology was tested and compared to standard human-based active tracking technology to understand the benefits and limitations of this new technique. An AUV and a researcher independently tracked stationary and moving targets of known location in order to compare their spatial and temporal accuracy. Both methods were then used to track a leopard shark, Triakis semifasciata, in the field. The autonomous vehicle accurately positioned both stationary and moving tags with a positional error of < 10 m. For stationary transmitters, the AUV and the researcher were comparable, but when tracking moving transmitters, the AUV had significantly better spatial accuracy. Throughout all trials, the AUV had a higher frequency of accurate location estimates than a researcher actively tracking. Based on these findings, the AUV was able to more accurately track and record the position of an acoustically tagged shark in the field. Using this new technology, researchers should be able to maintain or improve the spatial resolution of measurements when actively tracking acoustically tagged individuals and will be able to increase the temporal resolution of measurements while minimizing the potential influence of tracking on the behavior of the animal.