Real-time Passive Acoustic 3D Tracking of Deep Diving Cetacean by Small Non-uniform Mobile Surface Antenna

Detecting and localizing the echolocation clicks of sperm whales provides insight into their diving behavior, but existing methods are limited in range, imprecise, or costly. In this work, we demonstrate that we can obtain a high definition 3D track of deep diving cetaceans from a five-channel, small-aperture hydrophone array on a moving autonomous surface vehicle (ASV), enabled by the vessel’s hydrodynamic quality and a high recording sample rate. Real-time processing is achieved by splitting our non-uniform array into two parts for time delay of arrival estimation. Resulting 3D tracks depict the behavior of the cetacean in the abyss (−1.2 km), with one position per second. This high resolution allows us to observe a correlation between the repetition rate of the predator’s biosonar and the tortuosity of its track. Our proposed mobile observatory may offer new insights about whale behavior and its foraging success close to vessel traffic.