Passive acoustic detection of deep-diving beaked whales

TLDR

Beaked whales dive for long periods, are rarely sighted, and emit high‑frequency clicks that attenuate quickly, making passive acoustic detection a valuable but range‑limited complement to visual surveys. Under favorable conditions (e.g., 2 m s⁻¹ wind), a surface receiver can detect Cuvier’s beaked whales with high probability up to about 0.7 km if the listening period exceeds the typical 2.5‑hour deep‑dive interval. Detection distances beyond 4 km are unlikely and would require unusually low ambient noise or special propagation conditions.

Abstract

Beaked whales can remain submerged for an hour or more and are difficult to sight when they come to the surface to breathe. Passive acoustic detection (PAD) not only complements traditional visual-based methods for detecting these species but also can be more effective because beaked whales produce clicks regularly to echolocate on prey during deep foraging dives. The effectiveness of PAD for beaked whales depends not only on the acoustic behavior and output of the animals but also on environmental conditions and the quality of the passive sonar implemented. A primary constraint on the range at which beaked whale clicks can be detected involves their high frequencies, which attenuate rapidly, resulting in limited ranges of detection, especially in adverse environmental conditions. Given current knowledge of source parameters and in good conditions, for example, with a wind speed of 2m∕s, a receiver close to the surface should be able to detect acoustically Cuvier’s beaked whales with a high probability at distances up to 0.7km, provided the listening duration exceeds the deep dive interval, about 2.5h on average. Detection ranges beyond 4km are unlikely and would require low ambient noise or special sound propagation conditions.