Real‐time detection and tracking of beaked whales using a towed hydrophone array.

Abstract

Beaked whales spend the majority of their time at depth and are inconspicuous when they surface. Therefore, they are difficult to detect using only standard visual survey methods. However, recent advancements in acoustic detection have made passive acoustic monitoring from a towed array of hydrophones a viable alternative to visual survey methods for beaked whales. Beaked whales can be discriminated from other cetaceans by the unique characteristics of their echolocation clicks (duration >175 μs, center frequencies between 30 and 40 kHz, inter‐click intervals between 0.2 and 0.4 s and frequency upsweeps). These unique characteristics make it possible to use passive acoustic monitoring (PAM) to detect and track beaked whales in real‐time. In 2009 and 2010, we used PAM to identify areas of beaked whale habitat use in the Southern California Bight (SCB). This area is characterized by deep basins separated by islands and shallow ridges. We developed effective methods for detecting and tracking beaked whales in real‐time and identified previously unknown areas of beaked whale habitat use in the SCB. This work will allow for beaked whale habitat relationships to be explored on a relatively small scale and will contribute to efforts for effective management and conservation of beaked whales in the SCB.