A new acoustic method for passive sperm whale depth tracking

Sperm whales (Physeter macrocephalus) can dive in search of food to a depth of over 1500 m and return to the surface within approximately 90 minutes. This makes conventional visual observation methods impractical to locate and track these animals. However it is possible to use an acoustic method for this purpose since a diving whale produces a series of loud impulsive acoustic signals or `clicks´ at a fairly constant rate. In this paper, a new method for passive whale tracking is presented based on these signals. A recursive range estimation technique is presented using the angle of arrival and periodicity. The performance is evaluated using a synthesized whale range profile.