Cetacean Bioacoustics with Emphasis on Recording and Monitoring

Abstract

More than 80 cetacean species live in oceans, lakes, and rivers. For underwater navigation and recognition, whales and dolphins have developed unique sensory systems using acoustic signals. Toothed whales, such as dolphins and porpoises, have sonar using ultrasonic pulse trains called echolocations (Au, 1993). As top predators in the water, dolphins and porpoises rely on accurate and long-range sensory systems for catching prey. Dolphins have another type of vocalization called a whistle that is narrowband with a long duration. Most of the fundamental frequencies of whistles are in the human audible range, and this relatively low-frequency signal travels a longer range than sonar signals. The role of whistles are considered to maintain the mother–calf bond or to recognize each other in a breeding or migrating group of animals.