Computation of Dolphins’ Sound ASPL While Foraging

Abstract

Scheduled scientific surveys are a valuable asset in beginning to understand the behavior and vocalization of free-ranging cetaceans. The fortuity of a nonscheduled survey has proven to be beneficial as well. In October 2003 a team of biologist oceanographers began a trip aboard a 44.29 feet catamaran sailing boat from Piraeus Greece to Cape Verde Archipelago intending to observe free-ranging cetaceans. Acoustic recordings were conducted using a towed stereophonic hydrophone array consisted of two Benthos AQ4 type hydrophones. Photographs were taken in order to ensure species identification. Information on vocalization administration during foraging of Lagenodelphis hosei and Steno bredanensis has been acquired. Calculation of ASPL (apparent source power level) revealed that dolphins’ vocalizations did not match to usual vocalization activities. The relation of vocalization administration by dolphins with brain to mash ratio (BMR) is introduced as an additional predator’s strategy.