Echolocation signals of wild Atlantic spotted dolphin (<i>Stenella frontalis</i>)

TLDR

An array of four hydrophones in a symmetrical star configuration, spaced 45.7 cm apart and time‑synced with a video camera, was used to record the echolocation signals of Atlantic spotted dolphins in the Bahamas. The dolphins produced bi‑modal echolocation clicks with low‑frequency peaks at 40–50 kHz and high‑frequency peaks at 110–130 kHz, with the low‑frequency component dominating at low source levels and the high‑frequency component at high source levels, reaching peak‑to‑peak source levels of up to 210 dB re 1 μPa and varying with transmission loss, and these signal characteristics were similar to those of captive Tursiops truncatus, Delphinapterus leucas, and Pseudorca crassidens.

Abstract

An array of four hydrophones arranged in a symmetrical star configuration was used to measure the echolocation signals of the Atlantic spotted dolphin (Stenella frontalis) in the Bahamas. The spacing between the center hydrophone and the other hydrophones was 45.7 cm. A video camera was attached to the array and a video tape recorder was time synchronized with the computer used to digitize the acoustic signals. The echolocation signals had bi-modal frequency spectra with a low-frequency peak between 40 and 50 kHz and a high-frequency peak between 110 and 130 kHz. The low-frequency peak was dominant when the signal the source level was low and the high-frequency peak dominated when the source level was high. Peak-to-peak source levels as high as 210 dB re 1 μPa were measured. The source level varied in amplitude approximately as a function of the one-way transmission loss for signals traveling from the animals to the array. The characteristics of the signals were similar to those of captive Tursiops truncatus, Delphinapterus leucas and Pseudorca crassidens measured in open waters under controlled conditions.