Acoustic basis for fish prey discrimination by echolocating dolphins and porpoises.

Full Abstract

The biosonar system of dolphins and porpoises has been studied for about 5 decades and much has been learned [Au, W. W. L. (1993). The Sonar of Dolphins (Springer, New York)]. Most experiments have involved human-made targets; little is known about odontocetes' echolocation of prey. To address this issue, acoustic backscatter from Atlantic cod (Gadus morhua), gray mullet (Chelon labrosus), pollack, (Pollachius pollachius), and sea bass (Dicentrarchus labrax) was measured using simulated biosonar signals of the Atlantic bottlenose dolphin and harbor porpoise. The fish specimens were rotated so that the effects of the fish orientation on the echoes could be determined. Echoes had the highest amplitude and simplest structure when the incident angle was perpendicular to the longitudinal axis of the fish. The complexity of the echoes increased as the aspect angle of the fish moved away from the normal aspect. The echoes in both the time and frequency domains were easily distinguishable among the four species of fish and were generally consistent within species. A cochlear model consisting of a bank of band-passed filters was also used to analyze the echoes. The overall results suggest that there are sufficient acoustic cues available to discriminate between the four species of fish based on the echoes received, independent of aspect angle.

Author information

Author/s: Au, Whitlow W L (WW); Branstetter, Brian K (BK); Benoit-Bird, Kelly J (KJ); Kastelein, Ronald A (RA);

Affiliation: Hawaii Institute of Marine Biology, University of Hawaii, Kailua, Hawaii 96734, USA.

Journal and publication information

Publication Type: Journal Article; Research Support, U.S. Gov't, Non-P.H.S.

Journal: The Journal of the Acoustical Society of America (J Acoust Soc Am), published in United States. (Language: eng)

Reference: 2009-Jul; vol 126 (issue 1) : pp 460-7

Dates: Created 2009/07/16; Completed 2009/09/28;

PMID: 19603903, status: MEDLINE (last retrieved date: 9/28/2009)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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