Quantitative Measures of Anthropogenic Noise on Harbor Porpoises: Testing the Reliability of Acoustic Tag Recordings
In recent years, several sound and movement recording tags have been developed to sample the acoustic field experienced by cetaceans and their reactions to it. However, little is known about how tag placement and an animal’s orientation in the sound field affect the reliability of on-animal recordings as proxies for actual exposure. Here, we quantify sound exposure levels recorded with a DTAG-3 tag on a captive harbor porpoise exposed to vessel noise in a controlled acoustic environment. Results show that flow noise is limiting onboard noise recordings, whereas no evidence of body shading has been found for frequencies of 2–20 kHz.
KeywordsVessel Calibration DTAG-3 Flow noise
This work was funded by the German Federal Agency for Nature Conservation (BfN), Bonn, Germany. We thank J. H. Kristensen, L. D. Rojano, M. de Freitas, L. Delgado, the staffs at Fjord & Bælt and the Marine Biological Research Centre in Kerteminde, Denmark, for their assistance with data collection, and H. U. Riisgaard for providing the boat. The animals were maintained by Fjord & Bælt under Danish Nature Agency Permits SN 343/FY-0014 and 1996-3446-0021.
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