ECHOLOCATION RATES OF TWO HARBOR PORPOISES (PHOCOENA PHOCOENA) |
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Authors: | Tomonari Akamatsu Yoshimi Hatakeyama Takahito Kojima Hideo Soeda |
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Affiliation: | National Research Institute of Fisheries Engineering, Ebidai, Hasaki-chyo, Kashima-gun, Ibaraki 314-04, Japan;College of Agriculture and Veterinary Medicine, Nihon University, Setagaya-ku, Tokyo 154, Japan |
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Abstract: | The rate of occurrence of click trains of two harbor porpoises ( Phocoena phocoena ) were counted during 14 nights. We developed an echolocation signal detection system that was harnessed to a porpoise and activated a light when the animal emitted an echolocation signal. This device, referred to as a click-light, detects echolocation signals above 150 dB re 1 μPa in the 28–180 kHz range. Echolocation rates, i.e., occurrences of click trains, changed frequently, ranging from 0 to 25 per minute. Echolocation rates were affected by feeding, individual difference, and enclosure type such as the net enclosure and the pool. The porpoise echolocation rates seemed to show acclimation. |
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Keywords: | echolocation rate acoustic behavior harbor porpoise Phocoena phocoena clicks echolocation gill net accidental catch |
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