EFFECT OF THE SOUND GENERATED BY AN ACOUSTIC HARASSMENT DEVICE ON THE RELATIVE ABUNDANCE AND DISTRIBUTION OF HARBOR PORPOISES (PHOCOENA PHOCOENA) IN RETREAT PASSAGE, BRITISH COLUMBIA

We describe an experiment conducted to assess the impact of the sound generated by an acoustic harassment device (AHD) on the relative abundance and distribution of harbor porpoises (Phocoena phocoena) in Retreat Passage, British Columbia. During control periods when the AHD was inactive, the mean n...

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Bibliographic Details
Published in:	Marine mammal science Vol. 18; no. 4; pp. 843 - 862
Main Authors:	Olesiuk, Peter F., Nichol, Linda M., Sowden, Margaret J., Ford, John K. B.
Format:	Journal Article
Language:	English
Published:	Oxford, UK Blackwell Publishing Ltd 01-10-2002 Blackwell
Subjects:	acoustic harassment device Animal and plant ecology Animal, plant and microbial ecology Animals Autoecology Biological and medical sciences British Columbia Fundamental and applied biological sciences. Psychology harbor porpoise Mammalia Marine Phocoena phocoena sound Vertebrata Canada British Columbia North America America Canada, British Columbia INE, Canada, British Columbia, Retreat Passage Acoustic device sound Phocoena phocoena Environmental factor British Columbia Acoustic transmitter harbor porpoise Behavioral sequence Marine environment Vertebrata Mammalia Spatial distribution Repellent Cetacea Distance Comparative study Ecological abundance Response stimulus relation acoustic harassment device
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Summary:	We describe an experiment conducted to assess the impact of the sound generated by an acoustic harassment device (AHD) on the relative abundance and distribution of harbor porpoises (Phocoena phocoena) in Retreat Passage, British Columbia. During control periods when the AHD was inactive, the mean number of porpoises observed in the study area was 0.39 for broad area scans conducted with the naked eye and 0.48 for narrow sector scans conducted with binoculars. Abundance declined precipitously when the AHD was activated, to 0.007 porpoises per broad area scan and 0.018 per narrow sector scan. The mean number of porpoise resightings while tracking their movements also declined from 12.2 to 13.6 per sighting during control periods to 1.1–1.9 per sighting when the AHD was activated, which suggested that the few porpoises that ventured into the study area spent less time within it when the AHD was activated. The effect of the AHD diminished with distance. No porpoises were observed within 200 m of the AHD when it was activated. The number of sightings and resightings observed when it was activated was less than 0.2% of the number expected had there been no AHD effect at a range of 200–399 m, 1.4% the number expected at a range of 400–599 m, varied between 2.5% and 3.3% of the number expected at a range of 600–2,499 m, and was 8.1% the number expected at a range of 2,500–3,500 m, which suggested that the impact of the AHD extended beyond our maximum sighting range of 3.5 km.
Bibliography:	ArticleID:MMS843 ark:/67375/WNG-NJFWPN9H-C istex:4A3C113F28DAA7EA9F45E6EB89B3334384383D91 Current address: Department of Fisheries and Oceans, Pacific Biological Station, Nanaimo, BC V9R 6N7, Canada. Current address: General Delivery, Port Neville, BC VOP 1MO, Canada. ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23
ISSN:	0824-0469 1748-7692
DOI:	10.1111/j.1748-7692.2002.tb01077.x