Effective beam pattern of the Blainville's beaked whale (Mesoplodon densirostris) and implications for passive acoustic monitoring

This work was funded by two partners under the National Oceanographic Partnership Program: the Ocean Acoustics Program of the U.S. National Marine Fisheries Service, Office of Protected Resources, and the International Association of Oil and Gas Producers Joint Industry Programme on Exploration and...

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Bibliographic Details
Published in:The Journal of the Acoustical Society of America
Main Authors: Shaffer, Jessica Ward, Moretti, David, Jarvis, Susan, Tyack, Peter, Johnson, Mark
Other Authors: NERC, University of St Andrews. School of Biology, University of St Andrews. Marine Alliance for Science & Technology Scotland, University of St Andrews. Sea Mammal Research Unit, University of St Andrews. Sound Tags Group, University of St Andrews. Bioacoustics group, University of St Andrews. Scottish Oceans Institute
Format: Article in Journal/Newspaper
Language:English
Published: 2014
Subjects:
Echolocation signals
Physeter-macrocephalus
Clicks
Behavior
Tag
QH301 Biology
QH301
Physeter macrocephalus
Online Access:http://hdl.handle.net/10023/5090
https://doi.org/10.1121/1.4776177
Description
Summary:This work was funded by two partners under the National Oceanographic Partnership Program: the Ocean Acoustics Program of the U.S. National Marine Fisheries Service, Office of Protected Resources, and the International Association of Oil and Gas Producers Joint Industry Programme on Exploration and Production Sound and Marine Life. Research permits were issued to John Boreman (US NMFS 1121-1900), Peter Tyack (US NMFS 981-1578), and Ian Boyd (Bahamas permit #02/07). M.J. and P.T. are supported by the Marine Alliance for Science and Technology Scotland. The presence of beaked whales in mass-strandings coincident with navy maneuvers has prompted the development of methods to detect these cryptic animals. Blainville's beaked whales, Mesoplodon densirostris, produce distinctive echolocation clicks during long foraging dives making passive acoustic detection a possibility. However, performance of passive acoustic monitoring depends upon the source level, beam pattern, and clicking behavior of the whales. In this study, clicks recorded from Digital acoustic Tags (DTags) attached to four M. densirostris were linked to simultaneous recordings from an 82-hydrophone bottom-mounted array to derive the source level and beam pattern of the clicks, as steps towards estimating their detectability. The mean estimated on-axis apparent source level for the four whales was 201 dB(rms97). The mean 3 dB beamwidth and directivity index, estimated from sequences of clicks directed towards the far-field hydrophones, were 13 degrees and 23 dB, respectively. While searching for prey, Blainville's beaked whales scan their heads horizontally at a mean rate of 3.6 degrees/s over an angular range of some +/-10 degrees. Thus, while the DI indicates a narrow beam, the area of ensonification over a complete foraging dive is large given the combined effects of body and head movements associated with foraging. [http://dx.doi.org/10.1121/1.4776177] Publisher PDF Peer reviewed

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