Target Strength of Southern Resident Killer Whales (Orcinus orca): Measurement and Modeling
A major criterion for tidal power licensing in Washington’s Puget Sound is the management of the risk of injury to killer whales due to collision with moving turbine blades. An active monitoring system is being proposed for killer whale detection, tracking, and alerting that links to and triggers temporary turbine shutdown when there is risk of collision. Target strength (TS) modeling of the killer whale is critical to the design and application of any active monitoring system. A 1996 study performed a high-resolution measurement of acoustic reflectivity as a function of frequency of a female bottlenose dolphin (2.2 m length) at broadside aspect and TS as a function of incident angle at 67 kHz frequency. Assuming that killer whales share similar morphology structure with the bottlenose dolphin, we extrapolated the TS of an adult killer whale 7.5 m in length at 67 kHz frequency with -8 dB at broadside aspect and -28 dB at tail side. The backscattering data from three Southern Resident killer whales were analyzed to obtain the TS measurement. These data were collected at Lime Kiln State Park using a split-beam system deployed from a boat. The TS of the killer whale at higher frequency (200 kHz) was estimated based on a three-layer model for plane wave reflection from the lung of the whale. The TS data of killer whales were in good agreement with our model. In this paper, we also discuss and explain possible causes for measurement estimation error.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1038372
- Report Number(s):
- PNNL-SA-82872; PP0814000; TRN: US201208%%463
- Journal Information:
- Marine Technology Society Journal, 46(2):74-84, Vol. 46, Issue 2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ACOUSTICS
ADULTS
BACKSCATTERING
CETACEANS
DESIGN
DETECTION
FEMALES
KILNS
LUNGS
MANAGEMENT
MONITORING
MORPHOLOGY
PUGET SOUND
REFLECTION
REFLECTIVITY
SHUTDOWN
TARGETS
TIDAL POWER
TURBINE BLADES
TURBINES
target strength
Southern Resident killer whales
active sonar system
tidal power