Sounds and source levels from bowhead whales off Pt. Barrow, Alaska

Area of Science:

• Marine bioacoustics
• Arctic marine mammal research
• Cetacean communication

Background:

• Bowhead whales (Balaena mysticetus) produce complex vocalizations, including songs and moans.
• Understanding their acoustic communication is crucial for conservation in Arctic environments.

Purpose of the Study:

• To analyze the characteristics of bowhead whale vocalizations.
• To determine the acoustic properties and potential communication ranges of bowhead whale sounds in the Arctic.

Main Methods:

• Recording bowhead whale sounds using a 2.46-km hydrophone array in the Canadian Beaufort Sea.
• Analyzing sound characteristics, including frequency, duration, and source levels.
• Modeling sound propagation and detection limits based on ambient noise and whale sound source levels.

Main Results:

• Bowhead whale vocalizations included low-frequency moans (25-900 Hz) and complex songs (20-5000 Hz).
• Songs consisted of up to 20 phrases, with a mean duration of 66.3 seconds.
• Peak source spectrum levels for songs ranged from 158-189 dB re: 1 microPa, 1 m.
• Theoretical detection ranges were limited to 2.5 km for moans and 10.7 km for songs.

Conclusions:

• Bowhead whale underwater communication ranges are significantly shorter in shallow Arctic waters compared to deep-water regions.
• Environmental factors in the Arctic limit the effective range of bowhead whale acoustic signals.
• These findings have implications for understanding bowhead whale social behavior and the impact of anthropogenic noise.