Tracking blue whales in the eastern tropical Pacific with an ocean-bottom seismometer and hydrophone array

Area of Science:

• Marine Biology
• Bioacoustics
• Oceanography

Background:

• Blue whales (Balaenoptera musculus) are the largest animals on Earth.
• Understanding blue whale behavior and vocalizations is crucial for conservation efforts.
• The East Pacific Rise is a significant marine ecosystem.

Purpose of the Study:

• To investigate blue whale (Balaenoptera musculus) vocalizations and movements.
• To assess potential behavioral responses of blue whales to seismic airgun activity.
• To track individual blue whales using acoustic data.

Main Methods:

• Deployment of 25 ocean-bottom hydrophones and seismometers.
• Identification and analysis of blue whale call types (A, B, C, D).
• Utilizing a Bayesian inversion procedure to track whale locations via B-component calls.

Main Results:

• Recorded low-frequency calls from up to eight individual blue whales.
• Identified a common AB call sequence pattern with ~130-135s repetitions.
• Observed blue whales entering the area during seismic airgun activity.
• No correlation found between whale vocalization/movement and airgun activity.

Conclusions:

• Blue whale vocalizations can be tracked effectively using ocean-bottom acoustic arrays.
• The study did not find evidence of blue whale behavioral changes due to seismic airgun activity.
• Further research is needed for a comprehensive understanding of whale responses to anthropogenic noise.