The Southern California Behavioral Response Study found that some blue whales off the coast of California change their behavior when exposed to military sonar. This is one of the first studies to focus on how military sonar affects blue whales, specifically.
Scientists tagged blue whales with non-invasive suction cups that recorded acoustic data and high-resolution movements. The whales were then exposed to mid-frequency sonar sounds significantly less intense than the sonar used during U.S. military exercises. The researchers found that some whales altered their diving behavior and temporarily avoided important feeding areas.
For example, some of the whales that were engaged in deep feeding stopped eating and sped up or moved away from the source of the noise.
The researchers note that not all whales responded to the noise and not all responded in the same way.
A related study found that beaked whales — the ones most commonly killed in strandings — are highly sensitive to sonar. Unfortunately for the whales, their strong response was observed at noise levels well below those used by U.S. military exercises.
To learn more:
- Find the full study: Blue whales respond to simulated mid-frequency military sonar
- Read this summary about sonar and marine mammals
- Read the whole post from Duke: Military Sonar Can Alter Blue Whale Behavior
- Read why sonar is blamed for porpoise strandings in 2005 and whale beachings in 2012
- Check out this post about how noise affects fish
- Read this post about the potential impacts of navy testing
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