Great new paper from our colleagues over at SMRU on how sonar signals cause behavioural disturbance in Northern Bottlenose Whales…
This study was funded by the US Office of Naval Resources, the Norwegian Ministry of Defence and others and it involved controlled exposure experiments on tagged wild bottlenose whales. Multiple methods were used to test the effects of the sonar:
- Suction cup DTAGs were attached to the whale
- Visual observations were conducted from the source vessel
- Echolocation clicks were detected from a hydrophone array
During the sonar exposure the whale first turned towards the sound then dived to deep depths, moved away from the sonar and did not produce and foraging clicks. The dive conducted by the whale during exposure was the longest and deepest dive recorded for this species – at 94 minutes and 2339m. After exposure the whale showed unusual directional movement and multiple shallow dives. During sonar testing the acoustic and visual sightings of the whales dropped substantially.
These results demonstrate that the northern bottlenose whales are highly sensitive to acoustic disturbance which puts it at risk from marine construction and naval activity.
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Check out the other behavioural response studies we conducted on beaked whales in the Bahamas (for Navy sonar), papers and our other projects.