Changes in call rate and call level of migrating humpback whales (Megaptera novaeangliae) in response to seismic air guns
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View abstract on PubMed
Summary
This summary is machine-generated.Humpback whales exposed to seismic air gun surveys increased their vocalizations, suggesting a Lombard response to noise. However, responses were inconsistent, highlighting the need for further research on the ecological impacts of seismic surveys.
Area Of Science
- Marine Biology
- Bioacoustics
- Environmental Acoustics
Background
- Seismic air gun surveys for oil and gas exploration produce intense underwater noise.
- Baleen whales exhibit variable behavioral and vocal responses to seismic surveys, including changes in feeding, breeding, and migration.
- Previous studies show conflicting evidence regarding whale vocal responses, with some indicating increased calling (Lombard response) and others decreased calling (avoidance).
Purpose Of The Study
- To investigate if humpback whales (Megaptera novaeangliae) alter their social call rate and source level in response to seismic air gun signals.
- To determine if these vocal changes, if any, fall outside normal baseline vocal behavior.
- To assess the consistency and potential drivers of humpback whale vocal responses to seismic noise.
Main Methods
- Acoustic monitoring of humpback whales using suction-cup tags on 12 individuals exposed to seismic air guns.
- Comparison of call rates and source levels before, during, and after air gun exposure.
- Comparison of vocal parameters between exposed whales and 21 unexposed tagged whales.
Main Results
- Whales exposed to seismic air guns generally increased their call rate and call source level.
- Vocalizations of exposed whales were significantly higher than those of unexposed whales, consistent with a Lombard response.
- Not all whales responded vocally, and no clear dose-response relationship was found between received noise levels, proximity, and vocal changes.
Conclusions
- Humpback whales may exhibit a Lombard response to seismic air gun noise, increasing call rate and source level.
- Vocal responses to seismic surveys are inconsistent and potentially context-dependent.
- Further research is needed to understand whale perception of seismic signals and their ecological impact.
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