Variation in harbour porpoise activity in response to seismic survey noise

Enrico Pirotta*, Kate L. Brookes, Isla M. Graham, Paul M. Thompson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

78 Citations (Scopus)
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Animals exposed to anthropogenic disturbance make trade-offs between perceived risk and the cost of leaving disturbed areas. Impact assessments tend to focus on overt behavioural responses leading to displacement, but trade-offs may also impact individual energy budgets through reduced foraging performance. Previous studies found no evidence for broad-scale displacement of harbour porpoises exposed to impulse noise from a 10 day two-dimensional seismic survey. Here, we used an array of passive acoustic loggers coupled with calibrated noise measurements to test whether the seismic survey influenced the activity patterns of porpoises remaining in the area. We showed that the probability of recording a buzz declined by 15% in the ensonified area and was positively related to distance from the source vessel. We also estimated received levels at the hydrophones and characterized the noise response curve. Our results demonstrate how environmental impact assessments can be developed to assess more subtle effects of noise disturbance on activity patterns and foraging efficiency.

Original languageEnglish
Article number20131090
Number of pages4
JournalBiology Letters
Issue number5
Publication statusPublished - 21 May 2014

Bibliographical note

We thank colleagues at Kongsberg Maritime, Moray First Marine, Gardline Geosurvey and the Scottish Fishermen's Federation for essential support in the field, and those at DECC, PA Resources and Caithness Petroleum Ltd. for ensuring that this research was effectively integrated into their regulatory and commercial activities. The project benefitted at all stages from a scientific steering group and broad stakeholder group with statutory and NGO representation. We thank them, and Tim Barton, Keith Needham, Alex Douglas and the many other colleagues who provided support during both fieldwork and data analysis. Thanks to David Lusseau and two anonymous reviewers for their useful comments and suggestions.


  • activity budget
  • anthropogenic disturbance
  • environmental impact assessment
  • foraging efficiency
  • bottle-nosed dolphins
  • behavioral-responses
  • human disturbance
  • life-history
  • echolocation
  • cetaceans
  • impacts
  • population
  • ecology
  • waters


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