TY - JOUR
TI - Short-Term Disturbance by a Commercial Two-Dimensional Seismic Survey does Not Lead to Long-Term Displacement of Harbour Porpoises
AU - Thompson, P
AU - Brookes, K
AU - Graham, I
AU - Barton, T
AU - Needham, K
AU - Bradbury, G
AU - Merchant, N
T2 - Proceedings of the Royal Society B
AB - Assessments of the impact of offshore energy developments are constrained because it is not known whether fine-scale behavioural responses to noise lead to broader-scale displacement of protected small cetaceans. We used passive acoustic monitoring and digital aerial surveys to study changes in the occurrence of harbour porpoises across a 2000 km2 study area during a commercial two-dimensional seismic survey in the North Sea. Acoustic and visual data provided evidence of group responses to air gun noise from the 470 cu inch array over ranges of 5-10 km, at received peak-to-peak sound pressure levels of 165-172 dB re 1 mu Pa and sound exposure levels (SELs) of 145-151 dB re 1 µPa-2 s-1. However, animals were typically detected again at affected sites within a few hours, and the level of response declined through the 10 day survey. Overall, acoustic detections decreased significantly during the survey period in the impact area compared with a control area, but this effect was small in relation to natural variation. These results demonstrate that prolonged seismic survey noise did not lead to broader-scale displacement into suboptimal or higher-risk habitats, and suggest that impact assessments should focus on sublethal effects resulting from changes in foraging performance of animals within affected sites.
DA - 2013/11//
PY - 2013
VL - 280
SP - 8
UR - http://rspb.royalsocietypublishing.org/content/280/1771/20132001
DO - 10.1098/rspb.2013.2001
LA - English
KW - Marine Energy
KW - Wind Energy
KW - Fixed Offshore Wind
KW - Displacement
KW - Noise
KW - Marine Mammals
KW - Cetaceans
ER -