Data from: Harbour porpoise responses to pile-driving diminish over time

Estimating impacts of offshore windfarm construction on marine mammals
requires data on displacement in relation to different noise levels and
sources. Using echolocation detectors and noise recorders, we investigated
harbour porpoise behavioural responses to piling noise during the 10-month
foundation installation of a North Sea windfarm. Current UK guidance
assumes total displacement within 26 km of pile driving. In contrast, we
recorded a 50 % probability of response within 7.4 km (95 % CI = 5.7 –
9.4) at the first location piled, decreasing to 1.3 km (95 % CI = 0.2 –
2.8) by the final location; representing 28 % (95 % CI = 21 – 35) and 18 %
(95 % CI = 13 – 23) displacement of individuals within 26 km. Distance
proved as good a predictor of responses as audiogram weighted received
levels, presenting a more practicable variable for environmental
assessments. Critically, acoustic deterrent device (ADD) use and vessel
activity increased response levels. Policy and management to minimise
impacts of renewables on cetaceans have concentrated on pile-driving
noise. Our results highlight the need to consider trade-offs between
efforts to reduce far-field behavioural disturbance and near-field injury
through ADD use.