Abstract
Pile driving during the construction of offshore wind turbines has the potential to produce levels of
noise in the marine environment which may have a detrimental effect on marine animals. SMRU Ltd
were contracted by the Forth and Tay Offshore Developers Group to assess the potential impacts of
pile driving at multiple development sites on local marine mammal populations during the
construction of wind farms in the region.
A detailed description of the potential effects of pile driving noise on marine mammals is out with
the scope of this report; however we are concerned with two main types of impact. The first is
auditory injury leading to a reduction in the hearing abilities of animals (permanent and temporary
threshold shift) and the second is the elicitation of behavioural responses to sound which result in
animals being displaced away from areas around the piling activities.
The assessment approach combines three key pieces of quantitative information to estimate the
number of animals likely to be affected by each type of impact: 1) the predicted spatial pattern and
extent of underwater noise produced by piling activities, 2) the spatial pattern of abundance of
marine mammals across the area of potential impact, and 3) the way in which animals are predicted
to move in response to sound.
This report presents the results of these modelling exercises for both species of seal (harbour seal
and grey seal) and for bottlenose dolphins for 1) pile driving at the Neart Na Gaoithe site alone and
2) pile driving at the Neart Na Gaoithe site concurrent with pile driving at the Inch Cape site and Firth
of Forth Round 3 sites.