As in studies of effects of anthropogenic (human-made) sound on marine mammals, the sources of underwater noise related to offshore wind farms that are likely to have the greatest effects on fish concern impact noise due to pile driving during construction of the farms, rather than the tonal noise radiated during operation of the turbines. Even so, one extensive examination of "both the peer-reviewed and 'grey' literature" by two prominent experts on bioacoustics led them to conclude that "very little is known about effects of pile driving and other anthropogenic sounds on fishes, and that it is not yet possible to extrapolate from one experiment to other signal parameters of the same sound, to other types of sounds, to other effects, or to other species." [US1]
One European study [EU1] set out to investigate the claim made by a commercial fisherman that certain fish do not migrate between the towers in the Vindeby Offshore Wind Farm off the coast of Denmark when it is windy. The claim was based on the fisherman's catch at different locations around the wind farm. Underwater noise, among other phenomena, was investigated using measurements close to the towers (14 m). Results of this study were inconclusive. More recently [EU2], in studies of the Lillgrund wind farm off the coast of Sweden it was concluded that "In close vicinity (less than 10 m) to a turbine the received level (about 119 to 136 dB re 1 μPa for the 127 Hz component) are most likely sufficient to evoke a behavioural reaction in some species like cod", but that "It is only within a few meters of the foundations that the noise is at a level that could cause significant behavioural reactions as shown in aquaria and field studies."
US.1
"The effect of anthropogenic sources of sound on fishes"
A. N. Popper and M. C. Hastings
J. Fish Biol. vol. 75, 455-489.
2009
EU.1
"Possible effects of the offshore windfarm at Vindeby on the outcome of fishing: The possible effects of electromagnetic fields and noise"
K. Engell-Sørensen
Tech. Rep. 1920-03-001
Report prepared for SEAS-NVE, Hovedgaden 36, DK-4520, Svinninge, Denmark
January 21, 2002
EU.2
"Offshore Wind Farms-Ecological Effects of Noise and Habitat Alteration on Fish"
M. H. Andersson
Doctoral Dissertation
Department of Zoology
Stockholm University
Sweden
2011