Concern exists about the potential adverse effects of underwater sounds generated by pile-driving during the construction of offshore wind farms. Loud impulsive sounds, such as pile-driving sound, can cause fatal in juries in fish. Until recently, very little was known about the sound levels at which injuries or death occur in fish. We examined lethal effects of exposure to pile-driving sound in different larval stages of three fish species (common sole Solea solea, European sea bass Dicentrarchus labrax and herring Clupea harengus), representing different swim bladder developments. Controlled exposure experiments were carried out using the ‘larvaebrator’, a device that was developed to enable exposure of larval fish to pile - driving sounds in a laboratory setting. Recorded pile - driving sounds could be reproduced at zero-to-peak sound pressure levels up to 210 dB re 1 μPa2 (zero to peak pressures up to 32 kPa) and single pulse sound exposure levels up to 186 dB re 1 μPa2s. The highest cumulative sound expos ure level (SEL cum) applied was 216 dB re 1 μPa2s (999 strikes). Survival was monitored during a seven day (sole) or ten day (sea bass and herring) period. In two of the three larval studies (sole and sea bass), pilot experiments were carried out, which enabled a power analysis to determine the number of replicates required in the final experiments. The difficulty of obtaining herring larvae hindered pilot experiments for this species, and previous experiences were used to determine the number of replicates. The results of the larval studies showed no significant differences in mortality between the control group and the exposure groups for any of the species or larval stages.
This report was presented at a symposium at Naturalis in Leiden on September 8, 2015. A complete report containing brief abstracts of all studies presented at the symposium can be found here.