Pile-driving noise during construction is of particular concern as the very high sound pressure levels could potentially prevent fish from reaching breeding or spawning sites, finding food, and acoustically locating mates. This could result in long- term effects on reproduction and population parameters. Further, avoidance reactions might result in displacement away from potential fishing grounds and lead to reduced catches. Pile-driving noise was played to cod and sole held in two large (40 m) net pens located in a quiet Bay in West Scotland. Movements of the fish were analysed using a novel acoustic tracking system. Received sound pressure level and particle motion were measured during the experiments.
Collaborative Offshore Wind Research into the Environment (COWRIE)
Location of Research
Ardtoe, Ardnamurchan, West Scotland.
- Understand the effects of pile-driving sound sources on the behaviour of marine fish;
- Identify the threshold of exposure that lead to behavioural responses;
- Define the characteristics, scale and duration of responses as a function of exposure conditions; and
- Interpret the results with regard to pile-driving operations in the marine environment
- Interpret the results with regard to pile-driving operations in the marine environment.
- Not a single threshold but range over which behavioural response occurs; cod = 140-161 dB re 1µPa peak; sole = 144-156 dB re 1µPa peak, particle motion between 6.51x10-3 and 8.62 x10-4 m/s2 peak.
- Cod = tendency for higher swimming speed, significant freezing response, documented initial avoidance; Sole = significant increase in swimming speed, and initial avoidance.
- Reduction of uncertainty about behavioural reaction of marine fish to pile-driving sound; Incorporation of results of this study into offshore wind farm EIAs; further development of mitigation measures.