Pelagic fish and harbour porpoise at North Sea wind farms: acoustic investigation and science communication

Demuynck, J.M. (2026)

Doctoral Thesis

This thesis was embedded in the APELAFICO project and focussed on investigating effects of sound from North Sea offshore wind farms on pelagic fish and harbour porpoise. One of the goals of the project was to study the potential for using sound as a deterrent for fish to herd them away from acoustically dangerous sites of extreme overexposure. In a basin, herring were exposed to a set of acoustic stimuli designed based on a ‘looming sound’ hypothesis, and their behaviour was observed with underwater cameras and tracked with a tracking program. The fish responded to the sound stimuli in general, but not more strongly to the looming stimulus. In a follow-up study in the field, similar stimuli were played back to test on free-ranging fish, which were monitored with sensors placed on the seabed. This time, no spatial deterrence from the sound playback was observed. A multiple year study was conducted to monitor pelagic fish and harbour porpoise in existing wind parks at the Dutch-Belgian border. Notably, less pelagic fish but more harbour porpoise were observed inside the parks compared to similar locations outside the park (near shipwrecks). Finally, a study related to noise pollution for fish was also conducted in a different context and this time focussing on human behaviour. In the Blijdorp Rotterdam zoo, this study focused on improving communication towards visitors to reduce their sound production (talking and screaming), hoping to benefit the visitor experience and animal welfare at the aquarium. To measure the impact of different treatments, sound levels were measured and visitor surveys were conducted. The use of a sign with a message to reduce sound somewhat lowered the ambient sound levels at the aquarium. Visitors also reported that they found it important that the environment is not too loud. 

• Offshore wind farms
• Pelagic fish
• Atlantic herring
• Harbour porpoise
• Noise pollution
• North Sea
• Acoustic deterrence
• Science communication
• Zoo
• Aquarium
• Visitor noise

• All authors: Demuynck, J.M.
• Supervisor: Slabbekoorn, H.W.
• Co-supervisor: Rodrigues dos Santos Russo, P.M.; Hubert, J.
• Committee: Meijer, A.H.; Spaink, H.P.; Smeets, I.; Botteldooren, D.; Visser, F.
• Qualification: Doctor (dr.)
• Awarding Institution: Institute of Biology Leiden (IBL), Faculty of Science, Leiden University
• Date: 2026-03-13
• DOI: doi:10.60602/1887-4296692
• Sponsorship: NWO
• Grant number: NWA.1236.18.004