Likely effects of construction of Scroby Sands offshore wind farm on a mixed population of harbour Phoca vitulina and grey Halichoerus grypus seals

► Scroby Sands offshore wind farm is near harbour and grey seal haul out. ► Monitoring during construction showed harbour seal decline and grey seal increase. ► Noise generated by pile driving thought responsible for the harbour seal decline. ► Study highlights importance of finding alternatives to pile-driving in offshore wind farm construction.