Effects of the use of noise-mitigation during offshore pile driving on harbour porpoise (Phocoena phocoena)

In recent years, noise-mitigation technology became more efficient and noise levels during pile driving were reduced significantly. Using passive acoustic monitoring (PAM) datasets from 2016 (Nobelwind construction – no noise mitigation) and 2019 (Northwester 2 and SeaMade construction – Double Big Bubble Curtain) we analyse whether noise mitigation measures applied during the construction of offshore wind farms influenced the likelihood of detecting harbour porpoise (Phocoena phocoena) during pile driving in the Belgian part of the North Sea (BPNS). Exploratory analyses indicate reductions to the spatial and temporal extent of avoidance of the construction area by porpoise when noise mitigation is applied. Without noise mitigation, mean detection rates of porpoises reduced up to 15-20 km from the pile driving location. With noise mitigation however, mean detection rates of porpoises reduced to a lesser extent and this reduction mainly took place at 0-10 km from the pile driving.

RBINS Publication(s), Open Access, Report