Effect of offshore windfarms on the behaviour of harbour porpoises (Phocoena phocoena) in the North Sea : A review

Abstract

The demand of green energy has increased in the last decades, as fossil fuels are being phased out. Due to limited landmass, wind energy is moved to the sea. However, noise pollution due to construction of offshore wind farms (OWFs) can negatively impact the behaviour and habitat of sea mammals. One such sea mammal that is affected by this is the harbour porpoise (Phocoena phocoena). Some short term studies have found that underwater noise can cause behavioural changes in harbour porpoises but only a few long term studies have looked at the long-term effect of OWFs on the harbour porpoise population in the North Sea. In this review I looked into the literature regarding the topic of underwater noise pollution from OWFs. Furthermore, I also looked into the measuring techniques of underwater noise, known impacts of the construction of OWFs and the possible mitigation measures that can be taken during the life span of an OWF. I then discussed these findings, named knowledge gaps and noted other sources of human activity at sea that impact harbour porpoises. I concluded that although underwater noise from the construction of OWFs has a negative impact on harbour porpoises, long-term studies on the effect of OWFs are conflicting and therefore more research is needed. Furthermore, underwater noise pollution is not only dependent on OWFs but also shipping traffic and other human activities such as fishing, seismic activity and pollution are also of influence on the harbour porpoise populations in the North Sea.