Broad-scale acoustic monitoring for cetaceans and underwater noise in relation to offshore wind farm construction in Scotland

Abstract

Marine construction projects, such as offshore wind farms and port developments often use techniques that produce significant levels of noise underwater, which could have effects on marine wildlife. Marine Scotland is the government body responsible for regulating these activities in Scottish waters and for ensuring that wildlife populations are protected in line with legislation. Large scale offshore wind farm construction will begin to take place off the Scottish east coast in 2017, using piled foundations. To monitor for potential broad scale changes in distribution of protected cetacean species during construction activities, Marine Scotland have deployed an array of 30 click detectors and 10 broadband acoustic recorders across the Scottish east coast each summer since 2013. Here we present baseline distributions for dolphins and harbour porpoises, along with ambient noise levels recorded concurrently. Dolphin detections across the monitored area are highly variable, with some locations that are clearly favoured. Harbour porpoise are ubiquitous and in more than 60% of locations are detected on 100% of monitored days. This is likely to mean that there is more power to detect changes in porpoise distribution in relation to offshore wind farm pile driving than for dolphins.