Dear all, We are happy to announce that the following paper is now published in Scientific Reports:
Hermannsen, L., Mikkelsen, L., Tougaard, J., Beedholm, K., Johnson, M. and P.T. Madsen, “*Recreational vessels without Automatic Identification System (AIS) dominate anthropogenic noise contributions to a shallow water soundscape*”, Scientific Reports (2019) 9:15.477. In this paper, we conduct a case study correlating vessel presence to ambient noise levels in a shallow coastal area. The results show that recreational boats without AIS dominate the soundscape, including at frequencies that may impact harbour porpoises. We therefore emphasise the importance of accounting for recreational boats, in particular in shallow coastal waters, to not underestimate vessel noise loads and the impacts on marine species. To accompany this paper and to help improve models of vessel noise emissions, we have also published the recordings and theodolite tracks of 46 motorised recreational boats, divided into different boat types at zenodo.org (10.5281/zenodo.3465461). *Abstract* Recreational boating is an increasing activity in coastal areas and its spatiotemporal overlap with key habitats of marine species pose a risk for negative noise impacts. Yet, recreational vessels are currently unaccounted for in vessel noise models using Automatic Identification System (AIS) data. Here we conduct a case study investigating noise contributions from vessels with and without AIS (non-AIS) in a shallow coastal area within the Inner Danish waters. By tracking vessels with theodolite and AIS, while recording ambient noise levels, we find that non-AIS vessels have a higher occurrence (83%) than AIS vessels, and that motorised recreational vessels can elevate third-octave band noise centred at 0.125, 2 and 16 kHz by 47–51 dB. Accordingly, these vessels dominated the soundscape in the study site due to their high numbers, high speeds and proximity to the coast. Furthermore, recreational vessels caused 49–85% of noise events potentially eliciting behavioural responses in harbour porpoises (AIS vessels caused 5–24%). We therefore conclude that AIS data would poorly predict vessel noise pollution and its impacts in this and other similar marine environments. We suggest to improve vessel noise models and impact assessments by requiring that faster and more powerful recreational vessels carry AIS-transmitters. *Link to full text*: www.nature.com/articles/s41598-019-51222-9 Best regards, Line *Line Hermannsen, PhD* Postdoctoral fellow at Department of Bioscience, Aarhus University, Denmark Phone: (+45) 22 82 56 61 Email: [email protected] www.marinebioacoustics.com
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