*Article* **Turning Scientific Knowledge into Regulation: Effective Measures for Noise Mitigation of Pile Driving**

**Carina Juretzek, Ben Schmidt and Maria Boethling \***

Bundesamt für Seeschifffahrt und Hydrographie (BSH), Bernhard-Nocht Straße 78, 20359 Hamburg, Germany; carina.juretzek@bsh.de (C.J.); ben.schmidt@bsh.de (B.S.)

**\*** Correspondence: maria.Boethling@bsh.de

**Abstract:** Pile driving is one of the most intense anthropogenic noise sources in the marine environment. Each foundation pile may require up to a several thousand strokes of high hammer energy to be driven to the embedded depth. Scientific evidence shows that effects on the marine environment have to be anticipated if mitigation measures are not applied. Effective mitigation measures to prevent and reduce the impact of pile driving noise should therefore be part of regulation. The role of regulators is to demonstrate and assess the applicability, efficiency and effectiveness of noise mitigation measures. This requires both, scientific knowledge on noise impacts and the consideration of normative aspects of noise mitigation. The establishment of mitigation procedures in plans and approvals granted by regulatory agencies includes several stages. Here, we outline a step-wise approach in which most of the actions described may be performed simultaneously. Potential measures include the appropriate maritime spatial planning to avoid conflicts with nature conservation, site development for offshore wind farms to avoid undesirable activities in time and space, coordination of activities to avoid cumulative effects, and the application of technical noise abatement systems to reduce noise at the source. To increase the acceptance of noise mitigation applications, technical measures should fulfil a number of requirements: (a) they are applicable and affordable, (b) they are state-of-the-art or at least advanced in development, (c) their efficiency can be assessed with standardised procedures. In this study, the efficiency of noise mitigation applied recently in offshore wind farm construction projects in the German North Sea is explained and discussed with regard to the regulation framework, including the technical abatement of impulsive pile driving noise.

**Keywords:** ocean noise mitigation; ocean noise regulation; ocean sound measurement
