In their new Practitioner’s Perspective, Guiding principles for assessing the impact of underwater noise, published today (16th May 2018), Faulkner et al. present practical solutions for mitigating the effects of underwater noise on marine wildlife. See their work presented as an infographic here.

Underwater noise pollution poses a global threat to marine wildlife, from charismatic ocean giants like the blue whale to ecosystem cornerstones such as small fish, crustaceans, and zooplankton. As the ‘blue economy’ continues to grow, ever more noise-generating human activities are taking place in offshore and coastal waters of the global ocean. These include seismic surveys for oil and gas exploration, coastal construction projects such as port and harbour extensions, the installation of renewable energy infrastructure, and shipping traffic. The noise pollution emitted by these activities can drown out the sounds that marine mammals and some fish use to communicate, and can displace animals, increase physiological stress, and in some cases can cause auditory injury or mortality. To manage this threat, regulatory agencies often require developers to undertake an Environmental Impact Assessment (EIA) for major inshore and offshore projects. The EIA informs the regulator of the possible risks to acoustically sensitive species in the area, based on modelling to estimate the possible extent of adverse effects. Regulators may then grant or decline consent, or require additional mitigatory action to be taken.

The problems and the solutions

Scientific understanding of the impacts of underwater noise is advancing rapidly, and many EIAs do not yet apply appropriate methods and lack reference to the best available science. At the same time, regulators often lack the expertise to critically assess consent applications. To begin to bridge this gap, our article sets out clear guiding principles for assessing the impact of underwater noise, providing developers, regulators, and policymakers with a robust, science-based framework to address this emerging threat (see infographic) . Based on our experience of advising these stakeholders and of conducting assessments, we identify common shortcomings in current practice at each stage of the EIA process, and suggest remedies. Our purpose is to encourage more rigorous and informative assessments of underwater noise pollution, and to help orient newcomers to this rapidly evolving area.

Forward look – a more tranquil future  

An important tool to mitigate the impacts of underwater noise is reducing the amount of noise pollution emitted at source (noise abatement). Other approaches – such as avoiding sensitive locations and/or times of year, or using sonar systems which scare away marine mammals (acoustic deterrent devices) – will not reduce the amount of noise pollution emitted into the environment, which may affect other species that are not the target of such mitigation measures (e.g. fish or crustacean species). Noise abatement measures include: (i) bubble curtains and other acoustic barriers which can be placed around pile driving operations; (ii) ship quieting technologies; (iii) alternative technologies, e.g. using ‘vibroseis’ technology instead of airguns for seismic airguns. In some northern European countries, noise abatement technologies are already being routinely deployed for pile driving of offshore wind farms (e.g. in Germany, Denmark, Norway, Sweden, and the Netherlands), but in other jurisdictions it is rare for the effect of noise reducing technologies to be assessed, and consequently recommended or required by regulators.

The full article, Guiding principles for assessing the impact of underwater noise is free to read in Journal of Applied Ecology.