How can ports act to reduce underwater noise from shipping? Identifying effective management frameworks[Comment les ports peuvent-ils agir pour réduire le bruit sous-marin provenant du transport maritime? Identifier des cadres de gestion efficaces]

This paper aims to find mechanisms to align commercial interests with underwater noise reductions from commercial shipping. Through a survey and a series of interviews with representative stakeholders, we find that, while recognizing the large variations in the specificities of ports, port measures could promote the reduction of underwater noise emissions from commercial navigation by changes in hull, propeller and engine design; and through operational measures associated with speed reduction, rerouting and convoy transport. Although the impact of underwater noise emissions on marine fauna is increasingly severe and widespread, there is uncertainty as to the mechanisms, contexts and levels that should lead to actions, requiring preventive management. Ship owners already face significant investment and operating costs to comply with fuel, ballast water, NOx and CO2 requirements. To be successful, underwater noise programs must align with these factors. Based on a multiple criteria decision-making (MCDM) approach, we find a set of compromise solutions for a wide range of stakeholders. Ports could come up with measures such as reduced port fees and reduced waiting times for ships in ports, both depending on underwater noise performance. Cooperation between ports to step up actions through environmental indices and classification society ratings, and integration with actions of other ports could help support this. However, few ships know their baseline for underwater noise, as there are very few hydrophonic stations and measurement methods are not standardized. Costs increase and availability drops dramatically if the purchaser of the vessel wishes to improve the sound profile. With local demands for airborne noise near airports, global pressure on the aviation industry has been stimulated to adopt existing calming technology. This experience with aviation noise control may shed light on the underwater noise process.