How can ports act to reduce underwater noise from shipping? Identifying effective management frameworks

Through a survey and interviews with representative stakeholders, this paper aims to find mechanisms to align commercial interests with underwater noise reductions from commercial shipping. While acknowledging the wide variations in ports' specificities, port actions could support a reduction in underwater noise emissions from commercial shipping through changes in hull, propeller and engine design, and through operational measures associated with reduced speed, change of route and travel in convoy. Though the impact of underwater noise emissions on marine fauna is increasingly shown to be serious and wide-spread, there is uncertainty in the mechanisms, the contexts, and the levels which should lead to action, requiring precautionary management. Vessels owners are already dealing with 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. Ports could propose actions such as discounted port fees and reduced ship waiting times at ports, both depending on underwater noise performance. Cooperation between ports to scale up actions through environmental indexes and classification societies' notations, and integration with other ports' actions could help support this. However, few vessels know their underwater noise baseline as there are very few hydrophone stations, and measurement methodologies are not standardized. Costs increase and availability decreases dramatically if the vessel buyer wants to improve the noise profile. Local demands regarding airborne noise close to airports boosted global pressure on the aviation industry to adopt existing quieting technology. This experience of the aviation noise control could inform the underwater noise process. Since 2017, the Vancouver Fraser Port Authority has been implementing a voluntary vessel slowdown trial for commercial vessels in key known foraging areas for southern resident killer whales, which are locally considered an emblematic species.