Governing ship-generated underwater radiated noise in the Arctic: spatial fit, legal coordination, and implementation incentives

Rapid sea-ice loss and expanding shipping activity are increasing ship-generated underwater radiated noise (URN) across Arctic waters, with implications for acoustically dependent marine species and Indigenous subsistence and cultural practices. This Policy and Practice Review examines why existing mitigation measures produce uneven outcomes in the Arctic and how governance arrangements can better align spatial and ecological fit, legal and institutional coordination, and implementation and verification incentives. We synthesize International Maritime Organization (IMO) instruments, Arctic Council/Protection of the Arctic Marine Environment Working Group (PAME) assessments, selected national measures, port programs, classification standards, and peerreviewed literature. The evidence indicates that source-based technical measures, routing adjustments, and speed reduction are not uniformly effective: outcomes vary with ship type and operating condition, bathymetry, ice conditions, ecological timing, and assessment scale. Governance is further constrained by fragmented authority, uncertain regulatory expectations, and a distributional mismatch in which implementation costs are concentrated among shipowners while ecological and social benefits are widely shared. We recommend a phased and institutionally differentiated polycentric pathway. Arctic-specific scientific and Indigenous knowledge should be coordinated through existing regional and scientific processes; ship-source measures should be pursued through the IMO, Arctic States, ports, and classification systems within their respective mandates; the European Union Marine Strategy Framework Directive (MSFD) should be recognized within its applicable legal and geographic scope; and the Agreement on Marine Biological Diversity of Areas beyond National Jurisdiction (BBNJ Agreement) may provide a conditional biodiversity-oriented procedural interface in areas beyond national jurisdiction.