Management of Noise in a Busy Harbour Porpoise Protected Area

The Southern North Sea Special Area of Conservation (SAC) is the largest of a suite of sites designated to protect harbor porpoise (Phocoena phocoena) and its habitats in UK waters. It was identified as having high persistent densities of porpoise despite the area being highly industrialized and therefore noisy. Activities in and around the site include geophysical surveys, clearance of unexploded ordnance, and construction activities involving pile driving. Given the potential conflict between maintaining a favorable habitat status and continuing noisy activities, in 2020 the UK nature conservation agencies published guidance on how to assess and manage operations that could cause significant noise disturbance in porpoise SACs. The approach provides an equitable way of managing noise across industries, by defining area/time noise limits. The limits are used as references in impact assessments when planning activities, and measures such as noise abatement and scheduling are agreed between industry and regulators to ensure limits are not exceeded. At the core of this approach is the UK Marine Noise Registry, a database recording when and where impulsive noise occurs, for both past and future activities. This not only helps with planning but also allows for retrospective monitoring and has already provided useful insights for management.