Abstract
Special Areas of Conservation (SACs) have been designated for harbour porpoise with the main aims of protecting recognised important habitats for the species and avoiding significant disturbance in order to allow those habitats to contribute in the best possible way to supporting the species. The areas inside and around the SACs (in particular the Southern North Sea SAC) have, over the last couple of decades, experienced a certain level of noise disturbance, particularly from oil and gas exploration and military activities. Harbour porpoise are sensitive to underwater noise associated with these activities and field studies have shown that animals respond to the disturbance over relatively large areas, for example by moving away or changing activity patterns. Despite historical levels of noise, the cetacean survey data collected over the last two decades showed the SACs to sustain higher persistent densities of harbour porpoise than other areas, suggesting that animals may cope with a certain level of disturbance whilst still favouring those areas. More recently, the installation of offshore wind turbines has created temporary noisy areas with lower densities of porpoises (see noise guidance for detail and references). The scale of offshore wind installation planned over the next decades in some of these areas raises the potential for unprecedented disturbance, on top of a continuing background of noise from oil and gas and other sources. Given the now protected status of these areas, it is the responsibility of competent authorities to set the bar higher than in other areas within the species range, in terms of regulation, risk assessment, mitigation and monitoring applied to all industries producing noise and associated disturbance. The Statutory Nature Conservation Bodies (SNCBs), when developing advice on the management of noise, have tried to devise an approach that could be equally applied to all relevant industries, one that reduced accumulated noise at times of the year where porpoise occur in particularly higher densities and one that incentivised industry to look for less noisy alternatives and ways to reduce their disturbance footprint in time and space.
This note sets out the background to the development of advice on managing activities resulting in noise and disturbance to harbour porpoise in SACs. It also addresses the questions that have been posed over the last couple of years of consultation with stakeholders (see Annexes for list of held workshops and stakeholders), clarifying the rationale behind the advice. It is recognised that there is low confidence in the evidence base for the guidance. In common with other advice on marine management this guidance uses the best available evidence and is intended to be applied adaptively. This means that where evidence supports an alternative approach to noise management regulators can consider that in preference to the guidance.