Abstract
In June 2020, JNCC, together with Natural England (NE) and the Department of Agriculture, Environment and Rural Affairs in Northern Ireland (DAERA), published advice to competent authorities on what could constitute Significant Disturbance within harbour porpoise Special Areas of Conservation (SACs) in England, Wales and Northern Ireland marine areas (JNCC Report 654). This report also provided guidance on a noise management approach to keep underwater noise within levels that do not affect a site’s integrity. A key element of the approach is the estimation of the disturbance footprints resulting from impulsive noise-generating activities within and around SACs. The recommendation was that for each activity of concern, a fixed Effective Deterrence Range (EDR) would be used to estimate the area where harbour porpoise could be disturbed or deterred. Default EDRs were recommended for seven broad categories of activities, informed by published empirical ranges where the bulk of the effect constituting a reduction in porpoise vocal activity or sightings had been detected.
The 2020 guidance was the culmination of several years of inter-agency discussion as well as consultation with regulators, industry and Non-Governmental Organisations. The advised noise management approach aims to reduce accumulated noise at times of the year where harbour porpoise occur in higher densities, while incentivising industry to use low-noise methods to reduce their disturbance footprint in time and space.
As part of the 2020 guidance there was a commitment to regularly review the suitability of the EDRs, considering emerging evidence such as that gathered through monitoring and research. The first dedicated review was conducted in 2025 through two commissioned reports: Brown et al. (2025; JNCC Report 799) and Majewska et al. (2025; JNCC Report 798). The aim of these reports was to recommend default EDRs, through a review of the evidence underpinning the current EDRs and subsequently published studies (empirical and modelled) and, where possible, through revisiting existing data, with the aim of defining EDRs in a more standardised way. JNCC, NE and DAERA have considered the outcomes of the two reports, the robustness of the evidence reviewed and the remaining uncertainty and recommended updated EDRs in 2025 (JNCC Report 803).
The key advice can be found in the following two documents:
- Guidance on noise management in harbour porpoise SACs (2020, JNCC Report 654)
- Updated Effective Deterrent Ranges (EDRs) (2025, JNCC Report 803)
In addition, there are four other documents providing supporting information, including the evidence review reports produced in 2025:
- JNCC Report 799 (2025). Evidence review of harbour porpoise disturbance ranges in the context of the assessment and management of impulsive noise in Special Areas of Conservation: impact piling.
- JNCC Report 798 (2025). Evidence review of harbour porpoise disturbance ranges in the context of the assessment and management of impulsive noise in Special Areas of Conservation: unexploded ordnance clearance, explosives for decommissioning, seismic (airgun) survey, sub-bottom profilers, ultra-short baseline acoustic positioning, acoustic deterrent devices, multi-beam echosounders, and military sonar.
- JNCC Report 653 (2020). Background to the advice on noise management within harbour porpoise SACs in England, Wales and Northern Ireland.
- JNCC Report 652 (2020). Consultation Report: Harbour porpoise SACs noise guidance.
JNCC, NE and DAERA continue to commit to periodically reviewing the noise guidance to ensure it remains workable, effective and takes account of best-available evidence.
These reports may not be fully accessible for all users. If you need copies in a different format, please contact communications@jncc.gov.uk.
