Bristol Channel Approaches / Dynesfeydd Môr Hafren MPA


Status: Candidate Special Area of Conservation (cSAC)

Bristol Channel


The site spans the Bristol Channel between the northern coasts of Cornwall and Devon into Carmarthen Bay in Wales. 

Bristol Channel Approaches cSAC has been identified for the protection of harbour porpoise, and is estimated to support almost 5% of the Celtic and Irish Seas (CIS) Management Unit population within the UK.
This cSAC covers an area of 5 850km2, which is over 6 times the size of the Dartmoor National Park, and supports a diversity of habitat types, from reefs to mudflats. Water depth ranges from Mean Low Water (MLW) down to 70m along the western boundary. Harbour porpoise presence varies seasonally within this site. Porpoise occur within the site year round but during the winter, persistently higher densities of harbour porpoise occur
compared to other parts of the Management Unit.    
More detailed site information can be found on the Summary
tab below.


Bristol Channel Approaches boundary map.

This image will link to the MPA mapper and boundary downloads in due course


Legislation behind the designation: EU Habitats Directive 1992 transposed into UK law by the Conservation of Habitats and Species Regulations 2010 (as amended) within 12 nautical miles (nm), and the Offshore Marine Conservation (Natural Habitats &c.) Regulations 2007 (as amended) between 12nm out to 200nm or the UK Continental Shelf.


Protected Features:

Features Feature Type % of population Conservation Objectives

Harbour porpoise

Phocoena phocoena

        Annex II Species     

4.7% of the Celtic and Irish Seas

Management Unit

Maintain site integrity


Conservation Objectives
To avoid deterioration of the habitats of the harbour porpoise or significant disturbance to the harbour porpoise, thus ensuring that the integrity of the site is maintained and the site makes an appropriate contribution to maintaining Favourable Conservation Status for the UK harbour porpoise.

Site Timeline

The bullets below are a summary of the key milestones involved in the selection and designation of the Bristol Channel Approaches cSAC.  More detail can be found within the relevant documentation listed below.

  • December 2014: site submitted as initial advice to Government
  • June 2015: Site formally recommended to UK Government as a draft SAC (dSAC)
  • January - May 2016: Formal public consultation - site becomes a possible SAC (pSAC)
  • September 2016: post consultation advice submitted to UK Government
  • January 2017: Site submitted to the European Commission - site becomes a candidate SAC (cSAC)

Relevant documentation

The documents referred to below and any other historical documents relating to the Bristol Channel Approaches cSAC were produced during the selection and designation process and therefore may be out of date.  This Site Information Centre is the most up to date source of information for this site and will reflect any additional information gathered since these documents were produced.


Information about the SAC site selection process is available on the JNCC SAC pages.



Site overview

The Bristol Channel Approaches cSAC lies along the southwest coasts of Wales and England. This site straddles the Bristol Channel from Carmarthen Bay in the north to the northern coasts of Devon and Cornwall in the south. Designated for the protection of harbour porpoise Phocoena phocoena, this site supports an estimated 4.7% of the UK Celtic and Irish Sea (CIS) Management Unit (MU) population. This site is recognised as important for porpoises particularly during the winter when high densities persistently occur throughout the site.

Over half of the site lies in English inshore waters (0 – 12 nm from shore), with just over a sixth in Welsh inshore waters and the remainder extending into the offshore. As a result, Natural England (NE) and Natural Resources Wales (NRW), along with JNCC, have joint responsibility in producing statutory advice. 

Water depth in the Bristol Channel Approaches cSAC ranges between the Mean Low Water (MLW) mark and the 70m contour, with the majority 50m deep or shallower. Though much of the site is characterised by sandy and coarse sediment seabed, this cSAC supports a diversity of habitats, from small patches of rocky reef scattered throughout the site, to sandbanks, sea caves, sand/mudflats and salt meadows.

Data collated through the Joint Cetacean Protocol (JCP) were analysed to identify areas with persistently high harbour porpoise occurrence. The modelled outputs of this analysis demonstrate that the Bristol Channel Approaches cSAC persistently contains densities of porpoises which are within the top 10% of those for the Management Unit in winter. However, harbour porpoises do use the site year-round.


Site location:  The boundary of this cSAC will be available to view and download via the JNCC MPA Mapper. Coordinates for this cSAC are available from the Standard Data Form (SDF) listed in the Relevant Documentation.

Site area:  This site has an area of 5,850km2

Site depth range: The site ranges from Mean Low Water to 70m below sea level.

Charting Progress 2 Biogeographic Region: Western Channel and Celtic Sea region

Site boundary description
The Bristol Channel Approaches cSAC boundary was defined based on predicted areas with high densities of harbour porpoise over an 18-year period identified through data modelling. As a general principle, site boundaries were drawn tightly around the qualifying feature. The seaward boundaries were drawn using straight lines where possible; however, a balance was needed between more-complex site shapes drawn tightly around the feature and simple square/rectangular boundaries, so that the area of ‘non-interest-feature’ within the boundary was reduced. Further boundary principles were developed due to the nature of the modelled output. The modelling approach used 5 x 5 km grids, and so the model output was “blocky”, and further boundary smoothing methods were applied to simplify the boundary, without altering the site area by more than 5%. Coastal edges were defined by the MLW tide line.


The information for this site summary was adapted from documents listed in the Relevant Documentation section and incorporates any further information gathered since these documents were produced.


Detail available soon.



Detail available soon


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