West Wales Marine / Gorllewin Cymru Forol MPA


Status: Special Area of Conservation (SAC)

Click to link to the interactive map

Designated: February 2019


Situated off the coast of Wales from the Llŷn peninsula in the north to Pembrokeshire in the southwest, the West Wales Marine SAC has been identified as an area of importance for harbour porpoise. The site is three times the size of Snowdonia National Park covering 7,376km2.

This SAC overlaps a number of other SACs including parts of the Pembrokeshire Marine and Pen Llŷn a’r Sarnau SACs, and encompasses the entire Cardigan Bay SAC. Along the westward boundary, water depths of up to 100m are reached, though much of the site is 50m or shallower. The area included within the site covers important summer habitat for harbour porpoise, while part
of the site in Cardigan Bay was also identified as important during
the winter.
More detailed site information can be found on the Summary tab.



West Wales Marine boundary map.

Click on the image to link to the MPA mapper and boundary downloads


Legislation behind the designation: EU Habitats Directive 1992 transposed into UK law by the Conservation of Habitats and Species Regulations 2017 within 12 nautical miles (nm), and the Conservation of Offshore Marine Habitats and Species Regulations 2017 between 12nm out to 200nm or the UK Continental Shelf.


Protected features:

Features Feature Type Management Unit Conservation Objectives

Harbour porpoise

Phocoena phocoena

        Annex II Species     

Celtic and Irish Seas

Management Unit

Maintain site integrity


Conservation objectives
To ensure that the integrity of the site is maintained and that it makes an appropriate contribution to maintaining Favourable Conservation Status (FCS) for harbour porpoise in UK waters.

Site Timeline

The diagram below is a summary of the key milestones involved in the selection and designation of the West Wales Marine SAC.  More detail can be found within the Relevant Documentation or in the information tabs listed below.

Designation timeline

Relevant Documentation

Some documents linked below relating to the West Wales Marine SAC were produced during the selection and designation process and therefore may not be updated from point of submission to Europe in January 2017. This Site Information Centre is the most up to date source of information for this site and will reflect any additional information gathered since our advice to Government in 2016.


Site documents

  • SAC Selection Assessment Document (2017) –a more detailed overview of the cSAC, designated feature and rationale for site selection.
  • Conservation Objectives and Advice on Operations package - The package provides the conservation objectives for the site; the activities occurring within or close to the site with the associated level of risk to harbour porpoise; and consideration of management options for these pressures. This document was last updated in March 2019.
  • Draft Impact Assessment - a socio-economic impact assessment of the harbour porpoise SACs, produced for the public consultation held in 2016. 


Identification and selection process


Further documents relating to the evidence and analysis can be found on the Evidence tab, whilst documents published during the public consultation in 2016 can be found on the archived consultation page. Information about the SAC site selection process is available on the JNCC SAC pages.


Select the tabs below for further information:




Last updated: October 2017


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.


Site overview

Situated between the Llŷn peninsula in the north, and the Pembrokeshire coast in the southwest, and extending into Cardigan Bay, the West Wales Marine SAC is designated for the protection of harbour porpoise Phocoena phocoena, supporting an estimated 5.4% of the UK Celtic and Irish Seas Management Unit (MU) population. This cSAC spans an area over 3 times the size of Snowdonia National Park at 7,376 km2.


Though part of this site extends offshore, much of the site lies in the inshore waters (0-12nm) west of Wales and so both Natural Resources Wales (NRW) and JNCC have joint responsibility in producing statutory advice for this SAC. The whole SAC has been identified as an important summer area for harbour porpoise, and a smaller section to the south of the site, around Cardigan Bay, has also been identified as winter habitat for this species. Water depth ranges from the Mean Low Water (MLW) level down to 100m along the western boundary, but much of the site sits between 40 - 50m. The West Wales Marine SAC also covers a range of habitats including rock, coarse and sandy sediments and areas of mud.


Survey 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 West Wales Marine SAC occurs within the top 10% of persistent high density areas for harbour porpoise in UK waters for both winter and summer seasons. Further detail on the evidence for this SAC can be found on the Evidence tab.


Site location:

The boundary of this SAC are available to view and download via the JNCC MPA Mapper. Coordinates for this SAC are available from the Selection Assessment Document listed in the Relevant Documentation

Site area:

This site has an area of 7,376km2

Site depth range:

The site ranges from Mean Low Water to 100m below sea level

Charting Progress 2 Biogeographic Region:

Irish Sea and Western Channel and Celtic Seas Region


Site boundary description
The West Wales Marine SAC boundary was defined based on predicted areas with expected high densities of harbour porpoise identified through data modelling over an 18-year period. 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 “Mean Low Water” (MLW) tide line.



Last updated: October 2017


A range of data underpin this SAC, as described below. Given the extensive range and mobility of harbour porpoise, analyses to underpin site identification were completed at a UK scale; localised datasets were not used in isolation to define the boundaries of this SAC. Two types of data have been analysed to investigate harbour porpoise persistent densities in UK waters; these are effort-related sea-based data (collected from ships and aircraft) and effort-related land-based data (collect from coastal locations).


Data gathering and analysis

  • Sea-based data were collated through the Joint Cetacean Protocol (JCP), created in 2004, which is amongst the largest collation of standardised survey data on harbour porpoise in the world, comprising 39 data sources with data from at least 545 distinct survey platforms (ships and aircraft), representing over 1 million km of survey effort (coverage) over an 18-year period from 1994-2011. DHI (UK) Ltd. (DHI) were contracted by JNCC to undertake an analysis of these data in order to identify persistent areas of higher harbour porpoise density around the UK.
  • Land-based survey data were compiled from a wide range of UK sources; this was part of a contract with a consortium led by Sea Watch Foundation to analyse these data as an aid to identifying coastal areas of importance to harbour porpoises. Data for the analyses came from 678 locations and amounted to over 75,000 hours of survey effort and around 50,000 sightings over a 20-year period (1994-2014).
  • The survey data analyses underpinned the identification of the West Wales Marine SAC as an area with persistently higher density of porpoises in relation to other areas (IAMMWG, 2015). 
  • For further information on the data used and the process applied to identify the cSAC, please consult the West Wales Marine Selection Assessment Document, and Section two of ‘The use of harbour porpoise sightings data to inform the development of Special Areas of Conservation in UK waters’ (JNCC report 565), linked below. Further documents are also listed below in support of the identification of the West Wales Marine cSAC:
  • The identification of discrete and persistent areas of relatively high harbour porpoise density in the wider UK marine area JNCC Report No. 544 (2015) -  A report analysing all available at-sea data, in order to model the persistently important areas of UK waters for harbour porpoise by Heinänen, S. & Skov, H.
  • Analysis of long-term effort-related land-based observations to identify whether coastal areas of harbour porpoise and bottlenose dolphin have persistent high occurrence and abundance JNCC report No. 543 (2015) - A report analysing all available land-based data in order to establish persistently important coastal areas for harbour porpoise by Evans et al.
  • The use of harbour porpoise sightings data to inform the development of Special Areas of Conservation in UK waters JNCC report No. 565 (2015) - A report summarising the process undertaken by the Country Nature Conservation Bodies (CNCBs), using the results from the previous reports to identify the significant areas to propose as possible harbour porpoise SACs
  • Evidence supporting the Impact Assessment (2015) - ABP Marine Environmental Research Ltd working on behalf of the SNCBs have drafted an assessment of the potential social and economic impact of the cSACs. The supporting evidence for the Impact Assessment report is published in draft form to assist with identifying any additional information or evidence that would help improve it.
  • A Conservation Literature Review for the Harbour Porpoise (Phocoena phocoena) JNCC Report No. 566 (2015) -  A comprehensive review of relevant literature to support our understanding of behaviours, needs and threats regarding harbour porpoise in UK waters.



Additional relevant literature

References for further supporting scientific literature consulted during the identification of this site can be found in the West Wales Marine SAC Selection Assessment. Please be aware that although these sources contain information in relation to this MPA, they do not necessarily represent the views of JNCC.

  • Management Units for cetaceans in UK waters (JNCC report No. 547, 2015): Description of the Management Units (MUs) for the seven most common cetacean species in UK waters, including harbour porpoise. The Management Unit is the spatial scale defined as the most appropriate scale to apply management for a species considering abundance and distribution.


Knowledge gaps

If you are aware of any additional data or relevant scientific papers for this site made available since 2011 that we may not be aware of, please contact JNCC . Please note that due to the process of identifying boundaries, data are unlikely to impact the boundaries of the site, but may be used to support management decisions.


Conservation Advice


Last updated: March 2019


Conservation objectives

Conservation objectives set out the desired state for the protected feature(s) of an MPA. The conservation objectives for the protected feature of the West Wales Marine Special Area of Conservation (SAC) are available within the Conservation Objectives and Advice on Operations document. This information is useful if you are:

  • Preparing Habitats Regulations Assessments (HRAs) of proposed plans or projects that may affect the site;
  • Planning measures to maintain or restore the site and its qualifying feature;
  • Monitoring the qualifying features; and/or
  • Developing, proposing or assessing an activity, plan or project that may affect the site.


The conservation objectives for the West Wales Marine SAC are to ensure that the integrity of the site is maintained and that it makes the best possible contribution to maintaining Favourable Conservation Status (FCS) for harbour porpoise in UK waters.


In the context of natural change, this will be achieved by ensuring that:

1. Harbour porpoise is a viable component of the site;

2. There is no significant disturbance of the species; and

3. The condition of supporting habitats and processes, and the availability of prey is maintained.


JNCC is working to provide more detailed advice on the interpretation of the conservation objectives listed above. Supplementary advice is available in the advice package (linked above) and updates will be posted here when available.


Advice on Operations  

In line with Regulation 21 of the Conservation of Offshore Marine Habitats and Species Regulations 2017 which apply to the UK’s offshore marine area and Regulation 37(3) of the Conservation of Habitats and Species Regulations 2017, which apply to Welsh inshore waters, the advice on operations for the protected feature of the West Wales Marine SAC outlines knowledge of the nature and extent of activities taking place at the time of writing which may have a significant impact on the feature for which a site has been selected.


The advice on operations is based on JNCC and Natural Resources Wales's scientific knowledge of harbour porpoise at the time of writing, and their sensitivities to pressures. For the most up-to-date information about harbour porpoise within the site and the spatial distribution, please see the Evidence tab.


The advice on operations summarises ongoing activities occurring within or close to the site, with an assessment as to whether they pose a risk to harbour porpoise. This information is useful when assessing an activity, plan or project which may affect the protected features and JNCC has provided this to aid the cumulative assessment of impacts of human activities within the site. While every attempt has been made to ensure this information is accurate and kept up-to-date, the list is not to be considered exhaustive or definitive. The list does not, for example, include activities occurring off-site which may also be capable of affecting the protected features.  


The information contained within the advice on operations document and Evidence tab are useful if you are:

  • Carrying out any activity that may impact the site and need to find out how to operate within the law;
  • An authority providing advice on specific proposals; and 
  • An authority responsible for putting management measures in place.


Our scientific understanding of the ecology of the site, its integrity and its qualifying feature and how activities can affect it may change over time. JNCC and Natural Resources Wales conservation advice will be kept under review and will be periodically updated to reflect this and surveillance required under Article 17 of the Habitats Directive. Conservation advice for sites which straddle the 12nm boundary will continue to be developed jointly with the relevant Country Nature Conservation Body. Further information can be found on the Natural Resources Wales website.


JNCC is undertaking a review of the activities and management plan requirements for the West Wales Marine SAC with other relevant CNCBs and Regulators. Further detail will be provided when available. Further information on conservation advice in relation to this MPA can be found under the Conservation Advice tab.




Last updated: October 2017


JNCC is currently leading on the development of a strategy for biodiversity monitoring across all UK waters, to include Marine Protected Area (MPA) monitoring. For MPAs, data and evidence collected from monitoring activities will aim to:

  • Enable assessment of the status of the features within sites;
  • Enable assessment of the degree to which management measures are effective in achieving the conservation objectives for the protected features;
  • Support the identification of priorities for future protection and/or management; and,
  • Enable Government to fulfil its national and international assessment and reporting commitments in relation to MPAs and help identify where further action may be required.


Information on monitoring of this SAC will be provided here when it becomes available.




Last updated: October 2017


Every six years, Member States are required under Article 17 of the EU Habitats Directive to report on the conservation status of habitats and species listed under Annex I and II. For harbour porpoise, the Article 17 assessments consider conservation status both within the Natura 2000 network and in the wider sea with particular emphasis placed on status and trends in terms of population size, range and habitat quality. These assessments will also feed into six-yearly reports on the state of the marine environment under the Marine Strategy Framework Directive (MSFD), which aims to achieve Good Environmental Status (GES) by 2020.