Pisces Reef Complex MPA


Status: Candidate Special Area of Conservation and Site of Community Importance (cSAC/SCI)Click to link to the interactive map


The Pisces Reef Complex is located in the western Irish Sea, in the north-west mud basin. It is approximately midway between the Isle of Man and the coast of Northern Ireland.


The area consists of an extensive mud plain through which three areas of Annex I bedrock and boulder-dominated stony reef protrude. The three reefs rise 15-35m above the surrounding seabed and are composed of silty bedrock, with a patchy veneer of muddy sediment, due to sediment deposition from a localised scouring process.

The reefs themselves support a diverse community of brachiopods, ascidians, hydroids, sponges and fish.

The Pisces Reef Complex MPA overlaps with a candidate Special Area of Conservation/Site of Community Importance that has been identified for the protection of Harbour porpoise – the North Channel cSAC/SCI. For more information on this MPA, please see the North Channel MPA Site Information Centre.

More detailed site information can be found on the Summary tab below.


Map displaying MPA boundary and associated protected

feature data. Visit the JNCC MPA Mapper to further

view and explore data for this MPA.


Legislation behind the designation: EU Habitats Directive 1992 transposed into UK law by the Offshore Marine Conservation (Natural Habitats &c.) Regulations 2007 (as amended)


Protected Features:

Features Feature Type Conservation Objectives
1170 reefs Annex 1 Habitat*

Maintain in Favourable Condition


*For the latest Annex I habitat resource figures, please see the link to the latest Habitats Directive Article 17 reporting in the assessment tab.

The acquisition of new data may result in updates to our knowledge on feature presence and extent within this site. The most up to date information is reflected on the map on this page and in JNCC’s MPA mapper and the evidence underpinning this can be viewed in the evidence tab below.


Conservation Objectives
The overarching conservation objectives for the designated features of all protected sites in UK offshore waters is to ensure they either remain in, or reach favourable condition. The ability of a designated feature to remain in, or reach favourable condition can be affected by its sensitivity to pressures associated with activities taking place within or in close proximity to a protected site.

Specific information on the conservation objectives relating to this cSAC/SCI is provided in the Conservation Advice tab.

Site Timeline

The diagram below is a summary of the key milestones involved in the selection and designation of Pisces Reef Complex cSAC/SCI.  More detail can be found within the relevant documentation listed below.


Pisces Reef Complex Timeline

Relevant documentation

The documents referred to below and any other historical documents relating to [Insert site name] 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 MPA, 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 Pisces Reef Complex is located in the western Irish Sea, in the north-west mud basin.  It is approximately midway between the Isle of Man and the coast of Northern Ireland. The area consists of an extensive mud plain through which three areas of Annex I bedrock and boulder-dominated stony reef protrude.  The average seabed depth within the site boundary is approximately 100 m with a maximum of 150 m and a minimum of 70 m at the peaks of the rocky reef outcrops. The deepest depths are within the scour pits which encircle the outcropping rocky reefs.


The three reefs rise 15-35m above the surrounding seabed and are composed of tertiary igneous rock and boulders, with the reef tops composed of silty bedrock, with a patchy veneer of muddy sediment due to sediment deposition from a localised scouring process. The reefs support a diverse animal community, including hydroids (e.g Diphasia nugra), a range of sponges, including the cup sponge Axinella infundibuliformi, echinoderms, for example the cushion star fish Porania pulvillus and various crustaceans, for example the edible crab Cancer pagurus and squat lobster Munida rugosa. Additionally, the reef may provide shelter for juvenile fish, including blue whiting, bib, red gurnard and wrasse.  In particular, the mosaic of bedrock and stony reef provide a myriad of ledges and habitat niches. Of note is the occurrence of the Diphasia alata hydroid community which is not currently included within the Marine Habitat Classification for Britain and Ireland and is considered rare. The difference in species composition and abundance between the reefs and the surrounding mud plain highlights the importance of the reefs in providing a refuge for numerous species.

Site location:  Coordinates for this cSAC/SCI can be found in the Natura 2000 Standard Data Form listed in the Relevant Documentation.

Site area:  This site protects three key features covering a total area of 8.73 km2.  These three areas combined are approximately the same size as nearby Larne Lough.

Site depth range: The site sits in a mud basin, with the reef features protruding, sitting at their shallowest between 70m below sea level, and the deepest parts in the scour pits around the rock features reaching down to 150m below sea level. 

Charting Progress 2 Biogeographic Region: Irish Sea

Site boundary description

The site boundary for the Pisces Reef Complex cSAC/SCI has been defined using JNCC’s marine SAC boundary definition guidelines. The boundary is made up of three separate polygons enclosing the minimum area necessary to ensure protection of the Annex I habitats.  It does not include the areas of muddy sediment that lie between the reefs. 

The bedrock reef features were derived from collating survey data from various detailed acoustic and biological surveys. The areas of bedrock and stony reef that met the definition of Annex I reef were delineated based on the interpretation acoustic data, which showed a clear distinction between the hard and soft substrates.  Seabed modelling using the Benthic Terrain Modeller (NOAA) was also carried out for all three areas.  Refer to the Evidence tab for further detail on the data for this MPA.

As any bottom trawling that occurs in the area may pose a threat to the reef, the boundary includes a margin to allow for mobile gear on the seabed being at some distance from the location of a vessel at the sea surface. This buffer has been applied individually to each of the reef features of the site.

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. Please refer to the relevant documentation section for further details and information sources.


Site specific data
There is a range of data that underpin this cSAC/SCI. The full overview of the data used to support site identification, along with information on confidence in feature presence and extent is available in the Pisces Reef Complex cSAC/SCI Selection Assessment Document


JNCC will be adding relevant survey data for this MPA to our MPA interactive map in due course.


Some of the data for this cSAC/SCI has been collected through JNCC funded or collaborative surveys and some through other means.  Data from these surveys/this survey provide direct evidence confirming the presence of the protected features within the site.

Survey and data gathering


  • Geological investigations with a manned submersible in the Irish Sea and off western Scotland - 1971

IGS (now British Geological Survey, BGS) deployed a manned submersible (Pisces) in order to better establish the presence of hard substrate. This was focussed around what is now termed ‘Pisces Reef 2’, the central outcropping of the three features.  This report has not been digitised and is only available in hard copy.

  • ISSIA (Irish Sea Seabed Image Archive). A directory of seabed camera studies in the Irish Sea - 1999 

Irish Sea Seabed Image Archive (ISSIA) A directory of Seabed Camera Studies in the Irish Sea – compilation of images taken in the Irish Sea 1999.  Report 2.  This report has not been digitised and is only available in hard copy.

The Department of Energy & Climate Change (DECC) (then the Department of Trade and Industry: DTI) carried out a Strategic Environmental Assessment in the Irish Sea region in 2004 in order to better understand the implications of oil and gas exploration and production. 

As part of the SEA6 project geophysical survey work was completed in 2004 to investigate possible occurrences of methane-derived authigenic carbonate (MDAC), which form hard substrate on the sea bed.  A range of acoustic techniques were used including: 

Acoustic data: single-beam echo sounder (SBES), multi-beam echo sounder (MBES), side-scan sonar (SSS), and chirp sub-bottom profiler (SBP) in August 2004 (SV Meridian).

Ground-truthing data: photography, seabed sediment sampling (grab samples), and water sampling in October 2004 (SV Kommandor Jack).  

MDAC was not located at the Pisces Reef, but showed a substantial rocky outcrop lying within an area of soft muddy sediments. Analysis of the video and still imagery confirmed the presence of bedrock/stony reef and identified the major faunal communities.

  • MESH NW Shelf Consortium – testing habitat mapping protocols and ground-truth assessment methodology on selected seabed features - 2005/2006

MESH North Western Shelf Consortium (formed by Marine Institute, British Geological Survey, Department of Agriculture & Rural Development (DARD) (now Agri-Food Biosciences Institute: AFBI), Queen's University of Belfast and the University of Ulster) undertook survey work to test mapping protocols which included the Pisces Reef region: 

AFBI MESH Seabed Mapping - 2005 

The Agri-Food and Biosciences Institute of Northern Ireland (AFBI) tested habitat mapping protocols across several seabed features, including Pisces Reef. Sidescan, video tow, grab and sediment sample data were collected aboard the RV Corsytes.   

Marine Institute Seabed Mapping - 2006

The Irish Marine Institute collected acoustic and ground-truthing data in the area of Pisces Reef aboard the RV Celtic Voyager in 2006, including multibeam (MBES) and Sub-Bottom Profiler (SBP) acoustic data, alongside a single grab at each location for Particle Size Analysis (PSA).

  • Beaufort’s Dyke – North Channel Biophysical Survey - 2008

The British Geological Survey (BGS) were invited to participate in a survey of Beaufort's Dyke, North Channel in the Irish Sea by AFBI, aboard the RV Corystes in order to carry out seismic data collection over the Pisces Reef Complex. The purpose was to gather data which could be used to provide seismic profiling of features identified on the multi-beam echo sounder, supporting the findings of rocky reef protruding from the seabed. Subsurface data were gathered by sub-bottom profiler (sparker), and the data are archived by BGS.

  • Slieve Na Griddle rMCZ Site Verification Survey - 2012

JNCC commissioned the Centre for Environment, Fisheries and Aquaculture Science (CEFAS) to undertake an MCZ Site Verification survey on the recommended MCZ Slieve Na Griddle, the boundary of which overlaps two of the three reef features comprising Pisces Reef Complex cSAC/SCI.   High resolution multi-beam, video and grabs were collected, presenting comprehensive acoustic and further ground-truthing data for the two features names Pisces Reef 1 and 2. Reporting is underway and will be made available in due course.

  • Pisces Reef Complex cSAC/SCI and Slieve Na Griddle rMCZ Drop Camera Survey (CEND1414) - 2014

JNCC were offered the opportunity to use part of a planned survey in order to collect further targeted data within Pisces Reef Complex cSAC/SCI and Slieve Na Griddle rMCZ.  AFBI collected camera tow and still image data to further verify the extent of the Annex 1 Reef feature within the two southernmost extents of the cSAC/SCI. Reporting is underway and will be made available in due course.

The monitoring survey at Pisces Reef Complex cSAC/SCI was carried out in autumn 2015. A variety of data types were collected during the six-day survey including multibeam echosounder bathymetry and backscatter, chirper sub-bottom profiles, high resolution video and stills, and water samples to calibrate the camera frame mounted CTD.  The survey aimed to 1. Acquire sentinel monitoring data to support the ongoing monitoring time-series for the Pisces Reef Complex, and 2. Provide evidence on the structure, function and condition of the Annex I Reefs (both rocky and stony) against which the direction of change can be inferred over time.

Data analysis reports
Further analysis of data gathered as part of the surveys listed above are available via the following reports:

DECC commissioned the BGS to provide this technical report summarising the hydrocarbons prospectivity of SEA6, followed by a synthesis of the seabed and superficial geology in the region. This report pulled together the review of available information compiled by BGS in 2002

JNCC commissioned this project to generate an improved understanding of the sensitivities of subtidal sedimentary habitats, found in UK waters, to pressures associated with human activities in the marine environment. This work will contribute to supporting management advice provided for Marine Protected Areas, as well as UK marine monitoring and assessment work.

This report represents Phase 1 of this JNCC-commissioned project and focuses upon the recommendation and rationale of ecological groups based upon species characteristics previously defined by Tillin and Tyler-Waters (2013) and Alexander et al (2015).


References for further supporting scientific literature consulted during the identification of this site can be found in the Selection Assessment Document.

Knowledge gaps
If you are aware of any additional information not referred to in any of the relevant documentation listed on the main page, please contact JNCC



MPA Conservation Advice

Conservation objectives set out the desired state for the protected feature(s) of an MPA. The conservation objective for the protected feature of the Pisces Reef Complex cSAC/SCI has been set based on knowledge of the condition of the protected feature at the time of writing.  Further information on feature condition and the conservation objective is provided in the Pisces Reef Complex cSAC/SCI 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 features;
  • monitoring the condition of the qualifying features; or
  • developing, proposing or assessing an activity, plan or project that may affect the site


The conservation objective for the protected feature of the MPA is:


Subject to natural change, maintain the reef in favourable condition, such that:

The natural environmental quality is maintained

The natural environmental processes are maintained

The extent, physical structure, diversity, community structure and typical species representative of the reef in the Irish Sea are maintained.


JNCC is working to provide more detailed advice on the relatively broad, high level conservation objective listed above. This supplementary advice will be posted here as and when it becomes available.

Advice on operations

In line with Regulation (18) of the Offshore Marine Conservation (Natural Habitats, & c.) Regulations 2007 (as amended) which apply to the UK’s offshore marine area, the advice on operations (linked above) for the protected feature of the Pisces Reef Complex cSAC/SCI outlines current knowledge of the nature and extent of activities taking place which may have a significant impact on the feature for which a site has been selected.


The advice on operations is based on JNCC’s scientific knowledge of the biological communities present at the time of writing and their sensitivities to pressures. For the most up-to-date information about the biological communities present within the site and their spatial distribution, please see the evidence tab. Sensitivity information for biological communities identified within the site can also be found on MarLIN’s website.


JNCC also provides a list of activities occurring within the site and information on activity management in the activities and management tab. This information is also 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, activities and management tab, evidence tab, and MarLIN’s sensitivity assessments 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
  • an authority responsible for putting management measures in place


Our scientific understanding of the ecology of the site, its integrity and its qualifying features and how activities can affect them may change over time. JNCC’s 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 on JNCC's conservation advice work is available via our offshore MPA conservation advice webpage.


(June 2017)

Management status: Progressing towards being well managed

Progress is ongoing with the recommendation of fisheries management proposals to the European Commission. A monitoring survey was undertaken in 2016 to improve our understanding as to whether the MPA is moving towards or has reached its conservation objectives. Ongoing site condition monitoring work will be required however in order to conclude with confidence as to the degree to which the site is moving towards or achieving its conservation objectives.


This site forms part of the UK's contribution to the OSPAR commission’s network of MPAs and the Emerald network established under the Bern Convention. As the UK is a member of the OSPAR commission, JNCC are committed to ensuring that the OSPAR MPA network is ‘well-managed’ by 2020.

JNCC consider ‘well-managed’ to mean the timely progress of an MPA around the ‘MPA management cycle’. This involves:

  1. The documentation of appropriate management information - conservation objectives, advice on activities capable of affecting the protected features of a site, and spatial information on the presence and extent of the protected features of a site.
  2. The implementation of management measures - management actions considered necessary to achieve the conservation objectives of a site.
  3. Site condition monitoring programmes – collecting the information necessary to determine progress towards a sites conservation objectives.
  4. Assessment of progress towards conservation objectives – using available information to infer whether or not a site is moving towards or has achieved its conservation objectives.

The sub-sections that follow provide an account of the progress of Croker Carbonate Slabs cSAC/SCI around each of the four stages in the MPA management cycle.

The documentation of appropriate management information

  • The conservation objectives and advice on activities capable of affecting the conservation status of the protected feature of this site are available under the conservation advice tab.
  • JNCC are in the process of improving our MPA conservation advice packages. Further information is available on our conservation advice pages.
  • Spatial information on the presence and extent of the protected feature of this MPA is available via JNCC's MPA mapper.
  • JNCC are in the process of developing downloadable MPA data packages where appropriate permissions to share datasets are in place.


The implementation of management measures
This section details progress towards the implementation of management measures for activities considered capable of affecting the conservation status of the protected feature of the site. The protected feature of the site is considered to be sensitive to pressures associated with fishing and ‘licensable’ activities.


  • There is evidence of mobile demersal and pelagic activity within the MPA.
  • The site falls outside the UK’s 12 nautical mile limit and is to be exclusively managed under the EU Common Fisheries Policy (CFP). In accordance with Article 18 of the revised CFP, requests for management will be developed jointly between the UK Government and any Member States with a direct management interest in the area affected.
  • The Marine Management Organisation are the lead authority regarding the implementation of, and compliance with, any measures to managing fishing activity. Further information on progress is available via MMO’s web pages.

Licensable activities

  • Whilst ‘licensable’ activities such as oil and gas exploration and production do not take place within Pisces Reef Complex cSAC/SCI at present, any future proposals would have to comply with Article 6(3) of the EU Habitats Directive 1992, which is transposed into UK law by the offshore Marine Conservation (Natural Habitats& c.) Regulations 2007 (as amended).
  • Our conservation advice supports the consents process by setting out the conservation objectives for the protected feature of this MPA and advice on activities that may result in pressures to which the protected feature is considered sensitive.
  • Further information on JNCC’s role in the provision of advice for licensed activities in the UK offshore area is available on JNCC’s offshore industries advice webpage


Site condition monitoring
A baseline condition monitoring survey for this MPA was undertaken in 2016. The survey aimed to gather evidence to monitor and inform assessment of condition of the Annex I Reefs within the site. The results of this survey are not yet available. Further information will be made available under the monitoring tab in due course.

Assessment of progress towards conservation objectives
No long-term condition monitoring data is available to determine whether the MPA is moving towards or has reached its conservation objectives. The site has a ‘maintain’ conservation objective based on the findings of a vulnerability assessment (exposure the activities associated with pressures to which the protected features of the site are considered sensitive). This suggests the site may already be achieving or moving towards its conservation objectives. Site condition monitoring data would improve our confidence in this assessment. Further information will be provided under the assessment tab as it becomes available.



MPA Monitoring

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

  • Enable assessment of condition 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 MPA will be provided when it becomes available.


MPA Assessment

Assessments of the condition of designated features in offshore MPAs are required to report against our legal obligations. Ideally these assessments should be based on observed data, and then measured against targets for predefined indicators. However, for MPAs in offshore waters we do not always have the appropriate information to be able to do so. This is particularly true for seabed habitats, which are the main type of feature designated for protection in offshore MPAs. 

To address these challenges, JNCC has been an active partner in the development of new approaches and tools for the assessment of habitats and species for a variety of national and international status reports. They include the second cycle of the Conservation Status Assessment reports under the EU Habitats Directive, Charting Progress 2 (CP2) and the OSPAR Quality Status Report (QSR). JNCC continues to develop and pilot tools for the assessment of marine habitats and species in offshore waters to improve the quality and transparency of our offshore MPA assessments, and contribute to the monitoring of marine biodiversity in UK waters. These tools cover methods for producing interim assessments of site features and their responses to pressures, as well as developing more robust indicators for determining condition of the features.

Every six years, Member States are required under Article 17 of the EU Habitats Directive to report on the Conservation Status of Annex I habitats and Annex II species on the Habitats Directive.  The assessments should consider the habitat or species both within the Natura 2000 network and in the wider sea.  The latest report was submitted by the UK in 2013 and provided a second assessment of the conservation status of relevant habitats and species within UK marine waters during 2007-2012. The next report is for the period 2013-2018 and is due in 2019; information on the condition of features within SACs will make a contribution to this report. 

The assessments of features within MPAs 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.




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