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Wyville Thomson Ridge MPA

Status: Special Area of Conservation (SAC)

The Wyville Thomson Ridge is a rocky plateau situated in the Atlantic Ocean to the north-eastern part of the Rockall Trough.


Situated in the Atlantic Ocean to the north-eastern part of the Rockall Trough, The Wyville Thomson Ridge is a rocky plateau.  

It is composed of extensive areas of stony reef interspersed with gravel areas and bedrock reef along its flanks, and supports diverse biological communities representative of hard substratum in deep water including a range of sponges; stylasterid, cup and soft corals; brachiopods; bryozoans; dense beds of featherstars and brittlestars; sea urchins, sea cucumbers and sea spiders. The stony reef is thought to have been formed by the ploughing movement of icebergs through the seabed at the end of the last ice age.

More detailed site information can be found in the Summary section below.

Map displaying the Wyville Thomson Ridge MPA boundary and associated protected feature data. Visit JNCC's MPA Mapper to further view and explore data for this MPA.

Map showing Wyville Thomson Ridge Marine Protected Area and linking to the MPA mapper


Legislation behind the designation: EU Habitats Directive 1992 transposed into UK law by The Conservation of Offshore Marine Habitats and Species Regulations 2017 (as amended).


Protected Features

Feature Feature Type
1170 Reefs Annex 1 Habitat

Specific information on the conservation objectives relating to this site is provided in the Conservation Advice section.

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 Mapperand the evidence underpinning this can be viewed in the Monitoring and Evidence section.


Site Timeline

The diagram below is a summary of the key milestones involved in the selection and designation of Wyville Thomson Ridge SAC. More detail can be found within the Relevant Documentation section.

December 2004
Site formally recommended to the UK Government as a draft Special Area of Conservation (SAC).
June 2008
Impact Assessment and report on public consultation submitted. Site becomes a possible SAC.
August 2010
Submitted to the European Commission. The Habitats Regulations now formally apply to this MPA.
November 2011
Site is approved by the European Commission as a Site of Community Importance (SCI).
September 2017
Site is formally designated as a SAC by UK Government.


Relevant Documentation

The documents referred to below and any other historical documents relating to the Wyville Thomson Ridge SAC 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 JNCC's SAC webpages.

These resources are available on JNCC's Resource Hub.



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

The Wyville Thomson Ridge is located on the Scottish continental shelf edge approximately 150 km north-west of Cape Wrath, and extends in a north-westerly direction towards the Faeroe Bank. The Ridge divides the relatively warmer waters of the Rockall Trough from the relatively cooler waters of the Faroe-Shetland Channel, and is a transitional area between the two water masses.

The Wyville Thomson Ridge is approximately 20 km wide and 70 km long and rises from over 1,000 m depth to less than 400 m at the summit. The ridge is composed of extensive areas of stony reef interspersed with gravel areas and bedrock reef along its flanks. The stony reef is thought to have been formed by the ploughing movement of icebergs through the seabed at the end of the last ice age. These iceberg 'ploughmarks' consist of ridges of boulders, cobbles and gravel where finer sediments have been winnowed away by high-energy currents at the site, interspersed with finer sediment troughs up to 10m deep.

The rock and stony reef areas in the site support diverse biological communities representative of hard substratum in deep water, including a range of sponges; stylasterid, cup and soft corals; brachiopods; bryozoans; dense beds of featherstars and brittlestars; sea urchins, sea cucumbers and sea spiders. Communities on the bedrock reef vary in species composition between the two sides of the ridge due to the influences of different water masses. This combination of water masses in one area is unique in UK waters. Further detail on the evidence for this SAC can be found in the Monitoring and Evidence section.

Site location:  Co-ordinates for this SAC can be found in the Standard Data Form listed in the Relevant Documentation section.

Site area:  This site has an area of 1,740 km2, slightly larger than the neighbouring Shetland Isles.

Site depth range: The site is on a ridge at the edge of the continental shelf, sitting at 310 m, sloping down to its deepest at 1,010 m below sea-level.

Charting Progress 2 Biogeographic Region: The MPA spans the boundary between the Atlantic North-West Approaches, Rockall Trough and Faeroe/Shetland Channel region and the Scottish Continental Shelf region.

Site boundary description: The boundary for the Wyville Thomson Ridge SAC is a simple polygon defined by whole degrees and minutes, fully enclosing the minimum area necessary to ensure protection of the Annex I reef of the site. Bottom trawling is a threat to the reef and, therefore, the proposed 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.


Monitoring and Evidence

Last updated: November 2023

There are a range of data that underpin this SAC. 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 Wyville Thomson Ridge MPA SAC Selection Assessment Document. JNCC will be adding relevant survey data for this MPA to its MPA Mapper in due course.

Some of the data for this SAC have been collected through JNCC-funded or collaborative surveys, and some through other means. Data from these surveys provide direct evidence confirming the presence of the protected features within the site.


Survey and data gathering

  • 1517S Cruise Report: Monitoring survey of North-east Faroe Shetland Channel Natural Conservation MPA, Wyville Thomson Ridge SAC & West Shetland Shelf Nature Conservation MPA (2019) – The aim of the 1517S survey was to gather initial data for a site monitoring time-series for NEF, WTR and WSS. The survey gathered evidence to inform assessment of the condition of the protected features of the site for comparison against future data to monitor the rate and direction of any changes. This will allow assessment of the long-term effectiveness of current proposed management measures.
  • 1218S Cruise Report: Monitoring survey of Faroe-Shetland Sponge Belt Nature Conservation MPA, Rosemary Bank Seamount Nature Conservation MPA and Wyville Thomson Ridge SAC (2019) – The aims of the 1218S survey were to gather initial data for site condition monitoring time-series at Faroe-Shetland Sponge Belt NCMPA and Wyville Thomson Ridge SAC, and to gather data to better characterise the communities and habitats at Rosemary Bank Seamount NCMPA, to help inform future Marine Protected Area monitoring efforts at this site.
  • Monitoring survey of Wyville Thomson Ridge SAC (2017) – JNCC and Marine Scotland Science undertook a survey of three Scottish MPAs, including Wyville Thomson Ridge SAC. Fifteen video tows were collected over the iceberg ploughmark fields within the site to inform monitoring of the protected Annex I reefs.
  • Deep Links Project (2016) – A collaborative project between Plymouth University's Deep Sea CRU and University of Oxford, in partnership with JNCC and British Geological Survey, funded by NERC. During May and June 2016 the team undertook a 6 week research cruise in the North East Atlantic, including Wyville Thomson Ridge, on board the RRS James Cook collecting data. This project aims to investigate the theory that populations at bathyal depths are more isolated because the currents that transport larvae decrease with depth.
  • Wyville Thomson Ridge and Faroe-Shetland Channel Survey (2012) – This survey was a collaboration between JNCC and Marine Scotland Science. Video and camera imagery were collected to support evidence on the presence and extent of the Annex I reef feature of the Wyville Thomson Ridge.
  • Strategic Environmental Assessment (SEA) Survey 7 (2006) – This survey was commissioned by the Department for Trade and Industry (now Department for Energy and Climate Change (DECC)), as part of the Strategic Environmental Assessment (SEA) survey programme. This survey aboard the commercial research vessel Franklin, in which JNCC collaborated, collected acoustic and underwater imagery data from areas off the north and west coasts of Scotland including the Wyville Thomson Ridge.
  • Atlantic Frontier Environmental Network (AFEN) (1996–2000) – Southampton’s National Oceanography Centre undertook large-scale sampling of the shelf edge and slope west of Shetland on behalf of the Department for Transport and Industry (now the Department for Energy and Climate Change) on a series of surveys undertaken between 1996 and 2000. These surveys, in which JNCC collaborated, helped characterise the geology, geomorphology and fauna on the Wyville Thomson Ridge.
  • Towed Ocean Bottom Instrument (TOBI) surveys of the continental slope west of Shetland (1996/1998) – The National Oceanographic Centre (NOC) used side-scan sonar amongst other sampling methods to undertake a baseline environmental survey of the seafloor on the continental slope west of Shetland. This included the collection of extensive side-scan sonar data at the Wyville Thomson Ridge.

Data analysis reports


Additional relevant literature

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


Knowledge gaps

As part of the UK Marine Monitoring and Assessment Strategy (UKMMAS), JNCC led the development of a UK Marine Biodiversity Monitoring Strategy, working with partners across the UK monitoring community. The Strategy spans UK territorial and offshore waters, focusing on biodiversity in the wider environment and within Marine Protected Areas.  Its aim is to implement efficient, integrated monitoring of marine biodiversity to provide the evidence needed for all the UK's policy drivers.

The Marine Directorate of Scottish Government, in partnership with JNCC and NatureScot, developed a Scottish Marine Protected Area (MPA) monitoring strategy. The Strategy spans Scottish territorial and offshore waters, focusing on biodiversity within Marine Protected Areas. The Strategy is supported by a series of annexes which provide more detail on monitoring methods, collaborative working, current monitoring and a two year forward look for MPA monitoring in Scottish waters.

The evidence collected during MPA monitoring surveys is used in combination with other available evidence to:

  • Enable assessment of condition of the features within sites;
  • Contribute to the 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.

More detail on offshore MPA monitoring can be found on the Offshore MPA monitoring webpage. A list of monitoring surveys and relevant reports can be found on the MPA monitoring survey reports webpage.

If you are aware of any additional information not referred to here or in the Relevant Documentation section, please contact us.


Conservation Advice

Last updated: March 2018

Updated formal conservation advice is now available for this MPA. Further information on the approach used to develop this advice is available on our Conservation Advice webpages along with a Glossary of Terms used in JNCC's conservation advice and a short video explaining how to use the conservation advice packages. 

You must refer to this advice if you:

  • undertake a Habitats Regulation Assessment (HRA) for a plan or project that could impact the site;
  • provide information for a HRA;
  • respond to specific measures to support delivery of the conservation objectives for the site; and 
  • consider the need to put new or additional management measures in place.

You may also find it useful to refer to this advice if you:

  • Carry out any other activity that could impact the site.

We will engage with stakeholders to identify any lessons which JNCC can learn from customers who have used the advice, with a view to continuing to ensure it is fit-for-purpose.

The following table provides an overview of the components of the conservation advice, and provides hyperlinks to each of the products for this MPA. These elements together form JNCC’s formal conservation advice for this site and should be read in conjunction with each other. This updated advice replaces the previous Regulation 18 package for the site. This advice reflects the most up-to-date evidence held by JNCC (correct as of March 2018). 

Document Overview
Background Information Explains the purpose of the advice and when it must be referred to.

Conservation Objectives


Supplementary Advice on the Conservation Objectives (SACO)

The Conservation Objectives set out the broad ecological aims for the site. JNCC provides supplementary advice in the SACO which is essential reading to support interpretation of these conservation objectives.

You can use these documents to assess the impacts of your planned activity on the important attributes of the site.

Please note our current understanding of whether the available evidence indicates that each attribute needs to be recovered or maintained is not provided here. However links to available evidence for the site are provided and should you require further site-specific information for the site, please contact us.

Conservation Advice Statements

These statements provide a summary of the Supplementary Advice on the Conservation Objectives (SACO).

  • Site condition presents our up-to-date understanding of the condition of features within the site;
  • Conservation benefits which the site can provide, these help you understand what is important about the site and why it needs protecting; and
  • Conservation measures which JNCC considers are needed to support achievement of the conservation objectives. These provide clarity around measures needed to support restoration or maintenance of the feature(s) within the site.
Advice on Operations

Provides information on the activities capable of affecting site integrity and therefore achievement of the site’s conservation objectives.

This is a starting point for determining potential management requirements. It does not take into account the intensity, frequency or cumulative impacts from activities taking place. It is simply to advise you of the possible adverse impacts that your activity can have on a MPA’s features.

Use the advice on operations to determine those pressures your activity causes that could harm the habitat and/or species features of the site.

These resources are available on JNCC's Resource Hub.



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