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Holderness Offshore MPA

Status: Marine Conservation Zone (MCZ)

Holderness Offshore MCZ is located in the Southern North Sea region, approximately 11 km offshore from the Holderness coast.

The Holderness Offshore MCZ straddles the 12 nm territorial sea limit and is split between the offshore and territorial inshore area. Therefore advice for this MPA is jointly delivered with Natural England.


Holderness Offshore MCZ is located approximately 11 km offshore from the Holderness coast in the Southern North Sea region. The site boundary is partly delineated to the west by the 6 nm Territorial Seas limit and overlaps with part of the western area of the Southern North Sea SAC.

The site lies across the 12 nm territorial sea limit, and therefore advice for this MPA is jointly delivered with Natural England.

The seabed is dominated by Subtidal coarse sediment and hosts Subtidal sand, Subtidal mixed sediments and part of a glacial tunnel valley. The diverse seabed allows for a wide variety of species which live both in and on the sediment such as, crustaceans (crabs and shrimp), starfish and sponges. This site is also a spawning and nursing ground for a range of fish species for example lemon sole (Microstomus kitt), plaice and European sprat (Sprattus sprattus). Therefore, the species living both in and on the sediment may benefit from the protection afforded to the habitat features within this site.

The slow-growing bivalve, Ocean quahog (Arctica islandica) have been found in the site. Ocean quahog is a threatened/declining species of bivalve mollusc that can take up to 6 years to reach maturity and can live for over 500 years.

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

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

Map showing Holderness Offshore Marine Protected Area and linking to the MPA mapper


Legislation behind the designation: Marine and Coastal Access Act (2009)


Protected Features

Protected Feature Feature Type
Subtidal coarse sediment Broad-scale habitat
Subtidal sand Broad-scale habitat
Subtidal mixed sediments Broad-scale habitat
Ocean quahog (Arctica islandica) Species Feature of Conservation Importance
North Sea glacial tunnel valleys Feature of Geological Interest

Specific information on the conservation objectives related 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 Mapper and 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 the Holderness Offshore MCZ. More detail can be found within the Relevant Documentation section and in the post-consultation advice.

September 2011
Regional projects recommended a total of 127 MCZs to Defra and the statutory nature conservation bodies (SNCBs).
July 2012
SNCB advice to Defra on the 127 recommended MCZs.
October 2016
JNCC provided pre-consultation advice on the features found within Holderness Offshore proposed MCZ.
June 2018 – July 2018
Holderness Offshore MCZ included in formal public consultation on Tranche Three MCZs.
May 2019
Tranche three designations announced – Holderness Offshore MCZ designated


Relevant Documentation

The documents referred to below and any other historical documents relating to Holderness Offshore MCZ 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. Further information about the Marine Conservation Zone site selection process and historic MCZ advice is available on JNCC's MCZ webpage.

  • Holderness Offshore MCZ Designation Order – the official description of the site designation under the Marine and Coastal Access Act 2009. The Designation Order includes boundary co-ordinates, Conservation Objectives and a list of the designated features. More information on the designation, including a designation map and factsheet is available on Defra's website.
  • JNCC's pre- and post-consultation scientific advice for features proposed for designation in 2019.
  • JNCC's formal conservation advice for this site is available in the Conservation Advice section.



Last updated: May 2020

Information for this site summary was adapted from JNCC’s scientific advice to Defra on Holderness Offshore MCZ and incorporates any further information gathered since this advice was produced. Please refer to the Relevant Documentation section for further details and information sources.


Site overview

The Holderness Offshore MCZ lies partly in inshore and partly in offshore waters as it crosses the 12 nm territorial sea limit. The site is relatively shallow, ranging in depth from just over 5 m down to 50 m and covers an area of 1,176 km2. This site contains good examples of broad-scale habitats Subtidal mixed sediment, Subtidal sand and Subtidal coarse sediment. The site also contains an area of geological interest (the northern point of the Inner Silver Pit glacial tunnel). This area has a high species biodiversity and is an ecologically important area providing habitats for many species. The threatened and/or declining Ocean quahog (Arctica islandica) is also found within this MCZ which highlights the importance of the Holderness Offshore designation.

The site was first proposed for designation in 2011 by the Net Gain regional MCZ project for the broad-scale habitats Subtidal mixed sediments and Subtidal coarse sediment. Evidence supporting the designation of Subtidal mixed sediments and Subtidal coarse sediments was provided by the MB0120 survey in 2012, BGS seabed sediments and Cefas data mining contract. The MB0116 international bottom trawl survey as well as the 2016 Oceana survey identified the presence of Ocean quahog through specimens found in a grab; providing evidence for designation of this feature. A habitat map from survey provided evidence for the designation of Subtidal sand and further evidence for the designation of Subtidal mixed sediments. The MCZ Cefas ITT Survey in 2013 acoustic data supports the designation of the Inner Silver Pit area as a geological feature of interest within the Holderness Offshore site.

Further detail on the evidence for this MCZ can be found in the Monitoring and Evidence section.

Site location: Co-ordinates for this MCZ can be found in the Designation Order listed in the Relevant Documentation section.

Site area: 1,176 km2.

Site depth range: 5.1–50 m. 

Charting Progress 2 Biogeographic Region: Region 2 – Southern North Sea.

Site boundary description: The site is a polygon comprised of fourteen geodesic lines and is partly delineated to the west by the 6 nm Territorial Seas limit in line with the guidance provided by the MCZ project Ecological Network Guidance (ENG). The boundary of the Holderness Offshore MCZ has not changed since it was recommended by the Finding Sanctuary Regional MCZ Project in 2011.


Monitoring and Evidence

Last updated: November 2023

Site-specific data

There are a range of data that underpin this MCZ. The full overview of these data used to support site identification along with information on confidence in feature presence and extent is available in JNCC’s Tranche Three MCZ pre-consultation and post-consultation scientific advice for offshore Marine Conservation Zones proposed for designation in 2019. JNCC will be adding relevant survey data for this MPA to its MPA Mapper in due course.

Some of the data for this MCZ 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

  • Cefas/JNCC site verification survey of Holderness Offshore recommended MCZ (2012) – Cefas undertook a dedicated site survey CEND0812 in 2012. Acoustic data were acquired opportunistically on the transits between ground truth stations which were collected from the northern portion of the site over 43 stations using benthic grabs, videos and still images.


Data analysis reports

  • Holderness Offshore rMCZ Post-survey Site Report (2017) – This report provides an interpretation of the acoustic and ground truthing survey data collected by Cefas at the Holderness Offshore site during May 2012. The data was used to validate the predicted distribution of BSH and habitat FOCI.


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 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 data not listed here or scientific papers relevant to this site, please contact us.


Conservation Advice

Last updated: March 2021

Updated formal conservation advice for this MPA was produced in March 2021.  Further information on the approach used to develop this advice is available on our 'Conserving MPAs' webpage, along with a Glossary of Terms used in JNCC conservation advice and a short video explaining how to use the conservation advice packages. 

You must refer to this advice if you:

  • undertake an MCZ assessment for a plan or project that could impact the site;
  • provide information for such an assessment;
  • respond to specific measures to further 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 advice reflects the most up-to-date evidence held by JNCC (correct as of March 2021).  

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.

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 documents are available on JNCC's Resource Hub.


© JNCC/Cefas (2012)


Published: .

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