Skip to Content

Markham's Triangle MPA

Marine Conservation Zone (MCZ)

This relatively shallow site is located approximately 137 km from the Humberside coastline in the Southern North Sea region. The site is bordered to the east by a Dutch Special Area of Conservation known as Cleaver Bank. There are a variety of sediment types found within the site, ranging from sandy sediments and fine mud through to coarse gravel and pebbles, providing habitats to a diverse range of species.


Markham's Triangle MPA is located approximately 137 km from the Humberside coastline in the Southern North Sea region. Despite its offshore location it is relatively shallow, ranging in depth from only 25 to 50 m.

The site covers an area of 200 km2, protecting a variety of sediment types from fine mud and sand through to coarse gravel and pebbles. The variety of protected designated broad-scale habitats; Subtidal coarse sediment, Subtidal mixed sediments, Subtidal sand and Subtidal mud found in this site means it can support a wide variety of species. For example, bristleworms, venus cockles and sea cucumbers live within the coarser sediments, and burrowing molluscs such as razor clams live within sand regions of the sites. Starfish, sea urchins and crabs can be found living on the surface of the seabed throughout the site. The site contains habitats which support a range of fish species too. This includes commercially important flatfish species such as sole, plaice (Pleuronectes platessa) and European smelt (Osmerus eperlanus). 

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

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

Map showing Markham's Triangle 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 mud

Broad-scale habitat

Subtidal mixed sediments

Broad-scale 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 in this section 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 Markham’s Triangle 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 rMCZs to Defra and the statutory nature conservation bodies (SNCBs).
June 2018 – July 2018
Markham’s Triangle MCZ included in formal public consultation on Tranche Three MCZs.
May 2019
Tranche Three designations announced – Markham’s Triangle MCZ designated.


Relevant Documentation

The documents referred to below and any other historical documents relating to Markham’s Triangle 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.

  • Markham’s Triangle 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: July 2020

Information for this site summary was adapted from JNCC’s scientific advice to Defra on Markham’s Triangle 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

Markham’s Triangle MCZ is an offshore site spanning an area of approximately 200 km2 and is relatively shallow, reaching depths of only 25–50 m. The site is located 137 km from the Humberside coastline in the Southern North Sea region. It is characterised by a range of sedimentary habitats including, Subtidal sand, Subtidal coarse sediment, Subtidal mud and Subtidal mixed sediments. These habitats allow a variety of species to thrive, such as starfish, bristleworms, burrowing molluscs such as razor and venus clams, sea urchins, crabs, and a range of fish species including sole, plaice (Pleuronectes platessa) and European smelt (Osmerus eperlanus).

This site was recommended by the Net Gain regional MCZ project for broad-scale habitats Subtidal coarse sediment and Subtidal sand. Additional data collected during an MB0120 survey in 2012 identified two new features – Subtidal mud and Subtidal mixed sediments. High confidence the presence of Subtidal sand and Subtidal coarse sediment is supported by a full coverage habitat map from ground truth sample data from BGS and MB0120 surveys. The summary site report was produced following the MB0120 surveys. The UK BAP Priority Species European smelt has also been recorded within the site from the MB0116 survey.

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: 200 km2.

Site depth range: 25.1–50 m.

Charting Progress 2 biogeographic region: Southern North Sea.

Site boundary description: The site is comprised of three geodesic lines forming a simple triangle in line with the guidance provided by the MCZ project Ecological Network Guidance (ENG). The eastern boundary is approximately delineated by the median line with Dutch waters. The boundary of the Markham’s Triangle MCZ has not changed since it was recommended by the Net Gain 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 Markham’s Triangle MCZ (2014) – New acoustic data with 75% site coverage were collected by the RV Cefas Endeavour in April and May 2012 as part of the CEND 08/12 survey of Markham’s Triangle. Ground-truth samples were collected from 50 stations. Benthic grabs were used at all stations to collect sediments and infauna. An underwater camera system (camera sledge) was deployed at 21 stations to collect video and still images of the seabed.


Data analysis reports

  • Markham’s Triangle rMCZ Post-survey Site Report (2014) – Cefas undertook analysis of acoustic (bathymetry and backscatter) and ground-truthing data collected by dedicated survey in 2012 of the site. These data were used to produce an updated habitat map for the site and inform the presence of broadscale habitats and habitat FOCI and allow estimates to be made of their spatial extent within the site.


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: January 2021

Updated formal conservation advice for this MPA was produced in January 2021. Further information on JNCC’s approach used to develop conservation advice packages 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 January 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 feature(s) 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 the 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: .

Back to top