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Outer Thames Estuary SPA

Status: Special Protection Area (SPA)

The Outer Thames Estuary MPA lies along the east coast of England in the southern North Sea and extends northward from the Thames Estuary to the sea area off Great Yarmouth on the East Norfolk Coast. This SPA crosses the 12 nautical mile boundary and therefore statutory advice is provided jointly with Natural England.


The Outer Thames Estuary SPA is classified for the protection of the largest aggregation of wintering red-throated diver (Gavia stellata) in the UK, an estimated population of 6,466 individuals, which is 38% of the wintering population of Great Britain. It also protects foraging areas for common tern (Sterna hirundo) and little tern (Sternula albifrons) during the breeding season.


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

Map showing Outer Thames Estuary Marine Protected Area and linking to the MPA mapper

The SPA lies along the east coast of England in the southern North Sea and extends northward from the Thames Estuary to the sea area off Great Yarmouth on the East Norfolk Coast. This SPA crosses the 12 nautical mile boundary and therefore statutory advice is provided jointly with Natural England. The foraging areas protected for little tern and common tern, enhance the protection afforded to their feeding and nesting areas in the adjacent coastal SPAs (Foulness SPA, Breydon Water SPA and Minsmere to Walberswick SPA). The Outer Thames Estuary SPA overlaps with a Special Area of Conservation that has been identified for the protection of Harbour porpoise – the Southern North Sea SAC. For more information on this MPA, please see the Southern North Sea MPA Site Information Centre.

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




Legislation behind the designation: The Outer Thames marine Special Protection Area was classified by the UK Government to meet obligations set out in the Birds Directive (2009/147/EC), and is protected by The Conservation of Offshore Marine Habitats and Species Regulations 2017 (as amended). Other regulations apply in inshore waters.


Protected Features

Feature Feature Type
% of population Conservation objective
Red-throated diver Gavia stellata Annex I species 38% GB Maintain or enhance favourable condition
  Common tern Sterna hirundo Annex I species 2.66% GB Maintain or enhance favourable condition
Little tern Sternula albifrons Annex I species 19.64% GB Maintain or enhance favourable condition

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 section.


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. Information on the conservation objectives relating to this SPA is provided in the Conservation Advice section.


Site Timeline

The diagram below is a summary of the key milestones involved in the selection and classification of the Outer Thames Estuary SPA. 

November 2009
Formal consultation on the Outer Thames Estuary possible SPA (pSPA).
August 2010
Outer Thames Estuary classified as an SPA.
January – July 2016
Formal consultation on the addition of two new protected features and associated boundary elements.
October 2017
Classification of boundary amendments and two additional protected features.


Relevant Documentation

The documents referred to below and any other historical documents relating to The Outer Thames Estuary SPA were produced during the selection and classification process and therefore may be out of date. This Site Information Centre is the most up-to-date source of information for this SPA, and will reflect any additional information gathered since these documents were produced. Information about the SPA site selection process is available on JNCC's SPA webpages.

  • Standard Data Form – Details the SPA and the classified feature.  
  • Departmental Brief (May 2010) – Overview of the SPA, and rationale for the classification of the site for red-throated diver.
  • Departmental Brief (Nov 2015) – Rationale for the addition of common tern, little tern and associated boundary amendments. 
  • Conservation Objectives and Advice on Operations – Information about feature sensitivity, vulnerability and risk, and the Conservation Objectives for the classified feature of the site. This document will be updated in due course to reflect the October 2017 amendments to the site.  
  • Site Improvement Plan Overview of the current and predicted issues affecting the condition of the site's protected feature and outlines the priority measures required to improve the condition of the feature. It does not cover issues where remedial actions are already in place or ongoing management activities which are required for maintenance.



Last updated: April 2019

Information for this site summary was adapted from documents listed in the Relevant Documentation section. 


Site overview

The Outer Thames Estuary SPA lies along the east coast of England, predominantly in the coastal waters of the southern North Sea between the Thames Estuary and the east Norfolk coast. It covers an area of c. 3,924 km2, classified for the protection of wintering red-throated diver, breeding little terns and breeding common terns. This area supports the largest aggregations of wintering red-throated diver in the UK, 38% of the GB population. The foraging areas protected for little tern and common tern, enhance the protection afforded to their feeding and nesting areas in the adjacent coastal SPAs.

The area of the SPA contains areas of shallow and deeper water, with high tidal current streams and a range of mobile sediments, including several shallow sandbanks. Much of the area is less than 20 m water depth, extending into the 20–50 m depth contour towards the eastern boundary of the SPA.

The population estimate for wintering red-throated diver in the Outer Thames Estuary SPA was based on data collected from visual aerial surveys within the period from January 1989 to the winter seasons of 2005/06 and 2006/07. These data demonstrate that the Outer Thames Estuary SPA regularly supports numbers of red-throated diver that are well in excess of the percentage population threshold (>1% of the GB population of this species) identified under the UK SPA selection guidelines (Stroud et al. 2001).  

Between 2009 and 2013, shore-based counts and boat-based survey were undertaken to identify important foraging areas for little tern.  For common tern, a programme of boat-based visual tracking of foraging birds was undertaken between 2009 and 2011. Survey effort was prioritised at 10 colony sites around the UK, surveys were not undertaken at the colonies adjacent to the Outer Thames Estuary SPA. The resultant information on foraging locations chosen by the birds was combined with information on the habitat characteristics of those locations relative to other areas available to construct habitat association models of tern usage. These models were used to predict species specific tern usage patterns around these breeding colony SPAs

Further detail on the evidence for this SPA can be found on the Evidence section.

Site location: the boundary of this SPA can be viewed or downloaded via JNCC's MPA mapper. Boundary co-ordinates for the site are available from the site boundary map.

Site area: c. 3,924km2.

Site depth range:  Water depth ranges from mean low water to 20–50 m depth along the seaward boundary of the site.

Site boundary description: The SPA boundary is divided into three areas: the outer part of the Thames estuary; a separate area extending south along the coast from East Norfolk; and a third area lying seaward of this off Lowestoft. The landward boundary follows the Mean Low Water mark or the seaward boundaries of existing SPAs, whichever is furthest seaward, except where there was evidence of low densities of red-throated diver. The boundary is extends to Mean High Water (MHW) in places to encompass the foraging areas for little tern and common tern. The boundary of this SPA extends into offshore waters beyond 12 nautical miles; hence it is a site for which both Natural England and JNCC have responsibility to provide statutory advice.



Last updated: April 2019

The full overview of the data used to support site identification along with information on confidence in the occurrence and abundance of red-throated diver is available in the Outer Thames Estuary SPA Departmental Brief (2010). The respective information for the inclusion of little tern and common tern is available in the Outer Thames Estuary SPA Departmental Brief (2015)

Data for this SPA have been collected by the Nature Conservancy Council (NCC), the Joint Nature Conservation Committee (JNCC), the Wildfowl & Wetlands Trust (WWT) and the Natural Environmental Research Institute, Denmark (NERI). Surveys carried out by WWT and NERI were commissioned in response to proposals to develop wind farms in the Greater Thames and in other areas around the UK. The surveys were commissioned by a consortium of private companies, as well as DBERR (Department for Business Enterprise and Regulatory Reform, formerly Department of Trade and Industry (DTI), the Department for the Environment, Food and Rural Affairs (DEFRA) and The Crown Estate. Data from these surveys provide direct evidence for the numbers of red-throated diver within the site.


Survey and data gathering

  • Digital aerial survey (2013) – Two aerial surveys using high-resolution digital photography were undertaken by APEM in January, and February. These surveys provide the first population estimate for the SPA based on digital aerial survey techniques. Further details are available in the paper Goodship et al. 2015.
  • Visual aerial survey  (1988/89 – 2006/07) A series of three strip transect aerial surveys were undertaken in the winter seasons 1988/89 and 1989/90, and 20 line transect aerial surveys were conducted between the winter seasons 2001/02 – 2006/07. Further details on the methods and survey coverage are available in JNCC Report No. 374 below.
  • Little tern boat-based survey and shore-based counts (2009–2013) – Between 2009 and 2013 JNCC co-ordinated a programme of survey work to identify important foraging areas for little terns. Surveys were conducted during the chick-rearing period each year and comprised repeated shore-based counts of little tern seen at a series of observation stations at increasing distance from the colony locations, and repeated boat-based surveys along transects across the waters around colonies. These surveys sought to establish the distances both alongshore and offshore that little terns were travelling to feed. Further details are available in JNCC Report No. 548 below.
  • Larger terns boat-based visual tracking of foraging birds (2009–2011) – JNCC co-ordinated a programme of visual tracking work between 2009 and 2011 to identify important foraging areas at a number of UK colonies. These surveys were conducted during the chick-rearing period in each year and comprised repeated days of observations of individual terns whose tracks were followed by boat as they left the colony to forage. Further details are available in JNCC Report No. 500 below.
  • Seabird Monitoring Programme (SMP) (2011–2015) – The population estimates for breeding  common tern and little tern  within the Outer Thames Estuary SPA were derived from the most recently available numbers, at the time of classification (2015), from the Seabird Monitoring Programme (SMP) database. Where SMP data were unavailable, data from colony managers, local expert groups (Foulness Area Bird Survey Group, Foulness ringing group), or the Norfolk Bid & Mammal Report were used. Population estimates were calculated as the sum of the numbers of those species at each of the existing SPAs from which the individuals recorded at sea are most likely to originate.


Data analysis reports


Additional relevant literature

Please be aware that although these sources contain information which is of interest in relation to this SPA, they do not necessarily represent the views of JNCC.

  • Skov, H., Heinänen, S., Thaxter, C.B., Williams, A.E., Lohier, S. and Banks, A.N. (2016). Real-time species distribution models for conservation and management of natural resources in marine environments. Marine Ecology Progress Series, 542, 221–234.
  • Goodship, N., Caldow, R., Clough, S., Korda, R., McGovern, S., Rowlands, N. and Rehfisch, M. (2015). Surveys of Red-throated Divers in the Outer Thames Estuary. British Birds, 108, 506–513.
  • O’Brien, S.H., Webb, A., Brewer, M.J. and Reid, J.A. (2012). Use of kernel density estimation and maximum curvature to set Marine Protected Area boundaries: Identifying a Special Protection Area for wintering red-throated divers in the UK. Biological Conservation, 156, 15–21.
  • O'Brien, S.H., Wilson, L.J., Webb, A. and Cranswick, P.A. (2008). Revised estimate of numbers of wintering Red-throated Divers Gavia stellata in Great Britain. Bird Study, 55(2), 152–160.


Knowledge gaps

If you are aware of any additional data or relevant scientific papers for this site not listed in the relevant documentation section, please contact us.


Conservation Advice

Last updated: December 2020

Conservation objectives

Conservation objectives set out the desired state for the protected features of an MPA. The conservation objectives for the protected features of the Outer Thames Estuary SPA have been set based on knowledge of the condition of the protected features at the time of writing. The conservation and advice package is designed to help stakeholders understand how to interpret the conservation objectives and what it means for management of the site. JNCC and Natural England have published joint advice for this site.

The 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 enhance the site and its qualifying features;
  • monitoring the condition of the qualifying features; and/or
  • developing, proposing or assessing an activity, plan or project that may affect the site

The conservation objectives for the protected features of the SPA are to ensure that, subject to natural change, the integrity of the site is maintained or restored as appropriate, and that the site contributes to achieving the aims of the Wild Birds Directive, by maintaining or restoring:

  • the extent and distribution of the habitats of the qualifying features;
  • the structure and function of the habitats of the qualifying features;
  • the supporting processes on which the habitats of the qualifying features rely;
  • the populations of each of the qualifying features; and
  • the distribution of qualifying features within the site.

Supplementary advice on the conservation objectives is available on Natural England's website. These include feature-specific attributes as well as more information on how the objectives might be achieved.


Advice on operations

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

The advice on operations is based on JNCC and Natural England’s scientific knowledge of the feature at the time of writing and their sensitivities to pressures. For the most up-to-date information about the feature within the site and the spatial distribution, please see the Evidence section.

JNCC also provides a list of activities occurring within the site and information on activity management in the Activities and Management section. 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 section, and Evidence section, is 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/or 
  • 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 and Natural England’s conservation advice will be kept under review and will be periodically updated. Conservation advice for sites which straddle the 12 nm boundary will continue to be developed jointly with the relevant country nature conservation body. Further information on JNCC’s conservation advice work is available on the 'Conserving MPAs' webpage. Information can also be found on Natural England’s website.


Activities and Management

Last updated: December 2020

Management status: Progressing towards being well managed.

Monitoring currently implemented includes compliance with licence conditions, fishing vessel monitoring and condition monitoring of protected features. A baseline digital aerial monitoring survey of the Outer Thames Estuary SPA was undertaken in 2013 (Goodship et al 2015).

This site forms part of the networks of MPAs across the UK and contributes to international MPA networks such as that of the North-east Atlantic under OSPAR. As the UK is a contracting party to the OSPAR Commission, JNCC is committed to ensuring that the OSPAR MPA network is well-managed.

JNCC considers 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 site's 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 Outer Thames Estuary SPA around each of the four stages in the MPA management cycle.


1. 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 in the Conservation Advice section.


2. 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.

Natural England, who is jointly responsible for this site, has produced a Site Improvement Plan for the inshore aspect of this site. The plan provides a high-level overview of the issues (both current and predicted) affecting the condition of the sites protected features and outlines the priority measures required to improve their condition.

The protected feature of the site is considered to be sensitive to pressures associated with fishing and 'licensable' activities.


  • The Outer Thames Estuary SPA extends from the coastline beyond the 12 nm limit. Within 6 nm of the coast, only UK vessels operate and any management in this area would be implemented by Inshore Fisheries and Conservation Authorities (IFCAs) or the Marine Management Organisation. Between 6 nm and 12 nm, French and Belgian fishing vessels have access to the site, to implement any fishing restrictions in this area Defra would negotiate with the relevant governments before introducing national fishing prohibition orders applicable to all EU vessels or introducing CFP regulation measures. The section of the SPA lying offshore (beyond 12nm) is also fished by other member states including The Netherlands, Denmark, and Germany. Fisheries are managed through the Common Fisheries Policy (CFP) in all areas beyond 12 nm.
  • No site-specific fisheries management measures are currently in place to protect the classified features of this site. Defra and the Marine Management Organisation (MMO) are leading discussions with stakeholders regarding the development of management for sites on a regional basis. The MMO consulted on draft recommendations on how fisheries should be managed in this SPA in 2016. JNCC will provide advice on possible management options to support these discussions. Further information will be provided here as it becomes available.

Licensable activities

  • Commercial aggregate extraction occurs mostly in the northern extent of the SPA offshore from Great Yarmouth, with some further licence areas off Felixstowe in the north part of the southern section of the SPA.
  • One gas pipeline crosses through the site. Currently no licenced oil and gas blocks overlap the site.
  • There are a number of operational offshore windfarm developments, and associated export cables, located within the Outer Thames Estuary SPA (Kentish Flats 1 & 2, Gunfleet Sands Demo, Gunfleet Sands I & II, Scroby Sands, London Array 1). Offshore to the east of the SPA boundary, there are a further two operational windfarms, and two developments under construction.
  • Licensable activities such as renewable energy developments, aggregate extraction or oil and gas exploration and production taking place or that may take place within this SPA are managed in accordance with The Conservation of Offshore Marine Habitats and Species Regulations 2017 (as amended) and The Conservation of Habitats and Species Regulations 2017 (as amended).
  • Existing licensed activities that take place or may take place in the future within the Outer Thames Estuary SPA will continue to be managed in line with relevant legislation and application processes by the competent authorities. Further information on JNCC's role in the provision of advice for licensed activities in the UK offshore area is available on the offshore industry advice webpages


  • One power cable and a number of telecommunications cables currently cross through the MPA. A network of energy cables associated with wind renewable energy developments are also located within the site.
  • Cables are largely an unregulated activity in offshore waters depending upon the type of cable being laid (or maintained), where it is being laid between and whether the cable is part of a larger development (which may be regulated). Any cable not directly associated with an energy installation does not require a marine license beyond 12 nautical miles.
  • JNCC encourages early discussion from operators regarding any plans related to new or existing cables, and encourages the undertaking of non-statutory environmental impact assessments for new or existing cable projects to assess their effect on the protected features of the MPA.

Shipping and Ports

  • The SPA is situated in a busy marine area; subject to large-scale permanent infrastructure, busy shipping lanes, and other vessel movement. Impacts from shipping could cause a displacement of red-throated divers, though shipping activity has been undertaken in the Thames Estuary for many hundreds of years. The impacts from historical shipping on the red-throated diver population are unknown, shipping activities are largely confined to existing shipping lanes, which are already known to be avoided by Divers. Under international law, ships have a right of passage at sea including in areas designated as MPAs (unless management specifies the restriction of ship transiting as outlined through an International Maritime Organisation measure). 
  • Port of London is one of the UK’s largest ports and the Port of London Authority (PLA) has responsibility for ensuring safe navigation. Maintenance dredging of existing channels extends out into the deep water approach channels in the outer estuary. The proposed approach channel to the consented London Gateway Port (Dubai Ports World) will pass through the site. Felixstowe, the UK’s largest container port, the Port of Ipswich and the Port of Lowestoft also occur within the bounds of this SPA, along with the associated shipping traffic and channel maintenance activities. A new port facility at Great Yarmouth is currently under construction and is expected to accommodate container traffic.


3. Site condition monitoring

A baseline digital aerial monitoring survey was undertaken in 2013 (reported in Goodship et al. 2015). Further information is provided in the Monitoring section.


4. Assessment of progress towards conservation objectives

No long-term condition monitoring data are available to determine whether the SPA is moving towards or has reached its conservation objectives. The site has a ‘maintain or enhance’ conservation objective based on the findings of a vulnerability assessment (exposure to the activities associated with pressures to which the protected features of the site are considered sensitive). Continued site condition monitoring will improve our confidence in this assessment. Further information is provided in the Assessment section.



Last updated: October 2017

JNCC is currently leading on the development of options for biodiversity monitoring across all UK waters. JNCC’s advice for marine birds, which will include SPA monitoring, is anticipated to contain:

  • A summary of existing monitoring schemes which provide annual trends in abundance and breeding success of seabirds; and trends in the number of waterbirds using coastal sites to breed, stopover on migration or to over-winter; along with options to improve their precision;
  • Options for monitoring and surveillance of inshore and offshore aggregations of seabirds and waterbirds at sea and how these options can best be integrated with the above existing surveillance schemes (including whether co-ordinated monitoring of the existing/proposed marine SPA network can contribute to these); and
  • Integration with indicator development work for Marine Strategy Framework Directive.

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



Last updated: December 2020

Under Article 12 of the EU Wild Birds Directive (2009/147/EC), Member States are required to report every six years on their progress on the implementation of the Directive. Following the UK's exit from the European Union, this section will be updated to reflect the new assessment schemes once they are in place.


Published: .

This Site Information Centre (SIC) was created and last substantially updated prior to the end of the Transition Period following the UK’s exit from the European Union (31 December 2020). Therefore some of the content may still refer to EU legislation and management proposals or commitments which were correct at the time that the content was last updated. These references will be revised as necessary when the SIC is next substantially revised. Requirements through EU legislation are being retained in the UK so existing environmental protections and standards remain, and the protection given to habitats and species continues.

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