Seas off St Kilda proposed SPA

Status: Under Consultation - proposed Special Protection Area (pSPA)

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The consultation on this area closed at midnight on the 17 January 2017.

 Seas off St. Kilda pSPA

The proposed Seas off St Kilda SPA covers the waters around the St Kilda archipelago, about 50 km west of North Uist in the Outer Hebrides, Scotland. In spring and summer, this part of the Atlantic Ocean teems with more than 600,000 pairs of seabird, most of which breed on St Kilda.

The seabirds of St Kilda comprise the largest, oldest and most spectacular marine seabird community in western Europe and one of the most important in the whole North Atlantic. More than 7% of Britain’s breeding gannet population exploits the Seas around St Kilda, capturing mackerel, herring, sandeel, and other fish. Although capable of flying hundreds of kilometres, northern gannets Morus bassanus nesting on St Kilda feed mostly in the productive and readily accessible waters around the islands. Other iconic St Kilda seabirds using the site include fulmars, puffins, and the nocturnal storm-petrels, all of which occur in large numbers in the islands.

Seabirds breeding on St Kilda are already protected whilst on land and in the waters immediately surrounding the islands by the existing St Kilda SPA. The new proposed Seas off St Kilda SPA will complement the existing protection and ensure that the adjacent marine foraging area and the prey on which the seabirds depend are equally protected. These two sites will provide protection for the birds from their breeding sites all the way out to their most important feeding grounds.

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

Relevant Documents

The documents referred to below are specific to Seas off St Kilda pSPA and form JNCC’s advice and evidence package.  The consultation is inviting comments  on the Site Selection Document, which outlines the scientific case for the classification of the pSPA.  JNCC provide all the other documents listed below to support the consultation process with information on the suggested Conservation Objectives and Management Options for the site. JNCC are not consulting on these documents but would welcome any information to further develop the texts.

Site Selection Document  – This document is a detailed overview of the pSPA, the qualifying features and rationale for site selection.

Conservation Objectives and Reg 18 package  – This document contains the draft Conservation Objectives for the qualifying bird features of the site as well as information about the sensitivity of the features to human activities and their pressures on the environment.

Advice to Support Management  - This paper considers a range of activities taking place within the pSPA, and focuses on activities which we consider present a risk to the protected features.

Impact assessment  – Provided by Marine Scotland covering all Scottish SPA sites. The impact assessment will help people understand how the pSPA may impact on them and estimate the economic, environmental and social costs and benefits of the pSPA.

Leaflet – A summary leaflet about the pSPA has been created to distribute locally and at stakeholder events. A pdf version is also available to download here.


Should you wish to make a response please do so using this online form.

Information about the general UK SPA site selection process is available on the JNCC SPA  pages. In addition, details about how JNCC selected the most suitable pSPAs in UK offshore waters (Stage 2 of the UK SPA selection process) is provided here.


The Seas off St Kilda marine proposed Special Protection Area is being proposed by the UK Government to meet obligations set out in the Birds Directive (2009/147/EC). The Directive provides a framework for the conservation and management of, and human interactions with, wild birds in Europe.

Site details


UK offshore waters,

Scottish continental shelf

Location (Centroid*)

58° 05.705’N, 8° 31.333’W


 3,995 km2
Features proposed

Breeding season

northern gannet Morus bassanus,

northern fulmar Fulmarus glacialis, (assemblage).

common guillemot Uria aalge, (assemblage).

Atlantic puffin Fratercula arctica, (assemblage).

European storm-petrel Hydrobates pelagicus, (assemblage).

Site overview
The Seas off St Kilda proposed SPA (pSPA) is located in Scottish marine waters situated about 50 km northwest of North Uist in the Western Isles of Scotland. At the centre of the site is the St Kilda archipelago, consisting of the four islands Hirta, Dun, Soay and Boreray and a number of sea-stacs, which form the existing St Kilda SPA . The Seas off St Kilda pSPA will provide additional protection for five seabird species which use these surrounding seas for foraging.

The pSPA lies very close to the continental shelf edge, with water depth quickly increasing at the western and the northern boundary. Shelf-break fronts are a typical phenomenon at the shelf edge and, like almost all fronts, are regions of enhanced plankton production, leading to a higher fish production (Mann and Lazier 1991). The Seas off St Kilda are known to be high intensity nursery grounds of mackerel Scomber scombrus (Coull et al. 1998; Ellis et al. 2012), which is a common prey species of Northern gannets in UK waters.

Seas off St Kilda pSPA has the largest regularly occurring marine aggregation of breeding northern gannet identified in UK waters (Kober et al. 2012). Evidence of gannets using St Kilda as a breeding ground (or gannetry) extends back 2,100 years, where remains of gannets have been found within the human settlement. Gannets have a foraging range of 229 km (mean +/- 124 km) therefore in theory birds from the Flannan Isles and Sula Sgeir gannetries could also be using the Seas Off St Kilda site for foraging (Thaxter et al, 2012).

More details of these studies can be found in the Evidence tab.

Site boundary description: The boundary for this pSPA has been set based on data showing the extent of the northern gannet aggregation in the area.  It is a relatively simple polygon enclosing the minimum area necessary to ensure protection of the identified northern gannet hotspot around St Kilda (Kober et al. 2012). The other qualifying species, which form part of the breeding seabird assemblage, are quantified within the area used by northern gannet. The landward boundary of the Seas off St Kilda pSPA is adjacent to the existing St Kilda SPA to avoid overlap of the SPAs.

View the proposed boundary on a marine chart background

If you want to know more about the methods used to identify the Seas off St Kilda pSPA, please look at our web page on Marine SPA  Identification, which will provide some background on the different strands of work JNCC used to identify marine SPAs, or on the web page on ESAS methods, which will provide more details on the data and methods used for this work.



COULL,K.A., JOHNSTONE,R., & ROGERS,S.I. 1998. Fisheries Sensitivity Maps in British Waters. UKOOA Ltd.

ELLIS,J.R., MILLIGAN,S.P., READDY,L., TAYLOR,N., & BROWN,M.J. 2012. Spawning and nursery grounds of selected fish species in UK waters. Science Series Technical Report No. 147. CEFAS, Lowestoft, UK.

KOBER,K., WILSON,L.J., BLACK,J., O'BRIEN,S., ALLEN,S., WIN,I., BINGHAM,C., & REID,J.B. 2012. The identification of possible marine SPAs for seabirds n the UK: The application of Stage 1.1-1.4 of the SPA selection guidelines. JNCC Report No. 461.

MANN,K.H. & LAZIER,J.R.N. 1991. Dynamics of Marine Ecosystems: Biological-Physical Interactions in the Oceans. Blackwell Scientific Publications, Oxford.

THAXTER,C.B., LASCELLES,B., SUGAR,K., COOK,A.S.C.P., ROOS,S., BOLTON,M., LANGSTON,R.H.W., & BURTON,N.H.K. 2012. Seabird foraging ranges as a preliminary tool for identifying candidate Marine Protected Areas. Biological Conservation 156: 53-61.

Site specific data
The full overview of the data used to support site identification along with information on qualifying species is available in the Seas off St Kilda pSPA site selection document
Data for the identification of this pSPA have been collected by boat surveys for the ESAS database. Data from these surveys provide direct evidence confirming the presence of the protected features within this pSPA area. Information from the Seabird Monitoring Programme (SMP) database is used to supplement ESAS data to provide evidence of regular occurrence of species at the colonies most likely to be providing birds that forage in the Seas off St. Kilda. Tracking data were used to highlight the importance of this area to the breeding northern gannet populations from St. Kilda.

Data gathering

  • European Seabirds at Sea database

    The European Seabirds at Sea (ESAS) database is a collation of surveys of seabirds at sea in northwest European waters. Further information on ESAS and the analytical methods is summarised in marine SPAs for seabirds. At Seas off St Kilda pSPA, the analysis of the ESAS data determines the overall importance of the location for the qualifying species. It provides an estimate of the number of birds present at the site and information on how regularly they occur.

    The ESAS data showed that more than 67,000 birds used the Seas off St Kilda pSPA during the breeding season, including 50,000 northern gannets which use the site. This is the only area where northern gannet exceeded the 1% biogeographic population threshold (used to select SPAs) on a regular basis. The other species qualifying as part of the seabird assemblage are; northern fulmar, European storm-petrel, common guillemot and Atlantic puffin. Population estimates for these species can be found in the Site Selection Document.

  • Tracking data from St Kilda SPA
    In 2010, Wakefield et al. (2013) fitted 21 adult northern gannets from the St Kilda gannetry with Platform Terminal Transmitter tags. The study shows that northern gannets from St Kilda use Seas off St Kilda to forage during the breeding season and highlights the importance of the marine site to the breeding population at this particular gannetry.

Seabird distribution
The Seas off St Kilda proposed SPA was designed to protect primarily northern gannet during the breeding season. The boundary is therefore determined by the northern gannet distribution and aims to capture the most important area for this species.

Seabird features whose distributions are defining the proposed boundary
Northern gannet, breeding [view map]

Seabird features which are protected but which are not defining the proposed boundary
Within the boundary, is an important seabird assemblage of >20,000 individual seabirds present during the breeding season. The seabird assemblage distribution does not affect the Seas off St Kilda proposed SPA boundary, in fact important seabird areas for these species might well occur outside the boundary. Nevertheless the seabird number within the proposed boundary exceeds the threshold used to determine assemblage protection through the Birds Directive and therefore the breeding seabird assemblage is included as a feature in the proposal.

The most important seabird species making up the assemblage also occur as protected features in the Seas off St Kilda proposal. Just like the assemblage they jointly form, their distribution does not affect the proposed boundary and important areas for these species might well occur outside the boundary.    

Seabird assemblage, breeding [view map]

Named components of the breeding seabird assemblage:

                Northern gannet, breeding [view map]
                Northern fulmar, breeding [view map]
                European storm-petrel, breeding) [view map]
                Common guillemot, breeding [view map]
                Atlantic puffin, breeding [view map]



European Seabirds at Sea (ESAS) database

WAKEFIELD,E.D., BODEY,W., BEARHOP,S., BLACKBURN,J., COLHOUN,K., DAVIES,R., DWYER,R.G., GREEN,J.A., GRÉMILLET,D., JACKSON,A.J., JESSOPP,M.J., KANE,A., LANGSTON,R.H.W., LESCROËL,A., MURRAY,S., LE NUZ,M., PATRICK,S.C., PÉRON,C., SOANES,L.M., WANLESS,S., VOTIER,S.C., & HAMER,K.C. 2013. Space partitioning without territoriality in Northern Gannets. Science 341: 70.

Conservation objectives

The Conservation Objectives set out what needs to be achieved for the site to make the appropriate contribution to the conservation status of the features for which the site is designated and thus deliver the aims of the Birds Directive.

The draft conservation objectives for the protected features of the Seas off St Kilda pSPA have been set based on our understanding of what is important with regards to defining condition of the protected feature at the time of writing. Further information on  conservation objectives is provided in the Seas off St Kilda Conservation objectives and advice on operations document.



To avoid significant deterioration of the habitats of the qualifying species or significant disturbance to the qualifying species, subject to natural change, thus ensuring that the integrity of the site is maintained in the long term and makes an appropriate contribution to achieving the aims of the Birds Directive for each of the qualifying species.


This contribution would be achieved through delivering the following objectives for each of the sites qualifying features: 


a) Avoid significant mortality, injury and disturbance of the qualifying features, so that the distribution of the species and ability to use the site are maintained in the long-term;
b) Maintain the habitats and food resources of the qualifying features in favourable condition.



Further supplementary advice on the draft conservation objectives is provided in the Conservation objectives and advice on operations document.

Conservation Objectives are the starting point from which any management actions and monitoring programmes may be developed and should be considered when completing a Habitats Regulations Appraisal (HRA) for a proposed plan or project in or near this site.


Advice on operations

In line with Regulation (18) of the Offshore Marine Conservation (Natural Habitats, & c.) Regulations 2007 (as amended), the advice on operations identifies those operations (human activities) that may cause damage or deterioration to the qualifying species, or their supporting habitats, for which the Seas off St Kilda pSPA has been classified. This information will be useful if you are developing, proposing or assessing an activity, plan or project that might affect the site.

The greatest direct threats to northern gannet, northern fulmar, common guillemot and Atlantic puffin from human activities are likely to be energy production and extraction of living resources (fishing) activities (based on best scientific evidence at the time of writing). However, all may be sensitive to some pressures exerted by the following types of activity;

  • renewable energy developments: wind, wave and tidal.
  • marine hydrocarbon energy developments,
  • fishing activities
  • disturbance from activities such as shipping and recreational boating/yachting.
  • military activities
  • possibly industrial and agricultural liquid discharges and to waste disposal from munitions, but little is known and this is not assessed due to lack of evidence. 

These activities do not necessarily occur in or near the site at present however they are important to bear in mind to avoid potentially damaging activities from occurring within the pSPA in the future.

No assessments of sensitivity of European storm-petrel or any other petrel species to activities or pressures are available, and there is little evidence to help with assessments of what they might be sensitive to. Thus we cannot say anything at this stage about where we consider there could be a greater risk.

Any activity that can cause a pressure or pressures to which the feature may be sensitive could present a risk to the feature of not achieving the conservation objective and we advise competent authorities should manage these in order to reduce or remove the overall risk to the proposed site’s qualifying features. Further information on activities than can present a risk to the achievement of the site’s conservation objectives is available in the advice package.

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.



Management actions seek to avoid any adverse effects on the listed features from those pressures associated with human activities.  All activities (on or off-site) should be managed in such a way as to minimise disturbance and mortality of the proposed bird features themselves or the habitat and food resource on which they rely, to avoid the risk of impacting the local population level to ensure the site’s conservation objectives are achieved (Tillin et al, 2010).

JNCC has developed a management options paper  to support discussions with stakeholders about the management of activities within this pSPA. This paper considers a range of activities and developments taking place within the pSPA at the point of writing, and focuses on where we consider there could be a risk of the protected features not achieving their conservation objectives.   

TILLIN,H.M., HULL,S.C.,& TYLER-WALTERS,H. 2010. Development of a Sensitivity Matrix (pressures-MCZ/MPA features). Report to the Department of Environment, Food and Rural Affairs from ABPMer, Southampton and the Marine Life Information Network (MarLIN) Plymouth: Marine Biological Association of the UK. Defra Contract No. MB0102 Task 3A, Report No. 22.a