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Habitats Regulations Appraisal of Draft Plan for Offshore Wind Energy in Scottish Territorial Waters: Proposed Approach for the Screening and Assessment of the Short and Medium Term Options

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2. HRA Stage 4 and 5 - Methods for Screening

2.1 Introduction

This section reviews the methods, criteria and considerations that can be applied to review the pre-screening results and undertake the next screening stages of the HRA process. These next stages involve selecting the final list of the sites and interest features which are to be 'screened into' the AA either because there is a LSE or because a LSE cannot be excluded via the identified impact pathways. The impact pathways and impacting activities are listed in Appendix A of the pre-screening report ( ABPmer 2010a). Therefore, this next screening stage of the process determines which of these impact pathways needs to be taken into the assessment process because they represent a LSE.

It should be noted that LSE is not defined in the Habitats Regulations. The English Nature ( EN) Habitats Regulations Guidance Note 3 ( EN 1999) identifies LSE as a more than ' de minimis' change or, in other words, any effect "that may reasonably be predicted as a consequence of a plan or project that may affect the conservation objectives of the features for which the site was designated, but excluding trivial or inconsequential effects". The European Court Waddenzee judgement 6 provides further clarification on this aspect where it concludes that 'any plan or project not directly connected with or necessary to the management of the site is to be subject to an appropriate assessment of its implications for the site in view of the site's conservation objectives if it cannot be excluded, on the basis of objective information, that it will have a significant effect on that site, either individually or in combination with other plans or projects'. Furthermore, the same judgement adds 'where a plan or project not directly connected with or necessary to the management of a site is likely to undermine the site's conservation objectives, it must be considered likely to have a significant effect on that site. The assessment of that risk must be made in the light inter alia of the characteristics and specific environmental conditions of the site concerned by such a plan or project.'

Given the need for a high level of certainty to meet Habitats Regulations requirements, there is a presumption in favour of 'screening issues in' at this stage, following the precautionary approach. This will be important also for undertaking any detailed assessments (at this Plan-level or in future Project-level assessment work) where there needs to be sufficient confidence in the evidence base and that the delivery of projects under the plan can be sufficiently controlled to avoid adverse effect on integrity. This will include consideration both of the potential flexibilities in the plan (location and scale of development) as well as specific and proven additional mitigation measures where necessary. When considering the relevant screening methods to determine LSE (as presented in this report), it is therefore understood that there again needs to be a presumption in favour of including rather than excluding interest features and designated sites in the HRA process at this stage.

This precautionary approach is also enshrined in the process by which judgments are to be made (during the subsequent AA) about whether the integrity of sites are affected. In particular, under the Habitats Regulations, there is a need for a high level of certainty in the assessment conclusions (also following the precautionary principle). This is also highlighted within the Waddenzee judgement which concluded that 'a plan or project [that is] likely to have significant effect on the site is only to be authorised if it is ascertained that it will not adversely affect the integrity of the site (i.e. where no reasonable scientific doubt remains as to the absence of such effects).

In this context, the review below considers the approaches to be taken for screening each of the following groups of habitats and species:

  • Coastal, intertidal and subtidal habitats and associated species (Section 2.2);
  • Bird Species (Section 2.3);
  • Marine Mammal species (Section 2.4);
  • Migratory Fish and Freshwater Pearl Mussel (Section 2.5); and
  • Otter (Section 2.6).

This review and the preceding pre-screening report focused on qualifying interest features of the designated sites. As advised by SNH, at the next stage, further consideration will also be given to components of individual qualifying interest features within marine SACs (e.g. sparling (the European smelt Osmerus eperlanus) is a fish of conservation concern listed as a typical species of habitat features within the Forth of Tay and Eden SAC).

For each of the groups listed above, precedents that were followed for two previous Plan-level HRAs are described (as requested by the PSG). These precedents are:

  • The Pentland Firth Strategic Area ( PFSA) HRA ( ABPmer 2010b and 2010c) which related to the wave and tidal energy leasing round and
  • The Round 3 Offshore Wind Farm (R3 OWF) HRA (Entec 2009a and 2009b) which related to the plan for nine large-scale windfarm developments around the UK.

In both cases TCE were the lead competent authority with responsibility for producing the AA. As the R3 OWF plan dealt with offshore wind energy generation it will be of greatest relevance to the OWE Draft Plan HRA, however, both studies are considered to provide valuable guidance to screening approaches in this case. This review of precedents has been undertaken to ensure that the HRA for the OWE Draft Plan builds upon and learns from this previous work. Equally, it will help to ensure that this HRA does not depart from agreed methods and relevant guidance unless there is a clear rationale for doing so in the context of the specific issues associated with the OWE Draft Plan.

2.2 Coastal, Intertidal and Subtidal Habitats and Associated Species

2.2.1 Introduction

A large number of UK European/Ramsar sites (355) were identified within the pre-screening process for the medium term options ( ABPmer 2010a), on the basis that they have coastal, intertidal and subtidal habitats and associated species qualifying interests and these will be brought forward into the next phase of the screening process. The broad-scale approach that was taken at pre-screening, screened in all the European/Ramsar sites including those SACs with coastal marine habitat interest features that lie within 100km of the medium term options areas. This process will also have captured almost all designated sites that lie within 100km of the short term option areas although the pre-screening work for these options was carried out separately (Halcrow 2010). For the future HRA work this 100km boundary will be adjusted to ensure that it also lies 100km from all short term option areas and any new sites that are encompassed by this process will be identified.

As set out in the pre-screening report for the medium term options ( ABPmer 2010a), the 100km boundary has been applied because it defines a quantifiable and objective area that is likely to encompass many of the mobile species interest features (fish, seabirds and mammals) within designated sites which could be indirectly affected by the medium term OWE options. However, it has not been used to limit further review of more distant locations or to presume that all relevant features within this area for which impact pathway exists are necessarily affected. In particular, it is recognised that impacts (especially to foraging and migratory bird qualifying interests that are reviewed below) may extend to sites beyond this 100km boundary and this aspect will need to be considered throughout the HRA process.

During pre-screening, those SACs that were within the 100km area but had only inland (non-coastal) freshwater or terrestrial habitat and species qualifying interests were screened out. In the next stages of the HRA it will be possible to reduce this list for each of the short and medium term option areas based on a more detailed consideration about whether there is a LSE. In particular, a closer evaluation can be made about whether the wind energy development could have a direct or indirect effect on the qualifying habitat and species interests of the designated sites that were brought into the assessment at pre-screening. The direct impacts are those that occur to the qualifying habitats and the non-mobile species that they support, at locations where devices or cables are installed (with the non-mobile including prey species for mobile species). The indirect effects to habitats and the non-mobile species that they support could occur through alterations in the physical environment or the water quality conditions from changes to the hydrodynamic conditions and sediment transport pathways.

Such impacts to habitats, species and water quality conditions will be relevant to the screening of many of the SAC, SPA and Ramsar sites either because the habitats and species themselves are qualifying features (or are components of qualifying features). It will also be relevant where the habitats and the species they support play a key role in also supporting qualifying birds, marine mammals, fish interests of these designated areas. An outline approach for undertaking this next phase of screening is set out below in Section 2.2.3. However, in advance of this, and to provide a context for this review and an understanding of the precedents, a brief overview of the methods that were applied to screen and scope habitats for the R3 OWF and PFSAHRAs (Section 2.2.2) is presented.

2.2.2 Precedents for Plan-level Screening

The full list of the impact pathways by which coastal, intertidal and subtidal habitats and the non-mobile species they support can be directly and indirectly affected by offshore windfarm developments were set out in Appendix A (Tables A1 and A2 7) of the pre-screening report. The methods used to screen for such impacts during the two previous Plan-level HRAs are detailed below.

2.2.2.1 Round 3 Offshore Wind Farm HRA

Direct effects on coastal habitats will occur where there is a spatial overlap between the designated site boundary and proposed development footprint. For the R3 OWFHRA therefore, Entec (2009a) screened in all those sites where there is a spatial overlap between a designated site and either a development zone (in this case the Round 3 areas) or a proposed cable alignment. For all such sites it could not be concluded that there was no LSE and therefore the relevant habitats and/or species qualifying features of such designated sites were screened in.

In terms of the potential for indirect effects on habitats and species, it was concluded that there would be no LSE arising from hydrodynamic changes (erosion), sediment disturbance and transport (including any adverse effects from suspended sediment increase, water quality/toxicity or smothering) at any designated site that lies more than the distance of one tidal ellipse 8 away from a cable route or a zone boundary. This was based on evidence from plume studies that even fine particles mobilised from the sea bed settle out again to a large extent within the distance of one tidal excursion. While a plume may be visible beyond this point the concentrations of suspended solids are usually within the range of natural variation and much of the visible plume is due to lipids from damaged benthic animals (Coastline Surveys Ltd 1998 and Clay et al., 2008). This observation was supported by wave and sediment processes studies carried out for the Round 1 and Round 2 offshore windfarms. It was also concluded in this R3 OWF screening report that any noise disturbance to invertebrates would also be confined to an area that is no more than one tidal ellipse from a cable route or zone boundary. This issue of noise impacts to invertebrate species have not been screened into this OWE Draft Plan HRA9.

Entec (2009a) also cited a study into the environmental effects of cabling for offshore windfarms ( BERR 2008) which indicated that sediments suspended by cabling activities do not travel large distances from the cable location, and that the distance travelled is largely influenced by the type of sediment mobilised and the strength of the tidal flows (i.e. the tidal excursion). Studies and modelling undertaken for Round 1 and 2 offshore windfarms were also identified which have shown that cabling during optimum tidal conditions results in a depositional footprint for fine sediments in the order of 200m either side of the cable. On the basis of this research, it was concluded that the only sites that were potentially at risk of causing an indirect LSE on habitats or non-mobile species (due to sediment mobilisation and re-deposition) were those within one tidal excursion (tidal ellipse) around the zone boundary or the cable routes, using a data for a mean spring tide to ensure a precautionary approach. This approach was considered to be precautionary as it is based on transport of fine sediment and where the seabed is sandy, the transport distance will be less.

To consider the effects of cable alignments and landfall this Entec (2009a) study made broad but informed assumptions about the cable routes and landfall positions. It was assumed that all windfarms will connect directly to the mainland with no use of offshore interconnectors and, to inform this, studies by the National Grid and Electricity Networks Strategy Group ( ENSG 2009) were used to identify likely landfalls and substation connections.

Image 2 illustrates the options considered in this study. It was recognised, though, that zone developers could choose alternative cable routes which may have a lower impact on environmental features and/or European/Ramsar sites and it was not possible to assess all conceivable cable routes. It was noted that any assumptions about cable positions (and indeed other aspects of the proposals such as turbine locations, turbine types and capacity) within the plan-level HRA would need to be verified and their relevance addressed as part of project-level HRAs.

Image 2. Options considered for R3 OWF export cable routes based on studies by National Grid and ENSG

Image 2. Options considered for R3OWF export cable routes based on studies by National Grid and ENSG

(Entec 2009a)

2.2.2.2 Pentland Firth Strategic Area HRA

For the PFSA a 100km boundary was used in the pre-screening phase and all sties within that zone were included (see Image 3). For the next screening phase, the approach used was essentially same as that applied for the R3 OWFHRA but geared toward assessing the effects of the wave and tidal energy generating devices and arrays. All relevant designated sites within the PFSA boundary were screened in because of they spatially overlapped with the development zone and thus could be directly affected. To address the potential indirect effects the distance of one tidal excursion was determined around the border of the whole PFSA area. Then, any designated sites that lay within one tidal ellipse distance from the PFSA boundary was also included. Those SAC sites that supported habitats and non-mobile species qualifying interests but which lay outside of this tidal ellipse distance were excluded. It remained the case though, in the absence of project level information, that all designated sites within the PFSA and within the tidal ellipse boundary could be subject to direct and/or indirect effect from the wave and tidal energy leasing round and therefore all these sites were taken forward into the assessment phase of the HRA.

Image 3. Pentland Firth Strategic Area ( PFSA) and 100km screening zone

Image 3. Pentland Firth Strategic Area (PFSA) and 100km screening zone

( ABPmer 2010a)

For the PFSA study, the issue of cable alignments and landfall positions was not addressed in the same manner as for the R3 OWF work. In consultation with the key stakeholders it was agreed that 'there would be sufficient flexibility in terms of the options that are available for cable alignment and landfall position to ensure that effects on terrestrial or freshwater European/Ramsar sites can be readily avoided at a project level'. It was noted also that there could be no absolute guarantee of European/Ramsar sites being avoided and therefore it was recognised that terrestrial and freshwater sites which were excluded at the Plan-level HRA on this basis may need to be considered at project-level HRA if grid connectivity options/constraints do not allow such sites to be avoided. In this context, the sites where an effect was considered to be most likely were those closest to the shoreline. For this reason the marine habitats within coastal SAC sites in the PFSA were scoped into the assessment. This included sites with supralittoral dune habitats due to the functional link between coastal processes and wind-borne sediment transport mechanisms for dune formation. However, the remaining SACs within the 100km boundary around the PFSA (which support other non-mobile supralittoral and inland habitat features) were removed from the scope due to the absence of any hydrodynamic or ecological connectivity with the coastal or inshore environment. This included the vegetated sea cliff features and the coastal lagoons. Also the individual non-mobile supralittoral and inland habitat interest features within coastal SACs were also highlighted as being unaffected by the proposed PFSA Plan.

2.2.3 Screening Methods Review

It is proposed that the methods presented in the previous sections for assessing direct and indirect LSE on habitats and non-mobile species are also applied here for the OWE Draft Plan HRA. With respect to the direct impacts from the installation of the wind turbines, this will apply to those few locations where there is a clear spatial/physical overlap between the option areas and the boundaries of European/Ramsar sites. For such option areas it will not be possible to conclude that there is no LSE. This will also apply to any options areas where the export cable routes or landfalls will cross through a designated site. However, it is recognised that a further understanding about the likely areas of cable alignment and landfall location will be required to determine this.

To determine whether there is a potential for an indirect effect on habitats and non-mobile species, a UK-wide hydrodynamic model will be run to determine the distances covered by one tidal excursion throughout the coastal and offshore waters within which the short of medium option areas are located. This will describe the changes in tidal ellipse shape across this whole area. The reasons for using tidal ellipse distance have been presented above under the review of the R3 OWFHRA approach. Essentially, however, the nature of the tide is such that its movement is typically described as an almost closed ellipse this means that it can be viewed as a package of water will move to and fro over one tidal cycle, typically along a dominant axis, returning to almost the same position.

Thus the shape and distance of the tidal ellipse reflects the path followed by this parcel of water (and material suspended within it) over one excursion. A map of tidal ellipses from a UK-wide hydrodynamic model is shown in Figure 2. Using this map, the nearest ellipses surrounding the boundary of the short of medium option 'areas of search' will be selected and will then be 'moved' to that nearest boundary point to determine how far, and in which direction, a parcel of water will move from this edge to then return. Once this is done, a boundary line will be drawn around the limit of the tidal excursion that is defined. This new boundary will define a zone of potential indirect effect for each of the short and medium term options and, where possible, can be used to describe the same for potential cable routes. However, in considering both the direct and indirect effects of the cable infrastructure network, it is recognised that the alignment of cable routes and the positions of landfalls have yet to be determined. This will mean that defining areas of potential indirect effect around possible cable routes will not be possible for most if not all sites and in the light of this uncertainty it is likely to be necessary to adopt a precautionary approach to meet the requirements of the Habitats Regulations 10.

Although robust information defining the location of cable alignments is limited, it is clear that, some studies are available that can be used to indicate some generic potential options. For instance a Transmission Capital (2010) study for TCE identifies options to deal with energy outputs from the west coast short term option areas of Argyle Array, Islay, Kintyre, Wigtown and Solway Firth. This study provides a possible indication of where cable alignments and landfall location may occur for windfarms in this part of the Scottish coastline although it is recognised that, at this time, there are no defined routes for these or other short or medium term options areas. This study concludes that two or more extra high voltage direct current ( HVDC) cable circuits would be needed in addition to two offshore cable projects identifies in the Energy Network Strategy Group report ( ENSG 2009). It also identifies connection points across UK at Hunterston, Deeside, Kilroot, Tongland and Broughton Moor (see Image 4). During the assessment, other relevant documents detailing potential options will be reviewed to determine whether 'areas of search' can be identified for cable alignments and landfall positions. This will include the Scoping Reports for the proposed short-term options areas; as well as the Offshore Development Information Statement (National Grid 2010), the Scottish Executive's review of the cross border electricity transmission options ( SE 2007) and the Scottish Territorial Waters Offshore Windfarms East and west coast studies (Royal Haskoning 2009a and 2009b). It is recognised though these reviews (e.g. east and west coast grid studies) were commissioned for option appraisal purposes and these potential options may change as developer's progress with detailed design of the Short Term sites. Therefore, notwithstanding the availability of such information, it is likely that uncertainty will remain at the next screening and assessment phase of this HRA about the regions of direct and indirect effect from the cable routes. This uncertainty will need to be considered within the screening process and the assessments and it will need to be accommodated as part of the determinations that made about are proposed manner of the plan's implementation to ensure that there is no adverse effect on the integrity of designated sites. For the purposes of screening, this uncertainty will probably mean that it will not be possible to identify clear cable alignment locations (or even broad areas of search where such alignments could possible occur). In that event, to achieve the high level of certainty required under the Habitats Regulations, the screening process will need to be based solely on the 100km boundary that was used at pre-screening without any further re-screening.

Image 4. Preferred grid designs for connecting to 5 proposed offshore windfarms

Image 4. Preferred grid designs for connecting to 5 proposed offshore windfarms

(Transmission Capital 2010)

2.2.3.1 Summary of the proposed screening process

To summarise the approach described above, an iterative series of tasks has been identified to encompass the proposed LSE screening work. This will be undertaken for each of the 34 short and medium terms options. This process has been developed from the review of approaches taken during previously Plan-level HRAs (as described above) and through consultation with the PSG.

  • Step 1: Agree the list of relevant qualifying features with the PSG and screen out non-coastal habitats and species. This element has largely been completed during the production of the pre-screening report and also during consultations on the early draft of this working paper, however, it is possible that further refinements may be required during subsequent phases of the HRA process (e.g. including species that are components of individual 'estuary' qualifying interest features).
  • Step 2: Identify the best understanding about possible cable alignments and landfall positions to make assumptions and, if possible, identify 'areas of search' for these locations (as noted in preceding section, the first indications from the assessment review work are that this understanding will be insufficient to define areas with the high level of certainty required under the Habitats Regulations).
  • Step 3: Screen in all designated sites and associated habitat and non-mobile species interest features (recognising that these will include prey species for non-mobile birds, fish and marine mammals) that will be directly affected. This will be where there is spatial overlap between the short and medium term options areas or with any defined areas of search for cable alignments and landfalls.
  • Step 4: Undertake a review of tidal excursion patterns around the boundaries of each of the 34 short and medium term option areas as well as any defined areas of search for cable alignments. Then draw a new boundary at a distance of tidal ellipse form these boundaries where it is possible to do so with the requisite certainty (noting the information limitations sets out above).
  • Step 5: Screen in all designated sites and associated habitat and non-mobile species interest features (recognising that these will include prey species for non-mobile birds, fish and marine mammals) that could be indirectly affected because they lie at distances of less than one tidal excursion from any short and medium term options areas or from any defined areas of search for cable alignments and landfalls.
  • Step 6: Alter the pre-screening tables to indicate the coastal, intertidal and subtidal qualifying features that have been screened in or out for each of the 34 short and medium term option areas. Identify any designated sites that can be screened in or out on the basis of the above review (i.e. because there is no LSE for any of their qualifying interest features).
  • Step 7: Record the findings on the screening maps that will be prepared for each of the 34 short and medium term option areas and any defined areas of search for cable alignments.

2.3 Bird Species

2.3.1 Introduction

A large number of UK European/Ramsar sites were identified within the pre-screening process on the basis of their bird qualifying interests and these will be brought forward into the next phase of the screening process. The broad-scale approach that was taken at pre-screening, screened in all the European/Ramsar sites with bird qualifying interest features that lie within 100km of the medium term options areas but excluding species for which there was no LSE with the Draft OWE Plan because they are entirely resident within inland terrestrial habitats, do not forage at sea and do not migrate internationally. Following this review, there are a number of steps that can be undertaken to edit this list so that only sites and features for which there is a LSE are taken forward into the AA process. An outline approach for undertaking this screening is set out below in Section 2.3.3. However, in advance of this, and to provide a context for this review and an understanding of the precedents, an overview of the methods that were applied to screen and scope bird species for the R3 OWF and PFSAHRAs (Section 2.3.2) is presented.

2.3.2 Precedents for Plan-level Screening

The full list of the impact pathways by which habitats can be affected by offshore windfarm developments were set out in Appendix A (Tables A1 and A2) of the pre-screening report. The main sources of impact to bird populations include the potential for collision (during either offshore foraging excursions or during annual migratory movements) but other key impacts will be the direct and indirect effects on habitats as well as disturbance effects during construction or operational phases of the work. The methods used to screen for such impacts during the two previous Plan-level HRAs are detailed below.

2.3.2.1 Round 3 Offshore Wind Farm HRA

For the R3 OWF screening work (Entec 2009a), the first stage of the screening process for bird qualifying interests was to screen out those bird species that were at no risk of impact through the development of offshore windfarms or associated coastal infrastructure as part of the Round 3 plan. The species eliminated from the process were those that are entirely resident within the UK (i.e. do not migrate) and do not forage at sea. This included species associated with coastal areas, provided these areas are more than one tidal excursion from any of the cable routes (and thus outside the zone of potential direct disturbance or indirect effects on supporting habitat and prey species).

For Ramsar sites, those species that appear in the Ramsar selection Criteria 5 or 6 (i.e. the Ramsar site supports a waterbird assemblage or a population of international importance of a migratory species), including species' populations identified subsequent to designation for possible future consideration under Criterion 6, were used to identify Ramsar sites for inclusion in the screening process. Possible marine SPAs and extensions to existing SPAs were also included where they are likely to support foraging seabirds regularly using flight paths between the SPA and likely breeding colonies which cross Round 3 development zones.

A list of 103 migratory and seabird species were identified as being at risk from Round 3 activities. The list of UKSPAs and Ramsar sites which have been identified as supporting populations of these birds (including all sites with internationally important assemblages of waterfowl and seabirds) was presented. There were also a very large number of transnational sites that support breeding or migratory populations of species that could be affected by Round 3 activities. In view of their approach to the screening work (see below) it was not considered appropriate to list all these sites.

The sensitivities of relevant bird species to activities from the R3 OWF were listed and tabulated and only those that relate to the direct and indirect effects on habitats and those sensitivities related to disturbance during cable laying/removal within SPAs and Ramsar sites were used to conclude whether there will be a LSE on the avian interest of the site at the screening stage. For those sensitivities that related to the operation of turbines (collision with turbine blades, the barrier effects to bird movements that can be caused by turbines and noise/visual disturbance relating to turbine operation), Entec (2009a) observed that there is a dearth of empirical data demonstrating the level of effect on individual birds and/or populations in offshore windfarms, although there are some notable exceptions to this rule. Even when information gathered at onshore windfarms is used to supplement the knowledge base, there was considered to be insufficient data on the majority of species (particularly seabirds) to reach any reasoned conclusion and hence an LSE must be assumed.

Furthermore, Entec (2009a) noted that there is little information regarding the distribution of birds at sea, especially foraging seabirds. In order to undertake a robust assessment, the linkages between birds, potential zones of development and SPAs/Ramsar sites need to be understood. It was also noted that it was important to understand the number of birds using the zones in respect both of SPA and biogeographic populations but that, unfortunately, this information is not readily available and is only likely to be captured in a structured and usable format following focused survey effort. With a lack of quantifiable data on impacts and a dearth of information on geographical distribution, there was considered to be no basis for a reasoned assessment to be undertaken either during the screening process or subsequent AA of the Round 3 Plan. Entec (2009a) therefore concluded that it is appropriate to rely upon HRA work at the project-level.

2.3.2.2 Pentland Firth Strategic Area HRA

For the PFSA work, in the pre-screening, all the SPAs and the one Ramsar Site that were within the PFSA and the surrounding 100km boundary were included. In the next stage of screening all seabird interest feature species that lie within the PFSA itself were included because these birds will forage and loaf in coastal and offshore waters within the PFSA. At this stage, species that are confined to terrestrial habitats were excluded and these were Hen Harrier, Short-eared Owl and Peregrine Falcon.

To further consider which of the sites outside the PFSA (both within and beyond the surrounding 100km boundary) needed to be brought into the assessment, the British Trust for Ornithology ( BTO) carried out a review of the seabird foraging and 'at sea' data for the PFSA areas. They then provided advice about the additional interest features and sites that needed to be brought into the scope (especially the SPA and Ramsar sites that lie outside the PFSA boundary). As a result of this review and the advice received from consultees, consideration was given in the first instance to reviewing sites that supported Gannet, Fulmar and Manx Shearwater because these species forage over the greatest distances and could potentially forage in PFSA even from sites beyond the 100km boundary that might have been missed at first screening.

In addition to these sites, the inland Caithness and Sutherland Peatlands SPA was included because it supports Black-throated Diver, Red-throated Diver and Common Scoter and lies at the boundary of the PFSA. The Mousa SPA on the Shetland Islands (which lies 70km from PFSA boundary to the north-west) was also included. This site supports Artic tern and Storm Petrel. The evidence at that time indicated that these species forage over comparatively short distances (quoted as 25km and <50km respectively) and these may not use the PFSA area. However, this site and these interest feature species were included at screening stage on a precautionary basis pending further assessment work.

The other sites outside the PFSA (in the Shetland Island or the North Coast of the Scottish mainland) were considered but not included because they support bird species that would not forage within PFSA at levels that are likely to have a LSE based on the location of these sites and the expected foraging distances of the relevant interest feature species that they support.

2.3.3 Screening Methods Review

Following the pre-screening report for the OWE Draft Plan ( ABPmer 2010a), all SPA sites and all their associated bird interest species within 100km of the medium term option areas were initially included irrespective of whether they undertake coastal and offshore movements. Then, following the approaches taken for the previous HRAs, for the next stage of pre-screening, bird species were excluded where they will not be affected by the OWE Draft Plan because they are entirely resident within inland terrestrial habitats and do not forage at sea and do not migrate internationally (i.e. they are entirely resident within the UK). These bird species were Western Capercaillie, Scottish Crossbill, Golden Eagle (where this species is a qualifying features of inland non-coastal designated sites), Fair Isle Wren, Red-billed Chough and the Eurasian Marsh Harrier. SNH also confirmed that a number of bird species that are qualifying interests of SPAs as breeding populations only could also be screened out at this first stage. These birds species are Hen Harrier, Merlin, Eurasian Dotterel, Spotted Crake, Grey Heron, Little Stint, Curlew Sandpiper, Osprey, Peregrine and Short-eared Owl.

The next stage will be to consider the foraging behaviour of coastal and offshore bird colonies (whether these are overwintering or breeding populations). In particular the distances over which waterbirds forage will be a critical consideration. To inform this review, it will be possible to begin by drawing upon the review of seabird foraging distances that was undertaken by BTO as part of the PFSAHRA work ( ABPmer 2010b). This study identified the maximum distances seabird of seabird foraging based on review of studies including RSPB (2000), Furness & Tasker (2000), Thaxter et al. (2010) and Roos et al. (2010) along with the UK Seabirds at Sea data ( JNCC 2009). It was found that most birds typically forage within 100km of breeding site with the exception of the following species (for which the foraging distances are highlighted in brackets): Razorbill (150km); Guillemot (123km); Puffin (137km); Fulmar (245km); Gannet (540km); Manx Shearwater (330km). During the next phase of the HRA work, these distances will be reviewed as part of a further review of available information and based on advice received from SNH. For this review, the Birdlife International seabird foraging database (http://seabird.wikispaces.com) will act as the source of relevant information and the maximum foraging distances for key species will be identified. The list of species is expected to be as follows (with the maximum foraging distances are highlighted in brackets): -

  • Atlantic Puffin (200km);
  • Black-legged Kittiwake (200km).
  • Common Guillemot (200km);
  • Common Scoter (200km).
  • Manx Shearwater (400km).
  • Northern Fulmar (664km); and
  • Northern Gannet (640km).

Those bird qualifying features that do not forage in offshore waters (but instead only feed within coastal/intertidal habitats) could theoretically be excluded where their foraging habitats will not be directly or indirectly affected. Thus, the approach that will be adopted for assessing direct and indirect habitats effects will be applied and those birds that feed in coastal habitats that are greater than one tidal excursion from any of the option areas or from any potential cable route will be excluded. However, it is noted that many of these species are migratory and so the effects on these species during their migratory movements will need to be addressed. In addition, it is recognised that several species may move between sites outwith the main migratory periods. Waterfowl for instance may relocate to other sites during periods of adverse weather during the winter months. Therefore, it is likely that few if any bird qualifying features are likely to be excluded solely the basis that their main foraging habitats are not directly or indirectly affected by the proposed Draft OWE Plan.

The issue of how to deal with migratory birds is a key one for this HRA and it is understood that there is a limited amount of robust data on this aspect. This is recognised within the SEA (Marine Scotland, 2010b) which records that there is a lack of accurate data showing migratory routes as confirmed via correspondence with the RSPB and SNH. It also noted however, that the Wildfowl and Wetlands Trust ( WWT) are researching migration routes of several bird species in relation to proposed UK windfarm sites. The WWT work included mapping routes of Greenland Barnacle Geese, Greenland White-fronted Geese and Whooper Swans (Griffin et al., 2010) from or along the west coast of Scotland to Iceland and Svalbard Barnacle Geese routes from South-West Scotland to Norway and Svalbard. Geese and swans were the focus for this research as they tend to fly at less than 100m above sea level and could be at risk of collision with wind turbines. The destinations outside of the UK where tagged birds migrate to and from Scotland is reproduced in Table 1.

Table 1. Principal recovery locations for likely focal bird species for the SEA

Species

Principal Recovery Locations of Ringed Birds Outside of Mainland UK

Arctic Skua

Concentrated around Orkney and Shetland Isles

Arctic Tern

Concentrated around Orkney and Shetland Isles, Scandinavia, W Africa

Barnacle Goose (Nearctic)

Iceland, Greenland, Svalbard

Black-legged Kittiwake

USA, Greenland, Faroes, Continental Europe

Brent Goose (light bellied, E. Canada)

Svalbard

Common Tern

Continental Europe , Ireland, W Africa

Common Guillemot

Continental Europe, Scandinavia, Ireland, Orkney and Shetland Isles, Iceland

Corncrake

Unrecorded in Bird Atlas

European Storm Petrel

Ireland, Iceland, Faroe Islands, Scandinavia, Portugal, S Africa

European Shag

Ireland, Faroe Islands, Continental Europe, Scandinavia

Great Northern Diver

Unrecorded in Bird Atlas

Greenland White fronted Goose

Iceland, Greenland, Orkney

Herring Gull

Ireland, Orkney, Shetland Isles

Manx Shearwater

Ireland, Continental Europe

Migrating waterbirds

Various destinations

Northern Gannet

Ireland, Iceland, Continental Europe, Orkney, Shetland Isles, northern Scandinavia, NW Africa

Pink-footed Goose

Iceland, Greenland

Razorbill

Continental Europe, Scandinavia, Ireland, Orkney and Shetland Isles

Whooper Swan

Ireland, Western Isles, Orkney

(Marine Scotland, 2010b)

This table is derived from information within the BTO Migration Atlas Project report and is presented within the SEA Environmental Report (Marine Scotland, 2010b). As recognised within the SEA document, this information does not specifically describe the migration routes but presents a useful collection of ringing recovery information 'for birds that fly to and from Scotland (not necessarily from other parts of the UK)'. As part of the screening and assessment work the scientific literature relating to migratory pathways will be further reviewed to provide further information on the routes that are taken. However, even in advance of such a review, it is recognised that identifying distinct flyway routes will be difficult both because of the nature and limitations of available information on this subject and because these movements are likely to occur across broad fronts rather than along clearly definable routes.

The approach to be taken for making a judgment about LSE in relation to migrating birds will therefore require further consideration and ongoing consultation. However, there is no plan to include transnational sites. This is on the basis that, having included all the bird qualifying features affected across the defined 100km area (and beyond in some instances) during pre-screening, there is not expected to be any additional effect to birds in sites other member states. The only exception would be where there are bird qualifying species within member states sites that could migrate internationally through the 100km area but which would not also be a qualifying species for sites in the UK. There are not expected to be any such species that have not already captured by the above process.

2.3.3.1 Summary of the proposed screening process

To summarise the approach described in the preceding section, an iterative series of tasks has been identified to encompass the proposed LSE screening work. This will be undertaken for each of the 34 short and medium terms options. This process has been developed from the review of approaches taken during previously Plan-level HRAs (as described above) and through consultation with the PSG.

  • Step 1: Agree the list of relevant qualifying features with the PSG and screen out birds qualifying features interest features where they are confined to inland terrestrial habitats and do not migrate internationally. This element has largely been completed during the production of the pre-screening report and also during consultations on the early draft of this working paper, however, it is possible that further refinements may be required during subsequent phases of the HRA process.
  • Step 2: Identify the best understanding about possible cable alignments and landfall positions to make assumptions and, if possible, identify areas of search for these locations (as noted in preceding section, the first indications from the assessment review work are that this understanding will be insufficient to define areas with the high level of certainty required under the Habitats Regulations).
  • Step 3: Screen in the birds qualifying species that forage over distances of >100km (Atlantic Puffin, Black-legged Kittiwake, Common Guillemot, Common Scoter, Manx Shearwater, Northern Fulmar and Northern Gannet) and could potentially feed within or across the short or medium term options areas. This will screen in some designated sites that support these species but lie outside the 100km boundary zone (and have not previously been identified in the pre-screening review).
  • Step 4: Screen out birds species interest features (and where possible the relevant designated sites) that forage on the coastal zone but at distances of greater than one tidal excursion from the short or medium term options areas or from any possible cable routes (but recognising that these species may still be affected during migratory movements).
  • Step 5: Review flyway data to identify any overlap of migratory routes with short or medium term options areas to identify sites (both in UK and rest of Europe) for which LSE on features are possible.
  • Step 6: Consult further with PSG to agree the strategy for identifying the LSE on migratory bird species in the context of available information and the past approaches detailed above.
  • Step 7: Alter the pre-screening tables to indicate the bird species qualifying features that have been screened in or out for each of the 34 short and medium term option areas. Identify any designated sites that can be screened in or out on the basis of the above review (i.e. because there is no LSE for any of their qualifying interest features).
  • Step 8: Record the findings on the screening maps that will be prepared for each of the 34 short and medium term option areas and any defined areas of search for cable alignments.

2.4 Marine Mammal Species (Cetaceans and Seals)

2.4.1 Introduction

A large number of UK European/Ramsar sites were identified within the pre-screening process on the basis that they have marine mammal qualifying interests and these will be brought forward into the next phase of the screening process. The broad-scale approach that was taken at pre-screening, screened in all the European/Ramsar sites with marine mammal qualifying interest features that lie within 100km of the medium term options areas. Following this review, there are a number of steps that can be undertaken to edit this list so that only sites and features for which there is a LSE are taken forward into the AA process. An outline approach for undertaking this screening is set out below in Section 2.4.3. However, in advance of this, and to provide a context for this review and an understanding of the precedents, an overview is presented of the methods that were applied to screen and scope bird species for the R3 OWF and PFSAHRAs (Section 2.4.2).

2.4.2 Precedents for Plan-level Screening

The full list of the impact pathways by which marine mammals can be affected by offshore windfarm developments were set out in Appendix A (Tables A1 and A2) of the pre-screening report. One of the key considerations will be the effects of noise (including especially from piling during installation but also from operational noises during operation and decommissioning). In addition there are the risks of collision with the vessels that access the site during survey, construction, maintenance and decommissioning and there are also potential risks from habitat displacement and impacts upon prey distribution. The methods used to screen for such impacts during the two previous Plan-level HRAs are detailed below.

2.4.2.1 Round 3 Offshore Wind Farm HRA

For the purposes of the R3 OWF pre-screening study (Entec 2009a), and in the light of the consultations that were held during it, all UK sites with marine mammals were scoped into the assessment along with a large number of transnational sites. For common and grey seals the other European sites included those that west of the Skagerrak (north of Denmark) and north of Brest (France). This was on the basis that seals generally stay within reach of coastal haul out sites but that tracking of individuals had shown that they can feed up to several hundred kilometres offshore ( SMRU 2006). This encompassed an area that was greater than 300km from the nearest Round 3 area (see Image 2 for R3 OWF locations). For bottlenose dolphin and harbour porpoise the same study screened in sites that were west of the Kattegat (between Denmark and Sweden) and north of Porto (Portugal) which were some 600-700km from the nearest Round 3 area. The larger selection area for these species was warranted because cetaceans range over much greater areas than seals but those species in the Baltic or Mediterranean were unlikely to be affected by the R3 OWF plan.

Following pre-screening 105 designated sites with marine mammal interest features were identified of which, 24 were UKSACs, one was a UK Ramsar Site (Humber Estuary where there is a breeding colony of grey seals) and 80 were transnational SACs in Belgium, Germany, Denmark, Spain, France, Ireland, the Netherlands and Sweden. Image 5 shows the sites that were screened in for marine mammal qualifying interests as part of the R3 OWFHRA.

Image 5. Sites screened in for marine mammal qualifying interests as part of the R3 OWFHRA

Image 5. Sites screened in for marine mammal qualifying interests as part of the R3OWF HRA

(Entec 2009a)

In the screening/scoping phase Entec gave further consideration to the interlinked factors of:

  • The likelihood of presence of a significant number (in terms of populations associated with sites for which they are interest features) of each species in the vicinity of development zones or cable routes; and to
  • The likelihood of effects on individuals of that species if they are present in the vicinity of development zones or cable routes (the main potential for effect on marine mammals is from underwater noise), taking account of the mitigation measures that have been written into the Plan.

However, given the need to investigate noise effects further as well as the sensitivity of marine mammals and the distances over which they roam, all sites were taken forward into the AA stage which it was not possible to conclude that there would be no LSE. As a further guide to the OWE Draft Plan screening work the findings from the detailed study that was then undertaken for the AA (Entec 2009b) are outlines below. This review shows the ranges of the four marine mammal species that were reviewed.

Bottlenose Dolphin

Of the transnational sites which have bottlenose dolphin as an interest feature, it was concluded that individuals from 9 sites on the Western German and Dutch coasts and the northern French coast may interact with the Round 3 sites of the eastern UK. It was found that there was a lack of scientific evidence about the distribution of these species and that there was an insufficient understanding about the migration patterns of this species (or whether they migrate at all) which meant that and effect on these transnational sites could not be ruled out. For these sites, plan-level mitigation measures to control noise levels were identified to ensure that there would be no 'adverse effects on their integrity' ( AEOI). For the two UK sites in Wales (Cardigan Bay and Lleyn Peninsula) similarly plan level mitigation was identified to ensure that there would be no AEOI. For the one site in Scotland (Moray Firth) no adverse effects of plan were identified but it was noted that a project-level HRA was needed and, as part of that mitigation measures will need to be implemented to ensure no AEOI. All other sites were considered to be too distant for there to be an adverse effect. The evidence, for instance, indicates that populations on the west coast of Spain, France and Ireland do not overlap with Round 3 zones.

Harbour Porpoise

Within the AA it was recognised that, the distribution and behaviour of harbour porpoise is better understood than for bottlenose dolphin with some studies describing clear population boundaries for this species. This evidence meant that a judgment of no AEOI was reached for 22 of the transnational sites for which this species is an interest feature. The exceptions were 5 Belgian sites and 1 French site for which there was limited scientific information on migratory patterns for the harbour porpoises and which were relatively close to the R3 Zone 5 (which lies is off the East Anglian coast). For these 6 sites, plan-level mitigation measures to control noise levels were identified to ensure that there would be no AEOI. It was noted also that the Dogger Bank is a draft SAC (d SAC) for which the potential interest features could include harbour porpoise (as well as grey seal and common seal and sandbanks which are slightly covered by the sea at all times). Impacts to this site may need to be addressed once this site is proposed and if harbour porpoise is confirmed as a qualifying feature.

Common Seal

Within the R3 OWFAA, it was noted that common seals travel, on average, 50km to foraging areas with some tagged individuals having been found up to 150km from the haul-out sites (with a few foraging even further) for up to a couple of days at a time. On this basis it was concluded that all the sites in the UK except those on the north-west of Scotland could be adversely affected by one or more of the Round 3 zones. However, it remained unclear with available evidence, whether significant proportions of the SAC populations would frequent these zones. Therefore, plan-level mitigation measures were identified for all UK sites to minimise any adverse effects with the measures requiring to be defined further at project level. Given the distances involved it was considered to be highly unlikely that common seals from transnational SACs would be adversely affected with the exception of Dogger Bank in German Waters.

Grey Seal

Within the R3 OWFAA, it was noted that grey seals travel up to a few hundred kilometres for a couple of days at a time. On this basis it was concluded that all the sites in the UK except those on the north-west of Scotland and the Isles of Scilly could be adversely affected by one or more of the Round 3 zones. However, it remained unclear with available evidence, whether significant proportions of the SAC populations would frequent these zones. Therefore, plan-level mitigation measures were identified for all UK sites to minimise any adverse effects with the measures requiring to be defined further at project level.

2.4.2.2 Pentland Firth Strategic Area HRA

The approach taken for the PFSA pre-screening and scoping was to use a 100km boundary around the leasing round area and screen in all the sites supporting bottlenose dolphin, grey seal or common seal interest features that lie within that boundary. Based on advice received from SNH all the sites with marine mammal, grey seal and common seal interest features within the 100km area were included within the assessment. This included the Moray Firth SAC (bottlenose dolphin interest feature) which was located outside the PFSA but within the 100km external screening area. It also included five sites with common or grey seal interest features of which two were inside the PFSA area (Sanday SAC and Faray and Holm of Faray Sac) while a further three were at North Rona SAC, Mousa SAC and Dornoch Firth and Morrich More SAC. The approach of setting a 100km boundary was adopted based on: the lessons that were learned from the preceding R3 OWFHRA work; a review of cetacean and seal behaviour (across the PFSA particularly) and the feedback received during consultations with key stakeholders including SNH. SNH also recommended that the Yell Sound SAC in Shetland (common seal interest feature) which lies just outside this boundary was also included (thus six sites were considered in total). All the designated sites that were selected through this screening process were assessed equally within the AA which was informed by a separate review of evidence relating to marine mammal activities in the PFSA. For all sites, marine mammal feature mitigation measures at plan level had been identified before the HRA or were introduced into the plan in the light of the assessment's findings to ensure that there was no adverse effect on the integrity of any of these sites.

Image 6. SAC Sites and interest features outside the PFSA that were scoped into the assessment phase of the HRA

Image 6. SAC Sites and interest features outside the PFSA that were scoped into the assessment phase of the HRA

( ABPmer 2010b)

In summary therefore, a boundary of approximately 105km was applied for the PFSAHRA (i.e. the original 100km pre-screening boundary with some surrounding sites) to address risk to all marine mammal interest features. No other transnational or UK sites were included (the nearest transnational sites were some 800-1000km away). A 100km boundary was again applied for the pre-screening of the OWE draft plan and, building on the PFSA and R3 OWF precedents, the following section provide an overview of cetacean and seal ecology/behaviour to inform decisions about how the pre-screened sites should now be screened and scope prior to an AA.

2.4.3 Screening Methods Review

Within the OWE Draft Plan HRA it will necessary to consider the effects on grey seal, common seal and bottlenose dolphin (which are the three species which are qualifying interest features of UKSACs and were identified during the pre-screening process 11). Further details about the ecology and behaviour of these species are presented below and then a summary of the proposed screening approach (based on that applied for the PFSAHRA) is outlined.

Bottlenose Dolphin

Within the 100km area used for pre-screening, the only site with bottlenose dolphin as an interest feature was the Moray Firth SAC (as was the case for the PFSAHRA). The Moray Firth is part of the core range of the only known resident population of bottlenose dolphin in the North Sea (Scottish Executive, 2007). As noted above, scientific understanding about the offshore distribution of these species is limited although the evidence is that the Moray Firth SAC population are most frequently sighted within the inner Moray Firth with occasional observations from further offshore in the North Sea ( DECC, 2009). It is also known that they range across the coastal waters south of the Moray Firth. They typically reach St Andrews Bay but are also sighted within the Firth of Forth and north east England ( WDCS 2010).

In the 1980s, the core of the population's known range was focused in the inner Moray Firth but since the early 1990s, the population's range has expanded south such that the whole stretch of coastal waters to the Firth of Forth is considered to be a critical habitat for this species ( WDCS 2010). Surveys along the southern coast of the Moray Firth from 2001-2005 encountered bottlenose dolphins along the majority of this coastline, primarily in waters <25m depth (Robinson et al., 2007). The abundance estimates for this population range from 75-200 individuals from 1990-2002 but are subject to considerable uncertainty (Thompson et al., 2004). The abundance of bottlenose dolphin in the SCANS- II around the Northern Isles and Moray Firth has been estimated at 412 individuals and, most recently, the numbers on the east coast of Scotland has been estimated at 193 ( WDCS 2010).

Occasional North Sea offshore observations may indicate that these animals are also distributed offshore for at least for part of the year (Reid et al., 2003; SMRU, 2007). However, understanding of their offshore distribution is poor due to limited survey effort away from the coast. A recent review by WDCS (2010) actually identifies two forms of bottlenose dolphin; an offshore and a coastal form although little is known about the offshore forms and their relationships with coastal forms. Occasional visual and acoustic surveys in offshore waters of the Moray Firth have encountered very few bottlenose dolphins (Hastie et al., 2003, Talisman Energy ( UK) Limited, 2006, SCANS- II 2008). The Whale and Dolphin Conservation Society conducted surveys of the outer Moray Firth in 2008 and recorded no bottlenose dolphin sightings, with the main cetaceans recorded consisting of harbour porpoise and minke whale ( WDCS, 2009).

Image 7. Bottlenose dolphin abundance estimates

Image 7. Bottlenose dolphin abundance estimates

( WDCS 2010 and citations)

The distribution of bottlenose dolphin (based on current understanding of near-shore population and community structure) was also reviewed by the ASCOBANS/ HELCOM12 small cetacean population structure workshop (Evans and Teilmann, 2009). This proposed separate management units for a range of populations (recognising though that it is quite possible that some areas have overlapping communities with different movement patterns). Image 8 shows these areas with the 'North Sea ( NS) area being relevant to the Bottlenose Dolphins using Eastern Scotland from Caithness to the borders with England (and including the Moray Firth). This North Sea area is also illustrated in greater detail in Figure 3.

For the screening of Bottlenose dolphin therefore it is recommended, that the area in which the Moray Firth population are most frequently sighted (see Images 7 and 8) acts as a basis for spatially screening selected short and medium term options areas. Therefore, this interest feature will be relevant mainly for the short and medium term options areas that are located off the eastern Scottish coastline.

Image 8. Proposed management units for cetacean populations

Image 8. Proposed management units for cetacean populations

(Evans and Teilmann, 2009)

Grey and Common Seal

The movements of seals and the distances over which they move from their breeding and haul out sites is better understood than for cetacean species and it is possible to draw upon a range of studies that have been made the movements of seals fitted with satellite tags (Matthiopoulos et al., 2004; Sharples et al., 2008; Cunningham et al., 2009; McConnell et al., 1999; Tollit et al 1998 and Thompson et al. 1996). These studies show that there is a distinct difference between the distances that are covered by grey and common seals from their haul-out sites. In summary the key observations for each species have been as follows:

  • Grey Seals have been recorded up to 2100km from haul out sites and Farne Islands and Moray Firth grey seals have been recorded visiting sites in Pentland Firth and Orkney (Orkney is approximately 400km from the Farne Islands). In general however most tagged seals stay close to the coast (mean 39.8km for a foraging trip) with an average of 43% of a seal's time spent within 10 km of a haul-out site; and
  • Common or Harbour Seals typically cover shorter distances and generally move to alternative haul-out sites within a range of 75km although travel over 100km has been recorded. Most seals forage up to 60km from their haul-out site with half of the trips being within 25 km of a haul-out site. Most common seals returned to the same haul-out site from which they departed.

Given these movements it is recommended that the approach adopted for the PFSAHRA is used here for the screening of grey and common seal interest features. Essentially, this means taking forward all those sites that have been identified at the pre-screening stage and does not involve further considerations of marine mammal qualifying interests from outside of the UK (due to the distance between the OWE Draft plan option areas and the transnational designated sites).

Image 9. Estimated usage of the marine environment by grey (A) and common (B) seal

Image 9. Estimated usage of the marine environment by grey (A) and common (B) seal

(Matthiopoulos et al 2004, Sharples et al 2008 and DECC 2009)

2.4.3.1 Summary of the proposed screening process

To summarise the approach described above, an iterative series of tasks has been identified to encompass the proposed LSE screening work. This will be undertaken for each of the 34 short and medium terms options. This process has been developed from the review of approaches taken during previously Plan-level HRAs (as described above) and through consultation with the PSG.

  • Step 1: Agree the list of relevant qualifying features with the PSG. This element has been completed during the production of the pre-screening report and also during consultations on the early draft of this working paper.
  • Step 2: Identify the best understanding about possible cable alignments and landfall positions to make assumptions and, if possible, identify areas of search for these locations (as noted in preceding section, the first indications from the assessment review work are that this understanding will be insufficient to define areas with the high level of certainty required under the Habitats Regulations).
  • Step 3: Screen in all designated sites and associated seal species interest features that lie within 100km of any short and medium term options areas or of any defined areas of search for cable alignments .
  • Step 4: Screen in the Moray Firth SAC and associated bottlenose dolphin interest features for short and medium term options areas or for any defined areas of search for cable alignments that lie within the North Sea Population Management unit (see Figure 3).
  • Step 7: Alter the pre-screening tables to indicate the marine mammal species qualifying features that have been screened in or out for each of the 34 short and medium term option areas. Identify any designated sites that can be screened in or out on the basis of the above review (i.e. because there is no LSE for any of their qualifying interest features)
  • Step 8: Record the findings on the screening maps that will be prepared for each of the 34 short and medium term option areas and any defined areas of search for cable alignments.

2.5 Anadromous Fish and Freshwater Pearl Mussel

2.5.1 Introduction

A number of UK European/Ramsar sites were identified within the pre-screening process on the basis that they have anadromous fish qualifying interests and these will be brought forward into the next phase of the screening process. The broad-scale approach that was taken screened in all the European/Ramsar sites that lie within 100km of the medium term options areas.

The species that are relevant are the anadromous fish (i.e. those which live mainly at sea but spawn in freshwater) which are listed under Annex 1 of the Habitats Directive: Atlantic salmon ( Salmo salar); allis shad ( Alosa alosa); twaite shad ( Alosa fallax); sea lamprey ( Petromyzon marinus) and river lamprey ( Lampetra fluviatilis). One potentially relevant catadromous species (i.e. lives in freshwater but returns to the sea to spawn) is the European eel ( Anguilla anguilla). This is not listed in Annex I of the Habitats Directive, but it does form part of the qualifying criteria for some Ramsar sites. However, this species was not included as a qualifying species in any of the Ramsar sites that were identified at pre-screening and therefore only the anadromous species will be considered further as part of this HRA.

In addition, those designated sites with freshwater pearl mussel as a qualifying features were also added. This is because, while this is a sessile freshwater species, it relies on the anadromous Atlantic Salmon for dispersion during its larval phases and, therefore, any major declines in Atlantic Salmon populations (the impact pathways for anadromous fish being relevant) could translate to an indirect effect on this species also. Based on the past work, a proposed approach for undertaking the screening for these sites is set out below in Section 2.5.3. However, in advance of this, and to provide a context for this review and an understanding of the precedents, an overview is presented of the methods that were applied to screen and scope bird species for the R3 OWF and PFSAHRAs (Section 2.5.2).

2.5.2 Precedents for Plan-level screening

The full list of the impact pathways by which anadromous fish qualifying interests and, by association, freshwater pearl mussel qualifying features can be affected by offshore windfarm developments were set out in Appendix A (Tables A1 and A2) of the pre-screening report. One of the major issues for these species will be the effects of noise on fish qualifying interests during the construction and also operational phases of the work. In addition, the effects of changes to habitat, reductions in prey availability or alterations in water quality conditions (turbidity increases) are among the other key consideration. The methods used to screen for such impacts during the two previous Plan-level HRAs are detailed below.

2.5.2.1 Round 3 Offshore Wind Farm HRA

Within the R3 OWFHRA, the SACs and Ramsar sites in the UK which support anadromous fish qualifying species were identified and taken into the assessment process. In addition, the catadromous eel (as qualifying criteria of the Severn Estuary Ramsar site) was also included. Thus both types of migratory fish species were collectively referred to as diadromous.

Relevant estuarine and freshwater SACs were initially included in the pre-screening scope where a Round 3 zone is located within an estuarine area through which these diadromous fish must pass to reach these rivers, or where cable routes may affect such an estuary. Using these criteria, it was found that Zones 1, 2, 3, 4, 8 and 9 (as shown in Image 2) were associated with estuaries of SAC rivers that have migratory fish as interest features and were included in the screening process. No transnational sites were included on this list, as no cables make landfall on the continent and it was assessed that no Round 3 zones were close enough to mainland Europe to impede migration at sea of diadromous fish.

The subsequent screening in of direct and indirect effects (from turbidity) on diadromous fish species was undertaken based on the same approach as for habitats and non-mobile species. Thus, direct effects were identified where there is spatial overlap between cable laying routes and the designated sites (no direct effects from zones themselves will occur given their location), while indirect effects were identified where there is overlap with the tidal ellipse around these cable routes or around the R3 OWF zones (Entec 2009a). It was recognised though that the effect of noise required further consideration based on migratory routes, predicted noise levels and fish sensitivities. This aspect was therefore taken forward into the assessment phase.

Image 10. SACs screened for the presence of anadromous fish interest features

Image 10. SACs screened for the presence of anadromous fish interest features

(Entec 2009a)

2.5.2.2 Pentland Firth Strategic Area HRA

For the PFSAHRA, it was noted that there is limited information, on the distribution and migratory routes of anadromous fish in coastal waters and therefore the screening of sites with these interest features was based largely on the advice received from SNH. The three riverine SAC sites that support Atlantic Salmon and which lie along the landward boundary of the PFSA (i.e. the north coast of Scotland) were included because salmon will clearly pass through the PFSA to reach these sites. In addition, SNH recommended that two other sites were added to the scope. :

  • The River Oykel SAC (which lies outside the PFSA and within the 100km buffer zone) which has Atlantic Salmon Qualifying Interests; and
  • The River Spey SAC (which lies just beyond the 100km boundary) which supports Atlantic Salmon and Sea Lamprey interest features.

Also following previous advice from SNH that was provided as part of the R3 OWFHRA work, freshwater pearl mussel was also included in the assessment scope where relevant sites supported both this species and Atlantic salmon as interest features. As discussed above, this was due to the important role that salmon play in the life cycle of the pearl mussel. These two interest features are found at four sites where a LSE of Atlantic Salmon has previously been identified: the River Naver, River Borgie, River Spey and River Oykel SACs.

2.5.3 Screening Methods Review

As noted above, the screening methods that were applied for the R3 OWF and the PFSAHRA were broadly the same but had slight differences which, to some degree reflects the differences in the Plans and the greater risk posed to anadromous fish species from dynamic underwater tidal devices that were proposed as part of the PFSA plan (i.e. as opposed to static structure proposed for the windfarm projects). In general terms, the initial screening of the PFSA was more broad ranging and included a greater spatial extent of sites (including those at and beyond the 100km boundary) as opposed to the R3 OWFHRA (which focused on areas where the windfarms might hamper the migration of fish through species estuarine environments). For the screening of the short and medium term sites for the Draft OWE Plan an approach is proposed which essentially integrates both of these methods. In the first instance all sites supporting anadromous fish and freshwater pearl muscle interest features have been screened in across the 100km area surrounding the medium term option areas. To further screen these the latest understanding about fish migration patterns around the Scottish coast will be used to understand the relative position, and thus potential influence, of each of the short and medium term option areas along these migration pathways.

Following a review of available evidence (on Atlantic salmon and European eel) Malcolm et al. (2010) suggested a conceptual model on how Scottish salmon reaching the coast subsequently migrate towards their natal river (revising a previous model by Shearer (1992)). The revised model proposes that multi-sea winter ( MSW) salmon and 1 sea-winter (1 SW) grilse return both to the north and west coasts of Scotland, and may even reach the north east coast directly having passed Orkney and Shetland. In general this wide geographic distribution of potential arrival locations gives variable and apparent random directions of migration. After they reach the coast they move towards their home rivers, giving apparently variable patterns of migration for a given tagging position. Given that MSW salmon rivers dominate the north and east coasts, the dominant direction of movement for MSW fish caught on the west will be north and east. However, for grilse, the pattern of movement would depend on where they reach the shoreline and where their native river was located. For the east coast rivers south of Aberdeenshire the pattern appears clearer, with fish generally moving in a northward direction from the Northumberland coast, in agreement with Shearer (1992).

While there is a recognition that gaps in understanding clearly remain about how salmon (and especially smolts) migrate, this is considered to be the best available scientific understanding and this conceptual model to the screening process for the OWE Draft Plan. To do this the coastal regions of Scotland have been divided into five regions as shown in Figure 4. It is then possible to use these regions (alongside the location of the SACs which have anadromous fish and freshwater pearl mussel qualifying interests) to understand the extent to which short or medium term option areas might influence migrations. Based on these five regions, the proposed screening principles are

  • Areas in the 'South West' will need to screen in SACs within this region only. This is because anadromous fish will enter from the north mainly and are unlikely to pass through this area to get to other SACs (even if they enter from the south they clearly won't pass any other windfarm areas that are part of the Draft OWE Plan).
  • Areas in the 'West' will need to screen in SACs across all the regions surrounding the Scottish mainland ( NB Shetland doesn't have SAC designated for anadromous fish interests). This is because fish passing though this part of the coastline could move on to any of the designated SACs.
  • Areas in the 'North' and in 'Shetland' will need to screen in SACs in both the north and east. This is because fish passing though these regions are likely to be coming predominately from the north and then moving on to the SAC locations along these northern and eastern coasts.
  • Areas in the 'East' will need to screen in SACs within this region only (i.e. where the majority of SACs are located). This is because fish passing though this regions, from which ever direction they have arrived, are less likely to be moving through this region to SACs in other locations. It is recognised that the risk of impact is likely to be greater here given the proximity of the areas to the majority of designated sites.

Image 11. Dominant directions of travel for Atlantic salmon in Scottish coastal

Image 11. Dominant directions of travel for Atlantic salmon in Scottish coastal

(Malcolm et al., 2010)

2.5.3.1 Summary of the proposed screening process

To summarise the approach described above, an iterative series of tasks has been identified to encompass the proposed LSE screening work. This will be undertaken for each of the 34 short and medium terms options. This process has been developed from the review of approaches taken during previously Plan-level HRAs (as described above) and through consultation with the PSG.

  • Step 1: Agree the list of relevant qualifying features with the PSG. This element has been completed during the production of the pre-screening report and also during consultations on the early draft of this working paper.
  • Step 2: Identify the best understanding about possible cable alignments and landfall positions to make assumptions and, if possible, identify areas of search for these locations (as noted in preceding section, the first indications from the assessment review work are that this understanding will be insufficient to define areas with the high level of certainty required under the Habitats Regulations).
  • Step 3: Screen in all designated sites and associated anadromous fish interests that will be directly affected. This will be where there is spatial overlap between the short and medium term options areas or with any defined areas of search for cable alignments and landfalls.
  • Step 4: Screen in all designated sites and anadromous fish interests species interest features that could be indirectly affected because they lie at distances of less than one tidal excursion distance from any short and medium term options areas or from any defined areas of search for cable alignments and landfalls.
  • Step 5: Screen in anadromous fish for those short and medium term option areas (including cable route areas where known) that have the potential to affect fish migration around the coast and into designated estuaries or rivers. The approach to be taken here will depend upon the region in which the areas, and any possible cable routes, are located (as described above and shown in Figure 4). The approach will be as follows:
    • Areas in the 'South West' will need to screen in SACs within this region only;
    • Areas in the 'West' will need to screen in SACs across all regions ( NB Shetland doesn't have SAC designated for anadromous fish interests);
    • Areas in the 'North' and in 'Shetland' will need to screen in SACs in the north and east regions; and
    • Areas in the 'East' will need to screen in SACs within this region only (although the risk of impact is likely to be greater here given the proximity of the areas to the majority of designated sites).

This approach will be applied for salmon and lamprey species (noting that lamprey SACs are all located in the 'South West' and 'East' while Salmon SACs are present across all regions including Northern Ireland).

  • Step 6: Screen in freshwater pearl mussel for those short and medium term option areas (including cable route areas where known) using the approach adopted in Step 5 but recognising in this case that Atlantic salmon don't need to be a qualifying feature of the SAC for a site to be screened in.
  • Step 7: Alter the pre-screening tables to indicate the anadromous fish and freshwater pearl mussel qualifying features that have been screened in or out for each of the 34 short and medium term option areas. Identify any designated sites that can be screened in or out on the basis of the above review (i.e. because there is no LSE for any of their qualifying interest features).
  • Step 8: Record the findings on the screening maps that will be prepared for each of the 34 short and medium term option areas and any defined areas of search for cable alignments.

2.6 Otter

2.6.1 Introduction

At the pre-screening stage several European/Ramsar sites were included in the HRA. This approach screened in all European/Ramsar sites including SACs with otter features within 100km of the medium term options areas. In the next stages of the HRA it will be possible to revisit this list based on a more detailed consideration about whether there is a LSE. An outline approach for undertaking this next screening is set out below in Section 2.6.3. However, in advance of this, and to provide a context for this review and an understanding of the precedents, a brief overview of the methods that were applied to screen and scope habitats for the R3 OWF and PFSAHRAs (Section 2.6.2) is presented.

2.6.2 Precedents for Plan-level screening

The full list of the impact pathways by which otter can be affected by offshore windfarm developments were set out in Appendix A (Tables A1 and A2) of the pre-screening report. In particular, the OWE Draft Plan has the potential to affect otter populations directly where cable alignments and landfall infrastructure cause damage to key habitats or shelters at or near the shoreline or from collision with vessels moving to and from the site There is also the potential for indirect effects through visual disturbance. The methods used to screen for such impacts during the two previous Plan-level HRAs are detailed below.

2.6.2.1 Round 3 Offshore Wind Farm HRA

Within the R3 OWF screening review (Entec 2009a) it was concluded that otter are most likely to be affected by disturbance at the coast and within estuaries with the relevant impact pathway being 'increased vessel activity at ports where shipping activity is currently infrequent or absent'. During the initial pre-screening review therefore, the sites with otter as a qualifying species were included if they fell within one tidal excursion of a cable route or zone, on the basis that this distance would never be less than the distance over which disturbance (by noise or human activity) could affect this species 13.

2.6.2.2 Pentland Firth Strategic Area (Wave and Tidal Energy) HRA

During the PFSA screening and assessment, it was recorded (based on SNH advice about the impacts of development on otter ( SNH 2010) as well as relevant Regulation 33 documents ( SNH 2006)) that otter are vulnerable to the loss of their shelters (including those on the shoreline) and to loss of habitat which, in turn, can leave them more exposed to disturbance effects. Therefore, habitat damage and disturbance are interlinked factors. For the purposes of the PFSA therefore, both the impacts from visual disturbance (from vessels and other activities during survey work, construction, maintenance and decommissioning) and the presence of operational structures or visiting vessels (which could result in collision and/or mortality) were considered. However, as noted above, the PFSA study did not address landfall impacts and therefore, while it addressed the impacts to habitats from devices on coastal foraging grounds, it did not consider the direct impacts to coastal habitats and shelters from cable alignments.

Also in the PFSA assessment it was noted that, the distances offshore that foraging occurs is not clear but it is unlikely to be beyond water depths of greater than 10m (the depth at which they are identified as being at risk of entanglement in pots/creels). It was also identified that otter move large distances along riverine habitats (some are known to use 20km or more of river habitat) but that they also tend to be very territorial. The guidance on undertaking surveys to assess impacts upon this species ( SNH 2010) suggests that distances of 200-250m are appropriate. During the PFSAHRA screening and scoping study ( ABPmer 2010b), advice was sought from SNH (Rob Raynor Species Advisor) as to the distances over which otters may forage in order to identify which sites may be subject to a LSE from the Plan. It was recommended that a 10km boundary represents an appropriate buffer distances beyond which a plan or project would be unlikely to have a significant effect. This was the approach adopted for the PFSAHRA.

2.6.3 Screening Methods Review

For the OWE screening work it is proposed that a 10km boundary is identified around designated sites for which otter are an interest feature (based on the approach that was adopted for the PFSA projects). The evidence and guidance that is available would point to this being a highly precautionary approach and it is recognised that, in general terms, the risk to otter from wind turbines are lower than they are for mobile tidal devices (given that the former are static underwater) during a project's operational phases at least. -

2.6.3.1 Summary of the proposed screening process

To summarise the approach described above, an iterative series of tasks has been identified to encompass the proposed LSE screening work. This will be undertaken for each of the 34 short and medium terms options. This process has been developed from the review of approaches taken during previously Plan-level HRAs (as described above) and through consultation with the PSG.

  • Step 1: Identify the best understanding about the possible cable alignments and landfall positions to make assumption and, if possible, identify areas of search for these locations. As noted above, the first indications from the assessment review work are that this understanding will be insufficient to define areas with the high level of certainty required under the Habitats Regulations.
  • Step 2: Screen in otter for those short and medium term option areas (including cable route areas where known) that lie at distances of less than 10km from the designated sites.
  • Step 3: Alter the pre-screening tables to indicate the otter qualifying features that have been screened in or out for each of the 34 short and medium term option areas. Identify any designated sites that can be screened in or out on the basis of the above review (i.e. because there is no LSE for any of their qualifying interest features)
  • Step 4: Record the findings on the screening maps that will be prepared for each of the 34 short and medium term option areas and any defined areas of search for cable alignments.