Accidental Pollution

The potential for LSE on Annex II diadromous features of European sites as a result of accidental pollution can be discounted at this stage. The justification is as presented previously in section 5.3.3 - Construction Phase: Accidental Pollution.

Decommissioning Phase

The potential for impacts during the decommissioning phase are considered to be similar and potentially less than those outlined above in the construction phase (section 5.3.3 - Construction Phase) and have not been reiterated.

5.3.4. Determination of LSE for Annex II Diadromous Fish Species

Table 5.4 Open ▸ to Table 5.9 Open ▸ presents the results of the LSE determination assessment as a result of the Proposed Development on relevant qualifying interest features of the Tweed Estuary SAC, River Tweed SAC, River South Esk SAC, River Tay SAC, River Dee SAC and the River Teith SAC, respectively. These assessments are made in the absence of mitigation measures. The footnotes to the following tables provide a brief assessment to support the screening in or out of each of the likely significant effects on the identified SAC features. Where effects are not applicable to a particular feature they are greyed out.

Likely Significant Effects in combination

The LSE test requires consideration of the Proposed Development alone and/ or in-combination with other plans and projects. Therefore, it is not necessary at the LSE stage to consider sites/features for which an LSE ‘alone’ has already been identified, as in-combination effects will be considered at the Appropriate Assessment. The focus at this stage should be to identify sites/features for which no LSE alone was concluded, but there is potential for a LSE in-combination with other plans and projects (e.g. due to wide foraging ranges resulting in a species interacting with a large number of projects).
Given the highly precautionary method for site selection applied during this Screening assessment, it is considered that the consolidation of information regarding external plans and projects would not likely result in additional European sites or new effect pathways being identified for the Screening assessment.
For diadromous fish species, the potential for LSE alone is identified for all sites with the potential to be affected, therefore effects in-combination will be considered at Appropriate Assessment.

Table 5.4: LSE Matrix for Annex II Diadromous Fish Species of the Tweed Estuary SAC

a: Temporary habitat loss/disturbance – there is no potential for any direct physical overlap between the activities associated with all phases of the Proposed Development and the boundary of the European site. It can, therefore, be concluded that there is no potential for LSE on any Annex II diadromous fish qualifying interest features of the site from temporary habitat loss/disturbance.

b: Increases in SSC and sediment deposition - the extent of this impact, across all phases of the Proposed Development, will be spatially restricted to within the boundaries of the Proposed Development and the surrounding area (which will be refined through physical processes modelling to be undertaken for the EIA). Due to the distance between the Proposed Development and this site (29.0 km from the ECC and 42.0 km from the Proposed Development Array Area) and the highly mobile nature of migratory fish, it is concluded that there is no potential for LSE on any Annex II diadromous fish qualifying interest features of the site.

c: Underwater noise - there is potential for migratory species to be present within or transiting through the Proposed Development Array Area and potential area of impact (injury and behavioural) from underwater noise during construction and decommissioning. There is therefore considered to be the potential for LSE on Annex II diadromous fish features of the site during the construction and decommissioning phases. Noise levels will be substantially lower during the operation and maintenance phase and, as such, it is concluded that there is no potential for LSE on Annex II diadromous fish qualifying interest features of the site during the operation and maintenance phase.

d: Long-term habitat loss - there is no direct physical overlap between the footprint of the Proposed Development and the SAC. It can therefore be concluded that there is no potential for LSE on any Annex II diadromous fish qualifying interest features of the site from long-term habitat loss.

e: EMF – EMF emitted from subsea electrical cabling has the potential to interfere with the navigation of migratory fish. It is considered that there is potential for LSE on the Annex II diadromous fish qualifying interest features of the site from EMF during the operation and maintenance phase.

f: Colonisation of hard structures – artificial structures placed on the seabed (i.e. foundations and scour/cable protection) are expected to be colonised by a range of marine organisms leading to localised increases in biodiversity and potential changes in prey-predator interactions. It is considered that there is potential for LSE on the Annex II diadromous fish qualifying interest features of the site from the colonisation of hard structures during the operation and maintenance phase.

g: Accidental pollution – a good practice approach will be implemented as part of the Proposed Development via post-consent plans (e.g. a PEMMP) to reduce potential impacts associated with accidental pollution events across all phases of the Proposed Development, irrespective of the possible effects on European sites. Following advice from NS (2021) and MSS (2021), accidental pollution associated with construction activities is not considered as an effect pathway because this will be subject to other regulatory control through both legislation and the requirements for contingency plans. This rationale is taken to apply to all phases of the Proposed Development and the potential for LSE is discounted.

h: In-combination effects - Activities associated with planned projects or other activities in the vicinity of the Proposed Development have the potential to result in LSE to Annex II diadromous fish qualifying interest features of the site as a result of in-combination effects across all phases. Where potential for LSE has been concluded alone, the potential for LSE has been concluded in-combination.

Table 5.5: LSE Matrix for Annex II Diadromous Fish Species of the River Tweed SAC

b: Increases in SSC and sediment deposition - the extent of this impact, across all phases of the Proposed Development, will be spatially restricted to within the boundaries of the Proposed Development and the surrounding area (which will be refined through physical processes modelling to be undertaken for the EIA). Due to the distance between the Proposed Development and this site (33.6 km from the ECC and 46.6 km from the Proposed Development Array Area) and the highly mobile nature of migratory fish, it is concluded that there is no potential for LSE on any Annex II diadromous fish qualifying interest features of the site as a result of increased SSC and deposition.

c: Underwater noise - there is potential for migratory species to be present within or transiting through the Proposed Development Array Area and potential area of impact (injury and behavioural) from underwater noise during construction and decommissioning. There is therefore considered to be the potential for LSE on Annex II diadromous fish features of the site during the construction and decommissioning phases. Noise levels will be substantially lower during the operation and maintenance phase and, as such, it is concluded that there is no potential for LSE on any Annex II diadromous fish qualifying interest features of the site during the operation and maintenance phase.

d: Long-term habitat loss - there is no direct physical overlap between the footprint of the Proposed Development and the SAC. It can therefore be concluded that there is no potential for LSE on Annex II diadromous fish qualifying interest features of the site from long-term habitat loss.

e: EMF – EMF emitted from subsea electrical cabling has the potential to interfere with the navigation of migratory fish. It is considered that there is potential for LSE on Annex II diadromous fish qualifying interest features of the site from EMF during the operation and maintenance phase.

f: Colonisation of hard structures – artificial structures placed on the seabed (i.e. foundations and scour/cable protection) are expected to be colonised by a range of marine organisms leading to localised increases in biodiversity and potential changes in prey-predator interactions. It is considered that there is potential for LSE on Annex II diadromous fish qualifying interest features of the site from the colonisation of hard structures during the operation and maintenance phase.

Table 5.6: LSE Matrix for Annex II Qualifying Features of the River South Esk SAC

a: Temporary habitat loss/disturbance – there is no potential for any direct physical overlap between the activities associated with all phases of the Proposed Development and the boundary of the European site. It can, therefore, be concluded that there is no potential for LSE on any Annex II species that are qualifying features of the site from temporary habitat loss/disturbance.

b: Increases in SSC and sediment deposition - the extent of this impact, across all phases of the Proposed Development, will be spatially restricted to within the boundaries of the Proposed Development and the surrounding area (which will be refined through physical processes modelling to be undertaken for the EIA). Due to the distance between the Proposed Development and this site (44.5 km from the Proposed Development Array Area and 79.0 km from the ECC) and highly mobile nature of migratory fish, it is concluded that there is no potential for LSE on any Annex II species that are qualifying features of the site.

c: Underwater noise - there is potential for Atlantic salmon smolts and/or adults to be present within or transit through the Proposed Development array area and potential area of impact from underwater noise during construction and decommissioning. There is therefore considered to be the potential for LSE on the Atlantic salmon feature of the site during the construction and decommissioning phases of the Proposed Development. As the lifecycle of the freshwater pearl mussel is dependent on Atlantic salmon, there may be an indirect impact upon this feature of the site and LSE on freshwater pearl mussel cannot be excluded. Noise levels will be substantially lower during the operation and maintenance phase and, as such, it is concluded that there is no potential for LSE on Annex II species that are qualifying features of the site during the operation and maintenance phase.

d: Long-term habitat loss - there is no direct physical overlap between the footprint of the Proposed Development and the SAC. It can therefore be concluded that there is no potential for LSE on any Annex II species that are qualifying features as a result of long-term habitat loss.

e: EMF – EMF emitted from subsea electrical cabling has the potential to interfere with the navigation of migratory fish. It is considered that there is potential for LSE on Atlantic salmon from EMF during the operation and maintenance phase. As the lifecycle of the freshwater pearl mussel is dependent on Atlantic salmon, there may be an indirect impact upon this feature of the site and LSE on freshwater pearl mussel also cannot be excluded.

f: Colonisation of hard structures – artificial structures placed on the seabed (i.e. foundations and scour/cable protection) are expected to be colonised by a range of marine organisms leading to localised increases in biodiversity and potential changes in prey-predator interactions. It is considered that there is potential for LSE on Atlantic salmon from the colonisation of hard structures during the operation and maintenance phase. As the lifecycle of the freshwater pearl mussel is dependent on Atlantic salmon, there may be an indirect impact upon this feature of the site and LSE on freshwater pearl mussel cannot be excluded.

Table 5.7: LSE Matrix for Annex II Diadromous Fish Species of the River Tay SAC

a: Temporary habitat loss/disturbance – there is no potential for any direct physical overlap between the activities associated with all phases of the Proposed Development and the boundary of the European site. It can therefore be concluded that there is no potential for LSE on any Annex II diadromous fish qualifying interest features of the site from temporary habitat loss/disturbance.

b: Increases in SSC and sediment deposition - the extent of this impact, across all phases of the Proposed Development, will be spatially restricted to within the boundaries of the Proposed Development and the surrounding area (which will be refined through physical processes modelling to be undertaken for the EIA). Due to the distance between the Proposed Development and this site (82.8 km from the Proposed Development Array Area and 90.4 km from the ECC), it is concluded that there is no potential for LSE on any Annex II diadromous fish qualifying interest features of the site.

c: Underwater noise - there is potential for migratory species to be present within or transit through the Proposed Development array area and potential area of impact (injury or behavioural) from underwater noise during construction and decommissioning. There is therefore considered to be the potential for LSE on Annex II diadromous fish qualifying interest features of the site during the construction and decommissioning phases. Noise levels will be substantially lower during the operation and maintenance phase and, as such, it is concluded that there is no potential for LSE on any Annex II diadromous fish qualifying interest features of the site during the operation and maintenance phase.

e: EMF – EMF emitted from subsea electrical cabling has the potential to interfere with the navigation of migratory fish. It is considered that there is potential for LSE on any Annex II diadromous fish qualifying interest features of the site from EMF during the operation and maintenance phase.

f: Colonisation of hard structures – artificial structures placed on the seabed (i.e. foundations and scour/cable protection) are expected to be colonised by a range of marine organisms leading to localised increases in biodiversity and potential changes in prey-predator interactions. It is considered that there is potential for LSE on any Annex II diadromous fish qualifying interest features of the site from the colonisation of hard structures during the operation and maintenance phase.

Table 5.8: LSE Matrix for Annex II Qualifying Features of the River Dee SAC

a: Temporary habitat loss/disturbance – there is no potential for any direct physical overlap between the activities associated with all phases of the Proposed Development and the boundary of the European site. It can therefore be concluded that there is no potential for LSE on any Annex II species that are qualifying features of the site as a result of temporary habitat loss/disturbance.

b: Increases in SSC and sediment deposition - the extent of this impact, across all phases of the Proposed Development will be spatially restricted to within the boundaries of the Proposed Development and the surrounding area (which will be refined through physical processes modelling to be undertaken for the EIA). Due to the distance between the Proposed Development and this site (74.5 km from the Proposed Development Array Area and 114.5 km from the ECC), it is concluded that there is no potential for LSE on any Annex II species that are qualifying features of the site.

c: Underwater noise - there is potential for Atlantic salmon smolts and/or adults to be present within or transit through the Proposed Development array area and potential area of impact from underwater noise during construction and decommissioning of the Proposed Development. There is therefore considered to be the potential for LSE on the Atlantic salmon feature of the site during the construction and decommissioning phases. As the lifecycle of the freshwater pearl mussel is dependent on Atlantic salmon, there may be an indirect impact upon this feature of the site and LSE on freshwater pearl mussel cannot be excluded. Noise levels will be substantially lower during the operation and maintenance phase and, as such, it is concluded that there is no potential for LSE on Annex II species that are qualifying features of the site during the operation and maintenance phase.

d: Long-term habitat loss – there is no direct physical overlap between the footprint of the Proposed Development and the SAC. It can therefore be concluded that there is no potential for LSE on any Annex II species that are qualifying features of the site from long-term habitat loss.

f: Colonisation of hard structures – artificial structures placed on the seabed (i.e. foundations and scour/cable protection) are expected to be colonised by a range of marine organisms leading to localised increases in biodiversity and potential changes in prey-predator interactions. It is considered that there is potential for LSE on Atlantic salmon from the colonisation of hard structures during the operation and maintenance phase. As the lifecycle of the freshwater pearl mussel is dependent on Atlantic salmon, there may be an indirect impact upon this feature of the site and LSE on freshwater pearl mussel also cannot be excluded.

Table 5.9: LSE Matrix for Annex II Diadromous Fish Species of the River Teith SAC

a: Temporary habitat loss/disturbance – there is no potential for any direct physical overlap between the activities associated with all phases of the Proposed Development and the boundary of the European site. It can therefore be concluded that there is no potential for LSE on any Annex II species that are qualifying features of the site as a result of temporary habitat loss/disturbance.

b: Increases in SSC and sediment deposition - the extent of this impact, across all phases of the Proposed Development, will be spatially restricted to within the boundaries of the Proposed Development and the surrounding area (which will be refined through physical processes modelling to be undertaken for the EIA). Due to the distance between the Proposed Development and this site (137.2 km from the Proposed Development Array Area and 103.9 km from the ECC), it is concluded that there is no potential for LSE on any Annex II species that are qualifying features of the site during any phase of the Proposed Development.

c: Underwater noise - there is potential for migratory species to be present within or transit through the Proposed Development array area and potential area of impact from underwater noise during construction and decommissioning of the Proposed Development. There is therefore considered to be the potential for LSE on Annex II diadromous fish qualifying interest features of the site during the construction and decommissioning phases. Noise levels will be substantially lower during the operation and maintenance phase and, as such, it is concluded that there is no potential for LSE on any Annex II species that are qualifying features of the site during the operation and maintenance phase.

d: Long-term habitat loss - there is no direct physical overlap between the footprint of the Proposed Development and the SAC. It can therefore be concluded that there is no potential for LSE on any Annex II species that are qualifying features of the site from long-term habitat loss.

e: EMF – EMF emitted from subsea electrical cabling has the potential to interfere with the navigation of migratory fish. It is considered that there is potential for LSE on any Annex II species that are qualifying features of the site from EMF during the operation and maintenance phase.

f: Colonisation of hard structures – artificial structures placed on the seabed (i.e. foundations and scour/cable protection) are expected to be colonised by a range of marine organisms leading to localised increases in biodiversity and potential changes in prey-predator interactions. It is considered that there is potential for LSE on any Annex II species that are qualifying features of the site from the colonisation of hard structures during the operation and maintenance phase.

5.4. Assessment of LSE for Annex II Marine Mammals

A total of 24 European sites were identified in the initial screening process (section 4.3) to be taken forward for determination of LSE for Annex II marine mammals. These sites are listed below, broken down by country:

five sites in the United Kingdom

– Berwickshire and North Northumberland Coast SAC;

– Isle of May SAC;

– Firth of Tay and Eden Estuary SAC;

– Southern North Sea SAC; and

– Moray Firth SAC.

11 sites in Germany (see Table 4.3 Open ▸ );
five sites in Denmark (see Table 4.3 Open ▸ );
two sites in the Netherlands (see Table 4.3 Open ▸ ); and
one site in Sweden (see Table 4.3 Open ▸ ).

5.4.2. Site Overviews

The following sections provide a brief overview of each of the UK sites brought forward for consideration of LSE and a summary of their designated features. The Natura 2000 standard data forms are provided in Appendix 1 for all sites. This includes sites within other European Economic Area (EEA) states for which a potential transboundary impact has been identified. These sites are not therefore summarised in detail below.

Berwickshire and North Northumberland Coast SAC

The Berwickshire and North Northumberland Coast SAC is located approximately 30.1 km from the Proposed Development array area and 3.0 km from the proposed ECC (see Figure 4.3). The site is designated for grey seal, and the site supports approximately 3% of the British annual pup production of this species. Breeding, hauling out and moulting occurs on habitats above the Highest Astronomical Tide (HAT) in areas such as Staple Island within the Farne Islands. A large number of seals also haul out around Holy Island sands, Lindisfarne (Natural England and NatureScot, 2021).

Isle of May SAC

The Isle of May SAC lies at the entrance to the Firth of Forth, approximately 38.5 km from the Proposed Development array area and 20.9 km from the proposed ECC (see Figure 4.3). The site supports a breeding colony of grey seals and is the largest east coast breeding colony of grey seals in Scotland and the fourth-largest breeding colony in the UK, contributing approximately 4.5% of annual UK pup production (JNCC, 2020g).

Firth of Tay and Eden Estuary SAC

The Firth of Tay and Eden Estuary SAC is located approximately 42.5 km from the Proposed Development array area and 51.7 km from the proposed ECC (see Figure 4.3). The site is designated for harbour seal and supports a nationally important breeding colony of harbour seal, part of the east coast population of harbour seals that typically utilise sandbanks. Around 600 adults haul out at the site to rest, pup and moult, representing around 2% of the UK population of this species (JNCC, 2020h).

Southern North Sea SAC

The Southern North Sea SAC is located approximately 144 km from the Proposed Development array area and 151 km from the proposed ECC (see Figure 4.3) and is an area of importance for harbour porpoise. The site includes key winter and summer habitat for this species and supports an estimated 17.5% of the UK North Sea Management Unit (MU) population for harbour porpoise. Approximately two-thirds of the site, the northern part, is recognised as important for harbour porpoise during the summer season, whilst the southern part supports persistently higher densities during the winter (JNCC, 2017).

Moray Firth SAC

The Moray Firth SAC in north-east Scotland is located approximately 224 km from the Proposed Development array area and 151 km from the proposed ECC (see Figure 4.3). The site supports the only known resident population of bottlenose dolphin in the North Sea. The population is estimated to be around 195 individuals (Cheney et al., 1999). Bottlenose dolphins are present all year round, and while they range widely in the Moray Firth, they appear to favour particular areas (JNCC, 2020i).

5.4.3. Pathways for LSE: Potential Impacts on Marine Mammals

A list of potential impacts and effects on marine mammals that may result from the Proposed Development has been provided below (section 5.4.3 - Construction Phase to Decommissioning Phase). These are the impacts which must be taken into account when determining the potential for LSE on the designated sites and marine mammal qualifying interest features identified in section 4.3. The list of potential impacts on marine mammals has been compiled using the experience and knowledge gained from previous offshore wind farm projects and Natural England’s ‘advice on operations’ (Natural England and NatureScot, 2021; JNCC and Natural England, 2019) and the pressures data available on Scotland’s environment web (https://www.environment.gov.scot/) for individual features of sites. The list of potential impacts has also been informed by the SNCBs responses to the Initial Berwick Bank Wind Farm Proposal LSE Screening Report (see Table 1.1 Open ▸ ). Consideration of the potential impacts identified for Annex II marine mammals is presented in the following sections to inform the determination of LSE in section 5.4.3.

Construction Phase

Underwater Noise from Piling

Impact piling during construction may result in hearing damage/auditory injury (permanent threshold shift (PTS)) or behavioural disturbance/displacement of marine mammals.

Harbour Porpoise

Harbour porpoise were the most regularly sighted marine mammal species (2,049 sightings) during the 25 months of site-specific aerial surveys that were undertaken to inform the EIA for the Proposed Development, with sightings throughout the survey area. There were sightings of harbour porpoise in every month and sightings were considerably higher in April/May of both years (2020 and 2021) when compared to other months and generally sightings were lower later in the autumn and winter. The mean corrected density estimate across all monthly surveys for the aerial survey area was estimated as 0.24 animals per km2 (lower 95% confidence limit ©L: 0.063; upper 95% CL: 0.472). These findings are consistent with the results of other studies in the area including previous surveys in the Firth of Forth Round 3 Zone (Grellier and Lacey, 2012). The SCANS III density estimate for the block coinciding with the Proposed Development (Block R) is 0.599 harbour porpoise per km2 (CV 0.29; Hammond et al., 2017). The density estimates for harbour porpoise within the outer Forth and Tay region are predicted to be relatively low compared to other parts of the North Sea (Heinänen and Skov, 2015).
There is considered to be the potential for harbour porpoise from the Southern North Sea SAC to be present (e.g. foraging) within the Proposed Development and the potential zone of influence from underwater noise during piling. On this basis, there is considered to be the potential for LSE from construction noise on the Southern North Sea SAC. All other European sites with harbour porpoise as features are located more than 292 km from the Proposed Development and so a significant effect occurring to features of these sites is considered highly unlikely and all other European sites for harbour porpoise are screened out.

Bottlenose Dolphin

The Moray Firth population of bottlenose dolphins is the only known resident population of this species in the North Sea. The current population estimate of bottlenose dolphin abundance for the Coastal East Scotland MU population (within which the Moray Firth SAC lies) is 189 individuals (95% confidence interval (CI): 155 – 216) based on photo-ID counts between 2006 and 2007 (IAMMWG, 2021). It has been estimated that, on average, 52.5% of the bottlenose dolphin population use the waters of St Andrews Bay and the Tay estuary, with the entrance to the Firth of Tay and waters around Montrose shown to be consistently high use areas (Arso Civil et al., 2019). Only two sightings of bottlenose dolphin were made during the two years of site-specific aerial surveys undertaken to inform the EIA for the Proposed Development (one animal in October 2019 and six individuals in the same single sighting in April 2021). The SCANS III density estimate for the block coinciding with the Proposed Development (Block R) is 0.0298 bottlenose dolphin per km2 (CV 0.861; Hammond et al., 2017).
Bottlenose dolphin are mid-frequency cetaceans and so the disturbance ranges for this species from construction noise are likely to be less than those for harbour porpoise (a high frequency cetacean). The Moray Firth bottlenose dolphin population predominantly occurs in coastal areas (SSE, 2012). There is, however, considered to be the potential for bottlenose dolphin features of the Moray Firth SAC to be transiting through, or foraging in, the Proposed Development and zone of influence (i.e. injury or disturbance) from underwater noise. On this basis, there is considered to be the potential for LSE from construction noise on the bottlenose dolphin feature of the Moray Firth SAC.

Harbour Seal

Results of tracking studies have shown clear evidence of avoidance of offshore wind farms by harbour seals during pile driving, at ranges up to 25 km from piling sites. The same studies have also shown that avoidance behaviour is temporary and restricted to periods of active pile driving with seal distribution returning to pre-piling levels within two hours of the cessation of piling (Russel et al., 2016; SCOS, 2018). This evidence suggests harbour seal exhibit a short-term response to pile driving activity.
No harbour seals were sighted during the two years of site-specific aerial surveys undertaken to inform the EIA for the Proposed Development. There were however, 466 sightings categorised as ‘seal species’, some of which may have been harbour seals. SMRU predicted at-sea usage in the Proposed Development array area of 0.004 seals per km2 (see Figure 5.1). A study commissioned by the Forth and Tay Offshore Wind Developers Group (FTOWDG) presented analysis of telemetry data available from harbour seals tagged by SMRU in the East Scotland SMA between 2001 and 2008 (see Appendix 2). The analysis demonstrated that harbour seal movements are mostly coastal with little overlap with the Proposed Development (see Appendix 2). As discussed previously in section 4.3, the telemetry data does however, indicate connectivity between the Proposed Development and the Firth of Tay and Eden Estuary SAC (see Appendix 2).
As discussed in section 4.3, there is considered to be potential for harbour seals to forage at distances of up to 100 km from haul out sites, and on this basis, there is considered to be the potential for LSE from construction noise on European sites within this distance (i.e. Firth of Tay and Eden Estuary SAC).

Grey Seal

The results of a behavioural study (Aarts et al., 2018) which tracked grey seals during the construction of a wind farm in Dutch waters, have shown that grey seals display a diverse range of responses to pile driving, including: no behavioural change, altered surfacing and diving behaviour suggesting a transition from foraging behaviour to more horizontal movement, changes in swim direction away from the source, heading inshore, swimming perpendicular to the incoming sound, and stopping. Behavioural changes were on average greater and occurred more frequently at smaller distances (< 30 km) from the piling activity, however grey seals exposed to pile driving, even at close distances (< 30 km), returned to the same area on subsequent trips (Kirkwood et al., 2015; Aarts et al., 2018).
A total of 186 grey seals were sighted during the two years of site-specific aerial surveys undertaken to inform the EIA for the Proposed Development. In addition, there were 466 sightings categorised as ‘seal species’ which, given the at-sea usage data for the Proposed Development which suggests a maximum density of 1.896 seals per km2 (see Figure 5.1), the majority of these are expected to be grey seals. Telemetry data for grey seals tagged along the east coast of the UK show a large amount of overlap with grey seal movements and the Proposed Development (see Appendix 2). The telemetry data also suggest potential connectivity with the Isle of May SAC and the Berwickshire and North Northumberland Coast SAC (see Appendix 2).
As discussed in section 4.3, there is considered to be potential for grey seal to forage distances of up to 100 km and, on this basis, there is considered to be the potential for LSE from construction noise (piling) on European sites within this range (i.e. Berwickshire and North Northumberland Coast SAC and Isle of May SAC).

Figure 51: Grey (top) and Harbour (bottom) Seal At-sea Usage Estimates

Underwater Noise from Clearance of Unexploded Ordnance (UXO)

There may be a requirement for the clearance of UXOs from the Proposed Development which will be implemented via low order deflagration. The detonation of small charges as part of this process has the potential to result in hearing damage/auditory injury (permanent threshold shift (PTS)) or behavioural disturbance/displacement of marine mammals.

Harbour Porpoise

As outlined in paragraphs 223 and 224, there is considered to be the potential for harbour porpoise from the Southern North Sea SAC to be present (e.g. foraging) within the Proposed Development and the potential zone of influence from underwater noise generated during UXO clearance activities. On this basis, there is considered to be the potential for LSE on the Southern North Sea SAC. All other European sites with harbour porpoise as features are located more than 292 km from the Proposed Development and so a significant effect occurring to features of these sites is considered highly unlikely and all other European sites for harbour porpoise are screened out.

Bottlenose Dolphin

As outlined in paragraphs 225 and 226, there is considered to be the potential for bottlenose dolphin features of the Moray Firth SAC to be transiting through, or foraging in, the Proposed Development and zone of influence (i.e. injury or disturbance) from underwater noise generated during UXO clearance activities. On this basis, there is considered to be the potential for LSE from construction noise on the bottlenose dolphin feature of the Moray Firth SAC.

Harbour Seal

As outlined in paragraphs 227 to 229, no harbour seals were sighted during the two years of site-specific aerial surveys but telemetry data does indicate potential for connectivity between the Proposed Development and the Firth of Tay and Eden Estuary SAC. There is considered to be potential for harbour seals to forage at distances of up to 100 km from haul out sites, and on this basis, there is considered to be the potential for LSE from underwater noise generated during UXO clearance on European sites within this distance (i.e. Firth of Tay and Eden Estuary SAC).

Grey Seal

As outlined in paragraphs 230 to 232, there is considered to be potential for grey seal to forage distances of up to 100 km and, on this basis, there is considered to be the potential for LSE from underwater noise generated during UXO clearance on European sites within this range (i.e. Berwickshire and North Northumberland Coast SAC and Isle of May SAC).

Underwater Noise from Pre-construction Surveys

The impact of pre-construction related activities, and in particular geophysical surveys, may result in behavioural disturbance/displacement of marine mammals.

Harbour Porpoise

As outlined in paragraphs 223 and 224, there is considered to be the potential for harbour porpoise from the Southern North Sea SAC to be present (e.g. foraging) within the Proposed Development and the potential zone of influence from underwater noise generated during pre-construction surveys including geophysical surveys. On this basis, there is considered to be the potential for LSE on the Southern North Sea SAC. All other European sites with harbour porpoise as features are located more than 292 km from the Proposed Development and so a significant effect occurring to features of these sites is considered highly unlikely and all other European sites for harbour porpoise are screened out.

Bottlenose Dolphin

As outlined in paragraphs 225 and 226, there is considered to be the potential for bottlenose dolphin features of the Moray Firth SAC to be transiting through, or foraging in, the Proposed Development and zone of influence (i.e. injury or disturbance) from underwater noise generated during pre-construction surveys including geophysical surveys. On this basis, there is considered to be the potential for LSE from pre-construction surveys including geophysical surveys on the bottlenose dolphin feature of the Moray Firth SAC.

Harbour Seal

As outlined in paragraphs 227 to 229, no harbour seals were sighted during the two years of site-specific aerial surveys but telemetry data does indicate potential for connectivity between the Proposed Development and the Firth of Tay and Eden Estuary SAC. There is considered to be potential for harbour seals to forage at distances of up to 100 km from haul out sites, and on this basis, there is considered to be the potential for LSE from underwater noise generated during pre-construction surveys including geophysical surveys on European sites within this distance (i.e. Firth of Tay and Eden Estuary SAC).

Grey Seal

As outlined in paragraphs 230 to 232, there is considered to be potential for grey seal to forage distances of up to 100 km and, on this basis, there is considered to be the potential for LSE from underwater noise generated during pre-construction surveys including geophysical surveys on European sites within this range (i.e. Berwickshire and North Northumberland Coast SAC and Isle of May SAC).

Underwater Noise from Vessels and Other Vessel Activities

Disturbance of marine mammals may also arise during the construction phase from vessel use and other construction related activities (e.g. dredging, trenching, rock placement). The extent of this potential disturbance will be spatially restricted to within the boundaries of the Proposed Development and along vessel routes to ports used in support of the Proposed Development during the construction phase. Beyond this, the movements of vessels using already established vessel routes will be dispersed and will become part of the background vessel traffic.

Harbour Porpoise

Given the distance of the nearest European site for harbour porpoise from the Proposed Development (146 km for the Southern North Sea SAC), together with the fact that the uplift in vessel traffic will be small compared with existing baseline levels and that other construction related activities such as dredging, trenching or placement of rock protection will be intermittent and short term, it is not considered that vessel traffic associated with the construction of the Proposed Development will result in significant disturbance to harbour porpoise and so this impact is screened out of further consideration for this species.

Bottlenose Dolphin

There were only two sightings of bottlenose dolphins during the recent aerial surveys for the Proposed Development. This species is mainly encountered in inshore areas and therefore vessel noise during construction is unlikely to lead to LSE on the species. Any disturbance associated with activities near shore along the export cable route would be short term and as described above the baseline suggests that bottlenose dolphin is unlikely to occur along this part of the coast. Given the distance of the Moray Firth SAC from the Proposed Development (224 km to the array area), it is considered that the increase in vessel traffic and other activities (e.g. dredging, trenching, rock placement) associated with the construction of the Proposed Development will not result in significant disturbance to bottlenose dolphin and so this impact is screened out of further consideration for this species.

Harbour Seal

As discussed previously for underwater noise from piling, the usage of the Proposed Development by harbour seal is predicted to be low and there are no haul out sites near either landfall option which could be disturbed by construction activities along the proposed ECC. The nearest harbour seal haul out sites are located in the Firth of Forth, more than 20 km away (SCOS, 2020).
Although the location of ports to be used in support of the Proposed Development is not currently confirmed, it is likely that the majority of vessel movements will be to/from local ports on the east coast of Scotland and should any ports be located within the Firth of Tay then there is the potential for interaction between harbour seals using the Firth of Tay. There is also the potential for other construction related activities (e.g. dredging, trenching, rock placement) to interact with seals using the Firth of Tay. There is therefore the potential for vessel movements and other vessel activities to result in disturbance to the harbour seal feature of the Firth of Tay and Eden Estuary SAC.

Grey Seal

Site-specific surveys as well as desktop data sources (i.e. telemetry data and at sea usage data) all indicate an overlap of grey seal movements and the Proposed Development. Telemetry data also show potential connectivity with the two European sites screened into the assessment of LSE, Isle of May SAC and the Berwickshire and North Northumberland Coast SAC (see Appendix 2 and Figure 5.1). It is therefore considered that there is the potential for vessel movements and other vessel-related activities (e.g. dredging, trenching, rock placement) associated with the construction of the Proposed Development to result in disturbance to grey seal.
The closest seasonal haul out for grey seal is Fast Castle, which partially overlaps with the Berwickshire and North Northumberland SAC and is located within 2 km of the Thorntonloch Landfall, and ~5.5 km from the Skateraw Landfall (Figure 5.2). Given the distance (some 3 km to the south of the proposed landfall locations/cable route), it is unlikely that construction works at the landfall or activities associated with cable installation are likely to affect any individual hauled out using this site. On this basis, there is considered to be the potential for LSE from vessel noise and other vessel-related construction activities for grey seals at sea only (i.e. not when hauled out) from the Isle of May SAC and the Berwickshire and North Northumberland Coast SAC.

Figure 52: Designated Haul Out Sites for Grey and Harbour Seal in the East Scotland Seal Management Area

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