Effects in-combination
1473 An assessment of in-combination effects upon the qualifying Annex II marine mammal species of the Firth of Tay and Eden Estuary SAC arising from each identified impact is provided below.
1474 The potential to experience injury in terms of PTS by marine mammal receptors as a result of underwater noise due to piling and vessel use/other activities would be expected to be largely localised within the boundaries of the respective projects (assuming similar ranges of effect as presented for the Proposed Development). It is also anticipated that standard offshore wind industry construction methods (which include soft starts and visual and acoustic monitoring of marine mammals as standard) will be applied, thereby reducing the magnitude of the impact with respect to auditory injury occurring in marine mammals. Therefore, there is no potential for significant in-combination impacts for injury from elevated underwater noise during pilling and vessel use/other activities and the in-combination assessment focuses on disturbance only.
Assessment of in-combination effects during construction and decommissioning
Injury and disturbance from elevated underwater noise during piling
Tier 2
1476 Both projects screened in for the in-combination assessment for harbour seal (paragraph 1475) are located within a behavioural disturbance footprint of the Proposed Development. The outermost contour of 135 dB represents the edge of the area within which harbour seal may experience behavioural disturbance during concurrent piling at 4,000kJ hammer energy at Proposed Development. The assessment presented in the Inch Cape EIA (Inch Cape Offshore Limited, 2018) and original Seagreen EIA (Seagreen Wind Energy Ltd, 2012) estimated that 20 and 51 individuals could experience disturbance during piling at respective projects. The duration of any disturbance at Seagreen 1A Project will be relatively short and is currently planned to take place between April and July 2023 (i.e. more than two years before planning commencement of piling at Proposed Development (Seagreen Wind Energy Ltd, 2020)).
1477 The construction of Inch Cape and Seagreen 1A Project will be completed prior to commencement of piling at the Proposed Development so the potential for simultaneous piling, and therefore additive in-combination effects, with Proposed Development is highly unlikely. Nevertheless, as requested by consultees via Road Map process (see volume 3, appendix 10.3 of the Offshore EIA Report), population modelling was carried out to explore the potential of cumulative effects as a result of disturbance during piling to affect the population trajectory over time. Population modelling considered Seagreen 1A Project and Inch Cape Offshore Wind Farm and respective numbers of animals potentially impacted against the wider MU population (see volume 3, appendix 10.4 for methods applied in the model). Results of the cumulative iPCoD modelling for harbour seal showed that no impacts are predicted on the wider population resulting from disturbance due to cumulative piling events, with the mean impacted population the same as the mean unimpacted population at the 25 year time point. Therefore, it was considered that there is no potential for the long-term effects on this species within wider population as a result of cumulative piling at proposed Development and respective projects (see volume 3, appendix 10.4 for more details). As previously presented for iPCoD results for proposed Development alone (paragraph 919), these results are not in agreement with findings of Hanson et al. (2017), who suggested that the continuation of current decline trend in the Forth of Tay and Eden Estuary SAC could result in the species disappearing from this area within next 20 years. The reason for this discrepancy is that the revised demographic parameters to inform iPCoD models (Sinclair et al., 2020) indicate that with inclusion of the Firth of Forth counts, the total East Scotland MU counts appear to be relatively stable. Additionally, sporadic counts in the area indicate that the decline is localised within the SAC and may not represent the trends in the overall MU population (SCOS, 2020; Sinclair et al., 2020).
1478 In temporal terms, there is a potential that animals in the vicinity of the Firth of Forth and Tay will experience disturbance consecutively as piling at different projects progresses. As described in paragraph 1478, harbour seals although initially displaced due to pile-driving, are likely to return to the same area within two hours following cessation of piling. Therefore, it is highly unlikely that the reproductive and recruitment capability of the species will be affected. Additionally, given that the risk of simultaneous piling is very low, it is unlikely that in-combination effect as a result of piling has the potential to result in reduced reproductive success. Therefore, it is unlikely that the status of this population as a viable component of the site will be affected (noting that the population of this SAC is in decline due to factors not associated with the Proposed Development in-combination with other projects, see paragraph 1415).
1479 As described in paragraph 1411, during piling at Proposed Development, behavioural disturbance contours do not overlap with Firth of Tay and Eden Estuary SAC ( Figure 13.6 Open ▸ ). Given the limited extent of behavioural disturbance footprint of respective projects, harbour seals present in the vicinity of the habitats which they utilise throughout their life cycle (sandbanks and estuaries), are unlikely to experience disturbance. As such, piling activities are highly unlikely to change the distribution of species within site.
1480 Additionally, considering that there will be no overlap of piling phases with either of the projects and piling will be intermittent over medium term, it is anticipated that piling will not result in any long-lasting changes in the distribution of adult seals and the connectivity with areas of high importance within and outside the site is not expected to be impaired.
Figure 13.7: Adult Harbour Seal Telemetry Tracks Overlaid with Projects Considered in In-Combination Assessment (Except Moray West Due to Scale)
1481 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Firth of Tay and Eden Estuary SAC as a result of underwater noise during piling during construction with respect to the Proposed Development acting in-combination with Tier 2 projects.
Injury and disturbance from elevated underwater noise during site investigation surveys
Tier 2
1482 There is potential for in-combination effects from injury and/or disturbance from underwater noise due to site investigation surveys to harbour seal from the Firth of Tay and Eden Estuary SAC during the construction phase of the Proposed Development with the construction and operation and maintenance Eastern Link 1 and Eastern Link 2.
1483 The construction as well as operation and maintenance phases of Eastern Link 1 and Eastern Link 2, located respectively 14 km and 28 km from the Proposed Development array area, will overlap with the construction phase of the Proposed Development. Based on the Environmental Appraisals for both projects, the only underwater sound noise sources that are within hearing range of marine mammals and have potential to have an effect, are the operation of the USBL and the SBP (AECOM, 2022a; 2022b). The disturbance ranges for harbour seal were estimated as 63 m for USBL and 4,642 m for SBP. The detailed assessment of impacts as a result of underwater noise during the operation of SBP for both projects was presented for installation phase only. There are no disturbance ranges presented for the USBL for the Proposed Development alone but the disturbance range for SBP has been assessed as 2,045 m. Nevertheless, the assessment presented in paragraph 955 et seq. is based on the maximum disturbance range estimated as 7,459 m for vibro-coring. Using the published at-sea density maps (Carter et al., 2020), the assessment predicted that less than one individual could be disturbed as a result of vibro-coring (2.4% of the Firth of Tay and Eden Estuary SAC population). However, since the adult harbour seal telemetry tracks are mostly confined to the northern part of the Proposed Development array area ( Figure 13.7 Open ▸ ), only surveys taking place in close vicinity to this area could result in a potential disturbance.
1484 Based on the distance from the Proposed Development to both projects, the overlap of disturbance ranges is highly unlikely. The potential for an overlap exist only for site-investigation surveys taking place in the northern part of the Eastern Link 1, close to the Proposed Development export cable corridor and landfall ( Figure 13.3 Open ▸ ). Based on the telemetry tracks, the areas close to the landfall are not regularly visited by individuals from this SAC and although the connectivity between these areas and harbour seals from the Firth of Tay and Eden Estuary SAC cannot be discounted, the behavioural disturbance could potentially affect a negligible proportion of the population. It needs to be noted that site investigation survey equipment will not be operating continuously, it will be used when required for investigations of particular areas of the seabed where additional information is required to inform the construction.
1485 With foraging ranges of up to 50 km, harbour seals may be sensitive to a behavioural disturbance during the site-investigation surveys as they move between haul-outs and key foraging areas. Given the distance from Eastern Link 1 and Eastern Links 2 to the SAC (approximately 50 and 93 km, respectively), operation of the survey equipment is unlikely to disturb animals from this SAC within their main foraging grounds. Disturbance ranges during vibro-coring at Proposed Development have the potential to slightly overlap with foraging ranges of harbour seal from the Firth of Tay and Estuary SAC, however, given that alternative areas for foraging are widely available, the disturbance to seals is not considered likely to have a significant impact on food availability (see paragraph 1502 et seq. for the cumulative assessment of impacts as a result of changes in prey availability) and therefore on fitness and survival of the harbour seal population. Given that geophysical surveys will occur intermittently and are short in duration, harbour seals are anticipated to return to foraging grounds when the impact has ceased and therefore the connectivity with important habitats within and outside the site is unlikely to be impaired.
1486 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Firth of Tay and Eden Estuary SAC as a result of site investigation surveys during the construction phase with respect to the Proposed Development acting in-combination with Tier 2 projects.
Injury and disturbance from elevated underwater noise during UXO clearance
Tier 2
1487 There is potential for in-combination effects from injury and/or disturbance from underwater noise during UXO clearance to harbour seal from the Firth of Tay and Eden Estuary SAC during the construction phase of the Proposed Development with activities associated with Inch Cape Offshore Wind Farm and Moray West Offshore Wind Farm.
1488 Projects screened in for this in-combination assessment are expected to involve similar construction activities to those described for the Proposed Development alone, including UXO clearance activities. It is anticipated that, for all projects, impacts associated with these activities will require additional assessment under EPS licensing, however such applications are not yet available in the public domain.
1489 For the Proposed Development alone, the maximum range across which harbour seal have the potential to experience PTS due to high order detonation of 300 kg charge was assessed as approximately 2,085 m. PTS onset ranges for Inch Cape Offshore Wind Farm and Moray West are currently unknown but for the purpose of this assessment, we can assume that the maximum adverse scenario is not greater than assessed for the Proposed Development alone. Depending on the type of detonation and size of UXO, UXO clearance activities may have residual effects in respect to marine mammals and PTS injury. In November 2021, the UK government published a joint interim statement advising to use low noise alternatives to high order detonations where possible and it is anticipated that future developments will follow this guidance. However, due to a small inherent risk with these clearance methods that the UXO will detonate or deflagrate violently, accidental high order detonation can be expected as a maximum adverse scenario. Taking into account high order detonation of 300 kg charge and appropriate designed-in and secondary mitigation measures, there will be no residual risk of injury and therefore, it is highly unlikely that the reproductive and recruitment capability of the harbour seal will be affected.
1490 In terms of TTS, for the Proposed Development alone, the range across which harbour seal have the potential to experience TTS due to high order detonation of a 300 kg charge was as approximately 6,430 m (see paragraph 971 et seq.). TTS onset ranges for Inch Cape Offshore Wind Farm and Moray West Offshore Wind Farm are currently unknown, but for the purpose of this assessment we can assume that the maximum adverse scenario is no greater than assessed for the Proposed Development alone. A spatial maximum adverse scenario would occur where UXO clearance activities occur concurrently at the respective projects considered in the in-combination assessment. This is however highly unlikely, as due to safety reasons the UXO clearance activities takes place before other construction activities commence, and both projects considered in the CEA start their construction activities two years before commencement of construction at Proposed Development. Temporally however, sequential UXO clearance at respective projects could lead to a longer duration of effect. Since each clearance event results in no more than a one second ensonification event and since TTS is a recoverable injury, the potential for in-combination effects with respect to TTS is considered to be very limited. Therefore, in-combination effects caused by UXO clearance are considered unlikely to cause a change in reproduction and survival rates or alteration in the distribution of the harbour seal population from the Firth of Tay and Eden Estuary SAC. Given that effect of TTS is short in duration, connectivity with important habitats within and outside the site is also unlikely to be impaired.
1491 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Firth of Tay and Eden Estuary SAC as a result of underwater noise during UXO clearance during the construction phase with respect to the Proposed Development acting in-combination with Tier 2 projects.
Injury and disturbance from elevated underwater noise during vessel use and other activities
Tier 2
1492 There is potential for in-combination effects from injury and/or disturbance from underwater noise due to vessel use and other activities to harbour seal from the Firth of Tay and Eden Estuary SAC during the construction and decommissioning phase of the Proposed Development with activities associated with the following projects: Eyemouth disposal site, Inch Cape Offshore Wind Farm, Seagreen 1, Seagreen 1A Project, Eastern Link 1, Eastern Link 2, Neart na Gaoithe and Blyth Demo 2.
1493 Whilst there is no quantitative information available for noise disturbance ranges for offshore wind farms included in this CEA, it is anticipated that there will be a similar scale of effects with respect to noise effects as those described for Proposed Development alone (paragraph 995 et seq.). In terms of behavioural disturbance, the noise modelling predicted a maximum range of approximately 4 km for construction activities such as cable laying as well as activity of rock placement vessels (described in detail in volume 3, appendix 10.1 of the Offshore EIA Report) and therefore, there is a potential for disturbance effects to occur cumulatively. Given that construction activities for the other offshore wind projects have commenced in 2020 and that this is an area of relatively high vessel traffic (see paragraph 989 et seq. for more details), it can be anticipated that harbour seal from the Firth of Tay and Eden Estuary SAC demonstrate some degree of habituation to ship noise.
1494 As discussed in paragraph 874, there is likely to be a proportionate response of animals within the modelled contours (i.e. not all animals will be disturbed to the same extent). Most of the vessel traffic associated with offshore wind farms considered in the in-combination assessment will take place within the array areas of respective projects. Based on telemetry data, array areas of respective projects have connectivity with seals from the Firth of Tay and Eden Estuary SAC ( Figure 13.6 Open ▸ ). Vessel movements will also increase over construction phase along the Proposed Development export cable corridor. Although there is some connectivity of individual harbour seal telemetry tracks between the SAC and Proposed Development export cable corridor, majority of harbour seal movements are confined within the outer Firth of Tay and north-west to the Proposed Development array area ( Figure 13.6 Open ▸ ).
1495 The highest number of vessels movements was predicted during the construction phase of each offshore wind farm. Vessels will be moving to and from ports and harbours and this traffic is likely to intersect with the areas characterised by high density of harbour seal telemetry tracks (Figure 0.12). As presented in more detail in paragraph 1440, harbour seal display avoidance behaviour or alert reactions when vessels approach within 100 m of a haul-out site. Therefore, it is crucial for all projects to adhere to the Vessel Management Plans, which should include agreed routes and potential speed restrictions in order to reduce the disturbance. Given the existing levels of vessel activity within the Firths of Tay and Forth, it is expected that harbour seals could tolerate the effects of vessel presence to some extent. The impacts of construction will be highly localised, largely restricted to the boundaries of the respective projects (vessel movements intersecting the areas potentially important for harbour seal closer to the coast will be intermittent) and only a small area will be affected when compared to available foraging habitat for harbour seals. Therefore, it is anticipated that the connectivity with suitable foraging grounds and supporting habitats will not be impaired. Given that there will be a relatively small temporal overlap of the construction phases, with only one year of overlap with Inch Cape as well as Seagreen 1A Project and the Proposed Development, impacts associated with vessel use are considered is unlikely to result in reduced reproductive success and are unlikely to affect the status of this population as a viable component of the site (noting that the population of this SAC is in decline due to factors not associated with the Proposed Development, see paragraph 1419).
1496 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Firth of Tay and Eden Estuary SAC as a result of underwater noise during vessel use and other activities during the construction phase with respect to the Proposed Development acting in-combination with Tier 2 projects.
Tier 3
1498 There is currently no information on the impacts the Cambois connection will have on harbour seal, although the Scoping Report have listed the types of vessels to be used during construction, including cable lay vessels, pre-lay survey vessels, rock protection vessels, support vessels, guard vessels, and possible use of jack-up vessels (SSE Renewables, 2022e). There was no details about number of vessel round trips during the construction phase of Cambois connection. No data for vessel movements was presented for operation and maintenance phase of the Cambois connection.
1499 Due to lack of project information at this stage, it is not possible to undertake full, quantitative assessment for this impact and therefore a qualitative assessment is provided. The maximum range over which potential disturbance may occur for the Proposed Development alone as a result of drilled piling and jet trenching, is predicted out to 1,900 m and 2,580 m, respectively. Cable installation activities assessed for the Proposed Development alone have the potential to disturb marine mammals out to 4,389 m. Given the location of the SAC with respect to the Proposed Development and Cambois connection, there is no potential for cumulative overlap of behavioural ZoI at respective projects and this designated site.
1500 Adult harbour grey seal telemetry tracks do not indicate that individuals from this SAC regularly move within waters in the vicinity of the Cambois connection ( Figure 13.7 Open ▸ ). Nevertheless, the potential connectivity cannot be discounted and in offshore waters, construction activities could lead to a larger area of disturbance and larger number of animals disturbed compared to the Proposed Development alone if projects were to conduct construction activities over similar time periods. Given the existing levels of vessel activity within the Firths of Tay and Forth, it is expected that harbour seals could tolerate the effects of vessel presence to some extent. The impacts of operation and maintenance will be localised in the areas of small importance to harbour seal, largely restricted to the boundaries of the respective projects (vessel movements intersecting the areas potentially important for harbour seal closer to the coast will be intermittent) and only a small area will be affected when compared to available foraging habitat for harbour seals. Therefore, it is anticipated that the connectivity with suitable foraging grounds and supporting habitats will not be impaired.
1501 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Firth of Tay and Eden Estuary SAC as a result of underwater noise during vessel use and other activities during the construction phase with respect to the Proposed Development acting in-combination with Tier 3 projects.
Changes in fish and shellfish communities affecting prey availability
Tier 2
1503 The construction phases and/or operation and maintenance phases of projects screened into in-combination assessment may lead to in-combination temporary subtidal habitat loss/disturbance. The total in-combination temporary subtidal habitat loss is 145,325,450 m2 (145.3 km2), however this number is highly conservative as the temporal overlap in construction activities between projects will be small and therefore there will only be a small area of temporary habitat loss happening at any one time. The magnitude of long-term habitat loss caused by the presence of all structures on the seabed has been considered for the construction as well as operation and maintenance phases. The impacts have been assessed in-combination with Inch Cape Offshore Wind Farm, Neart na Gaoithe Offshore Wind Farm, and Seagreen 1, Seagreen 1A Project and Seagreen 1A Export Cable Corridor, Eastern Link 1 and Eastern Links 2 and may lead to long term subtidal habitat loss of up to 15,014,156 m2 (=15.0 km2).
1504 An increase in SSC and associated sediment deposition as a result of the installation of all wind turbines and offshore substation foundations and the installation of inter-array, interconnector and offshore export cables may result in short-term avoidance of affected areas by fish and shellfish which may have an indirect effect on harbour seals. Elevations in SSC are expected to be of short duration, returning to background levels relatively quickly. SSC is not expected to reach the concentrations required for an extended period for there to be any effect on fish and shellfish adult/larvae survival. Additionally, deposited sediments are expected to be removed quickly by the currents resulting in small amount of sediment being deposited. Therefore, the availability of suitable food supply for harbour seal within the wider area is not expected to be impaired as a result of increase in SSC and associated deposition.
1505 As outlined in paragraph 1026 et seq., harbour seals are generalist feeders and can forage on variety of species. They usually within 50 km from the coast, however studies demonstrated that in the outer Firth of Tay harbour seal movements are mostly coastal (see paragraph 1440). Given that the impacts associated with construction and decommissioning will be localised when compared to wider habitat available and largely restricted to the boundaries of the respective projects, only a small area will be affected when compared to available foraging habitat for harbour seal. Since the habitat is likely to return to the state that existed before the activity or event which caused change, the availability of suitable food supply for harbour seal is not expected to be impaired. Therefore, it is anticipated that the distribution and extent of habitats supporting the species will be maintained.
1506 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Firth of Tay and Eden Estuary SAC as a result of changes in fish and shellfish communities affecting prey availability during construction and decommissioning with respect to the Proposed Development acting in-combination with Tier 2 projects.
Tier 3
1507 There is potential for in-combination effects from changes in fish and shellfish communities affecting prey availability to harbour seal from Firth of Tay and Eden Estuary SAC during the construction and decommissioning phases of the Proposed Development with activities associated with the construction and operation of Cambois connection.
1508 The construction phase of Cambois connection may lead to in-combination temporary subtidal habitat loss/disturbance. The total in-combination temporary subtidal habitat loss/disturbance is 17,000,000 m2 (=17.0 km2), however this number is highly conservative as the temporal overlap in construction activities between projects will be small and therefore there will only be a small area of temporary habitat loss happening at any one time. The majority of this disturbance will not spatially overlap with the Proposed Development and where the overlap exist with the Proposed Development array area (previously impacted during the construction of the Proposed Development), it is expected to be highly localised and so the potential for repeat disturbance is considered low and unlikely to lead to an increase in the magnitude than predicted for the Proposed Development alone. The installation of Cambois connection can also result in a total area of long-term subtidal habitat loss of 306,000 m2. Adult harbour grey seal telemetry tracks do not indicate that individuals from this SAC regularly move within waters in the vicinity of the Cambois connection ( Figure 13.7 Open ▸ ). Therefore, it can be assumed that the area affected by temporary habitat disturbance/habitat loss within Cambois connection does not represent important foraging grounds for individuals from Berwickshire and North Northumberland Coast SAC.
1509 There is also a potential for in-combination effects associated with SSC and associated deposition. However, elevations in SSC during the construction phase will be of short duration, returning to background levels relatively quickly. SSC will not reach the concentrations required for an extended period for there to be any effect on fish and shellfish adult/larvae survival. Therefore, it is highly unlikely to have indirect impacts on harbour seals from the Firth of Tay and Eden Estuary SAC via changes to prey species.
1510 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Firth of Tay and Eden Estuary SAC as a result of changes in fish and shellfish communities affecting prey availability during construction and decommissioning with respect to the Proposed Development acting in-combination with Tier 3 projects.
Assessment of in-combination effects during operation and maintenance
Injury and disturbance from elevated underwater noise during site investigation surveys
Tier 2
1511 There is potential for in-combination effects from injury and/or disturbance from underwater noise due to site investigation surveys to harbour seal from the Firth of Tay and Eden Estuary SAC during the operation and maintenance phase of the Proposed Development with the operation and maintenance Eastern Link 1 and Eastern Link 2.
1512 The maximum design scenario for Proposed Development alone comprises of routine geophysical surveys estimated to occur every six months for first two years and annually thereafter. This equates to up to 37 surveys over the 35-year life cycle of Proposed Development ( Table 11.2 Open ▸ ). As presented in paragraph 1483, the detailed assessment of impacts on marine mammals as a result of underwater noise due to geophysical surveys during the operation and maintenance phase of the Eastern Link 1 and Eastern Link 2 is unavailable.
1513 An overview of potential impacts from as a result of behavioural disturbance due to elevated underwater noise during geophysical site investigation surveys is described in paragraph 1482 et seq. for the construction phase and has not been reiterated here for the operation and maintenance phase. The magnitude of the impact of underwater noise from geophysical surveys during operation and maintenance phase in combination with other projects considered in cumulative assessment could result in a negligible alteration to the distribution of harbour seal in the short-term, however the overlap of disturbance ranges is unlikely. Given that geophysical surveys will occur intermittently over operation and maintenance phases of respective projects and are short in duration, harbour seals are anticipated to return to foraging grounds when the impact has ceased and therefore the connectivity with important habitats within and outside the site is unlikely to be impaired.
1514 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Firth of Tay and Eden Estuary SAC as a result of site investigation surveys during the operation and maintenance phase with respect to the Proposed Development acting in-combination with Tier 2 projects.
Injury and disturbance from elevated underwater noise during vessel use and other activities
Tier 2
1516 Vessels involved in the operation and maintenance of other wind farms will include a similar suite of vessels as those described for the Proposed Development alone (see paragraph 1044 et seq.), such as vessels used during routine inspections, repairs and replacement of equipment, major component replacement, painting or other coatings, removal of marine growth and replacement of access ladders. Given that the number of vessel round trips and their frequency is much lower for the operation and maintenance phases compared to construction phases of the respective projects, the magnitude of the impact for disturbance as a result of elevated underwater noise due to vessel use and other activities is expected to be less than that assessed for the construction phase. However, the duration of the effect will be longer (over the 35-year operating lifetime of the Proposed Development).
1517 Whilst there is no quantitative information available for noise disturbance ranges for offshore wind farms included in this CEA, it is anticipated that there will be a similar scale of effects with respect to noise effects as those described for Proposed Development alone (paragraph 995 et seq.).
1518 It can be expected that after more than ten years of construction activities taking place in the vicinity of Firth of Forth (i.e. Seagreen 1 construction activities commenced in 2021 and the operation and maintenance phase of Proposed Development is expected to start from 2033), marine mammals present in the area will demonstrate some degree of habituation to ship noise.
1519 As discussed in paragraph 874, there is likely to be a proportionate response of animals within the modelled contours (i.e. not all animals will be disturbed to the same extent). Most of the vessel traffic associated with offshore wind farms considered in the in-combination assessment will take place within the array areas of respective projects. Based on telemetry data, array areas of respective projects have connectivity with seals from the Firth of Tay and Eden Estuary SAC ( Figure 13.6 Open ▸ ). Vessel movements will also increase over construction phase along the Proposed Development export cable corridor. Although there is some connectivity of individual harbour seal telemetry tracks between the SAC and Proposed Development export cable corridor, majority of harbour seal movements are confined within the outer Firth of Tay and north-west to the Proposed Development array area ( Figure 13.6 Open ▸ ).
1520 During the operation and maintenance phases of respective projects vessels will be moving to and from ports and harbours and this traffic is likely to intersect with the areas characterised by high density of harbour seal telemetry tracks ( Figure 13.7 Open ▸ ). As presented in more detail in paragraph 14591440, harbour seal display avoidance behaviour or alert reactions when vessels approach within 100 m of a haul-out site. Therefore, it is crucial for all projects to adhere to the Vessel Management Plans, which should include agreed routes and potential speed restrictions in order to reduce the disturbance. It is expected that harbour seal population would be able to tolerate the effect without any significant impact on reproduction and survival rates.
1521 During the operation and maintenance phase of the Proposed Development, the wind farms listed in paragraph 1515 will reach their decommissioning age before the Proposed Development reaches its decommissioning age in 2066. The environmental statements for respective projects predicted the number and type of vessels associated with decommissioning are expected to be, at worst, similar to construction.
1522 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Firth of Tay and Eden Estuary SAC as a result of underwater noise during vessel use and other activities during the operation and maintenance phase with respect to the Proposed Development acting in-combination with Tier 2 projects.
Tier 3
1523 There is potential for in-combination effects from underwater noise due to vessel use and other activities to harbour seal from the Firth of Tay and Eden Estuary SAC during the operation and maintenance of the Proposed Development with activities associated with the operation of Cambois connection.
1524 As presented in paragraph 1361, there were no details about the number of vessel round trips or type of vessels that will be used during operation and maintenance phase of Cambois connection (SSE Renewables, 2022e). Due to lack of detailed project information at this stage, it was not possible to undertake full, quantitative assessment for this impact.
1525 An overview of potential impacts for behavioural disturbance to harbour seal from the Firth of Tay and Eden Estuary SAC from elevated underwater noise due to vessel use and other activities is described in paragraph 1497 et seq. for the construction phase and have not been reiterated here for the operation and maintenance phase.
1526 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Firth of Tay and Eden Estuary SAC as a result of underwater noise during vessel use and other activities during the operation and maintenance phase with respect to the Proposed Development acting in-combination with Tier 3 projects.
Changes in fish and shellfish communities affecting prey availability
Tier 2
1527 There is potential for in-combination effects from changes in prey resources to harbour seal from the Firth of Tay and Eden Estuary SAC during the operation and maintenance phase of the Proposed Development with activities associated with the following projects: Inch Cape Offshore Wind Farm, Neart na Gaoithe Offshore Wind Farm, Seagreen 1, Seagreen 1A Project, Seagreen 1A Export Cable, Eastern Link 1, Eastern Link 2 and Eyemouth disposal site.
1528 Operation and maintenance activities at respective projects considered in in-combination assessment may lead to temporary subtidal habitat loss/disturbance of up to 32,287,197 m2. Additionally, Offshore Wind Farms listed above will reach their decommissioning age during Proposed Development operation and maintenance phase. However, it is important to note that the maximum design scenario for habitat loss from the respective projects is precautionary, as operation and maintenance activities will occur intermittently throughout the lifetime of the Proposed Development and the temporal overlap with activities at other projects is unlikely. As described in paragraph 1011, only a small proportion of the maximum footprint of habitat loss/disturbance may be affected at any one time, areas will start to recover immediately after cessation of maintenance activities. It is expected that harbour seal could come back to forage within areas previously disturbed after cessation of works and therefore the distribution and extent of habitats supporting the species outside of the SAC is unlikely to be impaired.
1529 In-combination impacts could arise from EMFs due to the presence of subsea cabling during the operation and maintenance phases of the Proposed Development as well as Inch Cape Offshore Wind Farm, Neart na Gaoithe Offshore Wind Farm, Seagreen 1, Seagreen 1A Project and Seagreen 1A Export Cable. A total length of up to 4,888 km of subsea cabling was estimated for all projects. The effect of EMF was predicted to be of local spatial extent. Considering the above, adverse effects on harbour seal as a result of changes in prey availability due to EMF are unlikely.
1530 As outlined in paragraph 1026 et seq., harbour seals are generalist feeders and can forage on variety of species. They usually within 50 km from the coast, however studies demonstrated that in the outer Firth of Tay harbour seal movements are mostly coastal (see paragraph 1440). Given that the impacts associated with operation and maintenance be localised when compared to wider habitat available and largely restricted to the boundaries of the respective projects, only a small area will be affected when compared to available foraging habitat for harbour seal. Since the habitat is likely to return to the state that existed before the activity or event which caused change, the availability of suitable food supply for harbour seal is not expected to be impaired. Therefore, it is anticipated that the distribution and extent of habitats supporting the species will be maintained.
1532 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Firth of Tay and Eden Estuary SAC as a result of changes in fish and shellfish communities affecting prey availability during operation and maintenance with respect to the Proposed Development acting in-combination with Tier 2 projects.
Tier 3
1533 There is potential for in-combination effects from changes in fish and shellfish communities affecting prey availability to harbour seal from Firth of Tay and Eden Estuary SAC during the operation and maintenance phase of the Proposed Development with activities associated with the operation of Cambois connection.
1534 In terms of temporary subtidal habitat loss/disturbance, there are no specific values for the operation and maintenance phase of Cambois connection which will occur during the operation and maintenance phase of the Proposed Development. Adult harbour grey seal telemetry tracks do not indicate that individuals from this SAC regularly move within waters in the vicinity of the Cambois connection ( Figure 13.7 Open ▸ ). Therefore, it can be assumed that the area affected by temporary habitat disturbance/habitat loss within Cambois connection does not represent important foraging grounds for individuals from Berwickshire and North Northumberland Coast SAC.
1535 Cambois connection has the potential to result in cumulative EMF effects from subsea electrical cabling within the Proposed Development. The Cambois connection is understood to have 680 km of cable. The effect of EMF was predicted to be of local spatial extent.
1536 The Cambois connection has the potential to create 306,000 m2 of new hard habitat associated with rock/mattress cable protection, which represents a change in seabed type, the effects of which are described in paragraph 1022 et seq. As the cable protection does not extend into the water column the opportunity for colonisation by some species is reduced. Due to reasons described in more detail in paragraph 1531, the presence of artificial structures in offshore waters is unlikely to benefit harbour seal population.
1537 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Firth of Tay and Eden Estuary SAC as a result of changes in fish and shellfish communities affecting prey availability during operation and maintenance with respect to the Proposed Development acting in-combination with Tier 3 projects.
Site conclusion
1538 In conclusion, with reference to the conservation objectives set for the Annex II marine mammal features of the site and the information presented in section 13.3, 13.4, 13.5 and 13.6.3, it can be concluded beyond all reasonable scientific doubt that there will be no Adverse Effect on Integrity on the Firth of Tay and Eden Estuary SAC in respect of the harbour seal qualifying interests.
1539 This finding is in relation to potential impacts associated with the Proposed Development during construction, decommissioning and operation and maintenance, acting alone and or in-combination.
13.6.4 Southern North Sea SAC
European site information
1540 The Southern North Sea SAC, covering an area of 36,951 km2, was designated to conserve harbour porpoise (JNCC, 2021b). The majority of the site lies offshore (88%), extending into English inshore waters (12%) and it is located 146 km to the south-east from the Proposed Development array area and 151 km from the Proposed Development export cable corridor. Population estimates within the site based on the 2016 survey are a minimum of 20,237 and a maximum of 41,538 individuals (JNCC, 2019a). The SAC area supports an estimated 17.5% of the UK North Sea MU population. The northern part supports higher densities of porpoises during the summer season (April to September), whilst the southern part is recognised as an important area during the winter season (October to March) (JNCC, 2021b).
1541 Harbour porpoise condition has not yet been assessed at this site, however, the site assessment assigns a grade of A conservation to the site, which is deemed excellent.
1542 Further information on this European site is presented in appendix A.