13.6 Information to Inform Assessment of Adverse Effects on Integrity
13.6.1 Berwickshire and North Northumberland Coast SAC
European site information
1118 Berwickshire and North Northumberland Coast SAC is located 4.1 km from the Proposed Development export cable corridor and 35 km from the Proposed Development array area. The SAC extends from St Abb’s Head in south-east Scotland to Alnwick in north-east England. The site is designated for Annex I habitats (considered separately in section 11.5.1), and grey seal. The breeding colonies within this SAC support around 2.5% of annual UK pup production. There are two large discrete grey seal breeding populations (the Farne Islands and Fast Castle) with different population dynamics, however, pup production in the SAC as a whole is continuing to increase and does not show any indication of reaching an asymptote (SCOS, 2020).
1119 The grey seal feature of the site was last assessed as being in ‘favourable maintained’ condition in November 2014[14].
1121 Further information on this European site is presented in appendix A.
Conservation objectives
1122 The conservation objectives for Berwickshire and North Northumberland Coast SAC have been developed jointly by NatureScot and Natural England and apply to the site and the individual species and/or assemblage of species for which the site has been classified. These high-level objectives are to ensure that, subject to natural change, the integrity of the site is maintained or restored as appropriate, and that the site contributes to achieving the Favourable Conservation Status of its qualifying features, by maintaining or restoring:
- the extent and distribution of qualifying natural habitat and habitats of the qualifying species;
- the structure and function (including typical species) of qualifying natural habitats;
- the structure and function of the habitats of the qualifying species;
- the supporting processes on which qualifying natural habitats and the habitats of qualifying species rely;
- the populations of each of the qualifying species; and
- the distribution of qualifying species within the site.
1123 As the most recent condition status of the grey seal feature of the site was ‘favourable’, it is assumed that the above list of conservation objectives must be maintained for grey seal.
1124 Supplementary advice on conservation objectives, last updated by NatureScot and Natural England on 13 March 2020[15] provide the site-specific attributes and targets specific to the grey seal feature of the site: These supplementary attributes and targets are considered in the assessments below and are provided for reference in appendix A.
Features and effects for assessment
1125 The potential for adverse effects has been identified for the following Annex II marine mammal features of this site:
- Grey seal.
1126 NatureScot and MS provided scoping advice in December 2021, which recommended use of SCOS (2020) pup production estimates to inform the size of grey seal populations at Berwick shire and North Northumberland Coast SAC and Isle of May SAC. In March 2022, NatureScot and MS revised this advice following a request for clarification and recommended the use of maximum population estimates from the JNCC Standard Data Forms instead (Marine Scotland, pers. comm on 17 March 2022). This results in a population of 1,000 individuals at Berwickshire and North Northumberland Coast SAC (JNCC, 2015a), which will be used as the reference population against which potential effects will be assessed.
1127 The following impacts associated with the construction and decommissioning of the Proposed Development were identified as having the potential for adverse effects on grey seal at this site:
- Injury and disturbance from underwater noise generated by the following activities:
– piling of fixed foundations;
– clearance of UXO;
– site investigation surveys; and
– vessel use and other activities.
- Changes in fish and shellfish communities affecting prey availability causing potential shifts in distribution, abundance and migration patterns, community structure, susceptibility to disease due to changes in prey availability.
1128 The following impacts associated with the operation and maintenance of the Proposed Development have been identified as having the potential for adverse effects on grey seal at this site:
- Injury and disturbance from underwater noise generated by site investigation surveys as well as vessel use and other activities; and
- Changes in fish and shellfish communities affecting prey availability causing potential shifts in distribution, abundance and migration patterns, community structure, susceptibility to disease due to changes in prey availability.
1129 The following assessment is structured to first assess whether the construction and decommissioning impacts will have an adverse effect on the integrity of the grey seal feature of the site, and then the impacts associated with operation and maintenance will be assessed. For the purposes of these assessments, the potential effects are considered in relation to the site’s conservation objectives.
Construction and decommissioning
Injury and disturbance from elevated underwater noise during piling
1130 Underwater noise could affect the population and distribution of the qualifying species. Underwater noise modelling has been undertaken to estimate the maximum potential injury ranges for underwater noise that could arise during construction and decommissioning in relation to grey seal. The modelling was based on the maximum design scenario (as outlined in Table 13.10 Open ▸ ) Table 13.10 Open ▸ with summary of noise modelling provided in paragraph 271 et seq.
1131 The maximum range for injury to grey seal was estimated as 118 m based on SPLpk and using the 1% constant CF (see paragraph 881 et seq). Taking into account the most conservative scenario and maximum grey seal densities ( Table 13.4 Open ▸ ), less than one grey seal was predicted to be potentially injured, which accounts for <0.1% of the Berwickshire and North Northumberland Coast SAC population. As outlined in paragraph 779, while a high proportion of tagged individuals were tracked between the Proposed Development marine mammal study area and the Berwickshire and North Northumberland Coast SAC ( Figure 13.1 Open ▸ ), a relatively high proportion were also tracked to the Isle of May SAC, with a small proportion travelling to sites further away. Therefore, whilst it is assumed that the single grey seal potentially injured may originate from the Berwickshire and North Northumberland Coast SAC (equating to <0.1% of the SAC population), this number is likely to be conservative due to the precautionary approach adopted in the assessment. With designed-in measures in place ( Table 13.11 Open ▸ ) which are in line with recommended best practice guidelines, the impact would result in a negligible risk of injury to grey seal.
1132 In terms of behavioural disturbance, up to 1,358 animals were predicted to be potentially disturbed from concurrent piling at a maximum hammer energy of 4,000 kJ ( Table 13.15 Open ▸ ). These results are considered highly precautionary as there is a number of conservative assumptions in subsea noise model (i.e. the maximum hammer energy of 4,000 kJ is unlikely to be reached at all piling locations (see paragraph 844 for more details)).
1133 The outer behavioural disturbance contours (135 dB) overlap with shallower, coastal areas south of the Proposed Development and therefore there was predicted to be a small overlap with northern part of the Berwickshire and North Northumberland Coast SAC ( Figure 13.1 Open ▸ ). However, although there is a potential for overlap of disturbance contours with northern section of the SAC, it is the southern half of the SAC which is an important breeding site for grey seals (SCOS, 2020; see Figure 13.1 Open ▸ where grey seal telemetry tracks are concentrated in waters around Farne Islands). Grey seals present in the southern part of the SAC, in the vicinity of the habitats which they utilise throughout their life cycle (submerged/partially submerged sea caves, intertidal mud/rock/sediment), are therefore unlikely to experience disturbance as these areas lie outside of the noise disturbance contours. As such, piling activities are highly unlikely to disrupt normal behaviours of grey seals or adversely affect maintenance of the supporting habitats.
Figure 13.1: Unweighted SEL Contours Due to Concurrent Impact Piling of Wind Turbine Piles at Maximum Hammer Energy (4,000 kJ) Overlaid With Adult Grey Seal Telemetry Tracks
1134 Grey seal in inshore waters could experience mild disturbance where these areas overlap with 135 dB disturbance contour. As advised by NatureScot, grey seal in Scotland tend to stay within 20 km of the breeding colony during the breeding season ( Table 8.1 Open ▸ ). Therefore, to investigate the number of animals potentially disturbed in the vicinity of the SAC, a 20 km buffer from the coast has been applied ( Figure 13.2 Open ▸ ). Based on Carter et al. (2020) seal at-sea density grids and the area of overlap between the 20 km foraging range and the outer disturbance contour, a maximum of 532 animals could potentially experience mild disturbance or barrier effects within the foraging range from Berwickshire and North Northumberland Coast SAC. Due to the low received noise levels it is expected that grey seals will exhibit some tolerance to the mild disturbance closer to the coast. With respect to barrier effects, as outlined in paragraph 1085 et seq, exclusion from key foraging grounds along the coast and altered behaviour could affect reproduction and lactation in females if feeding is reduced or inhibited. Given that animals would be potentially exposed only to low noise levels, these are unlikely to lead to barrier effects. Therefore, disturbance caused by piling is considered unlikely to cause a change in reproduction and survival rates.
1135 During piling, there is the potential for some animals to be temporarily deterred from the offshore areas. As grey seals feed in the water column over a variety of habitats, they may use different foraging areas at different times of the year to target seasonal prey. Telemetry data suggest that adult grey seals from Berwickshire and North Northumberland Coast SAC mostly use the area that only slightly overlaps with outer disturbance contours ( Figure 13.1 Open ▸ ), where seals are likely to experience mild disruptions of normal behaviours but prolonged or sustained behavioural effects, including displacement, are unlikely to occur (Southall et al., 2021). It must be also noted that behavioural disturbance contours presented in Figure 13.1 Open ▸ represent the maximum adverse scenario for concurrent piling at wind turbine locations where noise contours propagate in the direction of the Berwickshire and North Northumberland Coast SAC. Therefore, the disturbance contours will not reach that far towards the SAC during the piling at remaining wind turbine/OSP/Offshore convertor station platform locations. As described in paragraph 1084, grey seals although initially displaced due to pile-driving, are likely to return to the same area on subsequent trips following cessation of piling. Therefore, it is anticipated that piling will not result in any long-lasting changes in the distribution of adult seals from this SAC and the connectivity with areas of high importance within and outside the site is not expected to be impaired.
1136 As outlined in paragraph 884, the total duration of piling could potentially affect up to a maximum of five breeding cycles for grey seals. Piling activities will be intermittent and will occur over small timespan (372 days) within the piling phase (52 months) and therefore can affect grey seals over the medium term. Despite this, the results of the iPCoD modelling for grey seal against the ES plus NE MU population showed that the difference in population trajectory between the impacted and unimpacted population fall within the natural variance of the population (see paragraph 909 et seq.). Therefore, it was considered that there is no potential for the long-term effects on this species within wider population as a result of piling during construction phase of the Proposed Development (see volume 2, appendix 10.4 of the Offshore EIA Report).
1137 Significant adverse effects on the qualifying Annex II marine mammal feature grey seal of the Berwickshire and North Northumberland Coast SAC are not predicted to occur as a result of underwater noise during piling during the construction phase (i.e. in relation to maintaining the population, distribution of species within the site, connectivity and disturbance to species).
Conclusion
1138 The assessment has concluded that piling activities are highly unlikely to disrupt normal behaviours of grey seals. Animals would be potentially exposed only to low noise levels along the coast and these are unlikely to lead to barrier effects or strong behavioural responses. Therefore, disturbance caused by piling is considered unlikely to cause a change in reproduction and survival rates and will not influence the population of qualifying species. Given that grey seals are likely to return to the same area on subsequent trips following cessation of piling, piling will not result in any long-lasting changes in the distribution of seals from this SAC and the connectivity with areas of high importance within and outside the site is not expected to be impaired. As such, the conservation objectives for Annex II species, grey seal, will not be undermined.
1139 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Berwickshire and North Northumberland Coast SAC from injury or disturbance from elevated underwater noise during piling with respect to the construction of the Proposed Development acting alone.
Figure 13.2: Unweighted SELss Contours Due to Concurrent Impact Piling Overlaid With 20 km Buffer from the Coast Along the Berwickshire and North Northumberland Coast SAC
Injury and disturbance from elevated underwater noise during site investigation surveys
1140 The noise modelling showed that ranges within which there is a risk of PTS to grey seals as a result of geophysical surveys are relatively low with a maximum impact range of 65 m (due to operation of SSS, SBES and SBP; Table 13.20 Open ▸ and Table 13.21 Open ▸ ). For geotechnical survey activities, PTS impact thresholds for grey seal are not exceeded ( Table 13.21 Open ▸ ).
1141 There is potential for less than one animal to experience PTS as a result of geophysical and geotechnical site investigation surveys (<0.1% of the Berwickshire and North Northumberland Coast SAC population). The surveys are considered to be short-term as they will take place over a period of up to three months. It should be noted that since sonar-based systems have strong directivity, there is only potential for injury when marine mammals are directly underneath the sound source. With designed-in measures in place, due to the low risk of PTS occurring and the short-term duration of the geophysical surveys, no adverse effects associated with auditory injury to grey seals are predicted as a result of site investigations surveys ( Table 13.11 Open ▸ ). It is anticipated that there will be no introduction of barriers to wider movement or impact on connectivity between different important habitats for grey seals at the SAC as a result of elevated sound from site investigation surveys.
1142 In terms of behavioural disturbance, estimated maximum ranges for onset of disturbance are based on exceeding the 120 dB re 1 μPa (rms) threshold applicable for all marine mammals for continuous noise, noting that this threshold is for ‘mild disturbance’ and therefore is not likely to result in displacement of animals. The largest distance over which disturbance could occur potentially affect grey seal is out to approximately 7.5 km during vibro-coring. Using the published at-sea density maps (Carter et al., 2020) the maximum number of grey seals estimated to be disturbed was 210 grey seals as a result of vibro-coring (21% of the Berwickshire and North Northumberland Coast SAC population). However, this was shown to be highly precautionary when compared with estimates of the number of grey seal using site-specific densities derived from the Proposed Development aerial digital survey data. For example, based on the mean monthly density (0.276 animals per km2) and seasonal peak density (0.321 animals per km2) from aerial data, the number of grey seal affected by possible disturbance during vibro-core testing, would be 48 animals (4.8% of the SAC population) and 56 animals (5.6% of the SAC population), respectively. Therefore, although there is a potential for behavioural disturbance during the vibro-core survey, this survey is expected to be very short in duration with animals returning to baseline levels soon after surveys have ceased. Therefore, underwater noise during site-investigation surveys is unlikely to affect grey seal at a level that would substantially affect their behaviour and cause change in reproduction and survival rates.
1143 Significant adverse effects on the qualifying Annex II marine mammal feature grey seal of the Berwickshire and North Northumberland Coast SAC are not predicted to occur as a result of underwater noise during site investigation surveys during the construction phase (i.e. in relation to maintaining the population, distribution of species within the site, connectivity and disturbance to species).
Conclusion
1144 The assessment has concluded that there will be no introduction of barriers to wider movement for grey as a result of elevated sound from site investigation surveys. Therefore site investigation surveys will not result in changes to the distribution of qualifying species within the site. Underwater noise during site-investigation surveys is unlikely to affect grey seal at a level that would substantially affect their behaviour and cause change in reproduction and survival rates and therefore will not influence the population of qualifying species. As such, the conservation objectives for Annex II species, grey seal, will not be undermined.
1145 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Berwickshire and North Northumberland Coast SAC from injury or disturbance from elevated underwater noise during site investigation surveys with respect to the construction of the Proposed Development acting alone.
Injury and disturbance from elevated underwater noise during UXO clearance
1146 Based on the maximum design scenario of high order detonation, the underwater noise modelling results show that grey seal can be potentially affected by PTS at the maximum range of 2,085 m due to detonation of charge size of 300 kg ( Table 13.24 Open ▸ ). Conservatively, the number of grey seals that could be potentially injured by the high order UXO clearance event is up to 16 animals (Table 13.27). This represents a possible 1.6% of the Berwickshire and North Northumberland Coast SAC population. As outlined in paragraph 780, while a high proportion of tagged individuals were tracked between the Proposed Development marine mammal study area and the Berwickshire and North Northumberland Coast SAC ( Figure 13.1 Open ▸ ), a relatively high proportion were also tracked to the Isle of May SAC, with a small proportion travelling to sites further away. Therefore, this number is likely to be an over-estimation of the proportion of seals from the Berwickshire and North Northumberland Coast SAC affected.
1147 To reduce the potential of experiencing injury, designed-in measures, which are in line with recommended best practice guidelines, will be adopted as part of a MMMP (see Table 13.11 Open ▸ ). Given that there is a potential to experience auditory injury by grey seal at a greater range than can be mitigated by monitoring of the 1 km mitigation zone alone ( Table 13.24 Open ▸ ), an ADD will be deployed for a pre-determined length of time to deter marine mammals to a greater distance prior to any detonation. Activation of ADD for only 22 minutes is considered sufficient to deter grey seal from the potential injury zone as a result of high order detonation of 300 kg UXO ( Table 13.24 Open ▸ ). A draft MMMP has been developed for the purpose of mitigating the risk of auditory injury (PTS) to marine mammals from the proposed UXO clearance activities at the Proposed Development and this will be updated post-consent based on an assessment which will be provided as a part of the EPS licence supporting information.
1148 Moreover, low order techniques will be applied as the intended methodology for clearance of UXO and it is anticipated that only 10% of all UXO clearance events will result in high order detonation. The underwater noise modelling results show that grey seal can be potentially affected by PTS at the maximum range of 250 m due to detonation of 0.5 kg clearance shot ( Table 13.24 Open ▸ ), with one animal potentially affected ( Table 13.25 Open ▸ ). This accounts for 0.1% of the Berwickshire and North Northumberland Coast SAC population.
1149 Given that only small number of grey seals have the potential to be affected by PTS from UXO clearance events and mitigation measures are likely to reduce the risk of injury to low, an alteration in the distribution of the population from Berwickshire and North Northumberland Coast SAC is considered highly unlikely. Grey seals present in the vicinity of the habitats which they utilise throughout their life cycle (submerged/partially submerged sea caves, intertidal mud/rock/sediment), are unlikely to experience PTS as the maximum injury range is smaller than distance from the SAC to the Proposed Development area. As such, UXO clearance activities are highly unlikely to disrupt normal behaviours of grey seals or adversely affect maintaining supporting habitats.
1150 As described in paragraph 971, the threshold for potential TTS was also assessed as this represents a behavioural, fleeing response. Based on the maximum design scenario of high order detonation, the underwater noise modelling results show that grey seal can be potentially affected by TTS at the maximum range of 6,430 m due to detonation of charge size of 300 kg ( Table 13.32 Open ▸ ) with up to 156 grey seal individuals affected ( Table 13.33 Open ▸ ; 15.6% of the Berwickshire and North Northumberland Coast SAC population). Although approximately 10% of all clearance events (up to two UXOs) may result in high order detonation, low order techniques are the preferred option for UXO clearance. The underwater noise modelling predicted that grey seal can potentially experience TTS at the maximum range of 455 m due to detonation of 0.5 kg clearance shot following low order clearance ( Table 13.30 Open ▸ ) with up to one grey seal potentially affected ( Table 13.31 Open ▸ ). This accounts for 0.1% of the Berwickshire and North Northumberland Coast SAC population.
1151 TTS is a temporary hearing impairment and therefore animals are likely to fully recover from the effect. Therefore, effects caused by UXO clearance are considered unlikely to cause a change in reproduction and survival rates or alteration in the distribution of the population from Berwickshire and North Northumberland Coast SAC. Given that this effect is short in duration, connectivity with important habitats within and outside the site is also unlikely to be impaired.
1152 Considering the number of animals potentially affected by the PTS and TTS, respective proportions of the SAC population potentially affected and designed-in measures reducing the risk of adverse effects, it is highly unlikely that UXO clearance will influence grey seal of Berwickshire and North Northumberland population trajectory in the long-term.
1153 Significant adverse effects on the qualifying Annex II marine mammal feature grey seal of the Berwickshire and North Northumberland Coast SAC are not predicted to occur as a result of underwater noise during UXO clearance during the construction phase (i.e. in relation to maintaining the population, distribution of species within the site, connectivity and disturbance to species).
Conclusion
1154 The assessment has concluded that UXO clearance activities are highly unlikely to disrupt normal behaviours of grey seal. Since TTS is a temporary hearing impairment, it is unlikely to cause a change in reproduction and survival rates and will not influence the population of qualifying species. Changes in distribution of qualifying species within the site are highly unlikely. As such, the conservation objectives for Annex II species, grey seal, will not be undermined.
1155 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Berwickshire and North Northumberland Coast SAC from injury or disturbance from elevated underwater noise during UXO clearance with respect to the construction of the Proposed Development acting alone.
Injury and disturbance from elevated underwater noise during vessel use and other activities
1156 With regards to PTS, the modelling shows that for grey seal, the threshold for PTS is not exceeded by any vessel with the exception of rock placement vessels, for which an injury range of 5 m from the source was reported ( Table 13.36 Open ▸ ). PTS ranges for grey seal were not exceeded for any other activities except for cable laying, where an injury range of 5 m from the source was reported. The number of grey seals potentially affected within the modelled ranges for PTS from vessels and other activities were found to be less than one individual. For Berwickshire and North Northumberland Coast SAC, this equates to <0.1% of the grey seal population. As outlined in paragraph 780, while a high proportion of tagged individuals were tracked between the Proposed Development marine mammal study area and the Berwickshire and North Northumberland Coast SAC ( Figure 13.1 Open ▸ ), a relatively high proportion were also tracked to the Isle of May SAC, with a small proportion travelling to sites further away. Therefore, this number is likely to be an over-estimation of the proportion of seals from the Berwickshire and North Northumberland Coast SAC affected. Given that vessels will follow a Code of Conduct (including advice to operators to not deliberately approach marine mammals) and Navigational Safety Plan (NSP) combined with Vessel Management Plan (NSPVMP), the risk of potential auditory injury will be low.
1157 With regard to behavioural disturbance to grey seals, cable laying activities result in the greatest modelled disturbance ranges out to 4,389 m ( Table 13.37 Open ▸ ). Similar ranges for behavioural effects are predicted to occur due to underwater noise from installation and construction vessels as well as rock placement vessels with disturbance ranges of 4,389 m. In comparison, vessels such as excavator, backhoe dredger, pipe laying, geophysical survey vessel and jack up vessel as well as jack-up rig were predicted to result in disturbance ranges out to 300 m.
1158 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). Grey seal is likely to be sensitive to disturbance from vessel traffic. However, most of the vessel traffic associated with construction and decommissioning will take place within the Proposed Development array area and Proposed Development export cable corridor, at a distance where overlap of noise disturbance contours ( Table 13.37 Open ▸ ) with the southern half of the SAC which is an important breeding site for grey seals is unlikely. It is therefore highly unlikely that the reproductive and recruitment capability of the species will be affected. Construction activities will be carried out over a medium term and since the behavioural effect is considered to be highly reversible, it is highly unlikely that it will influence grey seal population trajectory in the long-term.
1159 Most of the vessel traffic associated with construction within the Proposed Development array area will take place at distances >35 km from the Berwickshire and North Northumberland Coast SAC. Vessel movements will also increase over construction phase along the Proposed Development export cable corridor. Therefore, due to the proximity of the landfall to the SAC there is a potential for overlap of disturbance ranges with northern section of the SAC. However, it is the southern half of the SAC which is an important breeding site for grey seals (SCOS, 2020; see Figure 13.1 Open ▸ where grey seal telemetry tracks are concentrated in waters around the Farne Islands)
1160 As previously described in paragraph 1107, Anderwald et al. (2013) suggested that in the study of displacement responses to construction-related vessel traffic, grey seals avoided the area due to vessel noise. Even if individuals are temporarily deterred from offshore foraging grounds, given that the impacts of construction will be highly localised and largely restricted to the boundaries of the Proposed Development, only a small area will be affected when compared to available foraging habitat for grey seals in the northern North Sea. Based on telemetry tracks, the area of high importance for grey seal does not overlap with Proposed Development array area nor the Proposed Development export cable corridor ( Figure 13.1 Open ▸ ). Therefore, it is anticipated that the availability of foraging grounds for grey seals from the Berwickshire and North Northumberland Coast SAC will not be significantly impacted.
1161 As outlined in paragraph 1110, foraging context is important when interpreting avoidance behaviour of grey seals and should be considered when predicting effects. Avoidance rates may depend on perceived risk versus the quality of the prey patch. Given the existing levels of vessel activity in the Proposed Development shipping and navigation study area (see volume 2, chapter 13 of the Offshore EIA Report) it is expected that grey seal could tolerate the effects of disturbance due to vessel movements without any impact on reproduction and survival rates and would return to previous activities once the impact had ceased.
1162 The effect during the decommissioning phase for both auditory injury and disturbance as a result of elevated underwater noise due to vessel use is not expected to differ or be greater than that assessed for the construction phase.
1163 Significant adverse effects on the qualifying Annex II marine mammal feature grey seal of the Berwickshire and North Northumberland Coast SAC are not predicted to occur as a result of underwater noise during vessel use and other activities during the construction and decommissioning phases (i.e. in relation to maintaining the population, distribution of species within the site, connectivity and disturbance to species).
Conclusion
1164 The assessment has concluded that vessel use, and other activities are highly unlikely to affect reproductive and recruitment capability of the species because important breeding areas within the SAC lie outside of the disturbance ranges. Therefore, underwater noise arising from vessel use will not influence the population of qualifying species. The overlap of disturbance ranges with the SAC is unlikely and therefore vessel use and other activities will not result in changes in the distribution of qualifying species within the site. As such, the conservation objectives for Annex II species, grey seal, will not be undermined.
1165 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Berwickshire and North Northumberland Coast SAC from injury or disturbance from elevated underwater noise during vessel use and other activities with respect to the construction and decommissioning of the Proposed Development acting alone.
Changes in fish and shellfish communities affecting prey availability
1166 As outlined in paragraph 1010 et seq., there is potential for changes to prey availability for grey seal during construction and decommissioning of the Proposed Development. These impacts include temporary and long-term habitat loss/disturbance, increased SSC and associated sediment deposition, and injury and/or disturbance from underwater noise and vibration.
1167 There is potential for temporary habitat loss/disturbance to affect up to 113,974,700 m2 of seabed during the construction phase, which equates to 9.7% of the fish and shellfish ecology study area (see volume 2, chapter 9 of the Offshore EIA Report). Only a small proportion of the maximum footprint of habitat loss/disturbance may be affected at any one time during the construction phase, with areas starting to recover immediately after cessation of construction activities in the vicinity. Additionally, habitat disturbance during the construction phase will also expose benthic infaunal species from the sediment, potentially offering foraging opportunities to some fish and shellfish species (e.g. opportunistic scavenging species) immediately after completion of works. It is expected that grey seal could come back to forage within areas previously disturbed after cessation of works and therefore their distribution and connectivity with important habitats within and outside the site is unlikely to be impaired in long term. With regard to grey seal main prey item, monitoring studies have shown that offshore wind farm construction has not led to significant adverse effects on sandeel populations and that recovery of sandeel occurs quickly following construction operations (see volume 2, chapter 9 of the Offshore EIA Report).
1168 In terms of indirect effects on marine mammals as a result of underwater noise, it is assumed that marine mammals would be disturbed from the area in vicinity of the noise source, and so any changes to the distribution of prey resources would not affect marine mammals as they would already be disturbed from the same (or larger) area.
1169 Changes to the prey species may also occur due to an increase in SSC and associated sediment deposition (short-term avoidance of affected areas by fish and shellfish). Sandeel eggs are likely to be tolerant to some level of sediment deposition due to the nature of re-suspension and deposition within their natural high energy environment. The effects on sandeel spawning populations are predicted to be limited. Therefore, the availability of suitable food supply for grey seals is not expected to be impaired as a result of increase in SSC and associated sediment deposition.
1170 As outlined in paragraph 1023 et seq., while grey seal has a predominantly flatfish and sandeel, the species can forage widely, sometimes covering extensive distances. Given that the impacts of construction will be highly localised and largely restricted to the boundaries of the Proposed Development, only a small area will be affected when compared to available foraging habitat for grey seals in the northern North Sea. Telemetry data showed wide-ranging behaviour of grey seals within the northern North Sea, suggesting that, due to the highly mobile nature of grey seals and presence of alternative prey resources and foraging grounds available in the wider area, grey seals will not be constrained by the temporary and reversable nature of impacts associated with construction. There may be an energetic cost associated with increased travelling, however, grey seal is not considered to be particularly vulnerable to this effect as foraging trips tend to be wide-ranging, out to 100 km from a haul out site (SCOS, 2018). There is also evidence that grey seal in Scotland tend to stay within 20 km of the breeding colony during the breeding season. Telemetry data suggest that adult grey seals from Berwickshire and North Northumberland Coast SAC mostly use the area south from the Proposed Development ( Figure 13.1 Open ▸ ). Due to the limited extent of effects associated with construction and decommissioning works, food availability within their foraging from the Berwickshire and North Northumberland Coast SAC is not expected to be impaired ( Figure 13.1 Open ▸ ). It is expected that grey seal population would be able to tolerate the effect without any impact on reproduction and survival rates.
1171 Significant adverse effects on the qualifying Annex II marine mammal feature grey seal of the Berwickshire and North Northumberland Coast SAC are not predicted to occur as a result of changes in fish and shellfish communities affecting prey availability during the construction and decommissioning phases (i.e. in relation to maintaining the cover and abundance of preferred food items required by the species).
Conclusion
1172 The assessment has concluded that grey seal distribution and connectivity with important habitats within and outside the site as well as the availability of suitable food supply is unlikely to be impaired in long term. Therefore there is no risk of structure and function of the habitats of qualifying species being affected. It is expected that grey seal population would be able to tolerate the effect of changes in fish and shellfish communities without any impact on reproduction and survival rates and the population of qualifying species will not be affected. As such, the conservation objectives for Annex II species, grey seal, will not be undermined.
1173 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Berwickshire and North Northumberland Coast SAC from changes in fish and shellfish communities affecting prey availability with respect to the construction and decommissioning of the Proposed Development acting alone.
Operation and maintenance
Injury and disturbance from elevated underwater noise during site investigation surveys
1174 As discussed in paragraph 1140 et seq., the maximum range at which there is a risk of PTS to grey seal as a result of site investigation surveys is 65 m. With designed in measures ( Table 13.40 Open ▸ ) implemented for the geophysical surveys, the risk of PTS occurring to grey seals will be low. With regard to behavioural disturbance, although a maximum potential disturbance range across all survey types is 7.5 km during vibro-coring, this survey is expected to be very short in duration with animals returning to baseline levels soon after surveys have ceased. It is also anticipated that there will be no introduction of barriers to wider movement or impact to connectivity between different important habitats for grey seals at the SAC as a result of site investigation surveys.
1175 The maximum design scenario for routine geophysical surveys is estimated as a survey every six months for the first two years and annually thereafter. This equates to 37 surveys over the 35-year life cycle of the Proposed Development ( Table 13.39 Open ▸ ). The magnitude of the impact could result in a negligible alteration to the distribution of grey seals only in close vicinity of the source. However, surveys are anticipated to be short-term in nature (weeks to a few months) and occur intermittently over the operation and maintenance phase. Given no overlap between the Proposed Development and Berwickshire and North Northumberland Coast SAC is expected, only a small proportion of grey seal SAC population could be potentially affected, and they would be able to tolerate the effect without any impact on reproduction and survival rates. Therefore, it is highly unlikely that site investigation surveys will influence grey seal population trajectory in the long-term.
1176 Significant adverse effects on the qualifying Annex II marine mammal feature grey seal of the Berwickshire and North Northumberland Coast SAC are not predicted to occur as a result of underwater noise during site investigation surveys during the operation and maintenance phase (i.e. in relation to maintaining the population, distribution of species within the site, connectivity and disturbance to species).
Conclusion
1177 The assessment has concluded that there will be no introduction of barriers to wider movement for grey seal as a result of elevated sound from site investigation surveys. Therefore site investigation surveys will not result in any long-lasting changes in the distribution of qualifying species within the site. Underwater noise during site-investigation surveys is unlikely to affect grey seal at a level that would substantially affect their behaviour and cause change in reproduction and survival rates and therefore will not influence the population of qualifying species. As such, the conservation objectives for Annex II species, grey seal, will not be undermined.
1178 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Berwickshire and North Northumberland Coast SAC from injury or disturbance from elevated underwater noise during site investigation surveys with respect to the operation of the Proposed Development acting alone.
Injury and disturbance from elevated underwater noise during vessel use and other activities
1179 As described in paragraphs 1044 et seq., vessel use during the operation and maintenance phase of the Proposed Development is considered a relatively small increase in the context of baseline traffic and the size and noise outputs from vessels will be similar to those used in the construction phase. The number of vessel round trips and their frequency will be much lower compared to the construction phase.
1180 Most of the vessel traffic associated with operation and maintenance within the Proposed Development array area will take place at distances >35 km from the Berwickshire and North Northumberland Coast SAC. It can be anticipated that the number of vessel movements will increase during the operation and maintenance phase along the Proposed Development export cable corridor when compared to baseline levels. Therefore, due to the proximity of the landfall to the SAC there is a potential for overlap of disturbance ranges with northern section of the SAC. However, it is the southern half of the SAC which is an important breeding site for grey seals (SCOS, 2020; see Figure 13.1 Open ▸ where grey seal telemetry tracks are concentrated in waters around Farne Islands).
1181 Given the existing levels of vessel activity in the Proposed Development shipping and navigation study area it is expected that grey seal could tolerate the effects of disturbance without any impact on reproduction and survival rate. It is anticipated that there will be no introduction of barriers to wider movement or impact to connectivity between different important habitats for grey seals at the SAC.
1182 Given that risk of injury will be reduced as vessels will follow a Code of Conduct and NSPVMP and since the behavioural effect is considered to be highly reversible, it is highly unlikely that vessel use and other activities will influence grey seal population trajectory in the long-term.
1183 Effects on grey seal at this SAC are considered to be the same or less than the effects of vessel use and other activities during the construction and decommissioning phases. It should be noted that operation and maintenance activities will occur over the full lifetime of the project (estimated to be 35 years) and therefore only a small proportion of vessel use and other activities will occur at any one time.
1184 Significant adverse effects on the qualifying Annex II marine mammal feature grey seal of the Berwickshire and North Northumberland Coast SAC are not predicted to occur as a result of underwater noise during vessel use and other activities during the operation and maintenance phase (i.e. in relation to maintaining the population, distribution of species within the site, connectivity and disturbance to species).
Conclusion
1185 The assessment has concluded that vessel use and other activities are highly unlikely to affect reproductive and recruitment capability of the species because important breeding areas within the SAC lie outside of the disturbance ranges. Therefore, it will not influence the population of qualifying species. The availability of foraging grounds for grey seals will not be impacted and therefore vessel use and other activities will not result in any long-lasting changes in the distribution of qualifying species within the site. As such, the conservation objectives for Annex II species, grey seal, will not be undermined.
1186 Therefore, it can be concluded that there is no risk of an Adverse Effect on Integrity on the Berwickshire and North Northumberland Coast SAC from injury or disturbance from elevated underwater noise during vessel use and other activities with respect to the operation of the Proposed Development acting alone.