Changes to prey availability
  1. During the operation and maintenance phase there are a number of ways in which effects on key prey species may occur, which are outlined in the section on Project Alone: Construction and Decommissioning – Changes to prey availability for the Forth Islands SPA gannet population. The same evidence base and context applies to the Noss SPA gannet population as to the Forth Islands SPA population in relation to the potential for such effects to lead to impacts on the population.
  2. Given this, it is considered that there is relatively little potential for the Noss SPA gannet population to be affected by changes to prey availability during the operation and maintenance phase, with any such effects being largely intermittent across a relatively small spatial extent. Consequently, it is considered that there is no potential for operation or maintenance related changes in prey availability to lead to an adverse effect on the Noss SPA gannet population.
Project alone: population-level impacts
  1. Based on the Developers Approach the potential loss of up to 1.5 gannets per year from the combined impacts arising from displacement and collisions equates to 0.005% of the breeding adult population.  This increases to up to 1.7 gannets per year; 0.006% of the adult population based on the Scoping A approach and 2.7 gannets per year based on Scoping B approach; equivalent to a 0.009% of the breeding adult population.  These levels of impact could increase the baseline mortality rate from between 0.12% and 0.21%.
  2. This level of impact is not predicted to cause a population level effect to the breeding gannet population at the Noss SPA.
Project alone: Conclusion
  1. For both the Developer and Scoping Approaches, the potential effects from the Proposed Development alone on the Noss SPA gannet population are predicted to be small, with the resultant population-level impacts also predicted to be very small and at levels that would not impact on the population being of a similar size to that which would occur in the absence of the Proposed Development. Given this, it is concluded that the effects from the Proposed Development alone would not result in an adverse effect on this population.
Effects in-combination
Effects of relevance to the in-combination assessment
  1. For the same reasons as described in Effects in-combination for the Forth Islands SPA gannet population, the potential for effects of the Proposed Development to act on the Noss SPA gannet population in-combination with other plans and projects is limited to displacement/barrier effect and collision risk pathways during operation and maintenance.
Displacement/Barrier effects  – operation and maintenance
  1. The approach and methods for estimating in-combination displacement mortality are described in Effects in-combination: Displacement/Barrier Effects – Operation and Maintenance for Forth Islands SPA gannet population above and in volume 3, appendix 11.6, annex E of the Offshore EIA Report.
  2. The potential mortality estimates derived for the other projects were combined with those for the Proposed Development to give in-combination estimates for the UK North Sea wind farm scenario, according to both the Scoping Approaches and Developer Approach (Table 5.263).
Table 5.263:
Estimated Annual Mortality of Noss SPA Gannets as a Result of Displacement From the Proposed Development Array Area and 2 km Buffer as Determined by the Scoping Approach and Developer Approach, In-Combination With Other UK North Sea Wind Farms

Table 5.263: Estimated Annual Mortality of Noss SPA Gannets as a Result of Displacement From the Proposed Development Array Area and 2 km Buffer as Determined by the Scoping Approach and Developer Approach, In-Combination With Other UK North Sea Wind Farms

 

  1. For the Proposed Development in-combination with the other UK North Sea wind farms, the additional annual mortality of adult gannet from the Noss SPA population predicted due to displacement represents between approximately 0.024% of the current adult breeding population at this colony (i.e. 27,460 individuals – Table 3.3 in volume 3, appendix 11.5 of the Offshore EIA Report), as determined by Developers Approach and between 0.024% and 0.073% based on Scoping Approaches A and B. In terms of percentage increases in the baseline annual adult mortality of the population, the estimates of adult displacement mortality equate to an increase of 0.53% for developers approach and 0.53 – 1.58% for the lower and upper estimates from the Scoping Approach.
  2. The potential levels of impact on the Noss SPA gannet population resulting from predicted displacement/barrier effects associated with the Proposed Development array area in-combination with other UK North Sea wind farms during the operation and maintenance phase are considered further below in the In-combination: population-level impacts section. This presents the outputs from PVAs of the combined in-combination effects of predicted displacement and collision mortality on the SPA population.
Collision risk - operation and maintenance
  1. The approach and methods for estimating in-combination collision mortality are described in Effects In-combination: Collision – Operation and Maintenance for Forth Islands SPA gannet population above and in volume 3, appendix 11.6, annex E of the Offshore EIA Report.
  2. The potential mortality estimates derived for the other projects were combined with those for the Proposed Development to give in-combination estimates for the UK North Sea wind farm scenario, according to both the Scoping Approach and Developer Approach (Table 5.264).

 

Table 5.264:
Predicted Collision Effects on the Noss SPA Gannet Population Due to the Proposed Development In-Combination With Other Projects in UK North Sea Waters. Estimates are Presented for Both the Scoping Approach and Developer Approach for Consented Designs

Table 5.264: Predicted Collision Effects on the Noss SPA Gannet Population Due to the Proposed Development In-Combination With Other Projects in UK North Sea Waters. Estimates are Presented for Both the Scoping Approach and Developer Approach for Consented Designs

 

  1. For the Proposed Development in-combination with the other UK North Sea wind farms, the additional annual mortality of adult gannets from the Noss SPA population predicted due to collisions represents 0.10% of the current adult breeding population at this colony (i.e. 27,530 individuals –Table 3.3 in volume 3, appendix 11.5 of the Offshore EIA Report) as determined by the Developer Approach, and approximately 0.10% of this population as determined by the Scoping Approach. In terms of percentage increases in the baseline annual adult mortality of the population the estimates of adult collision mortality equate to an increase of 2.24% for the Developer Approach and 2.27% for the Scoping Approach.
  2. The potential levels of impact on the Noss SPA gannet population resulting from the predicted collision mortality associated with the Proposed Development in-combination with either the other UK North Sea wind farms during the operation and maintenance phase are considered in more detail below in the In- combination: population-level impacts section. This presents the outputs from PVAs of the combined effects of predicted displacement and collision mortality on the SPA population.
In-combination: population-level impacts
  1. As for the Proposed Development alone, PVA was undertaken on the mortality to the adult and immature age classes predicted due to the combined displacement and collision effects associated with the Proposed Development in-combination with the other North Sea wind farms. This was on the basis of the potential mortality as determined by both the Scoping and Developer Approaches (see Table 5.263   Open ▸ and Table 5.264   Open ▸ above).
  2. The approach to the PVA and the metrics used to summarise the PVA outputs are as described for In-combination: population-level impacts for Forth Islands SPA gannet population above and in volume 3, appendix 11.6 of the Offshore EIA Report.

 

Table 5.265:
Projected 35 Year Population Sizes and Associated PVA Metrics for the Noss SPA Gannet Population Under Different Impact Scenarios for the Proposed Development In-Combination with Other UK North Sea Wind Farms

Table 5.265 Projected 35 Year Population Sizes and Associated PVA Metrics for the Noss SPA Gannet Population Under Different Impact Scenarios for the Proposed Development In-Combination with Other UK North Sea Wind Farms

  1. The predicted in-combination population-level impacts are small, irrespective of whether these are determined using the Developer or Scoping Approaches. For Developer Approach the CPS value indicates that the combined collision and displacement mortality associated with the Proposed Development in-combination with estimated impacts with other North Sea wind farms would result in a reduction of approximately 5% in the size of the SPA population after 35 years, relative to that in the absence of any wind farm effects (Table 5.265). Based on the Scoping Approach B the estimated reduction in the size of the population increases to approximately 6.8% after 35 years, relative to that in the absence of any wind farm effects (Table 5.265). The associated reduction in annual population growth rate (relative to that predicted under baseline conditions) is estimated to be no greater than 0.2%, whilst the centile value of 39.8 indicates a relatively large overlap in the distributions of the predicted impacted and unimpacted population sizes and, hence, a high likelihood of the impacted population being of a similar size to the unimpacted population after 35 years. As would be expected, the metrics for Scoping Approach A and the Developer Approach suggest smaller levels of impact (Table 5.265).
In-combination: Conclusion
  1. On the basis of the Scoping Approach, the potential effects from the Proposed Development in-combination with other UK North Sea wind farms on the Noss SPA gannet population are predicted to be small, with the resultant population-level impacts also predicted to be relatively small. In addition, the PVA metrics indicate that it is likely that the population would be of a similar size to that which would occur in the absence of the Proposed Development after 35 years. The metrics for the Developer Approach suggest even smaller levels of impact. Considering this within the context of a highly precautionary assessment, it is concluded that the in-combination scenario for both the Scoping and Developer Approaches would not result in adverse effect on the Noss SPA gannet population.

Assessment for the breeding seabird assemblage

  1. The breeding seabird assemblage for the Noss SPA is a qualifying feature on the basis of the SPA supporting in excess of 20,000 individual seabirds. Gannet is amongst the species identified in the citation as having nationally important populations which contribute to the Noss SPA breeding seabird assemblage.
  2. Potential impacts of the Proposed Development alone and in-combination with other UK North Sea wind farms on the breeding seabird assemblage for the SPA could arise via effects on the individual species within the assemblage feature. For both the Developer Approach and Scoping Approach, the assessments undertaken above identify no potential for an adverse effect on the SPA gannet population in relation to the Proposed Development alone and in-combination.
  3. Given the above, it is concluded that there is no potential for an adverse effect on the Noss SPA breeding seabird assemblage. This conclusion applies to the assessments undertaken according to both the Developer Approach and the Scoping Approach.

Site conclusion

  1. Based on both the Developer Approach and Scoping Approach it is concluded that the possibility of adverse effects can be discounted for the Noss SPA population of breeding gannet.

5.7.18.              Fetlar SPA

European site information and conservation objectives

  1. Fetlar is an island in the Shetland group, lying to the east and south respectively of the larger islands of Yell and Unst. The SPA is located approximately 452 km from the Proposed Development. Fetlar SPA overlaps North Fetlar SSSI, Lamb Hoga SSSI and Trona Mires SSSI and the seaward extension extends approximately 2 km into the marine environment. The SPA was classified in 1994, with the marine extension classified in 2009.
  2. There are two annex I qualifying seabird feature and the site qualifies under Article 4.2 by regularly supporting one migratory seabird species and in excess of 20,000 breeding seabirds ( Table 5.266   Open ▸ ). The potential for LSE has been identified in relation to great skua ( Table 5.266   Open ▸ ), with the effect pathways associated with LSE for each of these detailed in Table 3.1   Open ▸ and set out in the assessment below.
  3. The conservation objectives of this SPA (as determined from NatureScot’s SiteLink (NatureScot 2022) are:
  • To avoid deterioration of the habitats of the qualifying species (listed below) or significant disturbance to the qualifying species, thus ensuring that the integrity of the site is maintained; and
  • To ensure for the qualifying species that the following are maintained in the long term:

–           Population of the species as a viable component of the site;

–           Distribution of the species within site;

–           Distribution and extent of habitats supporting the species;

–           Structure, function and supporting processes of habitats supporting the species; and

–           No significant disturbance of the species.

  1. The Proposed Development does not overlap with the SPA, so that potential impacts on its qualifying features will only occur as a result of individuals from the colony occurring in the area (or vicinity) of the Proposed Development.
  2. Consequently, the focus of the assessment for this SPA population is concerned with the conservation objective to maintain or restore the populations of each qualifying feature because the other conservation objectives either apply to the site itself, and not to areas beyond the boundary, or are encompassed by the assessment of this conservation objective.
  3. Further information on this European site is presented in appendix 3A.

 

Table 5.266:
Details on the Qualifying Features of the Fetlar SPA

Table 5.266: Details on the Qualifying Features of the Fetlar SPA

*Named components of the assemblage only.

 

Assessment for the great skua population

  1. Great skua only occur in the North Atlantic, nesting at relatively high latitudes and wintering south of their breeding sites. Most great skua nest in the eastern Atlantic, with an estimated global breeding population of 16,000 pairs, of which approximately 60% nest on islands in north and west Scotland. Great skua also nests in Faroes, Norway and Iceland and a small population breed in Ireland. Great skua forage on fish obtained via Kleptoparasitism from other seabird species and discards from fishing boats. They also predate on other seabird species. Great skua have a large foraging range when breeding, with the mean maximum foraging range reported as being 443.3 km (±487.9) (Woodward et al. 2019).
  2. The Fetlar SPA great skua population is currently estimated to number 852 Apparently Occupied Territories (1,836 individuals) based on the most recent count in 2017. Great skua are listed on the Fetlar SPA citation as a named component of the breeding seabird assemblage.
The potential for impacts on the great skua population
  1. Potential impacts on the Fetlar SPA great skua population screened in for assessment are outlined in the HRA Stage One Screening Report (SSER, 2021b).
  2. From published information on great skua foraging ranges it is apparent that during the breeding period great skua from the Fetlar SPA could, in theory, occur within the area of the Proposed Development and the 2 km buffer around the Proposed Development Array area (Woodward et al. 2019). The breeding period for great skua is defined as mid-April to mid-September, following the NatureScot (2020) guidance
  3. Great skuas move south in autumn to winter at sea from the Bay of Biscay to the seas off west Africa and also North America returning north in the spring (Furness 2015), so that the non-breeding season is divided into autumn and spring passage periods (defined as August to October and March to April, respectively, with the winter period from November to February). Given the above, the Proposed Development may have potential effects on the Fetlar SPA great skua population during breeding and non-breeding periods.
Project alone: operation and maintenance
Collision risk
  1. Predictions of the number of great skua at risk from collisions due to the Proposed Development were calculated using the deterministic version of the SOSS offshore collision risk model (Band 2012, Offshore EIA Report, appendix 11.3 in Table 4.9). The assessment is based on the outputs from both options 2 and 3 of the CRM, which use the generic flight height data and for which option 2 assumes a uniform distribution of flight heights across the rotor swept zone and option 3 assumes the modelled flight height distribution (Band 2012, Johnston et al. 2014a,b). In accordance with the recommendations of the SNCBs (2014), an avoidance rates of 98.0% were applied to the outputs from option 2 and option 3, respectively. Annual great skua collision estimates are calculated.
  2. As outlined elsewhere (e.g. the St Abb’s Head to Fast Castle SPA kittiwake CRM) the CRMs for great skua were undertaken following:
  • The Scoping Approach of using the maximum monthly densities, and
  • The Developer Approach of using the mean monthly densities.
  1. Based upon the Developer Approach option 2 of the deterministic CRM with a 98.0% avoidance rate applied, the total annual collision mortality of great skua is 0.18 adults. Based on the Scoping Approach option 2 and a 98% avoidance rate the total annual mortality of great skua is estimated to be 0.35 ( Table 5.267   Open ▸ and Offshore EIA Report appendix 11.3 Table 4.9) for all modelled scenarios). The estimated impacts based on the use of option 3 were lower than 0.02 and 0.05 birds per year for Developer and Scoping Approaches respectively.

 

Table 5.267:
Predicted Collision Effects from the Proposed Development on Great Skua Population, as Determined by the Scoping Approach and Developer Approach. Estimates are for the Maximum Design Scenario and are Based on Option 2 of the Deterministic CRM Using a 98% Avoidance Rate

Table 5.267: Predicted Collision Effects from the Proposed Development on Great Skua Population, as Determined by the Scoping Approach and Developer Approach. Estimates are for the Maximum Design Scenario and are Based on Option 2 of the Deterministic CRM Using a 98% Avoidance Rate

 

  1. Based upon the estimates from option 2 of the CRM, the additional annual mortality of great skua is 0.18 birds per year based on the Developer Approach.  Under a worst-case scenario all 0.18 collisions per year have been assumed to be adults and apportioned to the Fetlar SPA breeding population. On this highly precautionary and unrealistic worst-case scenario it is estimated that the predicted collisions represent approximately 0.009% of the number of adults currently estimated to breed at this colony (i.e. 1,836 individuals) as determined by the Developer Approach and approximately 0.019% as determined by the Scoping Approach. In terms of percentage increases in the baseline annual adult mortality of the population (which is based on applying a mortality rate of 0.112 – Robinson 2022), the predicted adult collision mortality equates to increases of 0.09% and 0.17% for the Developer and Scoping Approaches, respectively.
  2. The estimated number of collisions per annum relates to impacts on the whole great skua population and not just adults from this SPA. Most impacts are predicted to occur during spring and autumn passage periods (Offshore EIA Report appendix 11.1: section 5.14) when approximately 6.1% of the North Sea great skua population are birds from Fetlar SPA (Furness 2015). Consequently, of the 0.18 collisions per year, 6.1% could be predicted to be on birds from this SPA, equating to collision mortality of 0.01 birds per year based on the Developers Approach and 0.02 birds per year based on Scoping Approach. This estimated number of collisions represent approximately 0.0005% of the number of adults currently estimated to breed at this colony (i.e. 1,836 individuals) as determined by the Developer Approach and approximately 0.001% as determined by the Scoping Approach.  In terms of percentage increases in the baseline annual adult mortality of the population (which is based on applying a mortality rate of 0.112 – Robinson 2022), the predicted adult collision mortality equates to increases of 0.005% and 0.01% for the Developer and Scoping Approaches, respectively.
Project alone: Conclusion
  1. For both the Developer and Scoping Approaches, the potential effects from the Proposed Development alone on the Fetlar SPA great skua population are predicted to be negligible, with the resultant population-level impacts also predicted to be negligible. Given this, it is concluded that the effects from the Proposed Development alone would not result in an adverse effect on this population.
Effects in-combination
Collision risk
  1. As detailed above, any effects from the Proposed Development alone on the Fetlar SPA great skua population resulting from collision during operation and maintenance will be very small impacting on no more than 0.001% of the adult population and increasing the adult mortality by no more than 0.01%. Consequently, it is considered that there is no potential for an effect from the Proposed Development to add to impacts at a population level that could cause an in-combination adverse effect.
In-combination: Conclusion
  1. On the basis of the above considerations, it is concluded that the estimated small population-level impacts resulting from the Proposed Development in-combination with the other UK North Sea wind farms would not produce an adverse effect on the Fetlar SPA great skua population. This conclusion applies irrespective of whether effects are determined according to the Scoping Approach or the Developer Approach.

Assessment for the breeding seabird assemblage

  1. The breeding seabird assemblage for the Fetlar SPA is a qualifying feature on the basis of the SPA supporting in excess of 20,000 individual seabirds. Great skua are amongst the species identified in the citation as having nationally important populations which contribute to the Fetlar SPA breeding seabird assemblage. No LSE was determined for the other species in relation to the Proposed Development (HRA Stage One Screening Report; SSER, 2021b).
  2. Potential impacts of the Proposed Development alone and in-combination with other UK North Sea wind farms on the breeding seabird assemblage for the SPA could arise via effects on the individual species within the assemblage feature. For the Developer Approach, the assessments undertaken above identify no potential for an adverse effect on the SPA great skua population in relation to the Proposed Development alone and in-combination.
  3. Given the above, it is concluded that there is no potential for an adverse effect on the Fetlar SPA breeding seabird assemblage. This conclusion applies to the assessments undertaken according to both the Developer Approach and the Scoping Approach.

Site conclusion

  1. Based on both the Developer Approach and Scoping Approach it is concluded that the possibility of adverse effects can be discounted for the Fetlar SPA population of breeding great skua and breeding seabird assemblage qualifying feature.

5.7.19.              Hermaness, Saxa Vord and Valla Field SPA

European site information and conservation objectives

  1. Hermaness, Saxa Vord and Valla Field SPA lies in the north-west corner of the island of Unst, Shetland, at the northernmost tip of Britain and approximately 507 km from the Proposed Development. The boundary of the SPA is coincident with that of the Hermaness SSSI, Saxa Vord SSSI, and Valla Field SSSI and the seaward extension extends approximately 2 km into the marine environment. The SPA was classified in 2001, with the marine extension classified in 2009.
  2. There is one annex I qualifying seabird feature and the site qualifies under Article 4.2 by regularly supporting three migratory seabird species and in excess of 20,000 breeding seabirds ( Table 5.268   Open ▸ ). The potential for LSE has been identified in relation to great skua and gannet ( Table 5.268   Open ▸ ), with the effect pathways associated with LSE for each of these detailed in Table 3.1   Open ▸ and set out in the assessment below.
  3. The conservation objectives of this SPA (as determined from NatureScot’s SiteLink (NatureScot 2020) are:
  • To avoid deterioration of the habitats of the qualifying species (listed below) or significant disturbance to the qualifying species, thus ensuring that the integrity of the site is maintained; and
  • To ensure for the qualifying species that the following are maintained in the long term:

–           Population of the species as a viable component of the site;

–           Distribution of the species within site;

–           Distribution and extent of habitats supporting the species;

–           Structure, function and supporting processes of habitats supporting the species; and

–           No significant disturbance of the species.

  1. The Proposed Development does not overlap with the SPA, so that potential impacts on its qualifying features will only occur as a result of individuals from the colony occurring in the area (or vicinity) of the Proposed Development.
  2. Consequently, the focus of the assessment for this SPA population is concerned with the conservation objective to maintain or restore the populations of each qualifying feature because the other conservation objectives either apply to the site itself, and not to areas beyond the boundary, or are encompassed by the assessment of this conservation objective.
  3. Further information on this European site is presented in appendix 3A.

 

Table 5.268:
Details on the Qualifying Features of the Hermaness, Saxa Vord and Valla Field SPA

Table 5.268: Details on the Qualifying Features of the Hermaness, Saxa Vord and Valla Field SPA

*Named components of the assemblage only

 

Assessment for the great skua population

  1. Great skua only occur in the North Atlantic, nesting at relatively high latitudes and wintering south of their breeding sites. Most great skua nest in the eastern Atlantic, with an estimated global breeding population of 16,000 pairs, of which approximately 60% nest on islands in north and west Scotland. Great skua also nests in Faroes, Norway and Iceland and a small population breed in Ireland. Great skua forage on fish obtained via Kleptoparasitism from other seabird species and discards from fishing boats. They also predate on other seabird species. Great skua have a large foraging range when breeding, with the mean maximum foraging range reported as being 443.3 km (±487.9) (Woodward et al. 2019).
  2. The Hermaness, Saxa Vord and Valla Field SPA great skua population is currently estimated to number 955 Apparently Occupied Territories (1,910 individuals) based on the most recent count in 2018.
  3. Potential impacts on the Hermaness, Saxa Vord and Valla Field SPA great skua population screened in for assessment are outlined in the HRA Stage One Screening Report (SSER, 2021b).
The potential for impacts on the great skua population
  1. Potential impacts on the Hermaness, Saxa Vord and Valla Field SPA great skua population screened in for assessment are outlined in the HRA Stage One Screening Report (SSER, 2021b).
  2. From published information on great skua foraging ranges it is apparent that during the breeding period great skua from the Hermaness, Saxa Vord and Valla Field SPA could, in theory, occur within the area of the Proposed Development and the 2 km buffer around the Proposed Development Array area (Woodward et al. 2019). The breeding period for great skua is defined as mid-April to mid-September, following the NatureScot (2020) guidance
  3. Great skuas move south in autumn to winter at sea from the Bay of Biscay to the seas off west Africa and also North America returning north in the spring (Furness 2015), so that the non-breeding season is divided into autumn and spring passage periods (defined as August to October and March to April, respectively, with the winter period from November to February). Given the above, the Proposed Development may have potential effects on the Hermaness, Saxa Vord and Valla Field SPA great skua population during breeding and non-breeding periods.
Project alone: operation and maintenance
Collision risk
  1. Predictions of the number of great skua at risk from collisions due to the Proposed Development were calculated using the deterministic version of the SOSS offshore collision risk model (Band 2012, Offshore EIA Report, volume 3, appendix 11.3 in Table 4.9). The assessment is based on the outputs from both options 2 and 3 of the CRM, which use the generic flight height data and for which option 2 assumes a uniform distribution of flight heights across the rotor swept zone and option 3 assumes the modelled flight height distribution (Band 2012, Johnston et al. 2014a,b). In accordance with the recommendations of the SNCBs (2014) avoidance rates of 98.0% were applied to the outputs from option 2 and option 3, respectively. Annual great skua collision estimates are calculated.
  2. Based upon the Developer Approach option 2 of the deterministic CRM with a 98.0% avoidance rate applied, the total annual collision mortality of great skua is 0.18 adults. Based on the Scoping Approach option 2 and a 98% avoidance rate the total annual mortality of great skua is estimated to be 0.35 ( Table 5.269   Open ▸ and see Offshore EIA Report, volume 3, appendix 11.3 Table 4.9) for all modelled scenarios). The estimated impacts based on the use of option 3 were lower by 0.02 and 0.05 birds per year for Developer and Scoping Approaches respectively.

 

Table 5.269:
Predicted Collision Effects From the Proposed Development on Great Skua Population, as Determined by the Scoping Approach and Developer Approach. Estimates are for the Maximum Design Scenario and are Based on Option 2 of the Deterministic CRM Using a 98% Avoidance Rate

Table 5.269: Predicted Collision Effects From the Proposed Development on Great Skua Population, as Determined by the Scoping Approach and Developer Approach. Estimates are for the Maximum Design Scenario and are Based on Option 2 of the Deterministic CRM Using a 98% Avoidance Rate

 

  1. Based upon the estimates from option 2 of the CRM, the additional annual mortality of great skua is 0.18 birds per year based on the Developer Approach. Under a worst-case scenario all 0.18 collisions per year have been assumed to be adults and apportioned to the Hermaness, Saxa Vord and Valla Field SPA breeding population. On this highly precautionary and unrealistic worst-case scenario it is estimated that the predicted collisions represent approximately 0.009% of the number of adults currently estimated to breed at this colony (i.e. 1,910 individuals) as determined by the Developer Approach and approximately 0.018% as determined by the Scoping Approach. In terms of percentage increases in the baseline annual adult mortality of the population (which is based on applying a mortality rate of 0.112 – Robinson 2022), the predicted adult collision mortality equates to increases of 0.08% and 0.16% for the Developer and Scoping Approaches, respectively.
  2. The estimated number of collisions per annum relates to impacts on the whole great skua population and not just adults from this SPA. Most impacts are predicted to occur during spring and autumn passage periods (Offshore EIA Report, volume 3 appendix 11.1: section 5.14) when approximately 10.2% of the North Sea great skua population are birds from Hermaness, Saxa Vord and Valla Field SPA (Furness 2015). Consequently, of the 0.18 collisions per year 10.2% could be predicted to be on birds from this SPA, equating to collision mortality of 0.02 birds per year based on the Developers Approach and 0.03 birds per year based on Scoping Approach. This estimated number of collisions represent approximately 0.001% of the number of adults currently estimated to breed at this colony (i.e. 1,910 individuals) as determined by the Developer Approach and approximately 0.002% as determined by the Scoping Approach. In terms of percentage increases in the baseline annual adult mortality of the population (which is based on applying a mortality rate of 0.112 – Robinson 2022), the predicted adult collision mortality equates to increases of 0.009% and 0.014% for the Developer and Scoping Approaches, respectively.
Project alone: Conclusion
  1. For both the Developer and Scoping Approaches, the potential effects from the Proposed Development alone on the Hermaness, Saxa Vord and Valla Field SPA great skua population are predicted to be negligible, with the resultant population-level impacts also predicted to be negligible respectively. Given this, it is concluded that the effects from the Proposed Development alone would not result in an adverse effect on this population.
Effects in-combination
Collision risk

As detailed above, any effects from the Proposed Development alone on the Hermaness, Saxa Vord and Valla Field SPA great skua population resulting from collision during operation and maintenance will be very small impacting on no more than 0.002% of the adult population and increasing the adult mortality by no more than 0.014%. Consequently, it is considered that there is no potential for an effect from the Proposed Development to add to impacts at a population level that could cause an in-combination adverse effect.

In-combination: Conclusion
  1. On the basis of the above considerations, it is concluded that the population-level impacts resulting from the Proposed Development in-combination with the other UK North Sea wind farms would not produce an adverse effect on the Hermaness, Saxa Vord and Valla Field SPA great skua population. This conclusion applies irrespective of whether effects are determined according to the Scoping Approach or the Developer Approach.

Assessment for the gannet population

  1. The Hermaness, Saxa Vord and Valla Field SPA gannet population is currently estimated to number 25,580 breeding pairs (Offshore EIA Report, volume 3, appendix 11.5) based on the most recent count in 2014. Gannet are listed on the Hermaness, Saxa Vord and Valla Field SPA citation as a named component of the breeding seabird assemblage.
  2. Potential impacts on the Hermaness, Saxa Vord and Valla Field SPA gannet population screened in for assessment are outlined in the HRA Stage One Screening Report (SSER, 2021b).
The potential for impacts on the gannet population
  1. The Proposed Development and associated buffers (e.g. as used in the estimation of displacement effects from the Proposed Development Array Area) do not overlap with the Hermaness, Saxa Vord and Valla Field SPA, so that potential impacts on its gannet population will only occur as a result of individuals from the colony occurring in the area (or vicinity) of the Proposed Development.
  2. From published information on gannet foraging ranges it is possible that during the breeding period gannets from this SPA could occur within the area of the proposed development and the 2 km buffer around the Proposed Development Array area (Woodward et al. 2019). However, Hermaness, Saxa Vord and Valla Field SPA is located 507 km from the Proposed development and therefore the use of the Proposed Development array area by gannet from this SPA during the breeding period is predicted to be relatively low. This is reflected in the findings of the apportioning exercise, which estimates that 0.5% of the gannets occurring on the Proposed Development Array area during the breeding season derive from this SPA colony (Table 4.4 in Offshore EIA Report, volume 3, appendix 11.5). The breeding period for gannet is defined as mid-March to September, following the NatureScot (2020) guidance
  3. During the non-breeding period gannets move south in autumn to winter at sea from the Bay of Biscay to the seas off west Africa, returning north in the spring (Fort et al. 2012), so that the non-breeding season is divided into autumn and spring passage periods (defined as October to November and December to mid-March, respectively, on the basis of applying the BDMPS defined periods within the context of the overall non-breeding period defined by NatureScot – Furness 2015, NatureScot 2020, (Table 3.4 in Offshore EIA Report, volume 3, appendix 11.5). Given the above, the Proposed Development may have potential effects on the Hermaness, Saxa Vord and Valla Field SPA gannet population during breeding and non-breeding periods.
Project alone: construction and decommissioning
Disturbance
  1. Direct disturbance to gannet during the maximum eight-year construction phase may arise within the Proposed Development as a result of increased vessel movements, as well as from other activities associated with the installation of the wind turbine foundations, cables and other infrastructure (see the section on Project Alone: Construction and Decommissioning – Disturbance for Firth of Forth gannet population; Table 4.1   Open ▸ ).
  2. The potential for disturbance effects during decommissioning is assumed to be the same (or less) as for construction, noting that the duration of the decommissioning phase will not exceed that of construction, and may be shorter.
  3. Gannet breeding at the Hermaness, Saxa Vord and Valla Field SPA are predicted to utilise the Proposed Development during the breeding season to a relatively low extent (Offshore EIA Report, volume 3, appendix 11.5). During the non-breeding periods, gannet distribution is not constrained by the location of the breeding colonies and birds from the SPA population are likely to occur across large expanses of oceanic and maritime waters (Frederiksen et al., 2012, Furness 2015). During the autumn and spring passage periods, the potential for effects of construction-related disturbance is lower than during the breeding season because the SPA gannets are essentially transiting through the waters within which the Proposed Development is located. The potential for effects of construction- and decommissioning-related disturbance is therefore low.
  4. Furthermore, given the low sensitivity of gannet to disturbance effects (Garthe and Hüppop 2004; Furness et al., 2013), and the relatively small areas that will be subject to activities with the potential to result in intermittent, temporary disturbance (see the section on Project Alone: Construction and Decommissioning – Disturbance for Forth Islands SPA gannet population), it is considered that there is no potential for construction or decommissioning related disturbance to lead to an adverse effect on the Hermaness, Saxa Vord and Valla Field SPA gannet population.
Displacement
  1. Gannet are considered to have a low sensitivity to disturbance, whilst potential effects of disturbance during the construction and decommissioning phases will only extend across a small part of the wider foraging areas used by the Hermaness, Saxa Vord and Valla Field SPA gannet population and be limited to, at most, an eight year period during construction (and a likely similar or shorter period during decommissioning). Furthermore, potential effects of disturbance will not occur simultaneously across the entirety of the Proposed Development Array Area or Proposed Development export cable corridor but will, rather, be carried out in different areas at different times. Thus, at any given time the potential for disturbance effects that could lead to displacement of gannet from this SPA will be limited to relatively small areas, with the potential effects also being of a temporary nature.
  2. Therefore, based upon the above, it is considered that there is no potential for the Hermaness, Saxa Vord and Valla Field SPA gannet population to be affected by displacement during the construction or decommissioning phases, with any such effects only extending across relatively small areas and tending to be temporary in nature. Consequently, it is considered that there is no potential for construction or decommissioning related displacement to lead to an adverse effect on the Hermaness, Saxa Vord and Valla Field SPA gannet population.
Changes to prey availability
  1. During construction and decommissioning there are a number of ways in which effects on key prey species of seabirds may occur, which are outlined in the section on Project Alone: Construction and Decommissioning – Changes to prey availability for the Forth Islands SPA gannet population. The same evidence basis and context applies to the Hermaness, Saxa Vord and Valla Field SPA gannet population as to the Forth Islands SPA population in relation to the potential for such effects to lead to impacts on the population.
  2. Given this, it is considered that there is relatively little potential for the Hermaness, Saxa Vord and Valla Field SPA gannet population to be affected by changes to prey availability during the construction and decommissioning phases, with any such effects being largely intermittent across a relatively small spatial extent, with most effects temporary in nature. Consequently, it is considered that there is no potential for construction or decommissioning related changes in prey availability to lead to an adverse effect on the Hermaness, Saxa Vord and Valla Field SPA gannet population.
Project alone: operation and maintenance
Disturbance
  1. Vessel use and associated activities within the Proposed Development array area and export cable corridor during the operation and maintenance phase may lead to direct disturbance of gannets from Hermaness, Saxa Vord and Valla Field SPA during the breeding and non-breeding periods, as outlined in the section on Project Alone: Operation and Maintenance – Disturbance for the Forth Islands SPA gannet population. The same evidence base and context applies to the Hermaness, Saxa Vord and Valla Field SPA gannet population as to the Forth Islands SPA population in relation to the potential for such effects to lead to impacts on the population during the breeding and non-breeding periods.
  2. Given the low sensitivity of gannet to disturbance effects at sea, the relatively small areas relative to the species’ foraging range that will be subject intermittently to potentially disturbing activities, and the fact that these potential effects will be reduced compared to the construction and decommissioning phases, it is considered that there is no potential for disturbance during operation and maintenance to lead to an adverse effect on the Hermaness, Saxa Vord and Valla Field SPA gannet population. This conclusion is consistent with the outcome of the EIA which ‘screened’ out gannet as a species for which detailed consideration of the effects of construction disturbance was required (volume 2, chapter 11 of the Offshore EIA Report).
Displacement/Barrier effects
  1. The approach used to derive predicted levels of mortality for Hermaness, Saxa Vord and Valla Field SPA gannets is as described in the section on Project Alone: Operation and Maintenance – Displacement/Barrier effects for the Forth Islands SPA gannet population (and in the Offshore EIA Report, volume 3, appendix 11.4)
  2. Estimates of gannet mortality for Hermaness, Saxa Vord and Valla Field SPA were produced using the SNCB matrix on the basis of both the Scoping Approaches and the Developer Approach (Offshore EIA Report, volume 3, appendix 11.4), with these estimates then apportioned to the Hermaness, Saxa Vord and Valla Field SPA gannet population as described in volume 3, appendix 11.5 of the Offshore EIA Report and in the section on Project Alone: Operation and Maintenance – Displacement/Barrier effects  for the Forth Islands SPA gannet population ( Table 5.270   Open ▸ ).

 

Table 5.270:
The Mean Peak Abundance Estimates of Gannet in the Proposed Development Array Area and 2 km Buffer for Each Seasonal Period, Together With the Proportion of Birds Estimated to Belong to the Breeding Adult Age Class and to be From the Hermaness, Saxa Vord and Valla Field SPA Population in Each Period. The Proportion of Adults Assumed to be Sabbaticals During the Breeding Season is Also Presented.

Table 5.270: The Mean Peak Abundance Estimates of Gannet in the Proposed Development Array Area and 2 km Buffer for Each Seasonal Period, Together With the Proportion of Birds Estimated to Belong to the Breeding Adult Age Class and to be From the Hermaness, Saxa Vord and Valla Field SPA Population in Each Period. The Proportion of Adults Assumed to be Sabbaticals During the Breeding Season is Also Presented.

 

Table 5.271:
Estimated Potential Annual Mortality of Hermaness, Saxa Vord and Valla Field SPA Gannets as a Result of Displacement From the Proposed Development Array Area and 2 km Buffer as Determined by the Scoping Approach and Developer Approach

Table 5.271: Estimated Potential Annual Mortality of Hermaness, Saxa Vord and Valla Field SPA Gannets as a Result of Displacement From the Proposed Development Array Area and 2 km Buffer as Determined by the Scoping Approach and Developer Approach

  1. Based upon the estimates and assumptions detailed above, the potential annual mortality amongst the SPA gannet population as a result of displacement is estimated as 0.8 adult and 0.1 immature birds based on the Developer Approach and the lower mortality rates for the Scoping Approach (i.e. Scoping Approach A) and 2.3 adult and 0.2 immature birds based upon the higher mortality rates for the Scoping Approach (i.e. Scoping Approach B) ( Table 5.271   Open ▸ ).
  2. The additional annual mortality of adult gannets from the Hermaness, Saxa Vord and Valla Field SPA population predicted due to displacement from the Proposed Development Array represents 0.001% of the current adult breeding population at this colony (i.e. 51,160 individuals – Table 3.3 in Offshore EIA Report, volume 3, appendix 11.5) as determined by the Developer Approach, and between approximately 0.001 – 0.004% of this population as determined by the lower and upper estimates from the Scoping Approach. In terms of percentage increases in the baseline annual adult mortality of the population (which is based on applying a mortality rate of 0.046 – see Table 2.7 of volume 3, appendix 11.6 of the Offshore EIA Report), the estimates of adult mortality equate to an increase of approximately 0.03% for the Developer Approach and of 0.03 – 0.10% for the lower and upper estimates from the Scoping Approach.
  3. The potential levels of impact on the Hermaness, Saxa Vord and Valla Field SPA gannet population resulting from the mortality predicted from displacement and barrier effects associated with the Proposed Development array during the operation and maintenance phase are considered to be relatively very small compared to the breeding population and the loss of up to 2.3 adult gannets per year will not cause a population level effect.
Collision risk
  1. The approach used to derive predicted levels of mortality for Hermaness, Saxa Vord and Valla Field SPA gannet is as described in the section on Project Alone: Operation and Maintenance – Collision risk for the Forth Islands SPA gannet population (and in the Offshore EIA Report, volume 3, appendix 11.3)
  2. Based upon option 2 of the deterministic CRM with a 98.9% avoidance rate applied, the annual collision mortality of gannet from the Hermaness, Saxa Vord and Valla Field SPA is predicted to be approximately 1.8 adults and 0.1 immatures as determined by the Scoping Approach, and approximately 1.3 adults and 0.1 immatures as determined by the Developer Approach ( Table 5.272   Open ▸ ).

 

Table 5.272:
Predicted Collision Effects From the Proposed Development on the Hermaness, Saxa Vord and Valla Field SPA Gannet Population, as Determined by the Scoping Approach and Developer Approach. Estimates are for the Maximum Design Scenario and are Based on Option 2 of the Deterministic CRM Using a 98.9% Avoidance Rate (See Text)

Table 5.272: Predicted Collision Effects From the Proposed Development on the Hermaness, Saxa Vord and Valla Field SPA Gannet Population, as Determined by the Scoping Approach and Developer Approach. Estimates are for the Maximum Design Scenario and are Based on Option 2 of the Deterministic CRM Using a 98.9% Avoidance Rate (See Text)

 

  1. The additional annual mortality of adult gannets from the Hermaness, Saxa Vord and Valla Field SPA population predicted due to collisions with wind turbines in the Proposed Development Array represents approximately 0.002% of the number of adults currently estimated to breed at this colony (i.e. 51,160 individuals – Table 3.3 in Offshore EIA Report, volume 3, appendix 11.5) as determined by the Developer Approach and approximately 0.003% as determined by the Scoping Approach. In terms of percentage increases in the baseline annual adult mortality of the population (which is based on applying a mortality rate of 0.046 – see Table 2.7 of Offshore EIA Report, volume 3, appendix 11.6), the predicted adult collision mortality equates to increases of 0.05% and 0.08% for the Developer and Scoping Approaches, respectively.
  2. The potential levels of impact on the Hermaness, Saxa Vord and Valla Field SPA gannet population resulting from the mortality predicted from collisions associated with the Proposed Development during the operation and maintenance phase are relatively very small compared with the breeding population. The potential loss of up to 1.8 gannets per year is not predicted to cause a population level effect.
Changes to prey availability
  1. During the operation and maintenance phase there are a number of ways in which effects on key prey species may occur, which are outlined in the section on Project Alone: Construction and Decommissioning – Changes to prey availability for the Forth Islands SPA gannet population. The same evidence base and context applies to the Hermaness, Saxa Vord and Valla Field SPA gannet population as to the Forth Islands SPA population in relation to the potential for such effects to lead to impacts on the population.
  2. Given this, it is considered that there is relatively little potential for the Hermaness, Saxa Vord and Valla Field SPA gannet population to be affected by changes to prey availability during the operation and maintenance phase, with any such effects being largely intermittent across a relatively small spatial extent. Consequently, it is considered that there is no potential for operation or maintenance related changes in prey availability to lead to an adverse effect on the Hermaness, Saxa Vord and Valla Field SPA gannet population.