10. Marine Mammals

10.1. Introduction

  1. This chapter of the Offshore Environmental Impact Assessment (EIA) Report presents the assessment of the likely significant effects (as per the “EIA Regulations”) on the environment of the Berwick Bank Wind Farm offshore infrastructure which is the subject of this application (hereafter referred to as “the Proposed Development”) on marine mammals. Specifically, this chapter considers the potential impacts of the Proposed Development seaward of Mean High Water Springs (MHWS) during the construction, operation and maintenance, and decommissioning phases.
  2. “Likely Significant Effect (LSE)” is a term used in both the EIA Regulations and the Habitat Regulations. Reference to LSE in this Offshore EIA report refers to “LSE” as used by the EIA Regulations. This Offshore EIA report is accompanied by a Report to Inform Appropriate Assessment (RIAA) (SSER, 2022d) which uses the term as defined by the Habitats Regulations.
  3. The assessment presented is informed by the following technical chapters:
  • volume 2, chapter 7: Physical Processes;
  • volume 2, chapter 9: Fish and Shellfish Ecology; and
  • volume 2, chapter 13: Shipping and Navigation.
    1. This chapter summarises information contained within volume 3, appendix 10.2. The technical report provides a detailed characterisation of the marine mammal species ecology within the vicinity of the Proposed Development and the wider northern North Sea, based on existing literature and site-specific surveys, and provides information on marine mammal species of ecological importance and conservation value. This chapter is also informed by a technical report developed to understand underwater noise emissions associated with the Proposed Development, which is included as volume 3, appendix 10.1.

10.2. Purpose of this Chapter

  1. The primary purpose of the Offshore EIA Report is outlined in volume 1, chapter 1. It is intended that the Offshore EIA Report will provide the Scottish Ministers, statutory and non-statutory stakeholders with sufficient information to determine the likely significant effects of the Proposed Development on the receiving environment.
  2. In particular, this marine mammals EIA Report chapter:
  • presents the existing environmental baseline established from desk studies, site-specific surveys and consultation with stakeholders;
  • identifies any assumptions and limitations encountered in compiling the environmental information;
  • presents the likely significant environmental effects on marine mammals arising from the Proposed Development and reaches a conclusion on the likely significant effects on marine mammals, based on the information gathered and the analysis and assessments undertaken; and
  • highlights any necessary monitoring and/or mitigation measures which are recommended to prevent, minimise, reduce or offset the likely significant adverse environmental effects of the Proposed Development on marine mammals.

10.3. Study Area

  1. For the purposes of the marine mammals characterisation, two appropriate marine mammals study areas were defined ( Figure 10.1   Open ▸ ):
  • The Proposed Development marine mammal study area: this area encompasses the Proposed Development array area and Proposed Development export cable corridor plus a ~16 km buffer (hereafter referred to as ‘Proposed Development aerial survey area’).
  • The regional marine mammal study area: marine mammals are highly mobile and may range over large distances and therefore, to provide a wider context, the desktop review considers the marine mammal ecology, distribution and density/abundance within the wider northern North Sea. The regional marine mammal study area also informs the assessment where the Zone of Influence (ZoI) for a given impact (e.g. underwater noise) may extend beyond the Proposed Development marine mammal study area.
    1. Regional marine mammal study area boundaries were discussed with NatureScot and Marine Scotland Science (MSS) during Road Map Meeting 1 and Road Map Meeting 2 (volume 3, appendix 10.3). In accordance with advice received during consultation, population level effects were informed by species Management Units (MUs). However, where MUs for a given species extended over a very large scale (e.g. minke whale Balaenoptera acutorostrata and white-beaked dolphin Lagenorhynchus albirostris), the assessment will also consider effects over a smaller scale; within Small Cetacean Abundance in the North Sea (SCANS) III Block R.

Figure 10.1:
Marine Mammals Study Areas

Figure 10.1: Marine Mammals Study Areas

10.4. Policy and Legislative Context

  1. Policy and legislation on renewable energy infrastructure is presented in volume 1, chapter 2 of the Offshore EIA Report. Policy and legislation specifically in relation to marine mammals, is contained in the Marine (Scotland) Act 2010, the Habitats Regulations (this is a collective term which include three sets of regulations, see section 2.4.1 of volume 1, chapter 2 for more details), Scotland’s National Marine Plan 2015, The Sectoral Marine Plan for Offshore Wind Energy 2020, Nature Conservation (Scotland) Act 2004 and the United Kingdom (UK) Marine Policy Statement. A summary of the legislative provisions and policy frameworks relevant to marine mammals is provided in Table 10.1   Open ▸ to Table 10.8   Open ▸ .

 

Table 10.1:
Summary of Marine (Scotland) Act 2010 Relevant to Marine Mammals

Table 10.1: Summary of Marine (Scotland) Act 2010 Relevant to Marine Mammals

 

Table 10.2:
Summary of the Habitats Regulations Relevant to Marine Mammals

Table 10.2: Summary of the Habitats Regulations Relevant to Marine Mammals

 

Table 10.3:
Summary of Scotland’s National Marine Plan Relevant to Marine Mammals

Table 10.3: Summary of Scotland’s National Marine Plan Relevant to Marine Mammals

 

Table 10.4:
Summary of Scottish PMFs Relevant to Marine Mammals

Table 10.4: Summary of Scottish PMFs Relevant to Marine Mammals

 

Table 10.5:
Summary of The Sectoral Marine Plan for Offshore Wind Energy 2020 Relevant to Marine Mammals

Table 10.5: Summary of The Sectoral Marine Plan for Offshore Wind Energy 2020 Relevant to Marine Mammals

 

Table 10.6:
Summary of the UK Marine Policy Statement Relevant to Marine Mammals

Table 10.6: Summary of the UK Marine Policy Statement Relevant to Marine Mammals

 

Table 10.7:
Summary of the Nature Conservation (Scotland) Act 2004 Relevant to Marine Mammals

Table 10.7: Summary of the Nature Conservation (Scotland) Act 2004 Relevant to Marine Mammals

 

Table 10.8:
Summary of The Scottish Biodiversity Strategy (Scotland’s Biodiversity, 2004) Relevant to Marine Mammals

Table 10.8: Summary of The Scottish Biodiversity Strategy (Scotland’s Biodiversity, 2004) Relevant to Marine Mammals

 

10.5. Consultation

  1. The Marine Mammals Road Map was a ‘live’ document which has been used as a tool to facilitate early engagement with stakeholders and subsequent engagement throughout the pre-application phase of the Proposed Development (volume 3, appendix 10.3). This has included reaching points of agreement on potential impacts to be scoped out of the assessment, and/or agreeing the level of assessment which will be presented for potential impacts scoped into the assessment, so that the focus in the Offshore EIA Report submission documents is on likely significant environmental effects as defined by the EIA Regulations. Marine mammal Important Ecological Features (IEFs) are those marine mammal receptors that have the potential to be affected by the Proposed Development. Additionally, these pre-Application consultation meetings have provided an opportunity for stakeholders to comment on the aerial survey data interim data analyses report (volume 3, appendix 10.2, annex A) and discuss data and methods used in the assessment of significance of effects on marine mammal IEFs (see paragraph 22 for the description of IEFs and section 10.11 for the assessment of likely significant effects).
  2. The Marine Mammals Road Map (up to date at the point of Application) is presented in volume 3 appendix 10.3 and documents meetings and records discussion points. At the request of Marine Scotland - Licensing Operations Team (MS-LOT) the Berwick Bank Wind Farm Audit Document for Post-Scoping Discussions (SSER, 2022d) (hereafter ‘the Audit Document) has been produced and submitted alongside the application to document discussions on key issues, post-receipt of the Berwick Bank Wind Farm Scoping Opinion (MS-LOT, 2021).
  3. A summary of the key issues raised during consultation activities undertaken to date of submission of the Offshore EIA report, specific to marine mammals is presented in Table 10.9   Open ▸ , together with how these issues have been considered in the production of this marine mammals Offshore EIA Report chapter. Where consultation responses provided with respect to 2020 Berwick Bank remain relevant and applicable to the current proposal, or where the SNCBs have directed reference to them, these have been incorporated into this chapter. Further detail is presented within volume 1, chapter 5 as well as volume 3, appendix 10.3.

 

Table 10.9:
Summary of Key Consultation of Relevance to Marine Mammals

Table 10.9: Summary of Key Consultation of Relevance to Marine Mammals


10.6. Methodology to Inform Baseline

10.6.1.              Desktop Study

  1. Information on marine mammals within the regional marine mammal study area was collected through a detailed desktop review of existing studies and datasets. Some of the key data sources are summarised in Table 10.10   Open ▸ . A comprehensive list of all literature and data reviewed is provided in volume 3, appendix 10.2 Marine Mammals Technical Report.

 

Table 10.10:
Summary of Key Desktop Reports

Table 10.10: Summary of Key Desktop Reports

 

10.6.2.              Identification of Designated Sites

  1. All designated sites within the regional marine mammal study area and qualifying interest features that could be affected by the construction, operation and maintenance, and decommissioning phases of the Proposed Development were identified using the three step process described here:

–           The known occurrence of species within the regional marine mammal study area was based on relevant desktop information (section 10.6.1) and site-specific surveys presented within volume 3, appendix 10.2.

  • Step 3: Using the above information and expert judgement, sites were included for further consideration if:

–           A designated site directly overlaps with the regional marine mammal study area such that:

10.6.3.              Site-Specific Surveys

  1. To inform the marine mammal Offshore EIA Report chapter, site-specific surveys were undertaken, in accordance with the methodology as presented during Road Map Meeting 1 (volume 3, appendix 10.3). A summary of the surveys undertaken to inform the marine mammal assessment of effects is outlined in Table 10.11   Open ▸ .

 

Table 10.11:
Summary of Site-Specific Survey Data

Table 10.11: Summary of Site-Specific Survey Data

 

10.7. Baseline Environment

10.7.1.              Overview of Baseline Environment

  1. The distribution of marine mammals in the North Sea is patchy, however historic and recent sightings indicate that it regularly supports 11 species of cetaceans and two species of pinnipeds (Weir, 2001; Hammond et al., 2013; Hammond et al., 2021; and NMPI, 2021). The distribution and abundance of marine mammals is highly correlated with the distribution of prey. Marine mammal species are highly mobile; however some areas hold a consistently higher number of individuals than others (e.g. the deep trench running parallel to the Aberdeenshire coast attracts minke whales due to abundance of prey species; NatureScot, 2020).
  2. Cetacean and pinniped distribution is species specific and not all species are likely to occur within the Proposed Development marine mammal study area. Aerial digital surveys carried out for the Proposed Development from March 2019 to April 2021 (the ‘Digital Aerial Surveys (DAS)) showed that the most common cetacean species within the Proposed Development marine mammal study area ( Figure 10.1   Open ▸ ) was harbour porpoise. Grey seal were also sighted frequently. Marine mammals which were sighted regularly during the DAS (2019-2021) included minke whale, white-beaked dolphin, bottlenose dolphin and harbour seal (please refer to volume 3, appendix 10.2 for details about marine mammal species visiting the area occasionally).
  3. A summary of the marine mammal baseline within the Proposed Development marine mammal study area, in the context of the regional marine mammal study area, is presented in Figure 10.12   Open ▸ and volume 3, appendix 10.2.


Table 10.12:
Summary of Marine Mammals Baseline Ecology

Table 10.12: Summary of Marine Mammals Baseline Ecology


  1. Table 10.13   Open ▸ presents density estimates and population assessments for marine mammals in the Proposed Development marine mammal study area for use in quantifying the scale of effects as part of the assessment of effects. For practical management purposes, the IAMMWG has identified MUs for cetaceans in UK and Irish waters and has provided an estimated abundance for each (IAMMWG, 2021). The Proposed Development marine mammal study area lies within the NS MU for harbour porpoise, the CES MU for bottlenose dolphin and the CGNS MU for white-beaked dolphin and minke whale (details are provided in volume 3, appendix 10.2; Figure 10.2   Open ▸ ). SCOS has defined MUs for both species of seals. Given that the Proposed Development marine mammal study area overlaps with the ES and NEE MUs, the population assessments are based on the latest abundance estimates for both MUs ( Figure 10.3   Open ▸ ). To provide context within the regional marine mammal study area, SCANS III Block R population estimates are presented along abundance estimates for relevant MUs harbour porpoise, bottlenose dolphin, white-beaked dolphin and minke whale ( Figure 10.4   Open ▸ ).

 

Table 10.13:
Density Estimates and Population Assessments for Marine Mammals in the Proposed Development Marine Mammal Study Area

Table 10.13: Density Estimates and Population Assessments for Marine Mammals in the Proposed Development Marine Mammal Study Area

1 Site-specific densities (mean and seasonal peak) estimated from Proposed Development aerial digital survey data (2019 to 2021).

2 Average coastal density derived from five-year average from Arso Civil et al. (2021) with proportion at the outer Firth of Tay assigned using habitat preference modelling data from Arso Civil et al. (2019).

3 SCANS-III (Hammond et al., 2021).

4 Mean and maximum across the Proposed Development marine mammal study area based on at-sea mean density maps (Carter et al., 2020).

5 Mean monthly density based on site-specific Proposed Development aerial digital survey data (2019 to 2021) and density based on at-sea mean usage maps (Carter et al., 2020) across the Proposed Development marine mammal study area.

 

Figure 10.2:
 Management Units for Cetaceans

Figure 10.2:  Management Units for Cetaceans

Figure 10.3:
Management Units for Seals

Figure 10.3:  Management Units for Seals

Figure 10.4:
Scans III Survey Blocks

Figure 10.4: Scans III Survey Blocks

10.7.2.              Designated Sites

  1. Table 10.14   Open ▸ summarises the designated sites presented in Figure 10.5   Open ▸ , that have been identified as having potential connectivity with marine mammal receptors identified in section 10.7.1 (agreed with MS-LOT through pre-Application consultation – see Table 10.9   Open ▸ ).

 

Table 10.14:
Designated Sites and Relevant Qualifying Interest Features Considered in the Marine Mammals Assessment

Table 10.14: Designated Sites and Relevant Qualifying Interest Features Considered in the Marine Mammals Assessment

Figure 10.5:
Designated Sites

Figure 10.5: Designated Sites

10.7.3.              Important Ecological Features

  1. The IEFs are those marine mammal receptors that have the potential to be affected by the Proposed Development. The importance of ecological features is dependent upon their biodiversity, social, and economic value within a geographic framework of appropriate reference (CIEEM, 2019). Marine mammal IEFs have been identified based on biodiversity importance, recognised through international or national legislation, conservation status/plans and on assessment of value according to the functional role of the species within the context of the regional marine mammal study area. Relevant legislation/conservation plans for marine mammals would include, for example: Annex II species under the Habitats Directive; Annex IV(a) of the Habitats Directive as EPS; species listed as threatened and/or declining by OSPAR; International Union for Conservation of Nature (IUCN) Red List species; UK Biodiversity Action Plan (BAP) priority species either alone or under a grouped action plan; and PMFs in Scotland. Table 10.15   Open ▸ presents the value/importance that has been assigned to each ecological feature All marine mammals with the potential to be affected by the Proposed Development are protected under some form of international legislation and/or are important from a conservation perspective in an international/national context and therefore the value of all marine mammal IEFs was determined to be international.

 

Table 10.15:
Marine Mammal IEFs and their Importance Within the Regional Marine Mammal Study Area

Table 10.15: Marine Mammal IEFs and their Importance Within the Regional Marine Mammal Study Area

10.7.4.              Future Baseline Scenario

  1. The EIA Regulations ((The Electricity Works (Environmental Impact Assessment) (Scotland) Regulations 2017, The Marine Works (Environmental Impact Assessment) (Scotland) Regulations 2017, the Marine Works (Environmental Impact Assessment) Regulations 2007, and The Town and Country Planning (Environmental Impact Assessment) (Scotland) Regulations 2017)), require that a “a description of the relevant aspects of the current state of the environment (baseline scenario) and an outline of the likely evolution thereof without development as far as natural changes from the baseline scenario can be assessed with reasonable effort, on the basis of the availability of environmental information and scientific knowledge” is included within the Offshore EIA Report.
  2. In the event that the Proposed Development does not come forward, an assessment of the future baseline conditions has been carried out and is described within this section.
  3. The baseline environment is not static and will exhibit some degree of natural change over time, even if the Proposed Development does not come forward, due to naturally occurring cycles and processes and additionally any potential changes resulting from climate change and anthropogenic activity. Therefore, when undertaking assessments of effects, it will be necessary to place any potential impacts within the context of the envelope of change that might occur over the timescale of the Proposed Development.
  4. Marine mammal species are known to be impacted by various anthropogenic activities, including offshore developments but also fisheries, anthropogenic noise and transportation. Avila et al. (2020) reported that between 1991 and 2016, globally almost all species of marine mammals (98%) were documented to be affected by at least one threat. Catch of marine mammals in active fishing gear (by-catch) was the most common threat category for odontocetes and mysticetes, followed by pollution (solid waste), commercial hunting and boat-collisions. Ghost-net entanglements, solid and liquid wastes, and infections were reported to be the main threats for pinnipeds.
  5. In addition to anthropogenic impacts, marine mammals are also vulnerable to indirect impacts, including global warming which can result in increasing sea temperatures. One of the most common responses of marine mammals to temperature changes are shifts in their spatial distribution, which has the potential to modify the ranges of certain species. Additionally, changes in water temperatures are likely to alter the life cycles of marine mammal prey species and may result in discrepancy between the abundances of prey species and those of marine mammals, affecting migratory marine mammal species and these displaying some site fidelity. Additionally, global warming could affect survival rates of marine mammals by affecting reproductive success, increasing the stress of the animal and fostering the development of pathogens (Albouy et al., 2020).
  6. Given that anthropogenic pressures are now superimposed by climatic changes, it is challenging to predict future trajectories of marine mammal populations in the absence of the project. In terms of data, for some species monitoring is not in place at the relevant temporal or spatial scales in order to assess the baseline dynamics of some marine mammal populations, especially for minke whale and white-beaked dolphin. Therefore, paragraph 29 et seq. is a summary of current and future pressures and where data is available, information about population dynamics is presented.

Harbour Porpoise

  1. In the North Sea, the harbour porpoise is considered vulnerable to bycatch in gillnets (Calderan and Leaper, 2019). Assuming that fishing vessel of 12 m or over follow the obligation to use pingers, Northridge et al. (2019) estimated UK porpoise bycatch in 2018 to be between 845 and 1,633 individuals with a best estimate of 1,150 individuals (CV=0.087), which is an increase comparing to 2017 with an estimate of 1,098 animals (Northridge et al., 2018).
  2. Another driver for harbour porpoise abundance is prey availability. Given that harbour porpoise has a high metabolic rate (Rojano-Doñate et al., 2018) and therefore has to feed regularly, it is thought to be highly dependent on year round proximity to food sources and harbour porpoise distribution and condition is considered likely to reflect the availability and energy density of prey (Santos and Pierce, 2003). Therefore, any changes in the abundance and density of harbour porpoise prey species have the potential to affect harbour porpoises foraging in an area.
  3. IAMMWG et al. (2015) reported that necropsies associated with harbour porpoise strandings have revealed parasite infections that may suggest adverse effects in harbour porpoises with an anthropogenic origin, such as contaminant discharges of Persistent Organic Pollutants (POPs). The impact of climate change on harbour porpoise remains poorly understood. Data from SCANS II and SCANS III suggested that the abundance of harbour porpoise in the NS MU is stable (IAMMWG, 2015; IAMMWG, 2021).
  4. The results of the most recent UK assessment of favourable conservation status show that the current range of harbour porpoises covers all of the UK's continental shelf and there appears to have been no change in range since 1994 (Paxton et al., 2016; JNCC, 2019a). The future trend in the range of this species has therefore been assessed as overall stable (good). Due to insufficient data the future trend in the population and consequently future prospects of harbour porpoise was assessed as unknown (JNCC, 2019a). Due to the establishment of SACs for this species in UK waters, the future prospects for the supporting habitat was assessed as good. The report on conservation status assessment for the species concluded that, assuming that conservation measures are maintained, and further measures are taken should other pressures emerge (or existing pressures change) then the future prospects for harbour porpoise in UK waters should remain favourable (JNCC, 2019a).

Bottlenose Dolphin

  1. Over the last 20 years, the size of the population of bottlenose dolphins off the east coast of Scotland has increased (Cheney et al., 2014; Cheney et al., 2018; Arso Civil et al. 2021) and their distribution has undergone a marked change with southern range expansion as recognisable individuals regularly occurring off eastern England (Arso Civil et al., 2019; Arso Civil et al., 2021). In the late 1980s and early 1990s the inner Moray Firth was assessed as the core area of occurrence, albeit surveys over the past ten years have shown that around 50% of the population use the Tay estuary and adjacent waters during summer months. The movement of individuals could be driven by environmental and biological factors, including seasonal changes in prey presence as well as social bonds within the population (Arso Civil et al., 2021). These findings are in line with study by Lusseau et al. (2004) which reported that bottlenose dolphin group sizes in Moray Firth were significantly related to prey abundance and that changes in the abundance of fish prey result in interannual variation in grouping patterns. Therefore, this study suggested that extrinsic factors could influence the structure of social community and parameters such as dispersal rate. Changes in prey abundance as a result of global warming are therefore likely to be major factor driving changes in bottlenose dolphin distribution.
  2. The results of the most recent UK assessment of favourable conservation status shown that the future trend in the range of bottlenose dolphin is, overall, stable (good) (JNCC, 2019b). However, although the pressures impacting bottlenose dolphin population and available habitat are not thought to be increasing and there are no threats identified which are likely to impact in the next 12 years, due to insufficient data to establish a current trend for this species, the future trend and consequently the future prospects for the population and habitat parameters are unknown (JNCC, 2019b). Therefore, the overall assessment of future prospects and conservation status for bottlenose dolphin is unknown (JNCC, 2019b).

White-beaked Dolphin

  1. Given that white-beaked dolphin is a species endemic to cold temperate waters of North Sea, increasing water temperature may lead to reduced areas suitable for foraging, and habitat loss (IJsseldijk et al., 2018). Macleod et al. (2005) reported that there has been a decline in the relative frequency of white-beaked dolphin strandings and sightings in north-west Scotland and attributed climate change as a major cause of this decline. Large scale population survey results of SCANS revealed no significant change in abundance of white-beaked dolphins in the North Sea between 1994 and 2016 (Hammond et al., 2013; Hammond et al., 2018). However, analysis of strandings data also suggested potential change in their distribution along North Sea coastline, with fewer animals being present in the more southern regions and stable numbers within the northern regions of the North Sea (IJsseldijk et al., 2018). The status of white-beaked dolphin is evaluated as ‘least concern‘ due to its widespread abundance, however their range is expected to shrink in response to increasing sea temperature (Macleod et al., 2018).
  2. The results of the most recent UK assessment of favourable conservation status shown that the future trend in the range of white-beaked dolphin is, overall, stable (good) (JNCC, 2019c). Population estimates indicate that the population is relatively stable (JNCC, 2019c). However, although the pressures impacting white-beaked dolphin population and available habitat are not thought to be increasing and there are no threats identified which are likely to impact in the next 12 years, due to insufficient data to establish a current trend for this species, the future trend and consequently the future prospects for the population and habitat parameters are unknown (JNCC, 2019c). Therefore, the overall assessment of future prospects and conservation status for white-beaked dolphin is unknown (JNCC, 2019c).

Minke Whale

  1. In coastal waters off east Scotland, sandeels are the main constituent of minke whale diet, however fish species such as pelagic herring and sprat are equally important for foraging whales in offshore waters (Robinson et al., 2009). The results of analysis of minke whales stomach contents in Icelandic waters suggested that a decrease in the proportion of sandeel and cold water species in the diet and an increase in gadoids and herring may reflect responses of minke whales to a changed environment, possibly driven by global warming (Víkingsson et al., 2014). Studies also suggest that minke whales are likely to shift their distribution as a response to the decrease in the abundance of the preferred prey species (Víkingsson et al., 2015).
  2. Major threats affecting minke whales in UK waters include direct and indirect interactions with fisheries. In Scotland, for example, evidence of entanglement in static fishing gear was present in as many as 50% of stranded minke whales examined from 1990 to 2010 (Northridge et al., 2010). Other impacts include boat strikes, exposure to anthropogenic noise, ingestion of contaminants and debris and the loss or degradation of critical habitat (Gill et al., 2000; Robinson et al., 2009). Data from SCANS II and SCANS III suggested that the abundance of minke whales in the CGNS is stable (IAMMWG, 2015; IAMMWG, 2021).
  3. The results of the most recent UK assessment of favourable conservation status shown that there is no evidence to suggest that minke whale range has changed since last report on conservation status in 2013 and therefore it has been assessed as, overall, stable (good) (JNCC, 2019d). The OSPAR Intermediate Assessment (IA) suggest that minke whale abundance in the Greater North Sea is stable (OSPAR IA, 2017; JNCC, 2019d). However, although the pressures impacting minke whale population and available habitat are not thought to be increasing and there are no threats identified which are likely to impact in the next 12 years, due to insufficient data to establish a current trend for this species, the future trend and consequently the future prospects for the population and habitat parameters are unknown (JNCC, 2019d). Therefore, the overall assessment of future prospects and conservation status for minke whale is unknown (JNCC, 2019c).

Harbour Seal

  1. The UK population of harbour seal has increased since the 2000s, however populations along the east coast of Scotland have generally declined and current population size is at least 40% below the pre-2002 level (SCOS, 2020). Continued declines are not evident in the Moray Firth, although there is no indication of recovery. At the time of writing, Hanson et al., 2017 reported that the ES MU the population is manly concentrated in the Forth of Tay and Eden Estuary SAC and therefore suggested that continuation of this trend in the SAC could result in the species disappearing from this area within next 20 years. There was not a clear single factor, which would explain the decline. It has been suggested that one of the factors driving this decline is reduction in food availability that could cause increased competition between conspecifics and with grey seals, followed by reduction in harbour seal condition as a result of this competition (reduced fecundity and/or pup survival) (Hanson et al., 2017; Damseaux et al., 2021; SCOS, 2020). Other studies also suggested that harbour seals might be exposed to domoic acid via consumption of contaminated prey at levels that may have the potential to cause harmful and lethal effects that would disrupt population dynamics (Jansen et al., 2015; SCOS, 2020). However, Sinclair et al. (2020) estimated that by 2016, the Forth of Tay and Eden Estuary SAC counts represented only approximately 15% of the ES MU. This has been corroborated by SCOS (2020) report, where the decline has been described as localised within the Forth of Tay and Eden Estuary SAC and not representative of the trends in overall MU population. However, more frequent count data from Firth of Forth is required in order to support this assumption (SCOS, 2020).
  2. The results of the most recent UK assessment of favourable conservation status shown that future trend in the range of harbour seal is, overall, stable (good) (JNCC, 2019e). Although the UK population of harbour seal has increased since 2000, the long-term trend indicates that the UK population is still below population documented in the late 1990s and declines were recorded at many sites, including the east of Scotland. Therefore, the current UK harbour seal population estimate has been considered as unfavourable-inadequate. Given that there is not predicted to be any increase in management which would outweigh threats to the species, future prospects of harbour seal population in the UK were assessed as poor (JNCC, 2019e). Although the pressures impacting harbour seal habitats are not thought to be increasing, and there are no threats identified which are likely to impact in the next 12 years, due to insufficient data to establish a current trend for this species, the future trend and consequently the future prospects for the habitat parameter are unknown (JNCC, 2019e).

Grey Seal

  1. UK grey seal numbers are currently stable or increasing throughout their monitored range (SMRU, 2020), suggesting that their population status is not under threat. Population dynamics depend on a colony, however, pup production at colonies in the North Sea continued to increase rapidly up to 2016 with annual increase of 11.5% per annum (p.a.). Increase in pup production between 2014 and 2018 was 7.5% p.a. and it has been suggested that some of the colonies are approaching carrying capacity (SCOS, 2020). Production at the Isle of May increased exponentially to 9.9% p.a. since surveys began in 1979, before reaching an asymptote of c.2,000 pups in the late 1990s (SCOS, 2020). Pup production in the Berwickshire and North Northumberland Coast SAC is continuing to increase and does not show any indication of reaching an asymptote (SCOS, 2020). The analysis of POPs in blubber from weaned grey seal pups on the Isle of May detected POP concentrations below the values that could cause severe toxic effect, however highlighted that even low concentrations are likely to cause endocrine disruption with unknown consequence for individual health and survival (Robinson et al., 2019). Other threats to grey seals include entanglement in marine and plastic debris, particularly discarded fishing gear, disturbance and climate change affecting availability of prey.
  2. Any changes that may occur during the design life span of the Proposed Development have been considered in the context of both greater variability and sustained trends occurring on national and international scales in the marine environment. While there is an indication that some populations are increasing (i.e. bottlenose dolphin, grey seal) or declining in numbers (i.e. harbour seal), it is challenging to define a future trajectory of marine mammal populations, especially without regular survey data (i.e. white-beaked dolphin, minke whale).
  3. The results of the most recent UK assessment of favourable conservation status shown that the future trend in the range of grey seal is, overall, stable (good_ (JNCC, 2019f). Modelling of population size at the beginning of each breeding season between 1984 and 2017 demonstrated an increasing trend and although the rate of increase has declined, the abundance estimate is above historic estimates (JNCC, 2019f). As the current conservation status for range and population is favourable for this species, the future prospects for both parameters are considered good (JNCC, 2019f). The future trend of grey seal habitat has been assessed as overall stable (good) (JNCC, 2019f).

10.7.5.              Data Limitations and Assumptions

  1. The data assumptions and limitations (detailed in volume 3, appendix 10.2, annex A) are typical of difficulties encountered with undertaking field surveys of marine mammals using aerial digital methods. A summary is provided in paragraph 46 et seq.
  2. DAS have been conducted monthly, however, due to unforeseen circumstances, the survey was not conducted in some months. For example, the April surveys in both 2019 and 2020 were not carried out, however, an additional survey was undertaken in early May 2020 to represent the delayed April 2020 survey and the survey programme was subsequently extended to include two surveys flown in April 2021 to provide additional data set for the month of April and compensate missed April 2019 survey. Similarly, there were some months when not all transects could be flown (e.g. due to technical issues or weather conditions) and so full coverage of the site was not possible. Additional camera data were analysed to compensate for this and to ensure the minimum percentage cover requirement was met. Another potential limitation is that the single survey day each month represents only a snapshot of marine mammal distribution and therefore it could not be assessed whether environmental conditions influenced sightings rates and only seasonal changes were considered. Additionally, detection probability was a limiting factor in recording marine mammals with weather conditions playing a significant role in the ability to detect a marine mammal. Identification to species-level can sometimes be difficult, particularly when distinguishing between grey sea and harbour seal at sea. Since there were a number of sightings recorded as ‘seal species’ and ‘cetacean species’, unidentified animals were allocated to grey seal and harbour porpoise respectively, based on the prevalence of this species in the vicinity of the Proposed Development. Finally, availability bias - the time when an animal is available for the detection either at the sea surface or just below the surface - is also a limiting factor. However, the relative density (harbour porpoise, grey seal, minke whale and white-beaked dolphin) calculated from data collected during the DAS was corrected for availability bias using a published correction factors based on the proportion of time individuals are likely to be at or near the surface and available for detection.
  3. The surveys were conducted based on the original boundary for Berwick Bank, which was subsequently refined. Since the refinement was a reduction of the Proposed Development array area, the coverage of the aerial surveys remains valid.
  4. Despite the limitations described above, the baseline assessment provides a comprehensive account of the marine mammals within the Proposed Development marine mammals study area as these site-specific data were corroborated by information collated via a detailed desktop review. It is therefore concluded that the data limitations presented above are not expected to affect the conclusions of the assessment, and the baseline presented provides a robust and appropriate characterisation of the area against which to undertake this assessment.

10.8. Key Parameters for Assessment

10.8.1.              Maximum Design Scenario

  1. The maximum design scenarios identified in Table 10.16   Open ▸ have been selected as those having the potential to result in the greatest effect on an identified receptor or receptor group. These scenarios have been selected from the details provided in volume 1, chapter 3 of the Offshore EIA Report. Effects of greater adverse significance than assessed in this chapter are not predicted to arise should any other development scenario, based on details within the Project Design Envelope (e.g. different infrastructure layout), be taken forward in the final design scheme.
  2. The maximum design scenario informing the assessment of potential impacts on marine mammals from ‘changes in fish and shellfish communities affecting prey availability’ is based on the maximum design scenario embedded in volume 2, chapter 9.
Table 10.16:
Maximum Design Scenario Considered for Each Impact as Part of the Assessment of Likely Significant Effects on Marine Mammals

Table 10.16: Maximum Design Scenario Considered for Each Impact as Part of the Assessment of Likely Significant Effects on Marine Mammals

10.8.2.              Impacts Scoped out of the Assessment

  1. Pre-Application consultation ( Table 10.9   Open ▸ ) has been used to facilitate stakeholder engagement on potential impacts to be scoped out of the marine mammal assessment. On the basis of these discussions, baseline environment and the project description outlined in volume 1, chapter 3 of the Offshore EIA Report, a number of potential impacts are proposed to be scoped out of the assessment for Marine Mammals. These have been agreed with key stakeholders through consultation as discussed in volume 1, chapter 5.
  2. Additionally, impacts were proposed to be scoped-out in The Berwick Bank Wind Farm Offshore Scoping Report (SSER, 2021a) and no concerns were raised by key consultees. Where discussions with consultees took place after the publication of the Berwick Bank Wind Farm Scoping Opinion (MS-LOT, 2022), these have been discussed with key stakeholders through further consultation (e.g. via Road Map Meetings). These post-scoping discussions are audited in the Marine Mammal Road Map (volume 3, appendix 10.3) or the Audit Document (SSER, 2022d).
  3. These impacts are outlined, together with a justification for scoping them out, in Table 10.17   Open ▸ . An indication of a phase of the development during which those impacts have a potential to occur is given by ticks and crosses (i.e. during scoping the accidental pollution has been considered as a potential impact during construction and decommissioning (tick), but not during the operation and maintenance phase (cross)).

 

Table 10.17:
Impacts Scoped Out of the Assessment for Marine Mammals (tick confirms the impact is scoped out)

Table 10.17: Impacts Scoped Out of the Assessment for Marine Mammals (tick confirms the impact is scoped out)

 

10.9. Methodology for assessment of effects

10.9.1.              Overview

  1. The marine mammals assessment of effects has followed the methodology set out in volume 1, chapter 6 of the Offshore EIA Report. Specific to the marine mammals EIA, the following guidance documents have also been considered:
  • Guidance for Ecological Impact Assessment in the UK and Ireland. Terrestrial, Freshwater, Coastal and Marine (Chartered Institute of Ecology and Environmental Management (CIEEM), 2018) - these guidelines combine the Guidelines for Ecological Impact Assessment in the UK and Ireland: Terrestrial, Freshwater and Coastal, 2nd edition (2016) and the Guidelines for Ecological Impact Assessment in Britain and Ireland: Marine and Coastal (2010); and
  • Guidelines for data acquisition to support marine environmental assessments of offshore renewable energy projects (Judd, 2012).
    1. In addition, the marine mammals assessment of effects has considered the legislative framework as set out in volume 1, chapter 2 of the Offshore EIA Report.