1. Introduction

  1. This Fish and Shellfish Ecology Technical Report provides a detailed baseline characterisation of the fish and shellfish ecology (e.g. species, communities and habitats) for the Berwick Bank Wind Farm (hereafter referred to as the ‘Proposed Development’). Data were collated through a detailed desktop study of the existing resources available for fish and shellfish within the northern North Sea study area, incorporating site-specific survey data and data from third party organisations.
  2. The aim of this technical report is to provide a robust baseline characterisation of the fish and shellfish resources within a defined study area (see section 2) against which the potential impacts of the Proposed Development can be assessed. To support the assessment of effects in the Environmental Impact Assessment (EIA), the ecological information presented in this technical report was used to identify a number of Important Ecological Features (IEFs). IEFs were determined based on the conservation, ecological and commercial importance of each identified feature within the Proposed Development fish and shellfish ecology study area relative to the northern North Sea fish and shellfish ecology study area.
  3. This technical report is structured as follows:
  • section 2: Study Area - Overview of the study areas relevant to the report;
  • section 3: Methodology - Overview of desktop study and site-specific surveys used to inform the baseline;
  • section 4: Baseline Characterisation – Details the results of desktop study and site specific surveys;

–      section 4.1: Broad descriptions of the fish and shellfish assemblages in the northern North Sea;

–      section 4.2: Broad descriptions of the fish and shellfish assemblages in the Forth and Tay Scottish Marine Region (SMR);

–      section 4.3: Fish Spawning and Nursery Grounds – Spawning and nursery grounds are described for key species;

–      section 4.4: Herring – A description of herring habitats and ecology (focussing on spawning);

–      section 4.5: Sandeel – A description of sandeel habitats and ecology;

–      section 4.6: Diadromous Fish: A description of diadromous fish ecology;

–      section 4.6.9: Shellfish: A description of shellfish habitats and ecology;

  • section 5: Summary – A summary of the information provided in the report;

–      section 5.2: Baseline - A summary of the baseline of fish and shellfish ecology; and

–      section 5.3: Important Ecological Features - Describing the IEFs to be considered in the EIA.

2. Study Area

  1. Fish and shellfish are spatially and temporally variable, therefore for the purposes of the fish and shellfish ecology characterisation, two study areas are defined. These are shown in Figure 2.1   Open ▸ and described here:
  • The Proposed Development fish and shellfish ecology study area has been defined with reference to the Proposed Development boundary that existed prior to the boundary refinement in June 2022. As the refinement resulted in a reduction of the Proposed Development array area, the fish and shellfish ecology study area is considered to remain representative and presents a conservative baseline against which the fish and shellfish assessment is undertaken. The Proposed Development fish and shellfish ecology study area has not therefore been realigned to the current Proposed Development boundary.
  • The northern North Sea fish and shellfish ecology study area encompasses the Proposed Development fish and shellfish ecology study area and a surrounding area defined by the boundary of the northern North Sea as defined by the biogeographic region identified as part of the Review of Marine Nature Conservation (RMNC) (2004). This is the regional study area and also encompasses waters of the Forth and Tay SMR. The northern North Sea fish and shellfish ecology study area provides a wider context for the fish and shellfish species and populations identified within the Proposed Development fish and shellfish ecology study area and will inform assessments of those impacts affecting fish and shellfish receptors over a larger scale (e.g. underwater noise).

 

Figure 2.1:
The Proposed Development Fish and Shellfish Ecology Study Area and the Northern North Sea Fish and Shellfish Ecology Study Area

Figure 2.1: The Proposed Development Fish and Shellfish Ecology Study Area and the Northern North Sea Fish and Shellfish Ecology Study Area

3. Methodology

3.1. Desktop Study

  1. Information on fish and shellfish within the Proposed Development fish and shellfish ecology study area was collected through a detailed desktop review of existing studies and datasets. These are summarised in Table 3.1   Open ▸ .

 

Table 3.1:
Summary of Key Desktop Reports

Table 3.1: Summary of Key Desktop Reports

 

3.2. Site-Specific Surveys

  1. A summary of the surveys undertaken to inform the fish and shellfish baseline characterisation is outlined in Table 3.2   Open ▸ . The location of site-specific sampling is presented in Figure 3.1   Open ▸ .
  2. Given the wide ranging and comprehensive desktop information and data sources available to characterise the fish and shellfish baseline, site-specific fish ecology surveys to inform the EIA for the Proposed Development were not proposed. However, the results from site-specific surveys primarily designed to inform the benthic subtidal and intertidal ecology baseline characterisation, which include records of small demersal fish species and shellfish species present in the Proposed Development array area and export cable corridor, have been used to inform the baseline characterisation for fish and shellfish ecology.
  3. Epibenthic beam trawl sampling was undertaken at 15 sampling locations distributed across representative sediment types to characterise epifaunal communities ( Figure 3.1   Open ▸ ).
  4. Epibenthic trawl sampling was undertaken using a standard 2 m scientific beam trawl (Lowestoft design) fitted with a knotless 5 mm cod end liner.
  5. Combined grab and Drop Down Video (DDV) sampling were also completed across the Proposed Development array area and export cable corridor, with Particle Size Analysis (PSA) data obtained from grabs used to inform habitat characterisations for sandeel Ammodytes sp., herring Clupea harengus and Neprops norvegicus (hereafter referred to as Nephrops), and species presence/absence records taken from both grab samples and DDV sampling ( Figure 3.1   Open ▸ ).
  6. Herring spawning habitat characterisation was undertaken using results of the PSA to determine the composition of the sediment at grab locations. Samples were categorised into prime, subprime, suitable and unsuitable based on their suitability as herring spawning habitat, using classifications derived from Reach et al. (2013) based on the relative proportions of gravel and mud in the grab samples. Data from the International Herring Larvae Survey (IHLS) were also utilised to show herring spawning habitats in line with guidelines published by Boyle and New (2018). The abundances of larvae below 10 mm per m2 were plotted on heat maps for the years 2007 to 2016 and also the average of those years combined. These maps, combined with the PSA data from site specific grab sampling, were used to determine where key spawning habitats were located within the vicinity of the Proposed Development fish and shellfish ecology study area (see section 4.4, Figure 4.10   Open ▸ to Figure 4.16   Open ▸ ).  
  7. Sandeel habitat characterisation was also completed, using a similar method as above where samples were categorised into prime, subprime, suitable and unsuitable, based on their suitability as sandeel habitat. Classifications were derived from Latto et al. (2013) based on the proportion of sand and mud in the grab samples. Incidental sandeel abundance data were collected from epibenthic beam trawls, alongside incidental presence/absence data of individual sandeels recorded within grab samples. The data was plotted into maps and reviewed alongside other desktop data sources to further characterise sandeel habitats within and around the Proposed Development fish and shellfish ecology study area (see section 4.5 for results).
  8. Nephrops presence within the Proposed Development fish and shellfish ecology study area was assessed through abundance data collected from epibenthic trawls, as well presence/absence data derived from DDV sampling (taken at grab sample sites and specific DDV transects). These data were plotted alongside favourable Nephrops habitat as identified in a benthic biotope map as shown in volume 3, appendix 8.1 (only Nephrops habitat has been presented, see section 4.7.8 for results).

 

Table 3.2:
Summary of Surveys Undertaken to Inform Fish and Shellfish Ecology Baseline Characterisation (See Also Volume 3, Appendix 8.1)

Table 3.2: Summary of Surveys Undertaken to Inform Fish and Shellfish Ecology Baseline Characterisation (See Also Volume 3, Appendix 8.1)

Figure 3.1:
Site-specific Survey Locations

Figure 3.1: Site-specific Survey Locations

4. Baseline Characterisation

4.1. Northern North Sea

4.1.1.    Desktop Study

  1. This section provides an overview of the fish and shellfish assemblages in the northern North Sea fish and shellfish ecology study area. The total British marine fish fauna is estimated to be 330 species, of which approximately 150 species are recorded from the North Sea (Maitland and Herdson, 2009). About 10% of the North Sea species are of significant commercial value and as such, the fish faunal abundance is affected by fishing pressure. The remaining species that occur in the North Sea are of little commercial value and so are not directly subject to fishing pressure. However, many of these species are of significant ecological importance as prey items for other marine species (e.g. birds and marine mammals).
  2. The North Sea can be divided by depth contours and broad biogeographical patterns with three main fish assemblages associated with the shelf edge and northern North Sea, the central North Sea and southern and south-eastern North Sea (Callaway et al., 2002). The northern and central North Sea (which coincides with the northern North Sea fish and shellfish ecology study area) has a significant difference in fish assemblage to the southern and eastern North Sea, mainly attributed to the difference in depth profile and water temperature (Teal, 2011). The fish assemblage in this area is dominated by demersal, benthopelagic, pelagic, diadromous and elasmobranch fish species.
  3. The spatial distribution of fish is determined by a range of factors including abiotic parameters such as water temperature, salinity, depth, local scale habitat features and substrate type, and biotic parameters such as predator-prey interactions and competition, alongside anthropogenic factors such as infrastructure and commercial fishing intensity. Demersal species include sandeel, whiting Merlangius merlangus, lemon sole Microstomus kitt, ling Molva molva, plaice Pleuronectes platessa and saithe Pollachius virens, with pelagic species including herring, and sprat Sprattus sprattus likely to be found in northern North Sea fish and shellfish ecology study area.
  4. The International Bottom Trawl Survey (IBTS) is a historical time series of bottom and pelagic fish trawl surveys in the north-east Atlantic and Baltic Seas. The northern North Sea fish and shellfish ecology study area sits within IBTS zones 3 and 4 and these areas have hence been used to gain further understanding of the fish assemblage in the northern North Sea over 2020 – 2021 (IBTS, 2021).
  5. Herring abundances within the IBTS are high with over thousands of individuals recorded per hour trawling. Herring abundance is also seasonal, with abundance being higher at the end of the year (Q3) than at the start of the year (Q1). The IBTS data showed a marked increase specifically in adult herring abundance during Q3, which supports existing literature on herring spawning seasons, as the influx of adult herring individuals in Q3 coincides with the spawning season (see Table 4.2   Open ▸ ).
  6. Whiting are highly abundant within the northern North Sea. IBTS data for 2020 (Q1 and Q3) – 2021 (Q1) showed abundances as high as 5,000 individuals per hour trawled. Notably, juvenile whiting (less than one year old) were not recorded at all in Q1 trawls, however in Q3 trawls, juvenile whiting abundances were on average the highest age category recorded. IBTS data showed low abundances of cod, with only tens of individuals recorded per hour trawled.
  7. Plaice are also widely abundant within the northern North Sea, with IBTS data indicating abundances of between 500 and 1,000 individuals regularly recorded per hour of trawling. No obvious differences in abundance associated with season or age distribution of individuals was observed in the 2020 (Q1 and 3) – 2021 (Q1) data. 
  8. Recorded abundance of mackerel Scomber scombrus was low during 2020 Q1, however higher abundances were recorded during Q3, and also in Q1 of 2021. This suggests that presence of mackerel in the northern North Sea can vary annually and can be sporadic, as shown by a particular haul capturing over 246,000 mackerel per hour trawled, with other hauls recording very few or no mackerel per hour trawled.
  9. Sprat have relatively high abundance, where thousands of individuals were frequently recorded per hour trawled. However, similar to mackerel, the abundances recorded were found to be quite sporadic, with low numbers being recorded frequently. There are no obvious differences in seasonal or age distribution of individuals recorded.

4.2. Forth and Tay Scottish MArine Region

4.2.1.    Desktop Study

  1. Several species of commercial and ecological importance are known to be present across and in the vicinity the Forth and Tay SMR including cod Gadus morhua, lemon sole, herring, mackerel, plaice, sandeel, saithe, sprat, spotted ray Raja montagui, spurdog Squalus acanthias, tope Galeorhinus galeus and whiting. The Forth and Tay SMR hosts important populations of shellfish species including Nephrops, European lobster Homarus gammarus, crab (edible (brown) crab Cancer pagarus and velvet swimming crab Necora puber) and squid Loligo sp. The distribution of lobster and crab species is highly dependent on habitat/substrate type due to the species preferences of habitat and low mobility. Many of these fish and shellfish species have high ecological value as prey species for marine mammals and seabirds (e.g. sandeel, herring, mackerel and sprat) as well as being of high importance for commercial fisheries (e.g. lobster, edible crab, king scallop Pecten maximus and squid) (see volume 3, appendix 12.1).
  2. Other offshore wind farm developments, either in construction or in planning stages, exist within and in the vicinity the Forth and Tay SMR ( Figure 4.1   Open ▸ ). Data collected through site-specific surveys for these other developments can be used to help characterise the fish and shellfish assemblage within the Forth and Tay SMR. Neart na Gaoithe Offshore Wind Project (NnG) is located within the Forth and Tay SMR and therefore data collected can be drawn upon to improve understanding of fish and shellfish assemblages in the Forth and Tay SMR. NnG also utilised beam trawl data from the benthic ecology characterisation which conducted 2 m beam trawl surveys (EMU, 2010). The NnG surveys were dominated by shrimp species Crangon sp. and Pandalus sp., with the most abundant fish species being long rough dab/American plaice Hippoglossoides platessoides, gobies Gobidae and common dab Limanda limanda. When NnG survey data were analysed using multivariate statistics, they showed that the majority of trawls fit into a large distinct group, with one smaller distinct group, characterised by lower species diversity, which was associated with trawls in nearshore locations.
  3. Epibenthic trawl data using 2 m beam trawls were also collected for what was known at the time as Seagreen Alpha/Bravo (IECS, 2012) (known since 2018 as Seagreen), located in vicinity of the Forth and Tay SMR and to the north of the Proposed Development fish and shellfish ecology study area. Only three trawls were conducted for this survey, so the characterisation of the assemblage is less comprehensive. However, these surveys also recorded relatively high abundances of Crangon sp. and Pandalus sp. as well as common dab. These trawls also recorded high numbers of starfish Asterias rubens and brittle stars Ophiura ophiura. Whilst the limitations of these surveys do not allow detailed conclusions to be drawn, it provides further evidence of the Forth and Tay SMR hosting a fish and shellfish assemblage consistent with that presented for NnG.
  4. The Inch Cape Offshore Wind Development, located in the Forth and Tay SMR, conducted otter trawls on four occasions over 2012. A total of 30 fish species and 20 macro-invertebrates were recorded across all surveys. The Fish and Shellfish EIA Report chapter for the Inch Cape offshore wind farm only reported abundance of species deemed as sensitive receptors, so a full list of species assemblage from the trawls is unavailable. Of the species deemed as sensitive receptors (sprat, herring, cod, allis shad Alosa alosa and twaite shad Alosa fallax), only sprat, herring and cod were recorded, with sprat being noticeably highest in abundance (total catch of 1,194 individuals) compared to herring (161) and cod (15). The absence of allis and twaite shad is to be expected due to the low reported incidence from other sources. These data are harder to compare to beam trawl survey data, as different species are targeted by the different gear types, however they provide a useful indication of the types of demersal and pelagic species present within and in the vicinity of the Forth and Tay SMR. 
  5. Commercial fishing data can be utilised to gain further understanding of the fish and shellfish assemblage within the northern North Sea fish and shellfish ecology study area. As described in volume 3, appendix 12.1, the vast majority of landings are comprised of shellfish, with Nephrops contributing the highest proportion of total landings, with European lobster, edible crab and king scallop also being major contributors within the Forth and Tay SMR. Mackerel contribute a small proportion of the commercial fisheries landings, but only within the inshore coastal areas off Berwick upon Tweed (ICES Rectangle 40E7). See volume 3, appendix 12.1 for further breakdown of commercial fisheries landings data. Species such as cod, haddock, and flat fish species are not specifically targeted by commercial fisheries within and in the vicinity of the Forth and Tay SMR.

 

Figure 4.1:
Location of Other Offshore Wind Developments Within and in the Vicinity of the Forth and Tay SMR

Figure 4.1: Location of Other Offshore Wind Developments Within and in the Vicinity of the Forth and Tay SMR

Elasmobranchs 

  1. Elasmobranchs are a cartilaginous fish group that comprises sharks, rays and skates, with species expected to be present in the Proposed Development fish and shellfish ecology study area including tope, spurdog, common skate Dipturus batis, spotted ray, and thornback ray Raja clavata. There are no specific fisheries for these species, however most of these species have commercial value, but not locally to the Proposed Development fish and shellfish ecology study area. Some of these species of elasmobranch have nursery grounds in or in close proximity to the Proposed Development fish and shellfish ecology study area (Ellis et al., 2012) (discussed further in section 4.3).
  2. Basking sharks Cetorhinus maximus may pass through the vicinity of the Proposed Development fish and shellfish ecology study area. The basking shark is a large, filter feeding species that is predominately solitary but may also occur in aggregations where there is dense zooplankton abundance (Speedie, 1999). The basking shark’s unique feeding strategy dominates all aspects of its ecology and life history; the basking shark is an obligate ram filter feeder whereby the flow of water across gill rakers within the mouth is controlled by swimming speed (Sims, 1999; Sims, 2008).
  3. Basking shark migration routes cover large distances from north Africa up to Scotland, using both the continental shelf and oceanic habitats in the upper 50 m to 200 m of the water column (Doherty et al., 2017). Distribution has been shown to be influenced by a range of environmental conditions (Austin et al., 2019); surface sightings of basking sharks are typically reported where sea surface temperatures range between 15°C and 17.5°C (Cotton et al., 2005; Skomal et al., 2004) where thermal fronts are present (Sims and Quayle, 1998; Jeewoonarain et al., 2000) and where zooplankton is in its greatest abundance (Sims and Quayle, 1998; Sims, 1999). Twenty-eight basking sharks tagged off Scotland and the Isle of Man in the summer showed an average migration distance of 1,057 km with movements starting in October (Doherty et al., 2017), however, none of the tagged basking sharks migrated to the east coast of Scotland. Due the migratory behaviour of basking sharks and routes through Scottish waters, basking sharks have the potential to be present within the Forth and Tay SMR and in the vicinity of the Proposed Development fish and shellfish ecology study area, however, the majority of basking shark sightings are located on the west coast of Scotland. No basking shark were recorded during 25 months of aerial marine mammal and bird surveys of the Proposed Development.

4.2.2.    Site-Specific Survey

  1. As outlined in section 3.2, 15 epibenthic beam trawls were undertaken across the Proposed Development fish and shellfish ecology study area ( Figure 3.1   Open ▸ ).
  2. Fish species prevalent in the epibenthic trawls included common dab, long rough dab, lesser sandeel Ammodytes tobianus and pogge Agonus cataphractus. As can be seen in Figure 4.2   Open ▸ , long rough dab was by far the most abundant fish species in beam trawls with over 14 individuals per 1,000 m trawled. That compared with long rough dab and lesser sandeel which were recorded at much lower abundances. Other commercially important species including cod, lemon sole and plaice were only recorded at very low abundances (e.g. between one and three individuals per 1,000 m trawled). Shellfish recorded in site-specific surveys (including trawl surveys) are discussed in section 4.7.
  3. Epibenthic trawl data were analysed using multivariate statistics using PRIMER v6 software statistical analysis package (Clarke and Gorley, 2006), to determine the similarity of fish assemblages between trawl sites. The data analysed were for fish species only. Analysis included hierarchical cluster analysis of the square root transformed fish dataset, together with a Similarity Profile (SIMPROF) test to test whether clusters were statistically distinct from one another. This identified three distinct assemblages within the fish trawl data, as can be seen in Figure 4.3   Open ▸ . Group C comprised 12 of the total 15 trawls with group B containing just one trawl and group a containing two trawls. This demonstrates that the majority of the trawls (group C) fit into a large distinct group showing a homogenous fish assemblage across the majority of trawl locations. The main species contributing to similarities within group C included common dab, lemon sole and pogge, with plaice, butterfish Pholis gunnellus, halibut, and sandeel also contributing but at lower abundances. Shellfish recorded in site-specific surveys (including trawl surveys) are discussed section 4.7.
  4. The two smaller groups (groups A and B) are different to the main group primarily due to the number of species. These trawls were particularly impoverished, specifically group B with only low abundances of three species recorded. The main contributing species to group A being long rough dab and four bearded rockling Enchelyopus cimbrius. This dissimilarity can be explained by the sample location, with the three dissimilar trawls (BT15 - BT17) being nearshore trawl locations in the Proposed Development fish and shellfish ecology study area export cable corridor ( Figure 3.1   Open ▸ ). The Proposed Development export cable corridor has a different benthic composition, with higher proportions of deep circalittoral mud sediment than in the Proposed Development array area which is characterised by deep coarse circalittoral and deep circalittoral sediments. Different habitat composition support different fish assemblages which can explain the significant differences between trawls in group C to groups A and B.
  5. Results from data collected during site-specific benthic subtidal surveys are in agreement with reports of fish and shellfish communities in and around the Forth and Tay SMR, which validates baseline data presented in section 3.2 from NnG, Seagreen and Inch Cape developments fish and shellfish studies. This indicates a consistent benthic fish assemblage within and in the vicinity of the Forth and Tay SMR. Other common species known within the region may not have been identified through site-specific surveys due to the sampling method used for epibenthic trawls (e.g. epibenthic trawls do not target pelagic species), however these have been characterised by desktop data sources.

Figure 4.2:
Fish Abundance per 1,000 m Trawled in Epibenthic Surveys

Figure 4.2: Fish Abundance per 1,000 m Trawled in Epibenthic Surveys

Figure 4.3:
Dendrogram of Fish Assemblages from Epibenthic Trawls Surveys within the Proposed Development Fish and Shellfish Ecology Study Area

Figure 4.3: Dendrogram of Fish Assemblages from Epibenthic Trawls Surveys within the Proposed Development Fish and Shellfish Ecology Study Area

 

4.3. Spawning and Nursery Grounds

  1. A number of fish species are known to have spawning and/or nursery grounds within the northern North Sea fish and shellfish ecology study area. Data from Cefas (Ellis et al., 2012; Coull et al., 1998) provides spatially explicit maps of the nursery/spawning areas for key species. It is worth noting that Coull et al. (1998) data may lack accuracy due to the age of the study and for this reason, it has only been used where no other data from Ellis et al. (2012) is available.
  2. Potential nursery and spawning areas in the North Sea for a range of species were identified by Coull et al. (1998), based on larvae, egg and benthic habitat survey data. Ellis et al. (2012) reviewed this data for several fin fish species in the UK waters, including the North Sea, providing an updated understanding of areas of low and high intensity nursery and spawning grounds. Further information regarding nursery areas is provided in Aries et al. (2014). The study assessed evidence of aggregations of ‘0 group fish’ (fish in the first year of their lives) around the UK coastline. These data were ascertained from species distribution modelling combining observations of species occurrence or abundance with environmental data (Aries et al., 2014). The outputs of this process have been suggested to be used as a guide for the most likely locations of aggregations of 0 group fish.
  3. Based on the above data sources, spawning areas for several species overlap the Proposed Development fish and shellfish ecology study area, including low intensity spawning for cod and plaice, non-specified spawning for Nephrops, sprat, whiting, lemon sole and herring, and high intensity for sandeel. Species with known spawning periods ( Table 4.2   Open ▸ ) and nursery habitats identified within the Proposed Development fish and shellfish ecology study area have been summarised in Table 4.1   Open ▸ and Figure 4.4   Open ▸ to Figure 4.7   Open ▸
  4. Cod are commonly found throughout the North Sea and have high intensity nursery grounds and low intensity spawning grounds overlapping the Proposed Development fish and shellfish ecology study area ( Figure 4.4   Open ▸ ) (Ellis et al., 2012), with spawning occurring between January and April with peak spawning occurring in April. The presence of cod nursery grounds is supported by outputs from Aries et al. (2014).
  5. Whiting have high intensity nursery grounds and low intensity spawning grounds throughout the Proposed Development fish and shellfish ecology study area ( Figure 4.4   Open ▸ ) with spawning occurring between May and July. Ideal conditions for whiting spawning include sandy substrate and fast movement of water. After the eggs hatch, the larvae drift in surface waters for a year, and then move closer to the seabed as juveniles. The presence of whiting nursery grounds is supported by outputs from Aries et al. (2014).
  6. Haddock Melanogrammus aeglefinus have a pelagic larval phase feeding on plankton before juveniles move down towards the seabed to exploit demersal prey resources, including small crustaceans and small fish. There is an unspecified intensity nursery ground to the east of the Proposed Development fish and shellfish ecology study area, which overlaps the Proposed Development fish and shellfish ecology study area array area marginally ( Figure 4.4   Open ▸ ). There are no haddock spawning grounds within the Proposed Development fish and shellfish ecology study area (Coull et al., 1998). The presence of haddock nursery grounds is supported by outputs from Aries et al. (2014) and may suggest higher intensity nursery grounds extending further into the Proposed Development array area than specified by Coull et al. (1998).
  7. Sprat spawning and nursery grounds (unspecified intensity) coincide with the Proposed Development fish and shellfish ecology study area, with only nursery grounds coinciding with the offshore export cable route ( Figure 4.5   Open ▸ ). The presence of sprat nursery grounds is not supported by outputs from Aries et al. (2014), with aggregations of 0 group fish seemingly limited to areas further inshore within the inner regions of the Firth of Forth.
  8. Mackerel have low intensity nursery grounds which coincide with the majority of the Proposed Development fish and shellfish ecology study area (Ellis et al., 2012), with no spawning grounds identified in the Proposed Development fish and shellfish ecology study area ( Figure 4.5   Open ▸ ). Mackerel spawn over summer months from May to August. The presence of mackerel nursery grounds is not supported by outputs from Aries et al. (2014), with no modelled observations of 0 group fish on the east coast of Scotland.
  9. Plaice mostly spawn between December and January, with peak spawning in January. Each female produces up to half a million eggs which drift passively in the plankton. Once the larvae reach a suitable size for settlement, they metamorphose into the asymmetric body shape and as young fish they inhabit mostly shallow water including tidal pools (Schreiber, 2013). In their second year they move into deeper water and are mostly found in a depth range of 10 m to 50 m. Low intensity nursery grounds coincide with the Proposed Development fish and shellfish ecology study area, with spawning grounds present in the Proposed Development export cable corridor ( Figure 4.5   Open ▸ ). The presence of low intensity nursery grounds for plaice is supported by outputs from Aries et al. (2014).
  10. Lemon sole key spawning activity is between April and September, with no defined peak periods. There are unspecified intensity nursery and spawning grounds for lemon sole which coincide with the Proposed Development fish and shellfish ecology study area ( Figure 4.5   Open ▸ ).
  11. Herring have high intensity nursery areas throughout the Proposed Development fish and shellfish ecology study area, with spawning grounds to the south which coincide with the Proposed Development export cable corridor marginally ( Figure 4.6   Open ▸ ) and more extensive spawning grounds to the north along the Aberdeenshire coast. The presence of high intensity nursery grounds for herring is not supported by outputs from Aries et al. (2014), with predicted aggregations of zero group herring found further inshore. Spawning times for herring are dependent on sub populations, but generally for the Buchan stock, which falls within the northern North Sea fish and shellfish ecology study area, spawning is seen between July and September, with the peak months being August and September. Sticky eggs are deposited preferably on gravel substrate and the eggs adhere to the seabed forming extensive beds (Drapeau, 1973; Rogers and Stocks, 2001). After hatching the larvae enter the plankton and drift with the current until reaching inshore nursery grounds. A year later they migrate further offshore to join adults at feeding grounds. A further review of the herring spawning and has been included in section 4.4.
  12. During the winter, sandeel remain in the sediment only emerging to spawn between January and February. The eggs are laid in clumps within sandy substrate until they hatch, after which they enter the water column. Sandeel will then metamorphose and settle in sandy sediments amongst adults (Van Deurs et al., 2009). Sandeel have high intensity spawning areas and low intensity nursery areas which coincide with the Proposed Development fish and shellfish ecology study area ( Figure 4.6   Open ▸ ). Sandeel ecology is detailed further in section 4.5.
  13. Spawning grounds in the North Sea have been further investigated by Marine Scotland Science (MSS) for cod, haddock and whiting (González-Irusta and Wright, 2016a; González-Irusta and Wright, 2016b; González-Irusta and Wright, 2017). These studies utilised generalised additive models applied to bottom trawl survey data (IBTS 2009 – 2015) to predict spawning habitat of North Sea cod, haddock and whiting. Cod spawning grounds were found to conform to the known widespread occurrence of spawning in the North Sea and was in agreement with previous studies of cod egg distribution, which suggests nearly all historical spawning areas are still in use (González-Irusta and Wright, 2016a). Haddock spawning grounds were found to have shifted southwards from predicted distribution, but generally conformed to historic reports (González-Irusta and Wright, 2016b). Whiting spawning areas were shown to have high inter annual variations in spawning, with two distinct areas of spawning in the south and in the west of the North Sea, however, it is suggested that spawning areas presented in Coull et al. (1998), may currently not be in use (González-Irusta and Wright, 2017).
  14. There are several low intensity nursery grounds for elasmobranchs species within or in close proximity to the Proposed Development fish and shellfish ecology study area including, tope, spurdog, common skate, and spotted ray ( Figure 4.7   Open ▸ ).


Table 4.1:
Species Known to Have Spawning and Nursery Grounds that Overlap with the Proposed Development Fish and Shellfish Ecology Study Area (Coull et al. (1998) and Ellis et al. (2012))

Table 4.1: Species Known to Have Spawning and Nursery Grounds that Overlap with the Proposed Development Fish and Shellfish Ecology Study Area (Coull et al. (1998) and Ellis et al. (2012))

 

Table 4.2:
Main Periods of Spawning Activity for Key Fish Species in the Proposed Development Fish and Shellfish Ecology Study Area (Spawning Periods are Highlighted in Yellow, Peak Spawning Periods Marked Orange) (Adapted from Coull et al. (1998); *Buchan stock)

Table 4.2: Main Periods of Spawning Activity for Key Fish Species in the Proposed Development Fish and Shellfish Ecology Study Area (Spawning Periods are Highlighted in Yellow, Peak Spawning Periods Marked Orange) (Adapted from Coull et al. (1998); *Buchan stock)

Figure 4.4:
Cod, Whiting and Haddock Spawning and Nursery Grounds and Overlaps with the Proposed Development Fish and Shellfish Ecology Study Area

Figure 4.4: Cod, Whiting and Haddock Spawning and Nursery Grounds and Overlaps with the Proposed Development Fish and Shellfish Ecology Study Area

Figure 4.5:
Sprat, Mackerel, Plaice and Lemon Sole Spawning and Nursery Grounds and Overlaps with the Proposed Development Fish and Shellfish Ecology Study Area

Figure 4.5: Sprat, Mackerel, Plaice and Lemon Sole Spawning and Nursery Grounds and Overlaps with the Proposed Development Fish and Shellfish Ecology Study Area

Figure 4.6:
Herring and Sandeel Spawning and Nursery Grounds and Overlaps with the Proposed Development Fish and Shellfish Ecology Study Area

Figure 4.6: Herring and Sandeel Spawning and Nursery Grounds and Overlaps with the Proposed Development Fish and Shellfish Ecology Study Area

Figure 4.7:
Tope, Spurdog, Common Skate and Spotted Ray Nursery Grounds and Overlaps with the Proposed Development Fish and Shellfish Ecology Study Area

Figure 4.7: Tope, Spurdog, Common Skate and Spotted Ray Nursery Grounds and Overlaps with the Proposed Development Fish and Shellfish Ecology Study Area

4.4. Herring

4.4.1.    Desktop Study

  1. Herring is a commercially important pelagic fish, common across much of the North Sea. Herring is a relatively large fishery; the most recently published figures (2020) for herring in the North Sea (ICES Area IVa to IVc) landed by Scottish vessels was 46,742 tonnes with a value of £26,078,000 (Scottish Government, 2020a).
  2. Herring stocks in the North Sea crashed as a result of overfishing in the latter part of the 20th century. Although there has since been a recovery, active management is required to prevent a recurrence (Dickey-Collas et al., 2010). A herring recovery plan to reduce fishing mortality was implemented in 1996 for the North Sea and was revised in 2004. Although this was considered generally successful, it was not as successful for those herring stocks found in the northern North Sea. A ban on discards for pelagic fisheries such as herring started on 1 January 2015.
  3. There are two herring fisheries certified as sustainable by the Marine Stewardship Council (MSC) in the North Sea (MSC, 2018). In addition to this, herring are listed as a Scottish Priority Marine Feature (PMF) (Fauchald et al., 2011 and Casini et al., 2004).
  4. Herring nursery grounds, as described in section 4.3 and shown in Figure 4.6   Open ▸ , are also widespread along the east Scottish and Northumberland coastlines (Ellis et al., 2012), with post larvae juveniles up to sub adults that are yet to reach sexual maturity feeding here until migrating to feeding grounds further offshore where they remain until reaching sexual maturity (ICES, 2006). Herring utilise specific benthic habitats during spawning, which increases their vulnerability to activities impacting the seabed. Further, as a hearing specialist, herring are vulnerable to impacts arising from underwater noise.
  5. Herring deposit eggs on a variety of substrates from coarse sand and gravel to shell fragments and macrophytes, although gravel substrates have been suggested as their preferred spawning habitat. Once spawning has taken place (the peak spawning months being August and September for the Buchan stock), the eggs take approximately three weeks to hatch after which the larvae drift in the plankton (Dickey-Colas et al., 2010; Cefas 2011).
  6. North Sea herring fall into a number of different ‘races’ or stocks, each with different spawning grounds, migration routes and nursery areas (Coull et al., 1998). North Sea autumn spawning herring have been divided into three, mainly self-contained stocks — the Buchan, Dogger and Downs herring groups, which show differences in spawning areas and spawning periods. The Buchan stock which spawn between around August and September off the Scottish east coast are most relevant to the Proposed Development fish and shellfish ecology study area as spawning grounds for this stock have been mapped to the north and south of the Proposed Development fish and shellfish ecology study area ( Figure 4.6   Open ▸ ).

4.4.2.    Site-Specific Surveys

  1. Herring spawning grounds are most accurately mapped using a combination of herring larval data and particle size data, as recommended by Boyle and New (2018). In order to characterise herring spawning habitats in the vicinity of the Proposed Development fish and shellfish ecology study area, these two factors have been considered to accurately determine where the key herring spawning ground for the Buchan stock are located, following the Boyle and New (2018) guidelines. That is, the area where herring are known to spawn most frequently, noting that there is some natural variability in spawning.

Particle size data

  1. As outlined in section 3.2, site-specific survey data were collected alongside desktop studies to assess the extent of suitable spawning habitat within the Proposed Development fish and shellfish ecology study area. Grab sampling surveys were completed and PSA was undertaken on the sediment samples collected which allowed classification of the sediment types according to Reach et al. (2013), as described in Table 4.3   Open ▸ . These classifications provided by Reach et al. (2013) were originally developed for the marine aggregates industry, drawing on work from Greenstreet et al. (2010b) investigating spatial interactions between the aggregate application areas and herring spawning habitat.
  2. Habitat suitability classifications for herring spawning, based on site-specific data, showed that the majority of the Proposed Development fish and shellfish ecology study area has unsuitable sediment for herring spawning, with a small patch of suitable habitat in the north-west section of the Proposed Development array area ( Figure 4.8   Open ▸ ).
  3. Figure 4.8   Open ▸ shows site-specific survey data alongside EMODnet seabed substrate data. The EMODnet seabed substrate data can also be used to assign habitat suitability for herring spawning, showing sandy gravel and gravel as preferred spawning habitat and gravelly sand as marginal spawning. Where no shading is present, the habitat in that area is unsuitable for herring spawning. On the whole, there is good alignment between the results of site-specific surveys and EMODnet seabed substrate data, with the Proposed Development array area containing mostly unsuitable habitat with a few patches of marginal habitat. The Proposed Development export cable corridor contains predominantly unsuitable habitat with a few small patches of marginal habitat. It is worth noting, that the EMODnet seabed substrate data is of lower resolution and accuracy than the results of the site-specific survey data but provide an overall picture of the surrounding substrate. Figure 4.9   Open ▸ shows the same EMODNet data, but for the wider area comprising the Buchan Stock spawning habitat. This shows more extensive areas of marginal spawning habitat to the north of the Proposed Development fish and shellfish ecology study area, coinciding with the area mapped by Coull et al. (1998) and a smaller area of marginal and potential spawning habitat to the south. These patterns in sediment composition are considered in the context of herring larval abundances, as discussed in paragraph 60.

 

Table 4.3:
Herring Potential Spawning Habitat Sediment Classifications Derived from Reach et al. (2013)

Table 4.3: Herring Potential Spawning Habitat Sediment Classifications Derived from Reach et al. (2013)

 

International herring larvae study data

  1. As outlined in paragraph 59, herring spawning grounds can be identified through monitoring of herring larvae, alongside data on sediment type. The IHLS conducts monitoring programmes where larvae numbers are recorded around the UK coastline and the North Sea. Herring larvae are identified as being recently hatched by their size, and therefore small herring larvae can be assumed to have been spawned recently and therefore in close proximity to the area where they are recorded. The IHLS present larval data by size per m2, with larvae under 10 mm long used as a cut off point for recently spawned larvae. Recently spawned larvae will not have drifted far from the location where eggs were spawned on the seabed and high abundances of these larvae are therefore a good indication of recent spawning activity local to where these were sampled. These data were plotted for each year from 2007 to 2016 in Figure 4.10   Open ▸ to Figure 4.14   Open ▸ showing the spatial distribution of herring spawning relative to areas of historical spawning grounds as identified by Coull et al. (1998), in line with guidance from Boyle and New (2018).
  2. These data show that the spawning area north of the Proposed Development array area identified by Coull et al. (1998) has had persistently high levels of spawning with relatively little variation from 2007 to 2016. The spawning area identified to the south of the Proposed Development fish and shellfish ecology study area, which intersects the Proposed Development export cable corridor, has had variable spawning levels from 2007 to 2016. It is worth noting that spatial variability of larval densities may be as a result of the timing of data collection and/or variation in ocean and tidal current speeds and direction, which may account for some of the variability shown to the south of the Proposed Development fish and shellfish ecology study area. Both spawning areas identified through Coull et al. (1998) and the IHLS heat maps are supported by habitat suitability data from EMODnet, as shown in Figure 4.8   Open ▸ and Figure 4.9   Open ▸ by the large patches of favourable and marginal spawning habitat to the north and south of the Proposed Development fish and shellfish ecology study area, which corresponds with spawning areas identified through particle size data and IHLS larval data.
  3. Each year of data were also presented cumulatively over the ten year period between 2007 and 2016 ( Figure 4.15   Open ▸ ) to gain an understanding of where the most common spawning grounds were over the time period. However, the cumulative analysis of spawning density can be skewed by particularly high-density years, which may have been an anomalous result. To mitigate this Figure 4.16   Open ▸ provides a composite of the individual years of herring larval data for the years 2007 to 2016. This shows where high numbers of herring larvae were consistently recorded, using a cut off of 100 larvae <10 mm in length per m2. Areas marked with darker blue patches indicate where spawning evidence was most regularly recorded and therefore indicates the core spawning habitat for the Buchan herring spawning stock. As shown in Figure 4.16   Open ▸ , there is a large patch of darker blue to the north of the Proposed Development fish and shellfish ecology study area which corresponds with the annual herring larval data high density areas. The Proposed Development fish and shellfish ecology study area and the area to the south is marked as lighter blue which reflects the variability in the spawning areas shown in the previous figures in the same area. These data align with what was reported in the post consent fish monitoring strategy report for Seagreen (Seagreen, 2019).
  4. Due to lack of ILHS survey data between 2017 and 2018, and a change in reporting strategy from IHLS, since 2019, more recent herring larvae data were not available for analysis. However, an ICES scientific report (ICES, 2021) noted that IHLS data for 2019 to 2020 in the Buchan area was in the same order of magnitude as previous years, therefore, it can be assumed that there are no significant changes from the results presented for 2007 to 2016 outside of normal annual variations.

Figure 4.8:
Herring Spawning Habitat Preference Classifications from EMODnet and Site-Specific Survey Data

Figure 4.8: Herring Spawning Habitat Preference Classifications from EMODnet and Site-Specific Survey Data

Figure 4.9:
Herring Spawning Habitat Preference Classifications from EMODnet and Site-Specific Survey Data Covering the Buchan Stock Herring Spawning Habitats

Figure 4.9: Herring Spawning Habitat Preference Classifications from EMODnet and Site-Specific Survey Data Covering the Buchan Stock Herring Spawning Habitats

Figure 4.10:
Herring Larval Density from IHLS Data Sets for 2007 to 2008

Figure 4.10: Herring Larval Density from IHLS Data Sets for 2007 to 2008

Figure 4.11:
Herring Larval Density from IHLS Data Sets for 2009 to 2010

Figure 4.11: Herring Larval Density from IHLS Data Sets for 2009 to 2010

Figure 4.12:
Herring Larval Density from IHLS Data Sets for 2011 to 2012

Figure 4.12: Herring Larval Density from IHLS Data Sets for 2011 to 2012

Figure 4.13:
Herring Larval Density from IHLS Data Sets for 2013 to 2014

Figure 4.13: Herring Larval Density from IHLS Data Sets for 2013 to 2014

Figure 4.14:
Herring Larval Density from IHLS Data Sets for 2015 to 2016

Figure 4.14: Herring Larval Density from IHLS Data Sets for 2015 to 2016

Figure 4.15:
Herring Cumulative Larval Density from IHLS Data Sets for 2007 to 2016

Figure 4.15: Herring Cumulative Larval Density from IHLS Data Sets for 2007 to 2016

Figure 4.16:
Herring Larval Density of over 100 per m2 per Year from 2007 to 2016

Figure 4.16: Herring Larval Density of over 100 per m2 per Year from 2007 to 2016