4.5. Sandeels

4.5.1.    Desktop Study

  1. There are a number of sandeel species present within the region. This section refers to sandeel species collectively, unless specified otherwise. The wider Forth and Tay SMR has been known historically to support important sandeel populations. The highest density of this population is focused on the Wee Bankie, however sandeels do range across much of the wider North Sea. In the early 1990s there was a substantial industrial sandeel fishery on the Wee Bankie, Marr Bank and Berwick Bank sandbanks. By 1993 landings from this area had peaked at over 100,000 t (Greenstreet et al., 2010a).
  2. In 2000, this industrial sandeel fishery was closed in response to concerns that the fishery was having a deleterious effect on sandeel stocks within the Forth and Tay SMR. The sandeel closure within this region (precautionary closure — Article 29a from Council Regulation No 850/88) had the effect of limiting sandeel fishing on most of the Forth and Tay SMR sandeel grounds. The fishery remains closed and sandeel abundance is monitored by Marine Scotland and ICES (2022).
  3. After the Forth and Tay SMR sandeel fishery closed, high levels of recruitment, combined with a lack of any significant fishing activity resulted in an immediate and substantial increase in the biomass of sandeel on the Wee Bankie sandbank. However, since 2001, sandeel biomass has steadily declined to levels that were similar to those observed when the sandeel fishery was active (Greenstreet et al., 2010). More recently sandeel stocks have recovered leading to an increase in sandeel fishing adjacent to the closed area. However, ICES recently stated “The escapement strategy [by which sandeel stocks are managed] is not sustainable for short-lived species unless the strategy is combined with a ceiling (Fcap) on fishing mortality” (ICES, 2022).
  4. Two sandeel species, Raitt’s sandeel Ammodytes marinus and lesser sandeel Ammodytes tobianus, are Scottish PMFs. Sandeel spend most of the year buried in the seabed, emerging in the winter to spawn (van der Kooij et al., 2008). Sandeel spawn a single batch of eggs in December to January, which are deposited on the seabed, several months after the active feeding season (April to September). The larvae hatch after several weeks, usually in February to March, and drift in the currents for one to three months, after which they settle on the sandy seabed. During the spring and summer, sandeel emerge during the day to feed in schools and at night return to bury in the sand. This is an adaptation to conserve energy and to avoid predation. There are indications that the survival of sandeel larvae is linked to the availability of copepod prey in the early spring, especially Calanus finmarchicus and that climate generated shifts in the Calanus species composition can lead to a mismatch in timing between food availability and the early life history of lesser sandeel (Wright and Bailey, 1993; van Deurs et al., 2009). Sandeel is an important prey species for many marine predators.
  5. Sandeel have a close association with sandy substrates into which they burrow. They are largely stationary after settlement and show a strong preference to specific substrate types. Studies in the laboratory (Wright et al., 2000) and in the natural environment (Holland et al., 2005) has focused on identifying the sediment characteristics that define the seabed habitat preferred by sandeel. Both approaches produced similar results, indicating that sandeel preferred sediments with a high percentage of medium to coarse grained sand (particle size 0.25 mm to 2 mm), and avoided sediment containing >4% silt (particle size <0.063 mm) and >20% fine sand (particle size 0.063 mm to 0.25mm). As the percentage of fine sand, coarse silt, medium silt and fine silt (particles <0.25 mm in diameter) increased, sandeel increasingly avoided the habitat (this finding was also supported by Wright et al. (2000) as reported by Mazik et al. (2015)). Conversely, as the percentage of coarse sand and medium sand (particles ranging from 0.25 mm to 2.0 mm) increased, sandeel showed an increased preference for this substrate.
  6. Work by Greenstreet et al. (2010b) draws on the research by Holland et al. (2005), to define four sandeel sediment preference categories, using hydro acoustic seabed surveys and nocturnal grab surveys. They merged fine sand, three silt grades and two coarser sand grades, to define two particle size classes, silt and fine sand and coarse sand, and then examined the combined effect of these two size grades of sediment particles on the percentage of grab samples with sandeel present. Latto et al. (2013) used this research to produce four sandeel sediment preference categories, which were defined as; Prime, Sub Prime, Suitable and Unsuitable (see Table 4.4   Open ▸ ).
  7. Further work has been completed by Langton et al. (2021) where a predicted distribution model for sandeel was developed, producing predicted density and probability of occurrence for sandeel around the British coastline. This modelling was undertaken based on the dependence of sandeel on particular habitat types, with the four main explanatory variables within the model being silt, depth, sand and slope, and was supported by sandeel fisheries data (e.g. data from Jensen et al., 2011). The results were mapped, highlighting areas of importance for sandeel populations in the North Sea, including the Forth and Tay SMR and the Proposed Development fish and shellfish ecology study area. Figure 4.17   Open ▸ presents the outputs of the modelling within the Proposed Development fish and shellfish ecology study area and shows that a large proportion of the Proposed Development fish and shellfish ecology study area has high probability of sandeel presence, with more discrete areas where predicted density is high. These areas also correlate to previous studies where marine mammals and birds are known to congregate and feed on sandeels (Langton et al., 2021).

Figure 4.17:
Model Derived Predictions of Density and Probability of Presence of Sandeel within the Proposed Development Fish and Shellfish Ecology Study Area (derived from Langton et al., 2021)

Figure 4.17: Model Derived Predictions of Density and Probability of Presence of Sandeel within the Proposed Development Fish and Shellfish Ecology Study Area (derived from Langton et al., 2021)

4.5.2.    Site-Specific Surveys

  1. As outlined in section 3.2, site-specific survey data were collected and reviewed alongside desktop studies to assess the extent of suitable sandeel habitat within the Proposed Development fish and shellfish ecology study area. Grab sampling was undertaken (see section 3.2). PSA was undertaken on the sediment samples collected which allowed classification of the sediment types according to Latto et al. (2013), as described in section 3.2. These classifications provided by Latto et al. (2013) were originally developed for the marine aggregates industry, drawing on work from Greenstreet et al. (2010b) and Holland et al. (2005), investigating spatial interactions between the aggregate application areas and sandeel habitat.
  2. Figure 4.18   Open ▸ shows the results of this analysis with sandeel habitat sediment preference classifications of prime, subprime, suitable and unsuitable habitat denoted. The distribution of the habitat suitability shows that the majority of the Proposed Development array area is prime to suitable habitat, with a small area to the north-west of the Proposed Development array area with unsuitable habitat. Within the Proposed Development export cable corridor, the majority of the grabs indicate that habitat is unsuitable.
  3. Figure 4.18   Open ▸ shows the site-specific survey data alongside EMODnet seabed substrate data which can also be used to assign habitat suitability for sandeel. For the purposes of considering sandeel habitats suitability across the Proposed Development fish and shellfish ecology study area  and surrounding areas, gravelly sand, (gravelly) sand, and sand in the EMODnet data were classified as preferred habitat and sandy gravel as marginal habitat. Where no shading is present, the habitat in that area is unsuitable for sandeel. 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 demonstrating mostly preferable habitat with a few patches of marginal habitat. The Proposed Development export cable corridor has a significant patch of unsuitable habitat, which matches PSA points of unsuitable habitat. There is some disagreement in the Proposed Development export cable corridor section where the habitat is indicated as preferred in the EMODnet data, but unsuitable by PSA. As described in section 4.2.2, the Proposed Development export cable corridor has been found to be dominated by muddy sediments, which further supports the site-specific survey results, which determine much of the Proposed Development export cable corridor as unsuitable. It is worth noting, that the EMODnet seabed substrate data is of lower resolution and accuracy than the results of the site-specific survey but provide an overall picture of the surrounding substrate.
  4. Further site-specific survey results from grab samples and epibenthic trawls, as shown in Figure 4.19   Open ▸ , has provided incidental data on abundance of sandeel within the Proposed Development fish and shellfish ecology study area. There were some instances where grab samples captured sandeel individuals. These are shown in Figure 4.19   Open ▸ , with records in grab samples shown as presence/absence and trawl data shown as abundances per 500 m trawled. The abundance data collected indicates higher abundances of sandeel in the north-western section of the Proposed Development array area, due to the highest presence within grab samples and higher numbers of sandeel in epibenthic trawls within that area. However, it should be noted that both of these data collection methods do not target sandeel specifically, therefore these results should be regarded as opportunistic. Conversely, whilst these opportunistic data may indicate higher abundances in specific areas, it cannot be interpreted as low abundance or absence where sandeels were not recorded, due to the lack of specificity of sampling methods for sandeels. The site-specific survey data and desktop data indicate that sandeels are likely to be present across the Proposed Development array area and less likely in the Proposed Development export cable corridor.

 

Table 4.4:
Sandeel Habitat Sediment Classifications Derived from Latto et al. (2013)

Table 4.4: Sandeel Habitat Sediment Classifications Derived from Latto et al. (2013)

Figure 4.18:
Sandeel Habitat Preference Classifications from EMODnet and Site-specific Survey Data

Figure 4.18: Sandeel Habitat Preference Classifications from EMODnet and Site-specific Survey Data

Figure 4.19:
Sandeel Habitat Preference Classifications with Site-Specific Abundance Data

Figure 4.19: Sandeel Habitat Preference Classifications with Site-Specific Abundance Data

4.6. Diadromous Fish

  1. The term diadromous fish is used in this Technical Report to describe fish that migrate between fresh water and the marine environment. There is the potential for diadromous fish species to migrate to and from Scottish rivers in the vicinity of the Proposed Development fish and shellfish ecology study area and, therefore, they may migrate through the Proposed Development fish and shellfish ecology study area to rivers during certain periods of the year (National Biodiversity Network (NBN) Atlas, 2019).
  2. The fish and shellfish ecology assessment for Seagreen (Seagreen, 2018) observed seven diadromous species of relevance: Atlantic salmon Salmo salar, sea trout Salmo trutta, sea lamprey Petromyzon marinus, river lamprey Lampetra fluviatilis, European eel Anguilla anguilla, allis and twaite shad Alosa alosa and Alosa fallax and sparling (European smelt) Osmerus eperlanus. The species which were considered as having the greatest potential to be present within the vicinity of Seagreen, and similarly the Berwick Bank Wind Farm, were Atlantic salmon, sea trout, European eel and the lamprey species.
  3. No site-specific surveys were undertaken to inform the assessment of effects on diadromous fish species. For the purposes of the assessment of effects, it will be assumed that the aforementioned species are likely to be present within the Proposed Development array area and/or Proposed Development export cable corridor, during key migration periods (e.g. adult migration to spawning rivers and smolt migration from natal rivers in the vicinity of the Proposed Development fish and shellfish ecology study area). Depending on the key migration periods, there will be a greater/lesser likelihood of fish being present in the Proposed Development fish and shellfish ecology study area.
  4. Timings of diadromous fish species migration are presented in Table 4.5   Open ▸ , which displays the key migration times of diadromous fish species, and also the length of time each species spends in fresh water and at sea. 

 

Table 4.5:
Overview of Life Histories for Diadromous Fish Relevant to the Proposed Development Fish and Shellfish Ecology Study Area (Seagreen, 2018)

Table 4.5: Overview of Life Histories for Diadromous Fish Relevant to the Proposed Development Fish and Shellfish Ecology Study Area (Seagreen, 2018)

 

4.6.2.    Atlantic Salmon

  1. Salmon is of considerable cultural and conservation importance (Hindar et al., 2010) and in Scotland represents an important part of the rural economy (Radford et al., 2004). However, in recent decades, and especially the past thirty or so years, there have been declines in rod catch data across much of the species’ range (Scottish Government, 2020b) There are many pressures on Atlantic salmon stocks in both marine and freshwater environments, including commercial and recreational exploitation of stocks, disease, impacts related to farmed salmon and climate change (ICES, 2017b). Atlantic salmon is an Annex II species under the Habitats Directive and is a feature of various Special Areas of Conservation (SAC). They are also a PMF in Scotland, and an Annex III species under the Bern Convention.
  2. A Marine Scotland report on salmon fishery statistics (Marine Scotland, 2017) summarised rod and line, net and coble and fixed engine fisheries data for the period 1952 to 2016, based on completed fisheries returns. Rod caught spring salmon catches have declined since records began and are at a historically low level. The overall catch of salmon and, in later months, grilse, however, generally increased up to 2010, then fell sharply (second lowest on record in 2014) before recovering slightly in 2015 and 2016. By 2016 the reported catch and effort for the fixed engine and net and cobble fisheries were the lowest since records begin in 1952.
  3. The Salmon Conservation Regulations which came into force in 2016 included measures to prohibit the killing of fish in coastal waters and in estuaries and rivers where the stocks were determined to be in poor conservation status. The great majority of rod and line caught salmon from the recreational fishery are returned to the water. In 2020, 93% of the annual rod catch, and 99% of the spring rod catch, were released (Scottish Government, 2020b).
  4. Following spawning by adult salmon in Scottish east coast rivers, the ova mature into fry and then parr before migrating to sea as smolts. At sea, the smolts grow rapidly and after one to three years they return as adults to spawn, most commonly to their natal river. Many Atlantic salmon die after spawning, but some return to sea as kelts and may return again to rivers to spawn (Mills, 1989). Atlantic salmon are known to migrate in relation to diurnal cues. Evidence provided by Smith and Smith (1997) suggests that Atlantic salmon upstream migration into rivers is related to tidal phase and time of day. Up-estuary movements leading to river entry were found to be predominantly nocturnal and occur during ebb tides, with entry into nontidal reaches of rivers also being nocturnal, however significantly associated with tidal phase (Smith and Smith, 1997). Smolts migrating downstream/offshore have also been found to increase migratory activity nocturnally, with daytime utilised more for prey detection and predator avoidance (Hedger et al., 2008). Dempson et al. (2011) also found a small but significant increase in migratory movements nocturnally when compared to daytime, which suggests a slight preference for nocturnal migration.
  5. Malcolm et al. (2015) used metadata to assess the timing of smolt emigration across Scotland. This suggests that most fish leave rivers between mid-April and the end of May. These results do not include the period spent by smolts in the coastal environment after leaving their native rivers. There was evidence that smolt emigration is becoming earlier (by around 1.5 days per decade over a period of around 50 years).
  6. Migration of Atlantic salmon smolts through the Cromarty Firth and into the Moray Firth was tracked in a study undertaken for Beatrice Offshore Windfarm Ltd. by Glasgow University (BOWL, 2017). The study results indicated an eastwards migration of the tagged fish along the southern coast of the Moray Firth. Results also showed the majority of fish to remain predominantly within the upper 1 m of the water column during migration. Mortality of smolts was considered to be mainly attributable to predation and there was a strong relationship between group survival, early migration and group size.
  7. Atlantic salmon smolts were tracked using acoustic telemetry in the River Deveron (south coast of the Moray Firth) and adjacent coastal areas (Lothian et al., 2017). Deveron fish had higher swim speeds in the early marine phase compared with the river. The majority of fish left the river in darkness on a flooding tide. Early marine migration speed decreased with increased environmental acoustic noise levels. Fish movements in the marine environment appeared more influenced by water currents than geographical features.
  8. It has been suggested that once in the marine environment, the east coast Scotland ‘post smolts’, as they are known, are transported by North Sea currents firstly towards northern Norway and then into the Norwegian Sea (Holst et al., 2000; Jonsson et al., 1993). Smolt emigration at sea is poorly understood, however, and Malcolm et al. (2010) outlined a concept that fish from Scotland head west to feed and grow, utilising waters off west and east Greenland, as well as the Faroe Islands, as evidenced by recaptures of Scottish fish in all of these areas. This includes fish from the Aberdeenshire Dee, Tay and North Esk rivers.
  9. Rod catch data from rivers on the east coast of Scotland can provide insight into the general trends of salmon populations within the vicinity of the Proposed Development fish and shellfish ecology study area. Data provided by Marine Scotland have been interrogated, with a focus on the following rivers relevant to the Proposed Development fish and shellfish ecology study area: Tweed, Forth, Tay, South Esk and Dee. At a simple level, Figure 4.20   Open ▸ evidences that salmon migrate to/from a number of rivers in the vicinity of the Proposed Development fish and shellfish ecology study area and therefore should be assumed very likely to pass through the Proposed Development fish and shellfish ecology study area, either as smolts or returning adults. This is consistent with the assumptions made within the Seagreen Alpha/Bravo Natural Fish and Shellfish Resource EIA Report (Seagreen, 2012).
  10. This is further supported by recent evidence from the Moray Firth (Newton et al., 2017; Newton et al., 2019; Gardiner et al., 2018a) which suggests that smolts migrating from their rivers in the Moray Firth head directly across the North Sea relatively rapidly. It is thought that this route, rather than moving in a coastal direction upon leaving their natal rivers, allows them to take advantage of east flowing currents which cross the North Sea. This fast progress away from the coast limits exposure to predators close to the coast. It also reduces the potential for interaction with marine renewables developments (including offshore wind). Similar evidence of a rapid easterly migration out into the North Sea has also been shown for the River Dee in Aberdeenshire (Gardiner et al., 2018b). Therefore, it could be assumed that smolts from other east coast rivers (e.g. Tay, Forth and South Esk) would move in a similar fashion.

Figure 4.20:
Catch Data for Rod Caught Atlantic Salmon using Marine Scotland Data (2011 to 2020)

Figure 4.20: Catch Data for Rod Caught Atlantic Salmon using Marine Scotland Data (2011 to 2020)

4.6.3.    Sea Trout

  1. Sea trout are found in rivers streams and lakes, preferring cold, well oxygenated upland waters. They spawn in rivers and streams with swift currents, usually characterized by downward movement of water into gravel, favouring large streams in the mountainous areas with adequate cover in the form of submerged rocks, undercut banks, and overhanging vegetation (Fishbase, 2021a). There is limited information regarding sea trout migration patterns, however available information suggests predominantly inshore and local (to the river) use of the marine environment (Malcolm et al., 2010). Figure 4.21   Open ▸ evidences that sea trout migrate to/from a number of rivers in the vicinity of the Proposed Development fish and shellfish ecology study area, however sea trout mainly stay close to the coastline and do not travel very far from the estuaries of their natal rivers. Sea trout are also known to be a host species for freshwater pearl mussel, see section 4.7.7 for further detail.

4.6.4.    European Eel

  1. European eels inhabit all types of benthic habitats from streams to shores of large rivers and lakes, migrating to the Sargasso Sea to spawn. Eel larvae are brought to European waters by the Gulf Stream and transform into glass eel and then elvers which migrate up estuaries around the Scottish coast, colonising, rivers and lakes. When sexual maturity is reached, they leave the river and migrate to the sea, covering great distances during their spawning migration (5,000 to 6,000 km) (Fishbase 2021b). It is a possibility that European eel will pass through the vicinity of the Proposed Development fish and shellfish ecology study area and therefore these will be considered as IEFs.

4.6.5.    Sea Lamprey

  1. The sea lamprey is a primitive, jawless fish resembling an eel. It is the largest of the lampreys found in the UK. It occurs in estuaries and easily accessible rivers and is an anadromous species (i.e. spawning in freshwater but completing its life cycle in the sea) (JNCC, 2021a). Like the other species of lamprey, sea lampreys need clean gravel for spawning, and marginal silt or sand for the burrowing juveniles (ammocoetes). Sea lamprey spend most of their adult life at sea and are parasitic on a number of fish species and other marine fauna. Sea lampreys have a preference for warmer waters in which to spawn, which coincide with warmer spring temperatures in Scottish rivers (see Table 4.5   Open ▸ ) (JNCC, 2021a). It is a possibility that sea lamprey will be present in the vicinity of the Proposed Development fish and shellfish ecology study area and therefore these will be considered as IEFs.

4.6.6.    River Lamprey

  1. The river lamprey is found in coastal waters, estuaries and accessible rivers, but some populations are permanent freshwater residents, however the species is normally anadromous (i.e. spawning in freshwater but completing part of its life cycle in the sea) (JNCC, 2021b). They live on hard bottoms or attached to larger fish like cod and herring due to their parasitic feeding behaviour, with spawning taking place in pre-excavated pits in riverbeds. Due to their preference for estuarine waters, it is unlikely that river lamprey will be found within the Proposed Development fish and shellfish ecology study area and have therefore been scoped out with agreement of stakeholders (volume 2, chapter 9).

4.6.7.    Allis and Twaite Shad

  1. The allis shad and twaite shad are members of the herring family and are difficult to distinguish between one another (JNCC, 2021c; JNCC 2021d). The habitat requirements of twaite shad are not fully understood. On the River Usk and the River Wye, twaite shad are known to spawn at night in a shallow area near deeper pools, in which the fish congregate. The eggs are released into the water column, sinking into the interstices between coarse gravel/cobble substrates (JNCC, 2021c). The allis shad also has poorly understood habitat requirements. It grows in coastal waters and estuaries, spending most of its adult phase in the marine environment, but migrates into rivers to spawn, swimming up to 800 km upstream in continental Europe. Adults spawn at night with the eggs released into the current where they settle among gaps in gravelly substrates. Spawning sites tend to be shallow gravelly areas adjacent to deep pools are thought to represent optimal spawning habitat (JNCC, 2021d). These species are considered unlikely to be found in significant numbers within the vicinity of the Proposed Development fish and shellfish ecology study area, however they are considered to ensure a precautionary approach.

4.6.8.    Sparling (European Smelt)

  1. Sparling or European smelt inhabit estuaries and large lakes, spending much of its life in the estuarine zone, with just short incursions in the littoral zone. Sparling enter rivers to spawn on sandy or gravelly bottoms, usually in fast flowing waters of lake tributaries or shallow shores of lakes and rivers (Fishbase, 2021c). Due to their preference of estuarine waters when they do enter the marine environment, it is unlikely that sparling will be found within the Proposed Development fish and shellfish ecology study area.

Figure 4.21:
Catch Data for Rod Caught Sea Trout using Marine Scotland Data (2011 to 2020)

Figure 4.21: Catch Data for Rod Caught Sea Trout using Marine Scotland Data (2011 to 2020)

4.6.9.    Designated Sites

  1. Designated sites which have fish and shellfish qualifying features and which have been considered in the fish and shellfish assessment are described in Table 4.6   Open ▸ , and the locations of the Special Areas of Conservation (SACs) and Nature Conservation Marine Protected Areas (MPAs) are displayed in Figure 4.22   Open ▸ .

 

Table 4.6:
Designated Sites Within the Northern North Sea Fish and Shellfish Ecology Study Area and Qualifying Interest Features

Table 4.6: Designated Sites Within the Northern North Sea Fish and Shellfish Ecology Study Area and Qualifying Interest Features


Figure 4.22:
Designated Sites with Fish as Qualifying Features

Figure 4.22: Designated Sites with Fish as Qualifying Features

4.7. Shellfish

  1. Shellfish is a colloquial and fisheries term for exoskeleton bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Commercial landing data can be used as a proxy for identifying species present in the vicinity of the Proposed Development fish and shellfish ecology study area, which include Nephrops, edible crab, European lobster, velvet swimming crab, king scallop, and squid, as described in volume 3, appendix 12.1. Site-specific epibenthic trawl data (section 3.2) recorded Nephrops, edible crab and king scallop within the Proposed Development fish and shellfish ecology study area, albeit in low abundances. Shellfish found in high abundances in epibenthic trawls included brown shrimp Crangon crangon and other shrimp species (Pandalidae); however, these are not a main target of commercial fisheries. Site-specific surveys for Seagreen Alpha/Bravo (Seagreen, 2012) also reported edible crab, velvet swimming crab and king scallop in the results of beam trawls.  Habitats within the Firth of Forth Banks Complex MPA (which overlaps spatially with the FSF study area) support ocean quahog aggregations, which are a designated feature of the MPA in their own right. As impacts to ocean quahog are inherently tied to impacts on subtidal habitats and supporting habitats within the MPA, ocean quahog is assessed in volume 2, chapter 8 and the Berwick Bank Wind Farm Marine Protected Area Assessment (SSER, 2022b).

4.7.2.    King Scallop

  1. Scallops show a preference for areas of clean firm sand, fine or sandy gravel and may occasionally be found on muddy sand. Distribution of this species is invariably patchy (Marshal and Wilson, 2009; Carter, 2009) but the areas with greatest abundance tend to be areas of little mud and with good current strength. In Scottish waters, scallops spawn for the first time in the autumn of their second year, and subsequently spawn each year in the spring or autumn. After settlement, scallops grow until their first winter, during which growth usually ceases. Thereafter, growth resumes each spring and ceases each winter, causing a distinct ring to be formed on the external surface of the shell.
  2. King scallops are targeted commercially through dredge fisheries within the Proposed Development fish and shellfish ecology study area, with the majority of the activity, albeit at a moderate level, concentrated in the north-west section of the Proposed Development fish and shellfish ecology study area (see volume 3, appendix 12.1). Higher intensity scallop dredging is present immediately north of the Proposed Development fish and shellfish ecology study area.

4.7.3.    European Lobster

  1. The European lobster can be found throughout the British coasts on rocky substrata, down to depths of 60 m. European lobster are actively fished in areas in the vicinity of the Proposed Development fish and shellfish ecology study area and are likely to occur in the Proposed Development fish and shellfish ecology study area (see volume 3, appendix 12.1). 

4.7.4.    Edible Crab

  1. Edible crab is a relatively long-lived species that are found on all coasts around Britain from the intertidal zone down to depths of 100 m. They live on rocky, gravelly substrate which they bury into. Following spawning there is a larval dispersal phase of around 30 to 50 days. Like European lobster, edible crab are actively fished in areas in the vicinity of the Proposed Development fish and shellfish ecology study area and are likely to occur in the Proposed Development fish and shellfish ecology study area (see volume 3, appendix 12.1). 

4.7.5.    Velvet Swimming Crab

  1. Velvet swimming crab can be found around the coast of Britain and are found on stony/rocky substrate intertidally and down to depths of 100 m (Howson and Picton, 1997). Velvet swimming crab are targeted by commercial fisheries with higher commercial values available in continental Europe and they are often caught alongside European lobster and edible crab (see volume 3, appendix 12.1). Velvet swimming crab were recorded in site-specific surveys within the Proposed Development fish and shellfish ecology study area and therefore can be assumed to be present within the Proposed Development fish and shellfish ecology study area.

4.7.6.    Squid

  1. Squid species are reported to be found over sand and muddy bottoms (Wilson, 2006) and mostly demersal in nature and therefore often bycatch in demersal fisheries (Bellido et al., 2001) with research on squid determining that they are probably batch spawners. However, this can vary dependant on species, with other species utilising hard substrate for spawning purposes (Guerra and Rocha, 1994). In Scottish waters, squid exhibit a distinct seasonal migration pattern, travelling up to 500 km from the west coast of Scotland to the east coast in the winter months (Hastie et al., 2009). Squid are targeted by commercial fisheries, although main areas of fishing activity is within coastal waters and only overlap the Proposed Development export cable corridor (see volume 3, appendix 12.1). 

4.7.7.    Freshwater Pearl Mussel

  1. The freshwater pearl mussel Margaritifera margaritifera is an endangered species of freshwater mussel. Freshwater pearl mussels are similar in shape to common marine mussels but grow much larger and live far longer. They can grow as large as 20 cm and live for more than 100 years, making them one of the longest-lived invertebrates (Skinner et al., 2003). These mussels live on the beds of clean, fast flowing rivers, where they can be buried partly of wholly in coarse sand or fine gravel. Mussels have a complex life cycle, living on the gills of young Atlantic salmon or sea trout, for their first year, without causing harm to the fish (Skinner et al., 2003). Freshwater pearl mussel is fully protected under Schedule 5 of the Wildlife and Countryside Act 1981 (as amended) and is also listed on Annexes II and V of the Habitats Directive and Appendix III of the Bern Convention. The conservation status of the species is reflected in its listing as Endangered on the International Union for Conservation of Nature (IUCN) Invertebrate Red List. While there is no potential for direct impacts on this species from the Proposed Development fish and shellfish ecology study area (as this is an entirely freshwater species), indirect impacts may occur due to effects on their host species (i.e. Atlantic salmon and sea trout) during their marine phase.

4.7.8.    Nephrops

Desktop study

  1. Nephrops, known variously as the Norway lobster, Dublin Bay prawn, langoustine or scampi, is a slim, orange pink lobster which grows up to 25 cm long, and is considered to be the most commercially important crustacean in Europe (Bell et al., 2006). Nephrops are exploited throughout their geographic range, from Icelandic waters to the Mediterranean and the Moroccan coast.
  2. Nephrops are opportunistic predators, primarily feeding on crustaceans, molluscs and polychaete worms. They inhabit muddy seabed sediments and show a strong preference for sediments with more than 40% silt and clay (Bell et al., 2006). They build and spend significant amounts of time in semi-permanent burrows which vary in structure and size but typically range from 20 cm to 30 cm in depth (Dybern and Hoisaeter, 1965). Due to strong habitat preferences, distribution patterns of Nephrops are determined by the presence of suitable habitats, with higher abundances found on more favourable substrates.
  3. Female Nephrops usually mature at three years of age and reproduce each year thereafter. After mating in early summer, Nephrops spawn in September, and carry eggs under their tails (described as being 'berried') until they hatch in April or May. The larvae develop in the plankton before settling to the seabed six to eight weeks later (Coull et al., 1998). Unspecified intensity nursery and spawning grounds for Nephrops are present within the western section of the Proposed Development fish and shellfish ecology study area ( Figure 4.23   Open ▸ ).

Site-specific survey

  1. As discussed in paragraph 105, Nephrops display a strong preference for muddy sediments (silt and clay), therefore the majority of the Proposed Development fish and shellfish ecology study area is unsuitable for Nephrops as sands and gravel dominate the Proposed Development array area. The exception is within the Proposed Development export cable corridor, where the substrate is characterised by muddy sediments (see volume 3, appendix 8.1).
  2. Incidental observations were made of Nephrops from DDV and trawl surveys during the epibenthic trawl survey and combined grab and DDV sampling conducted within the Proposed Development fish and shellfish ecology study area. As shown in Figure 4.24   Open ▸ , DDV data were displayed as presence/absence records and trawls recording abundances per 1,000 m trawled. Figure 4.24   Open ▸ also shows biotope mapping produced within volume 3, appendix 8.1, where a large proportion of the Proposed Development export cable corridor was assigned the biotope SS.SMu.CFiMu.SpnMeg – Seapens and burrowing megafauna. This biotope is often associated with high abundance of Nephrops (JNCC, 2021e).  
  3. The location of Nephrops identified through site-specific surveys, correlated strongly with results of the biotope mapping, with all recordings of Nephrops, through trawls and DDV surveys, occurring within the area identified as the Seapens and burrowing megafauna biotope. This showed that Nephrops were present in the suitable substrates in the Proposed Development export cable corridor.

Figure 4.23:
Nephrops Spawning and Nursery Grounds and Overlaps with the Proposed Development Fish and Shellfish Ecology Study Area

Figure 4.23: Nephrops Spawning and Nursery Grounds and Overlaps with the Proposed Development Fish and Shellfish Ecology Study Area

Figure 4.24:
Nephrops Abundances Recorded During Site-Specific Surveys

Figure 4.24: Nephrops Abundances Recorded During Site-Specific Surveys