This website is no longer being updated. Please go to GOV.SCOT

Scottish Marine and Freshwater Science Volume 1 No 18: Further Scottish Leasing Round (Saltire Prize Projects): Regional Locational Guidance

Listen

3.6 West of Shetland

Summary

The north-west coast of Mainland Shetland displays a high level of wave resource. The seabed is composed of a variety of habitat types from solid rock, to sands and gravels and the depth in the inshore region is typically between 30 and 50 m. There are a number of suitable ports in the vicinity such as Sullom Voe and Scalloway. The grid is likely to have sufficient capacity to support wave energy generation should the planned improvements take place, although local connections would still be required. There is no marked military activity within the site. However, the area is highly regarded for the species and habitats it supports, particularly the seabirds but also seals, cetaceans, otters and rocky reefs. As such it contains many designated sites for conservation purposes and is under consideration as a new SPA. This is also an important fishing ground for the shellfish and pelagic sector. Much of the inshore section of the site is marked as a sailing area by the RYA. It should be noted that in the case of Shetland, in addition to other licenses, a Works Licence will also be required under the Shetland County Council Act ( ZCC Act). The Shetland SSMEI Marine Atlas and Marine Spatial Plan (2010) are valuable resources for further information about site characteristics and the national and regional policy context.

3.6.1 Technological Constraints

3.6.1.1 Wave Resource

The annual mean significant wave height increases further offshore from 2.3 m near the coast of Esha Ness to = 2.8 m at a distance of 8 km offshore (Fig. 3.6.2). The summer maximum (1.8 m) is far lower than in winter (3.6 m). Similarly, the mean wave period varies between 8.1 s in winter and 6.3 s in summer. There is little variation within the site however (annual mean wave period is 7.2 to 7.6 s). The wave power mirrors the trend in height and period (Fig. 3.6.1). The annual mean in this area varies between 10.7 and 32.8 kW/m of wave crest. In winter, it is considerably greater (= 56.2 kW/m compared to = 11.5 kW/m in summer).

Figure 3.6.1: West of Shetland: Annual mean wave power density (source: OS, BGS, DTI)

Figure 3.6.1: West of Shetland: Annual mean wave power density

Figure 3.6.2: West of Shetland: Annual mean significant wave height (source: OS, BGS, DTI)

Figure 3.6.2: West of Shetland: Annual mean significant wave height

3.6.1.2 Tidal Streams

The tides south-west of the island of Papa Stour are relatively strong (between 1.3 m/s and 0.5 m/s during springs and neaps respectively) (Fig. 3.6.3). The tides in the remaining area are far weaker (between 0.1 and 0.6 m/s). The spring tidal range off the coast of Esha Ness reaches 1.76 m and 1.67 m off the island of Papa Stour.

Figure 3.6.3: West of Shetland: Mean spring tidal peak flow (source: OS, BGS, DTI)

Figure 3.6.3: West of Shetland: Mean spring tidal peak flow

3.6.1.3 Bathymetry and Seabed

The seabed in the south-east sector of the site is predominantly sandy gravel and gravelly sand (Fig. 3.6.4). The depth in this region varies between 30 and 50 m. The depth increases further offshore to >100 m. The majority of the mid and northern component of the site is slightly gravelly sand and is a depth of 20 to 100 m. There is an area of sandy gravel off the north-western tip of Mainland Shetland surrounded by a wide expanse of slightly gravelly sand.

Figure 3.6.4: West of Shetland: Bathymetry and seabed sediments (source: OS, BGS)

Figure 3.6.4: West of Shetland: Bathymetry and seabed sediments

3.6.1.4 Existing Infrastructure

Grid connection: There is currently no connection between Shetland and the Scottish mainland. Demand (~50 MW in the Shetland Isles) is mostly met by local power generation, a wind farm and Sullom Voe terminal. SHETL are planning a 600 MWHVDC link to the Scottish mainland to accommodate power generated by the Viking Energy wind farm proposal which has an estimated completion date of October 2014. Connection of wave/tidal devices is contingent on local reinforcement of the existing 33 kV network in Shetland. Whether or not the interconnector proposal proceeds, SSE is planning an energy storage, active network and demand approach on Shetland to start in 2011, in order to accommodate the full demand of Shetland (~50 MW) from renewables.

Ports and harbours: Nearby ports that could be used for installation and servicing are located in Scalloway, Sullom Voe, Tofts Voe and on Papa Stour (Fig. 3.6.5). The larger port of Lerwick is >70 km away. Both Sullom Voe and Lerwick have been identified as locations where development of facilities for wave and tidal energy could take place ( SE & HIE, 2010).

Figure 3.6.5: West of Shetland: Existing infrastructure (ports and cable landings) (source: OS, TCE, DECC)

Figure 3.6.5: West of Shetland: Existing infrastructure (ports and cable landings)

3.6.2 Other Constraints

3.6.2.1 Commercial Uses

TCE energy leases: There are none within this site (Fig. 3.6.6).

Fish or shellfish farms: There are fish farms in Rona's Voe and Hamna Voe but these are in areas of calmer water with less wave power potential.

Cables or pipelines: There is a submarine pipeline to the north of the proposed site originating from Orka Voe immediately north of Sullom Voe.

Figure 3.6.6: West of Shetland: Existing commercial use (source: OS, SeaZone Hydrospatial, TCE, Kingfisher)

Figure 3.6.6: West of Shetland: Existing commercial use

3.6.2.2 Military

Figure 3.6.7: West of Shetland: Military practice areas (source: OS, SeaZone Hydrospatial)

There is no military activity marked within this site.

Figure 3.6.7: West of Shetland: Military practice areas

3.6.2.3 Shipping

The waters around Shetland have been identified by the IMO as an area to be avoided by some types of vessels. As stated on the Admiralty chart,

"To avoid the risk of pollution or severe damage to the environment, all vessels over 5000 GT, carrying or capable of carrying oil or other liquid hazardous cargoes in bulk, should avoid the areas indicated."

Additionally, the northern-most point of Shetland Mainland has been identified as a MEHRA (Fig. 3.6.8).

The density of ships is relatively low in this area to the west of Shetland with numbers ranging from 0 to 23 shipping movements through the site (2009-10). There is a ferry route between the west Mainland and Papa Stour, which runs up to twice a day. There is limited shipping traffic (up to 174 movements/year) between Scalloway in the south-west and the north-west Mainland. Ships also cross the northern edge of the site (up to 95 movements/year) travelling between Sullom Voe to the Foinaven Oil Structures west of northern Shetland.

Figure 3.6.8: West of Shetland: Shipping (source: OS, SeaZone Hydrospatial, DECC, Anatec Ltd)

Figure 3.6.8: West of Shetland: Shipping

3.6.2.4 Commercial Fishing

Both the data for larger fishing vessels (= 15m) and qualitative data from anecdotal evidence ( SSMEI Shetland Pilot, 2010), suggest that the west coast of Shetland supports a rich and varied fishery (Fig.s 3.6.9-12). Data from larger vessels demonstrate the site supports a relatively large demersal fishery (plaice, megrim, saithe, whiting, haddock and cod). The SSMEI Pilot (2010) indicates a number of important areas for haddock, saithe, cod and whiting, particularly in St Magnus Bay in the south-east of the site and off the north-west Mainland coast. Fishing for shellfish mostly occurs in the east, closer to shore. The SSMEI Pilot (2010) suggests that the inshore region (within 10 km) is important for edible crab, lobster, scallop and Nephrops. Most pelagic fishing takes place to the north and west of the site, but there is evidence of mackerel and monk fish caught in the north-west.

Figure 3.6.9: West of Shetland: Commercial landings (tonnes) of pelagic and demersal fish and shellfish (source: OS, MSS)

Figure 3.6.9: West of Shetland: Commercial landings (tonnes) of pelagic and demersal fish and shellfish

Figure 3.6.10: West of Shetland: Commercial landings (value) of pelagic and demersal fish and shellfish (source: OS, MSS)

Figure 3.6.10: West of Shetland: Commercial landings (value) of pelagic and demersal fish and shellfish

Figure 3.6.11: West of Shetland: Local Shetland fishermen descriptions of location of important finfish grounds (source: OS, SSMEI Shetland Pilot)

Figure 3.6.11: West of Shetland: Local Shetland fishermen descriptions of location of important finfish grounds

Figure 3.6.12: West of Shetland: Local Shetland fishermen descriptions combined with habitat distribution of important shellfish grounds (source: OS, SSMEI Shetland Pilot)

Figure 3.6.12: West of Shetland: Local Shetland fishermen descriptions combined with habitat distribution of important shellfish grounds

3.6.2.5 Environment

Designated Areas

There are several designated sites within the boundaries of the proposed area (Fig. 3.6.13). The island of Papa Stour lies in the south of the site and contains multiple designations. It qualifies as an SPA for Arctic tern ( Sterna paradisaea) and ringed plover ( Charadrius hiaticula), an SAC for its sea caves and sublittoral reefs and is also a biological SSSI. The SPA of Ronas Hill - North Roe & Tingon in the north Mainland is designated for the red throated diver, which may venture offshore seasonally. At the eastern extent of the site in the west and north-west Mainland, there are two geological SSSIs; Esha Ness coast and the Villains of Hamnavoe. There are also three NSAs on the west and north-west mainland that overlook the site; Muckle Roe, Esha Ness and Fetherland.

South of the site, the SPA encompassing the island of Foula and neighbouring waters harbours a spectacular seabird assemblage including Arctic skua ( Stercorarius parasiticus), Arctic tern, fulmar, great skua, guillemot, kittiwake, Leach's petrel, puffin and razorbill. Foula is also an SAC, SSSI and NSA. A large component of the southern extent of the site is under consideration by the JNCC as a possible SPA for offshore bird aggregations.

Figure 3.6.13: West of Shetland: Designated areas (source: OS, SeaZone Hydrospatial, SNH, JNCC, SG)

Figure 3.6.13: West of Shetland: Designated areas

Protected Species

This region harbours numerous seabird colonies, although these are considerably smaller than other locations in the Shetland archipelago such as Foula, Sumburgh Head or Hermaness (Fig. 3.6.14). Prevalence of seabirds at sea is particularly high around the north-west Mainland. Other diving seabirds that could be at higher risk in this area include species such as guillemot, razorbill, gannet, and Manx shearwater. Shetland is one of the most important locations for red-throated divers in the UK. The Cetacean Atlas (2003) suggests that relatively low numbers of cetaceans are found within the site (Fig. 3.6.15). However, contrary to this, the SSMEI (2010) and Weir et al. (2001) highlight the importance of the area for a number of species, such as minke and killer whale, off the coast of Papa Stour and west Mainland. The Atlantic white-sided dolphin is relatively common in the Faroe-Shetland Channel during the summer months (Macleod et al., 2003). Other species recorded in this site are white-beaked dolphin and harbour porpoise (Weir et al., 2001; Cetacean Atlas, 2003).

The SSMEI (2010) marks a number of sites important for seals. Common seal colonies are found on the west coast of Papa Stour and to the north-west around the coast of west and north-west Mainland. Grey seal colonies are also found on the coast of Papa Stour, around Muckle Roe on the west Mainland and in Ronas Voe. The area has not been reported as a notable habitat for otters in the SSMEI (2010), although otters are prevalent throughout much of Shetland.

Figure 3.6.14: West of Shetland: Seabirds at sea and seabird colonies (source: OS, JNCC)

Figure 3.6.14: West of Shetland: Seabirds at sea and seabird colonies

Figure 3.6.15: West of Shetland: Cetaceans, turtles and basking sharks (source: OS, NBN, MCS, JNCC)

Figure 3.6.15: West of Shetland: Cetaceans, turtles and basking sharks

Protected Habitats

Much of the seabed in the site qualifies as a UKBAP priority habitat (Fig.s 3.6.16-17). Those found in the site include sublittoral sands and gravels, horse mussel beds and maerl ( L. glaciale).

Figure 3.6.16: West of Shetland: Seabed habitats (predicted by EUNIS) (source: OS, JNCC)

Figure 3.6.16: West of Shetland: Seabed habitats

Figure 3.6.17: West of Shetland: UKBAP Priority species and habitats (source: OS, NBN)

Figure 3.6.17: West of Shetland: UK BAP Priority species and habitats

Sensitive Areas for Commercial Fish

This area has been noted as a sensitive area for fish during all months with the exception of July or October. The area is used by a large number of species as a nursery site including, blue whiting, haddock, lemon sole, mackerel, Norway pout, saithe and sandeel (Fig. 3.6.18). Many of these species (lemon sole, Norway pout, sandeel and whiting), as well as herring, use this area for spawning (Fig. 3.6.19).

Figure 3.6.18: West of Shetland: Nursery grounds for commercial species (source: OS, MSS, CEFAS)

Figure 3.6.18: West of Shetland: Nursery grounds for commercial species

Figure 3.6.19: West of Shetland: Spawning grounds for commercial species (source: MSS, CEFAS)

Figure 3.6.19: West of Shetland: Spawning grounds for commercial species

3.6.2.6 Cultural Heritage

There are many ship wrecks marked within the site, none of which are officially protected (Fig. 3.6.20). There are also a number of SAMs on the adjacent coast, such as the broch of Hamnavoe and Sae broch near Esha Ness and numerous other sites marked for archaeological interest ( SSMEI Shetland Pilot, 2010).

Figure 3.6.20: West of Shetland: Cultural heritage (source: OS, Historic Scotland, SeaZone Hydrospatial)

Figure 3.6.20: West of Shetland: Cultural heritage

3.6.2.7 Recreation

The proposed site cuts into the RYA sailing area that surrounds the coast of Shetland (Fig. 3.6.21). A number of sites around this section of coastline have been marked as of interest for recreation by the SSMEI Shetland Pilot (2010) for SCUBA, boating and tour operators. These are located off west Mainland, off Papa Stour, to the north-west of Papa Stour, Esha Ness and north of Fethaland.

Figure 3.6.21: West of Shetland: Recreational use (source: OS, RYA, SG)

Figure 3.6.21: West of Shetland: Recreational use