Scottish Marine and Freshwater Science Volume 5 Number 9: Strategic Surveys of Seabirds off the West Coast of Lewis to Determine Use of Seaspace in Areas of Potential Marine Renewable Energy Developments

2. Introduction

Project background

2.1 The Scottish Government has met its target to generate 31% of Scotland's electricity demand from renewable sources by 2011 and has now set new targets of 50% of electricity demand by 2015 and 100% by 2020 using renewable sources. This will be achieved through a balanced portfolio of both offshore and onshore technologies including wave and tidal devices. The west coast of Lewis has some of the best marine energy resources in the country and has been identified as a potential location for a number of wave and tidal energy devices.

2.2 As identified in the 2007 Marine Renewables Strategic Environmental Assessment ( SEA) there is a need to identify and evaluate potential interactions between offshore renewable developments and marine wildlife and habitats.

2.3 Though some data are available regarding the marine wildlife found on and around the Isle of Lewis, data regarding the use of the marine areas by seabirds and marine mammals are incomplete and additional data are required to understand how the area is used by wintering and breeding seabird populations and marine mammals.

2.4 The aim of this project is to establish how seabird and marine mammal populations are distributed in relation to the areas of interest for wave and tidal renewable energy devices through the use of digital aerial surveys and ground vantage point surveys.

Sensitivity of seabird and marine mammal populations to wave and tidal devices

2.5 The potential impacts of offshore marine energy devices on seabirds and marine mammals can be categorised as collision causing direct or indirect mortality, displacement due to construction, maintenance or operational disturbance or habitat loss, and barrier effects where device arrays are, or are perceived to be, impassable obstacles ( RSPB 2012).

2.6 Diving birds are considered to be potentially sensitive to the deployment of tidal stream and wave devices ( WWT Consulting 2010, Smith et al. 2011, and Furness et al. 2012).

2.7 Furness et al. (2012) identified black guillemots Cepphus grylle, razorbills Alca torda, shags Phalacrocorax aristotelis, guillemots Uria aalge, cormorants Phalacrocorax carbo, diver species Gavia spp. and puffins Fratercula arctica as the species most vulnerable to negative impacts from tidal renewable energy turbines in Scottish waters due mainly to their pursuit diving strategy for finding and catching prey underwater.

2.8 Similarly Wilson et al. (2007) identified all regularly occurring marine mammals as potentially at high risk from underwater renewable energy devices due to their spending the majority of their lives underwater and even those benthic feeders passing through the water column to the surface to breathe.

Ornithological and marine mammal interest around the west coast of Lewis

Ornithology

2.9 The Isle of Lewis, along with the other islands in the Outer Hebrides, is an important area for breeding seabirds with a number of Special Protected Areas ( SPAs) designated in accordance with the Birds Directive (Directive 2009/147/ EC) because of the presence of internationally important seabird assemblages and breeding populations.

2.10 The Isle of Lewis itself contains the Lewis Peatlands SPA and Ramsar site, an important breeding area for black-throated divers Gavia arctica and red-throated divers G. stellata. While these species breed on freshwater sites within the SPA they will also forage and winter in coastal areas. Other SPAs adjacent to the Isle of Lewis include the Flannan Isles (west of the island) and the Shiant Isles (east of the island) both of which hold important assemblages of breeding seabirds with 50,000 and 200,000 individual seabirds respectively (Joint Nature Conservation Committee 2011a). These islands hold important populations of fulmars Fulmarus glacialis, shags, Leach's storm-petrels Oceanodroma leucorhoa, kittiwakes Rissa tridactyla, guillemots, razorbills and puffins.

2.11 In the surrounding area there are a number of other SPAs which include seabirds as part of their designation. To the south west the St. Kilda archipelago has approximately 600,000 seabirds breeding including over 50,000 pairs of gannets and 155,000 pairs of puffins. To the south the Monach Islands hold breeding populations of common terns Sterna hirundo, little terns Sterna albifrons, razorbills and black guillemots along with another large assemblage of breeding seabirds.

2.12 The west coast of Lewis is within mean-maximum foraging range (Thaxter et al. 2012) for: fulmars, Leach's storm-petrels, kittiwakes, guillemots, razorbills and puffins from the Flannan Isles SPA; fulmars, European storm-petrels Hydrobates pelagicus, Leach's storm-petrels, gannets Morus bassanus, guillemots and puffins from North Rona and Sula Sgeir SPA; fulmars, guillemots and puffins from the Shiant Isles SPA; fulmars, gannets and puffins from St. Kilda SPA; fulmars, kittiwakes and guillemots from Handa SPA; and fulmars, guillemots and puffins from Cape Wrath SPA, with the highly mobile fulmars and gannets in theory being able to reach the study area from any Scottish breeding colony.

Marine mammals and sharks

2.13 The Outer Hebrides are probably the richest area of the UK for marine mammals with around 20 species of cetacean recorded in the region over the last 30 years and hold important breeding areas for both harbour seals Phoca vitulina and grey seals Halichoerus grypus.

2.14 All cetacean species are currently offered 'strict protection' under the EU Habitats Directive.

2.15 Harbour porpoises Phocoena phocoena are the most widespread and commonly recorded cetacean species around the Outer Hebrides year round, particularly in the Sound of Barra, around the Monarch Islands and inlets around the Isle of Harris (Evans 2000, Reid et al. 2003). There are more records of this species from the summer (June to September) from the Outer Hebrides, but whether this reflects actual abundance or sampling bias is unclear (Reid et al. 2003) Harbour porpoises are protected under Annex II of the Bern Convention and Annex II of the EU Habitats and Species Directive (1992). It is included on the Oslo and Paris Convention ( OSPAR) first list of threatened and declining species and is also protected under The Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas ( ASCOBANS) which applies to all odontocetes (toothed whales and dolphins) except sperm whale. Signatories are obliged to apply conservation, research and management measures prescribed in its Annex to all species.

2.16 White-beaked dolphins Lagenorhynchus albirostris are commonly seen in waters of the Outer Hebrides with concentrations of sightings around the northern point of the Isle of Harris and around Isle of Lewis (Evans, 2000, Reid et al. 2003). The majority of sightings are made between July and September (Evans, 2000). This species is protected by the Wildlife and Countryside Act 1981, ASCOBANS and the Bonn Convention. They are also included on Annex IV of the EC Habitats Directive.

2.17 Risso's dolphins Grampus griseus are widespread around the Outer Hebrides. They are most commonly sighted in the north east of the islands around the Eye Peninsula, Lewis and the inshore waters of the Isle of Harris, with most records made between May and September (Evans, 2000, Reid et al. 2003). Risso's dolphin is protected under appendix II of both the Bern and Bonn Conventions. It is also protected under appendix IV of the EU Habitats and Species Directive (1992). As with the harbour porpoises, Risso's dolphins are also covered by ASCOBANS.

2.18 Other species recorded most years around the Isle of Lewis include near shore records of minke whales Balaenoptera acutorostrata, a small number of bottlenose dolphins Tursiops truncates around the north of Isle of Lewis and south of South Uist , occasional groups of common dolphins Delphinus delphis, and killer whales Orcinus orca of which around 10 individuals have been identified . Other species such as white-sided dolphins Lagenorhynchus acutus and humpback whales Megaptera novaeangliae have occasionally been recorded around the Outer Hebrides. (Evans, 2000, Reid et al. 2003).

2.19 The Monach Islands is one of the largest breeding colonies in the world for grey seals ( Halichoerus grypus) but there are also important breeding areas on the islands to the south west of Harris and also on North Rona, north of the Butt of Lewis. Grey seals are listed on Annex II of the EC Habitats Directive. About 39% of the world population of grey seals are found in Britain and 90% of these breed in Scotland.

2.20 Harbour seals ( Phoca vitulina) are listed on Annex II of the EC Habitats Directive and are common on the east coast of the Outer Hebrides with approximately 8% of the UK population found there (Duck, 2000). Local declines have led to the implementation of a Conservation Area for common seals extending across Western Isles coastal waters under the Marine (Scotland) Act 2010, which restricts the issue of control licenses.

2.21 Basking sharks Cetorhinus maximus are regularly recorded around the Isle of Lewis and the rest of the Outer Hebrides. The north western Scottish coast has been identified as a Basking Shark "hotspot" with relatively high numbers observed during the summer months (The Basking Shark Project).

2.22 Basking sharks are listed as Endangered on the IUCN Red List of Threatened Species and has full protection under the Wildlife & Countryside Act 1981 (as amended by the Nature Conservation (Scotland) Act 2004, is protected under appendix I and II of the Bonn Convention and is listed on the 2004 Initial OSPAR list of threat and/or declining species.

2.23 The north-eastern coastal waters off Lewis are included in the Eye Peninsula to the Butt of Lewis Marine Protected Area ( MPA) search location. The search location is for four proposed protected features, Risso's dolphin, sandeels Ammodytes spp. and geodiversity features associated with the Quaternary of Scotland and Marine Geomorphology of the Scottish Shelf Seabed (Scottish MPA Project 2012).