Caithness CWS - Nature - Highland Biodiversity - Framework Document

A Draft Framework for Biodiversity in Highland

THE SEAS

A high proportion of Highland’s population live near the coast, and many depend on the sea for their livelihood or recreation. Fishing is a mainstay primary industry, which brings considerable local income, although there are issues of managing inshore waters to accommodate all those fishing it and to ensure the maintenance of stocks. Aquaculture, particularly salmon and shellfish farming has also brought both jobs and prosperity to some of Highland’s most economically fragile and peripheral areas. However the growth of this industry has raised concerns over disease and environmental degradation. Species such as seals fuel strong debate. The seas remain an important transport route for freight, and oil exploration and its conveyance harbours the continual threat of marine pollution. There are difficult issues to be tackled. The oceans are wild areas which we harvest not farm, and the natural environment has a vital role to play in assuring this continued bounty. Although increasing numbers of people are enjoying the marine environment through diving, recreational boating and wildlife boat tours, it remains the most unknown aspect of our environment, too easily out of sight and therefore mind.

The biodiversity resource: Key habitats and species in Highland

The sea and seabed around Scotland support a tremendous variety of wildlife. This is due to the complexity of the environment, there being both warm ocean currents from the south (the Gulf Stream) and cold sub-Arctic waters from the north, variations in tidal range and geology.

Sublittoral sands and gravels are the most common habitats found below the level of the lowest low tide around the UK, in a wide variety of environments. The diversity of wildlife living there varies depending upon the degree of environmental stress, for example the degree of wave action. Many of the inshore areas are important nursery grounds for juvenile commercial fish species, and offshore sand and gravel habitats support internationally important fish and shellfish fisheries. Although widespread, this group of habitats is particularly under threat from fishing, aggregate dredging, pollutants and those activities which may affect tidal flow regimes, wave exposure or sediment deposition. The West Coast Sea lochs, the Cromarty Firth and Skye are all noted as locations for specific variants of these habitats.

Mud habitats in deep water occupy the sea bed below 20-30m in many areas of the UK’s marine environment, including sea lochs. They support a very high diversity of small burrowing animals, including sea pens, Nephrops norvegicus (scampi) and urchins. The majority of deep sea habitats are fished, principally for Nephrops using benthic trawls or creels. The impacts of creels are thought to be minimal, whereas trawling can be very detrimental. Marine fish farms can also pose a threat , through anchoring and discharges of feed and chemicals from sites with poor water circulation . The west coast of Scotland is the most important part of the UK for this habitat, which is present in all the sea lochs.

Maerl beds are created by several species of red algae that form a coral- like structure in high energy environments. They are known to be present in less than 1% of the UK’s inshore waters, occurring off the southern and western coasts of Britain. Highland is particularly significant for maerl beds. The Sound of Arisaig, Upper Loch Torridon and Handa Sound all have large areas of maerl beds, also there are areas in Loch Carron. Maerl is significant not only in its own right but also for its value as nursery grounds for scallops.

Horse mussel (Modiolus modiolus) beds form at depths of between 5 and 70 m in fully saline, often moderately tide-swept areas off northern and western parts of the British Isles, both in sea lochs and in open areas of sea.. They are long lived species and recruitment is slow, such that they are very vulnerable to disturbance as recovery is very slow, if it occurs at all. Fishing, particularly using trawls and dredges, is known to be damaging, and other physical impacts such as aggregate extraction are also likely to be detrimental. The impacts of pollution are unknown. Whilst horse mussels are widespread as individuals, beds are uncommon. Small areas of beds occur within Lochs Duich, Long and Alsh (candidate SAC).

Particular note should be made of the significance of the west coast sea lochs, which support so many of the nationally important coastal and marine habitats.

Habitats classified as UK BAP priority habitats which occur in Highland

Sublittoral sands and gravels

Maerl beds

Mud habitats in deep water

Modiolus modiolus reefs (horse mussel)

Lophelia pertusa reefs, Sabellaria alveolata reefs, Sabellaria spinulosa reefs and Serpulid reefs are marine UK BAP priority habitats which do not occur in Highland.

UK BAP Priority species recorded in Highland associated with marine habitats

Otter, harbour porpoise, baleen whales, toothed whales, small dolphins

marine turtles

Common scoter (a duck)

Commercial marine fish, deep water fish (for example black scabbard fish, blue ling, orange roughy), common skate, twaite shad, allis shad,

basking shark

sea pen, northern hatchet shell, a fan shell, native oyster.

Ascophyllum nodosum ecad mackii (unattached brown algae)

Some other species of conservation interest

Common and grey seals

Great northern, black and red throated divers, Slavonian Grebes use coastal areas in winter and spring. Eider duck

Wild salmon and sea trout.

Key biodiversity objectives

To maintain and enhance the rich marine heritage of coastal waters, through the promotion of the sustainable management of fish stocks and aquaculture.

To promote local involvement in the management of coastal waters.

To raise public awareness of the value of the marine biodiversity resource.

Trends and issues