Protecting and Promoting Scotland's Freshwater Fish and Fisheries

1 SCOTLAND'S FRESHWATER FISH

1.1 Scotland's freshwater fish populations and communities are of international natural heritage value. They contribute to Scotland's native biodiversity, and they play an essential role in the aquatic food chain. They are also the basis for fisheries of global renown which are particularly important for the economies of rural areas. In combination, these fish and fisheries contribute much to Scotland's sense of identity. It is therefore important to promote a wide awareness of the value of Scotland's freshwater fish and protect them from threats to their viability. This chapter describes the Scottish freshwater fish fauna.

1.2 In terms of the number of species, Scotland has a relatively impoverished native freshwater fish fauna that developed over the last 10,000 years. The fish fauna that now exists is the result of many introductions over the years. The number of species now present is double the original number of native species.

1.3 Of the 42 species of fish found in Scottish fresh waters, only half have arrived by natural colonisation. The species present are shown in Box 1.

Box 1. Fish found in Scottish fresh waters.

* - occasional marine vagrants

1.4 The Biological Records Centre is in the process of developing an atlas of UK fish distribution. More detailed information about the status of many of the fish species that support fisheries in Scottish fresh waters is held by the Freshwater Fisheries Laboratory (see Annex A).

Salmon and sea trout 1.5 Scottish river systems support one of the largest and most diverse of the Atlantic salmon resources in Europe, with nearly 400 salmon rivers supporting many hundreds of populations, each of which is genetically distinct. Scotland supports some of the most important commercial and recreational salmon fisheries in the world. However, declines in catches and stocks have been reported throughout the North Atlantic region, particularly among early-running, multi-sea-winter salmon. Catches of sea trout have also declined in recent years, especially in the north and west of the country.

Atlantic salmon

Trout

1.6 This highly 'flexible' species shows great diversity of form, including sea trout, riverine brown trout, ferox trout and burn trout populations that have been isolated above waterfalls since the last Ice Age. There are many fisheries for brown trout throughout the mainland of Scotland and in the Northern and Western Isles. In some areas, these fisheries are much more important, both socially and economically, than the fisheries for salmon.

Other Salmonids

1.7 Scotland is also a stronghold for Arctic charr, with perhaps 200 separate populations. Research shows that these are genetically distinct between, and even within, lochs. Unusually, all of these complete their life cycles in fresh water; elsewhere in its range (e.g. Canada, Scandinavia) the Arctic charr is anadromous, like salmon and sea trout. In Scottish lochs, the charr is the principal prey of 'ferox' trout. Another species, the brook charr, often called the American brook trout, was introduced from North America towards the end of the 19^th Century and a number of lochs have been stocked with it. This fish appears only to thrive in the absence of brown trout, which readily out-compete it. At about the same time, the rainbow trout was introduced to Scotland from western North America. Strictly speaking, this fish is not a trout, but a member of the genus that includes the various species of Pacific salmon.

1.8 Over the last 150 years or so, the European grayling has been introduced to a number of rivers in Scotland, including the Tweed, Tay, Clyde, Ayr, Nith, Annan, Water of Leith, Almond (West Lothian) and Esk (Midlothian). This fish supports an important recreational fishery, particularly during the annual close times for trout and salmon.

Other freshwater fish

1.9 Several other species, such as powan, vendace, sparling, the lampreys and shads, reflect the marine origin of Scotland's freshwater fish fauna. Some are known from only a handful of sites in Britain.

1.10 The European eel is one of the original colonisers. Three life history stages are found in Scotland: elvers ascending the rivers, growing yellow eels in lochs and rivers, and descending adult silver eels beginning their spawning migration to the Sargasso Sea. The International Council for the Exploration of the Sea (ICES) and the European Inland Fisheries Advisory Commission (EIFAC) have expressed concern about the reduced numbers of elvers entering river systems throughout Europe 1.11 Other coarse fish species (see Box 1) have been introduced over a long period of time to support fisheries. Scotland has a relatively impoverished natural fish fauna. The number of species has doubled as a result of introductions, many of them brought in for angling purposes. In some species, reproductive isolation has led to a high degree of genetic diversity. A number of fish species support fisheries of international renown, assets that are particularly important in rural areas.

Clockwise from top left - stone loach, eel, pike, roach.