The Scottish Government

Scotland has a relatively impoverished natural fish fauna. The fish community which now exists includes many introductions which have been made over the years, many of them brought in for angling purposes. A number of fish species support fisheries of international renown, assets that are particularly important in rural areas. In some species, reproductive isolation has led to a high degree of genetic diversity.

Salmon and Sea Trout

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. Catches of sea trout have also declined in recent years.

Salmon spawn in late autumn and winter, in rivers and streams, providing the flow of water is good. Once the eggs have hatched, usually the following spring, they become alevins and feed off their yolk sacs while remaining in the gravel. Following emergence from the gravel they become fry, establish territories for feeding and eventually develop into parr.

After 1, 2 or 3, and sometimes 4 or 5 years, the parr change in appearance and behaviour and migrate downstream in the spring as smolts. A proportion of parr do not develop into migratory smolts; many, particularly male fish, remain in freshwater, become sexually mature, and may take part in spawning.

Once in the sea, salmon grow very quickly and after one or more years they begin their migration back to where they were born.

The fish that return after only one winter at sea are referred to as grilse. Others that spend two or more winters at sea are known as salmon, and may weigh as much as 10-15 kilos.

Following spawning, the fish are referred to as kelts, and most will die.

Trout

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 Northern and Western Isles.

Other Salmonids

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. 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. At about the same time, the Rainbow trout was introduced. Over the last 150 years or so, the European grayling has been introduced to a number of rivers in Scotland, including the Tweed, Forth, Tay, Clyde, Ayr, Nith and Annan. This fish supports an important recreational fishery, particularly during the annual close times for trout and salmon.

Other Freshwater Fish

Several other species, such as powan, vendace, sparling, the lampreys and shads, reflect the marine origin of Scotland's native freshwater fish fauna.

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.

Other species, including pike and perch, and cyprinid fishes, such as carp, tench and rudd, can also be found in Scottish fresh waters.