About freshwater fish

An important role

Freshwater fish play an important role in Scottish society and the fisheries, and particularly angling, opportunities that they provide have supported rural communities for many years. That said, however, the native fish fauna of Scotland is considered to be impoverished when compared to that found in other parts of the UK and Europe. Most of the fish which originally colonised Scottish freshwaters did so from the sea, occupying and using new freshwater environments as the ice sheet which covers Scotland 10-15,000 years ago retreated northwards at the end of the last ice age. All of the species that we now regard as conservation priorities within Scotland, such as lamprey, Atlantic salmon, trout, Arctic charr, powan, vendace, smelt (sparling), shad and eels, all colonised Scotland in this way. Both three-spined and nine-spined sticklebacks also used this marine route to invade Scottish freshwater habitats, and some of these populations, particularly those containing spine-deficient forms, are also considered to be of conservation value. Another species worthy of mention is the Atlantic sturgeon, a species rarely seen in Scottish waters, but still considered to be part of our native fauna.

How they got here

Some other species commonly seen in our lochs and large rivers, such as pike, perch, roach, minnow and stone loach may have arrived here via the land bridge that once connected rivers in the south east of England with continental Europe. Man has, however, played the most significant role in the spread of new fish populations around Scotland. Most of these translocations, or introductions, were carried out in an attempt to establish new sport fisheries, or in some cases to provide fish for food. Some of these fish, such as perch, roach grayling and pike, now support a significant, and growing, fishery resource.

The problem with some introductions

Other fish translocations from other parts of the UK have, however, caused considerable damage to either the Scottish freshwater fish fauna, or their habitats. The introduction of ruffe to Loch Lomond is the most cited example, and this species, which feeds on the eggs of powan, is now firmly established there. New controls to regulate the introduction of freshwater fish will hopefully ensure that such introductions do not take place in future.

Some of our now 'resident' fish fauna has come from further afield. The widespread use of rainbow trout, introduced from North America in the 1970s', has led to the development of a significant, and valuable, fishery for this species. Other species, such as the brook charr have also been introduced to a small number of Scottish sites and, unlike rainbow trout, have established self-sustaining populations.

Incredibly diverse

Scotland has a fish fauna which, despite the relatively low number of species, is both incredibly diverse and located at the western limits of their European geographical range. Some species, such as the Arctic charr, show remarkable levels 'hidden biodiversity' and Atlantic salmon which exhibit a wide range of life-history patterns, as well as supporting a world class fishery are of particular note. We hope that you take the time to learn more about our lesser known, but still incredibly important, fish species.