Scotland represents the northern extent of lamprey distribution in Europe, with few populations found north of the Great Glen. This is thought to be due to the cold temperatures in more northerly rivers which restrict or prevent breeding. Scottish populations are therefore important in maintaining the natural range of the three species both within the UK and Europe.
Lampreys are vulnerable to several threats of which the most potent is thought to be water pollution. There are many rivers in lowland Scotland from which lamprey populations have declined or disappeared, probably as a result of historical increases in pollution from industrial expansion, as well as changes in land use. Their sensitivity to pollution was demonstrated in the River Clyde where, following improvements to water quality, salmon returned long before river lampreys. However, lamprey ecology is still relatively poorly understood and more research is needed to further our understanding of the fascinating species that inhabit our rivers.
Juvenile lamprey are unusual in living in silt beds, parts of the river that are not commonly used by any other fish species. Therefore this habitat is often not considered in river management and can be vulnerable to activities that fail to take account of the presence of lampreys. Lampreys have also been targeted for use as bait, particularly by pike fishermen. Two tonnes of lampreys are removed annually from the River Ouse in Yorkshire for this purpose - indiscriminate removal of adults for bait can pose a threat to populations and is therefore discouraged.