There are three species of lampreys in Scotland: the brook, river and sea lamprey and all three are known to occur in the River Spey. They belong to a primitive group of vertebrates called the ‘Agnatha’ which means ‘without jaws’. As the name suggests, lampreys lack jaws and instead have very primitive mouthparts surrounded by a large flexible lip that acts as a sucker. This curious feature provides the scientific name for the lamprey family, Petromyzonidae, which translates as ‘stone suckers’.
Lampreys have a long, cylindrical body, similar to an eel but they have several unusual features which differ from most fishes including, a skeleton of cartilage, no scales, and a single nostril located on the top of the head in front of the eyes. Gill covers are absent and instead they have a series of seven sac-like gills which open directly through holes on each side of the head.
The sea lamprey is the largest of the three species with adults reaching a length of one metre and weighing up to 2.5kg. Adult sea lampreys are a brownish-grey colour with extensive black mottling, but close to breeding time their colour lightens to a golden brown. Although illusive, adult sea lampreys have been observed spawning in the mainstem of the Spey as far upstream as Kingussie. The adults build spawning redds in the river bed, rather similar to salmon redds, typically around in June/July.
The river and brook lampreys, which are closely related to one another, are far smaller. They are both similar in colour, with adults having a dark olive or brown back and a lighter, silvery belly. The river lamprey is intermediate in size between the other two species with adults usually measuring around 30cm, while brook lampreys are the smallest with adults only attaining a length of 15cm. The Brook lampreys are found through the Spey and its tributaries, however, river lampreys appear less common with only a few sightings.
All three lamprey species have a similar life cycle with the adults migrating upstream to spawn in a depression in gravel beds, in pairs or a group. After the eggs hatch, the blind juvenile lampreys, or ammocoetes, migrate downstream to silty, slower-flowing parts of the river where they live in burrows until adulthood. Once the ammocoetes become adults they leave the silt beds. The brook lampreys complete their lifecycle within the river while the river and the sea lamprey migrate to the sea as adults before returning to spawn. All three species are generally poor swimmers so migration routes to and from the sea need to be kept free from barriers such as dams and weirs. Careful management of their spawning habitat and juvenile habitat is also required to ensure suitable silt beds are present throughout the river and to ensure this is achieved the Spey was designated as a Special Area of Conservation for the sea lamprey. Surveys of the lamprey populations within the Spey were carried out in 2002 and report is available in the online research library. For further information on the lamprey can be found on the River Runner website.