River Lamprey Lampetra fluviatilis
Lampreys are amazing primitive fish, they are one of only two species of fish that survived the jawless stage of vertebrate evolution. Lampreys are of high ecological value. They can play an important role in processing nutrients, nutrient storage and nutrient cycling. River lamprey migrate from coastal feeding grounds to freshwater, moving at night and resting during the day. They need clear water and suitable gravels, silt or sand.
River lamprey are between 30 – 50 cm long. Lamprey is a primitive, jawless fish with a sucker mouth. It uses its mouth to attach to other fish to feed from them. It is one of the most primitive vertebrates still alive today. It is small and similar to an eel. Its sucker rasps away at the flesh and bodily fluids of other fish, but it can also feed on carrion. The river lamprey is bluish-grey on the back and sides, and white underneath, reaching up to 1m long.
When lamprey reach their spawning ground, they build a ‘nest’ for their eggs. They can be considered ecosystem engineers because their nest building activities can shape river channels and create other micro habitats for other species. Brook and river lamprey spawn in a ‘ball’ which may be up to 50 lampreys all together. Once hatched, their larvae drift downstream with the current. They settle in a ‘nursery habitat’ with fine, soft riverbed and well oxygenated, slow-flowing water. At this stage they feed on algae and bacteria. They may stay in this area, buried in the silt, for up to 5 years before they transform into pre-adults. River lamprey continue to the sea.
Habitat degradation threatens lamprey – in the spawning areas they need good quality water and river bed. Man-made barriers can be a risk to lamprey trying to migrate up rivers to spawn. River Lamprey is quite rare in the UK and is on the Red list of threatened species. The lower Derwent is designated as a Special Area of Conservation (SAC) where the lamprey is known to spawn.
The Ryevitalise project has actually discovered lamprey as far up river as Ness Hall, so perhaps they are coming to the upper parts of the Derwent catchment!
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