European river lamprey

Species of freshwater lamprey

The European river lamprey (Lampetra fluviatilis), also known as the river lamprey or lampern, is a species of freshwater lamprey.

Adult river lampreys measure from for the sea going forms and up to for the lake forms. The very elongate body is a uniform dark grey above, lightening to yellowish off white on the sides and pure white below. Like all lampreys, these fish lack paired fins and possess a circular sucking disc instead of jaws. They have a single nostril and seven small gill slits on either side behind the eye. The teeth are sharp and these fish can be told from the rather smaller brook lamprey (Lampetra planeri) by the fact that the two dorsal fins are more widely separated.

The European river lamprey is found in coastal waters around almost all of Europe from the north west Mediterranean Sea north to the lakes of Finland, Scotland, Norway (Mjøsa), Wales (Cors Caron), and Russia, including rivers in the Alps; especially in Nakkila, Finland, European river lampreys are a traditional local delicacy. Initially, in 1996, its conservation status was rated "near threatened" but since 2008 it has been rated as being of "least concern" following recovery of populations after pollution problems in central and western Europe. In August 2018, Spain declared it officially extinct in its territory.

Like many lampreys, this species feeds as an ectoparasite and parasite of fish. It clings on to the flanks or gills of the fish with its sucker and rasps at the tissues below.

The European river lamprey has a reproduction cycle similar to that of salmon. River lampreys migrate upstream from the sea to spawning grounds in autumn and winter. Spawning activity is greatest in the springtime (like the brook lamprey) and after spawning, the adults die. The young larvae, known as ammocoetes, spend several years in soft sediment before migrating to the sea as adults. It is thought that these fish spend two to three years in marine habitats before making the return trip to spawn.