European river lamprey
Species of freshwater lamprey
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Through Parasitism
Description
Adult river lampreys measure from 25 to 40 cm (10 to 16 in) in the marine forms and up to 28 cm (11 in)in the lake forms. The very elongated body is uniformly dark grey on top, paler to yellowish off-white on the sides and pure white underneath. Like all lampreys, they lack paired fins and have a circular sucking disc instead of jaws. They have a single nostril and seven small gill slits on each side behind the eye. The teeth are sharp and these fish can be distinguished from the somewhat smaller brook lamprey (Lampetra planeri) by the fact that the two dorsal fins are more widely separated.
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Distribution
The European river lamprey is found in coastal waters around almost all of Europe from the northwestern 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 and Latvian coastal towns such as Carnikava, Salacgrīva and Pāvilosta European river lampreys are a traditional local delicacy.
Its conservation status was originally listed as Near Threatened in 1996, but since 2008 it has been listed as Least Concern, following recovery of populations after pollution problems in central and western Europe. However, an assessment for the Baltic Sea published in 2014 classified the river lamprey as "Near Threatened" in this region, supported by the IUCN's 2024 classification. In August 2018, Spain declared it officially extinct in its territory.
Prey
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 tissue underneath.
Taxonomy
River lampreys belong to the same genus as the brook lamprey and are thought to be very closely related. Current thinking suggests that European brook and river lampreys are a paired species, with the river lamprey representing the anadromous (seagoing) form of the resident brook lamprey. However, this is an area of active research.
Reproductive cycle
The European river lamprey has a reproductive cycle similar to that of the 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.
Statistics
As ammocoetes, these animals are difficult to identify beyond genus level (Lampetra) because of their close resemblance to brook lamprey. They average 30 cm in length as adults, and some may be considerably smaller (20 cm), but in any case they are considerably larger than adult brook lampreys (12–14 cm). They generally weigh 150 g, and their maximum lifespan is about 10 years.