River Lamprey

Identification

The river lamprey (Lampetra fluviatilis) is a jawless, eel-like fish with a circular sucker mouth lined with small teeth. The body is smooth and scaleless, dark on top and silvery below. Adults reach 25-40 cm. Distinctive features include seven gill openings behind each eye and the absence of paired fins.

Ecology

The river lamprey is parasitic: adults attach to larger fish and feed on blood and body fluids. After several years in the sea or IJsselmeer, river lampreys migrate upstream in autumn to spawn on gravel and sandy beds. Adults die after spawning. The blind larvae (ammocoetes) live buried in soft sediment for years, filter-feeding on organic matter.

In the Netherlands

With 878 observations in our database, the river lamprey is the most common lamprey species in the Netherlands. The species migrates upstream via the major rivers (Rhine, Meuse, Waal). The river lamprey is protected under the Habitats Directive and the Dutch Nature Conservation Act. Fish passages at weirs and dams are crucial for restoring migration routes.