Sea Lamprey

Identification

The sea lamprey (Petromyzon marinus) is the largest lamprey species in the Netherlands, reaching up to 120 cm. The body is cylindrical and scaleless, with a striking marbled pattern of dark brown to yellow. The large, circular sucker mouth features concentric rows of sharp teeth. Seven gill openings are clearly visible.

Ecology

The sea lamprey is an anadromous parasite: adults live in the sea and attach to large fish such as cod, salmon, and even seals. Using their rasping tongue, they scrape flesh and blood. For reproduction, they migrate upstream and dig redds in gravel beds. The larvae (ammocoetes) spend 5-7 years as blind filter-feeders in river sediment before migrating to sea.

In the Netherlands

With 394 observations in our database, the sea lamprey is regularly recorded in the major rivers and the Wadden Sea. The species is protected under the Habitats Directive (Annex II). Restoring free migration routes through fish passages is essential. The Haringvliet dam with its partial opening provides new opportunities for this migratory species.