Limnetica 33

Landlocked populations of sea lamprey (Petromyzon marinus) cause tremendous damage to native fish species: nevertheless, none of these populations have been described in Europe. The first record of an introduction of anadromous P. marinus into a reservoir in Europe (Portodemouros, NW Spain) is described. Data suggest that this landlocked population was not successful and did not settle in the area because the haematophagous feeding phase was not viable. This agrees with the difficult transition from an anadromous haematophagous life history to a freshwater haematophagous life history. However, the settlement of stable populations of sea lamprey in lakes or reservoirs with more appropriate host populations cannot be discarded.