Genetic analyses of European minnow, Phoxinus phoxinus, in a river system outside its native range indicate multiple invasions from different sources

European minnow Phoxinus phoxinus (L.) from four different water bodies (the lakes Eivindbuvatn and Grungevatn, and the hydroelectric reservoirs Stavatn and Totak) in the upper part of the Tokke drainage system, outside the native range of this species, and from one possible source population (River Hunnselva), were analysed to identify the origin of a newly established population in Stavatn Reservoir. Amplified fragment length polymorphism analyses identified three genetically different populations in the Tokke drainage system, well separated from the purported source population. Thus, the River Hunnselva population connected to a brown trout, Salmo trutta L., hatchery from which European minnow theoretically could have hitchhiked' was not the source. As such, the dispersal of European minnow in Norway, even in a restricted area within one drainage system, appears to occur from multiple sources and possibly involves the illegal use of the species as live bait.