Experimental transmission of Gyrodactylus salaris Malmberg, 1957 (Platyhelminthes, Monogenea) from the Atlantic salmon (Salmo salar) to the European eel (Anguilla anguilla)

Laboratory experiments were designed as follows in an attempt to evaluate the potential importance of eels in dispersal of Gyrodactylus salaris: exposure of uninfected eels to infected salmon; exposure of infected eels to uninfected salmon; exposure of uninfected eels to infected eels; indirect infection of uninfected eels; parasite transmission preference, using "two-choice" host tests; and parasite survival on eels following their isolation. Gyrodactylus salaris was found to be transmissible from salmon to eels, and vice versa, both at 4 and 13 °C. Eel to eel transfer of G. salaris was also demonstrated, as was infection of fish from the bottom of the tank. Transmission of G. salaris to eels also occurred in the "two-choice" host tests. Transmission rate was positively correlated with water temperature and transmission was more frequent from dead than living infected salmon. The maximum duration of infection on eels was 8 days. The transfer of infection to eels is thought to parallel events in nature and forms part of the dispersal mechanism of G. salaris.