Infectivity of an emerging fish parasite Gyrodactylus sprostonae in juvenile carp (Cyprinus carpio)

The gill monogenean ectoparasite Gyrodactylus sprostonae is an emerging pathogen within recreational UK carp fisheries, and a major cause of mortality in adult carp. This gill infection has only been noted in adult carp and not in juveniles, and no reports of its fundamental infection dynamics exist. The current study compared the infective potential of G. sprostonae between adult and juvenile common carp (Cyprinus carpio) and quantified parasite numbers on the body surface and gills of infected juveniles at two temperatures (14 and 24°C). G. sprostonae was able to infect the body surface and the gills of juvenile carp, and temperature significantly impacted the duration of infection and number of parasites. Interestingly, however, all juveniles under both temperature treatments lost their infections after a maximum of 40 days, with no observed clinical signs of parasitaemia or mortalities. This study therefore indicates that G. sprostonae does not appear to be harmful to juvenile common carp, and we discuss why this infection only seems to impact prised adult carp in the UK.