Susceptibility of corkwing wrasse Symphodus melops, goldsinny wrasse Ctenolabrus rupestis, and Atlantic salmon Salmo salar smolt, to experimental challenge with Vibrio tapetis and Vibrio splendidus isolated from corkwing wrasse

The virulence of two Vibrio strains, previously isolated from diseased corkwing wrasse Symphodus melops and identified as V. tapetis and V. splendidus, to corkwing and goldsinny wrasse Ctenolabrus rupestris and to Atlantic salmon Salmo salar, was studied under laboratory conditions. Both bacteria were shown to be opportunistically pathogenic to corkwing wrasse, causing significantly higher mortality in the challenged groups than in the controls. Bacterial cultivation of kidney samples and re-isolation of V. tapetis and V. splendidus from most mortalities confirmed the two strains as the probable cause of mortality in the challenged groups. The control group also suffered relatively high mortality, but no specific pathogens that were suspected to be the main cause of death were isolated, other than a mixture of Vibrio spp. and, in the case of one individual, atypical Aeromonas salmonicida. Following injection challenge with both bacterial strains, no mortality was recorded in Atlantic salmon. In bath challenge trials with goldsinny wrasse, only slight mortality was observed in the challenged groups and the unchallenged control group. Bacterial examination showed that atypical Aeromonas salmonicida was the probable cause of death in both bath challenged and control groups of goldsinny wrasse, and no indication of infection by any Vibrio sp. was found.