Development of Infections of Gyrodactylus colemanensis Mizelle and Kritsky, 1967 (Monogenea) and the Effect on Fry of Salmo gairdneri Richardson

The development of infections of Gyrodactylus colemanensis Mizelle and Kritsky, 1967 (Monogenea) and their effect on fry of Salmo gairdneri Richardson are examined experimentally. Starting with initial infections of 1 to 10 worms per fry, intensity in 2 replicate groups increased to peaks of 55 and 65 on day 22 post-infection and declined to 0 by days 67 and 85 post-infection. The parasites were numerically aggregated within the host groups and there was a negative correlation between intensity and fish size. Infections did not influence growth or survival of the host and produced no clinical signs of disease.