Abstract
The effect of ultraviolet disinfection (22-63×103μW·sec/cm3) of water supply on hatching rate of salmon eggs, masu salmon (Oncorhynchus masou) and chum salmon (O. keta) were examined.
The results obtained are summarized as follows:
1) Viable bacterial counts were decreased about 90% in ultraviolet treated water, but viable fungi counts did not decrease to the same degree as the bacterial counts.
2) The eying rate and hatching rate were about 20% higher in the ultraviolet treated hatching tray than the untreated control, the fungi infection rate of the egg decreased about 19%.
3) Utilization of disinfection of hatchery water supply by ultraviolet irradiation was expected to increase the eying rate and the hatching rate.
