Abstract
Salmonid fish are important species for hatchery reared and released fish. Flounders and shrimp are also important species for seed production and sea-farming in Japan. Viral disease is one of the limitations of successful propagation of these species. Methods currently used to control viral diseases are 1) hygiene and sanitation in facilities, 2) disinfection of rearing and waste water using U. V. irradiation, ozonization and electrolyzation, 3) selection of pathogen-free brood stock by cell culture isolation and detection of specific antibody against important pathogens with ELISA or viral gene with PCR, 4) health monitoring of hatched fry by cell culture isolation and detection of pathogens by immunological and molecular biological methods, 5) control of normal intestinal flora by feeding bacteria producing antiviral substances, and 6) temperature manipulation. Under these circumstances, hatched fish and shrimp are healthy and specific pathogen free, but there is still a possibility of infection by some pathogens in environmental waters after they are moved to ponds or net pens outside of facilities. For prospective studies, development of effective vaccines, vaccine injection machines and immunological tools for evaluation of vaccination effect are necessary.
