The influence of fish age and water temperature on mortalities of rainbow trout, <i>Salmo gairdneri</i> Richardson, caused by a European strain of infectious pancreatic necrosis virus

Abstract

Abstract. Rainbow trout fry were infected by a pathogenic Sp type of infectious pancreatic necrosis virus isolated in France. Fry held at 10°C and infected at different ages showed a decrease of sensitivity with increasing age and ceased to be susceptible to the disease when 20 weeks old. Mortality was delayed at 6°C and lowered or suppressed at 16°C. When fry were moved from 10 to 16°C before infection mortality was also lowered but not when they were moved from 16 to 10°C. Late infection of siblings kept at different temperatures before infection suggested a relation between the number of degrees x days and the final mortality recorded.