A virus disease of sockeye salmon: Interim report

Since 1951 a disease, usually occurring in late spring or early summer, has caused severe losses in 3- to 12-month-old fingerling sockeye salmon in hatcheries in the State of Washington. The disease is characterized by an explosive outbreak, mortality usually 80 percent or greater, and a residual spinal deformity in a small percentage of the surviving fish, and its specificity for the one species of salmon, Oncorhynchus nerka. (The anadromous strain of this species is commonly known as sockeye, blueback, or red salmon, while the fresh-water strain is called kokanee or silver trout.) The etiological agent is believed to be a virus.