Incidence of Viral Erythrocytic Necrosis among Hatchery Reared Salmonids of Oregon

Abstract

A survey was undertaken to determine the incidence of viral erythrocytic necrosis (YEN) among hatchery reared salmonids in the state of Oregon. Thirty-five different stocks of fish were examined. Included were steelhead trout (Salmo gairdneri), coho (Oncorhynchus kisutch), chum (O. keta), chinook (O. tshawytscha), and kokanee (O. nerka) salmon. Inclusion bodies typical of VEN were found in the red blood cells of fish from 9 of the 35 stocks examined. Chum salmon were most heavily infected, but inclusion bodies were also detected in blood from coho and chinook salmon and steelhead trout. Progeny of selected populations of VEN infected adults were examined and cytoplasmic inclusions were found in erythrocytes of chum and coho juveniles.