Epizootiology of Tumors in a Population of Juvenile English Sole (Parophrys vetulus) from Puget Sound, Washington

Abstract

An epizootic skin tumor disease affected young-of-the-year English sole (Parophrys vetulus) near Seattle, Wash. The 1969 year-class had an incidence of 18.7%. The epizootic wave began in August and peaked in October. Incidence rapidly declined thereafter. The disease coincidentally attacked winter and summer influxes. There was no difference in growth between age-group 0 normal and tumorous fish, but age distribution of tumorous fish indicated longevity differed. Tumors were more numerous on younger fish. Angioepithelial nodules grew until transforming into epidermal papillomas, which reached maximum weight in age-group II. There were no differences in sex ratios between normal and tumorous fish.