Transmission of walleye dermal sarcoma and lymphocystis via waterborne exposure

A study was conducted to determine if walleye dermal sarcoma could be exper imentally transmitted by waterborne exposure of tumor-free walleyes Stizost edion vitreum to tumor-positive walleyes by cohabitation. Uninfected walley es were placed in a common raceway with tumor-positive fish for either 5 or 15 d. Direct contact between the two groups of fish was prevented by two s creen barriers. The exposed fish were then maintained in the laboratory for a total of 20 weeks. Walleye dermal sarcoma developed in 89% and 71% of th e fish exposed for 5 and 15 d, respectively. There was no significant diffe rence (P > 0.05) in incidence of tumors between the two groups of fish expo sed for different lengths of time.