US Fish & Wildlife Service


Date of this Version



Published in Journal of Parasitology, VOL. 60, NO. 3, JUNE 1974


On 27 May 1970, Mason Shouder, Michigan Fisheries Biologist, discovered some abnormal eggs in a ripe sturgeon, Acipenser fulvescens. The fish were taken from the Black River near Cheboygan, Michigan, which is barricaded from Lake Huron by a dam built in the 1920's. Normal ripe eggs were black spheres; the abnormal ones were enlarged and grayish (Fig. 1). About 20% of the eggs were affected and attached to the wall of the uterus in saclike structures. The ovary was also abnormal, being flaccid. In May 1973, a single infected egg was found in vodka-prepreserved eggs from a ripe sturgeon from the same locality; only one of 1,391 eggs (0.07%) was found infected.