Date of this Version
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.