Biochemical Evidence of Stock Differentiation in the Bloater (Coregonus hoyi) in Lake Michigan

Abstract

Electrophoretic analysis of five samples of the bloater, Coregonus hoyi, from five geographic areas in the Wisconsin waters of Lake Michigan in two successive years indicated that genetic differences among samples were too low to detect the presence of distinct stocks. Although significant heterogeneity among locations was found in 1982, it was in the form of a gradual south - north allele frequency cline at one polymorphic locus, PGM-C, in liver. Cluster analysis (UPGMA) of Cavalli-Sforza and Edwards chord distances between samples produced a dendrogram representative of a continuously distributed population. Absence of activity at the PGM loci in the 1983 samples weakened comparison of diversity between years, and the remaining loci analyzed in 1983 did not show differences among locations. Four samples from three areas in one year from Michigan waters indicated the presence of three stocks of bloaters. Significant differences in allele frequencies among samples from Frankfort, Ludington, and Saugatauk were found at the IDH-B liver loci. No such differences were found at the same loci in Wisconsin samples, indicating that fish from the east and west side of the lake are genetically different.