Management Implications of Mitochondrial DNA Variation in Walleye Stocks

Abstract

This study has examined the potential use of mitochondrial DNA (mtDNA) variation as a tool for identifying and managing stocks of walleye Stizostedion vitreum. Using 10 informative restriction endonucleases, we examined mtDNA variation in 847 walleyes from 68 populations across the species' range. Thirty-four mtDNA haplotypes were recognized, 21 of which were observed only in single fish. Eighty-nine percent of the walleyes sampled were members of one of three major haplotypes. These three haplotypes showed distinct geographic distributions: haplotype 1 (12% of all fish) predominated in the east, haplotype 4 (58%) in the central range, and haplotype 10 (19%) in the northwest. The other 10 haplotypes were locally distributed and were most useful for identifying stock and for detecting past transfers of fish. Walleyes from the Mississippi and Gulf Coast drainages possessed mtDNA haplotypes divergent from one another and absent from the core of the species' distribution. Widespread and often undocumented introductions of fish complicate the use of mtDNA analyses for walleye stock identification. However, because of its maternal inheritance, mtDNA is a potentially useful marker for tracing the success of stocked populations.