The product of the study is a state-of-the-art interactive World Wide Web data base of 10-15 microsatellite loci for 800-1000 walleye and 600-1000 yellow perch, along with genetic analyses of their relationships, distribution patterns, and stock structures. The web program shows where each fish and population sample "fits in" to stock structure and patterns across the Great Lakes. The data base then will serve as a baseline for use by fisheries researchers and managers for years to come. An output target goal is to invite samples and continued use after the grant on an as-need and by-request basis at low cost (estimated as $25/fish), providing a growing interactive data base for widespread scientific and agency fisheries management.

Before this project began, the Stepien lab completed analysis of 6 microsatellite loci and sequences from the entire mitochondrial DNA control region for 400 walleye and 150 yellow perch, and was part of a 2003 Great Lakes Fishery Commission Restoration Act project to test 200 new walleye unknowns using various genetic techniques (with 2 other labs, both Canadian). The current research extended and went far beyond that work to analyze a much larger data set, implement a low-cost high-throughput procedure, and produce a working interactive genetic data base. The project also compared the other data sets and studies to this one (for example, our mitochondrial DNA control region sequence data bases). The Ohio Division of Natural Resources and the Lake Erie Committee helped to develop the ideas for this proposal and served as testers/users.

Dr. Stepien and her laboratory are currently working on developing the nuclear microsatellite and mitochondrial DNA sequence data bases at the Great Lakes Genetics Laboratory at the University of Toledo. Postdoctoral research associate Dr. Rex Strange (2004-6) helped to develop the microsatellite data set for walleye.  Ph.D. candidate Oswaldo Jhonatan Sepulveda-Villet is working on his dissertation study of variation in yellow perch. Further information may be obtained from the Lake Erie Center website at www.lakeerie.utoledo.edu.

Our Great Lakes Genetics Laboratory held a workshop on the project results for fishery managers and scientists on December 1, 2005.  The workshop was interactive and focused on the use of molecular genetic tools to identify stocks of walleye, yellow perch, and smallmouth bass in the Great Lakes.  We have continued to update the Great Lakes fishery agencies on the progress of the project.

Dr. Stepien and her laboratory have analyzed 10 microsatellite loci for 1000+ walleye to date from the 10 primary spawning sites in Lake Erie, as well as Lakes Superior, Huron, Michigan, St. Clair, and Ontario. In addition, these samples are being analyzed in a broadscale phylogeographic perspective across their native range in relation to historic glacial refugia patterns. Results indicate that major spawning sites are genetically separable, indicating appreciable stock structure, even within Lake Erie.

Ph.D. student Osvaldo Jhonatan Sepulveda-Villet , working with Dr. Stepien , has analyzed 8 microsatellite loci for yellow perch in 3 spatial scales: across Lake Erie, the Great Lakes, and in comparison to outlying populations, including Atlantic coastal relict populations, Lake Winnepeg, and Lake Champlain. Results show that the nuclear DNA microsatellite data set is complementary with mtDNA patterns of stock structure. 

Abstract of Lake Erie walleye paper by Strange and Stepien 2007 published in Canadian Journal of Fisheries and Aquatic Sciences: Discerning population genetic structure is challenging for highly vagile open water animals, as contemporary gene flow may obscure historic phylogeographic patterns. We examined genetic variation among all 10 major river and reef spawning groups of walleye (Sander vitreus vitreus)in Lake Erie for evidence of isolation by distance, segregation by physiographic partitions, and natal site fidelity using 10 nuclear DNA microsatellite loci. Results revealed that although most spawning groups were distinguishable, relationships did not correspond with physiographic basins or dis-tances among localities.  Bayesian analyses showed connectivity among some southern shore spawning groups, which included the largest-sized groups. Significant genetic divergence was discerned among walleye spawning in the river systems of eastern Lake Erie, as well as in two sites in western Lake Erie, along with marked isolation from Lake St. Clair. Population structure of Lake Erie walleye thus appears to reflect the interaction of two different intrinsic factors: isolation due to natal site fidelity that maintains patterns of divergence, and connectivity due to individuals that stray from their natal sites to spawn.

 Abstract of Great Lakes walleye paper by Stepien, Murphy, and Loher in review: The walleye is a large and vagile percid fish whose greatest abundances and distribution center in the Great Lakes.  Many Great Lakes walleye stocks crashed by the mid-twentieth century and although some recovered, other historic spawning groups were lost, demonstrating that identification of native spawning groups is of utmost conservation importance.  We analyzed allelic variation at 10 nuclear microsatellite loci to test for genetically discernable stock structure among 742 walleye in 19 spawning groups across the Great Lakes.  Results revealed considerable divergence among most spawning groups and population areas, with almost no gene flow among different lakes.  Some intra-lake gene flow was evident among spawning locations along the southwest Lake Erie shore.  The greatest genetic demarcation divided Great Lakes walleye population groups between the Upper versus Lower Lakes.  The second most prominent division separated Lakes Erie from Ontario populations, the third separated Lake Superior stocks, and the fourth distinguished riverine spawning groups in the eastern basin of Lake Erie.  These broad scale patterns reflect the vestiges of divergence of these populations in two or more separate glacial refugia, as well as their contemporary maintenance through spawning site specificity.  Although walleye may travel among lakes, the vast majority return to their natal sites to spawn.  In Lake Erie, eastern riverine spawning groups are readily discernable from one another despite ample opportunity for gene flow.  Although some genetic variation in walleye may have been obscured by anthropogenic activities, many distinct native population stocks remain whose maintenance should be of fundamental conservation importance.