The smallmouth bass Micropterus dolomieu (family Centrarchidae) is one of the most popular sport fishes in the lower Great Lakes, with greatest fishing effort concentrated in Lake Erie. The "National Survey of Fishing, Hunting and Wildlife-Associated Recreation" from the U.S. Dept. of the Interior, the U.S. Fish and Wildlife Service, and the U.S. Department of Commerce states that Great Lakes anglers spent U.S. $1.4 billion in 1996. Of the 2.04 million anglers and 20 million angler days on the Great Lakes, 746,000 (37% of the anglers and 6.4 million angler days) were on Lake Erie. Smallmouth bass population structure has been little-studied to date and no prior population genetic investigations based on DNA sequences were found in a search of the scientific literature or in the N.I.H. GenBank data base. The Ohio Division of Wildlife (ODW) is presently focusing on studying the smallmouth bass populations and harvests on Lake Erie, to determine abundance, distribution, growth, diet, and factors affecting reproductive success. Our study interfaced with that study and those being conducted by other management agencies and universities, in order to assess the genetic diversity and population structure of smallmouth bass across the Great Lakes, with concentration in Lake Erie. We specifically tested the hypotheses of whether differences occurred among population samples in the eastern, central, and western basins of Lake Erie and among specific spawning sites in each, in order to assess the distribution of genetic variation. This genetic survey assisted management agencies in determining the role of specific spawning sites in contributing to the genetic diversity of the overall population(s).

Variation at eight nuclear microsatellite DNA loci have been analyzed for 666 smallmouth bass from 28 locations, including 425 individuals in Lake Erie; as well as Lakes Superior, Huron, and Ontario, and outgroups from the Mississippi, Ohio, St. Lawrence, and Hudson River drainages. Variation based on mitochondrial DNA control region and cytochrome b sequences is being assessed with Ph.D. student W. Calvin Borden, who was funded by this project in Dr. Stepien's Great Lakes Genetics Laboratory's former location.  Results to date reveal marked genetic differences among lake and river populations, as well as surprisingly high divergences among closely spaced riverine sites. Results do not fit an isolation by geographic distance prediction for fine scale genetic patterns, but show weak correspondence across large geographic scales. Genetic relationships thus are consistent with hypotheses regarding divergent origins through vicariance in glacial refugia, followed by colonization pathways establishing modern-day Great Lakes populations, and maintenance through behavioral site fidelity. Conservation management practices thus should preserve genetic identity and unique characters among smallmouth bass populations.

This investigation provided fundamental data on the genetic variability and stock structure of smallmouth bass in the Great Lakes, key to maintaining diversity for successful fisheries and ecological management. Preserving genetic variability of stocks and maintaining their habitats is important for ensuring diverse and resilient species for sustainable fisheries. Genetic diversity is believed to enable native species to inhabit a variety of environments and withstand perturbations, such as exploitation, habitat degradation, and effects of invading species. It is essential that we analyze genetic diversity of the smallmouth bass at the present time and incorporate the results in our fisheries and environmental policies, including stocking programs, potential protection of some spawning areas, and procedures that help to maintain genetic variation. This project benefitted the public through providing data for maintaining a sustainable smallmouth bass fishery. This investigation was important for education and training in fisheries genetics and ecology of the Great Lakes.

Data analyses tested for differences among spawning groups, populations, lake basins, and lakes. This protocol was tested with the Ohio Division of Wildlife and  other management agencies, enabling them to monitor genetic variability and stock structure of populations. The resulting sequence data sets were deposited in the NIH GenBank database, making them available to all interested esearchers through the World Wide Web. We have established web sites to rapidly disseminate the results at http://www.lakeerie.utoledo.edu. Reports and reprints also are being disseminated yearly to all agencies and researchers that are interested in this project, and are available by e-mailing carol.stepien@utoledo.edu.