Walleye
The scientific name of Walleye is Sander vitreus (it used to be called Stizostedion vitreum and that's what you will find in field guides published up until recently. The older generic name of Sander is now used). Walleye are members of the perch family, Percidae, and their closest relatives are Sauger (which has also been renamed and is now Sander canadensis).
Walleye average around 2 lbs in northern lakes, but can get up to 10lbs. They are fish predators with large mouths and eyes that are specialized for hunting at night or in murky water. Large females lay many more eggs than small females (a 5 lb female can lay more than 100,000 eggs on the bottom). More information
The native range of Walleye was much smaller than its current range in North America: St. Lawrence-Great Lakes, Arctic, and Mississippi River basins from Quebec to Northwest Territories, and south to Alabama and Arkansas (see map in the Fishbase Summary, originally from Page and Burr 1991).
Walleye have been introduced widely (see map below) for sport fishing.
During the glaciation of North America the area which is now Wisconsin was under the ice sheet, and the fish of the upper Mississippi River basin moved south to refugia in the lower Mississippi basin (for a fun visual overview of "how the Great Lakes formed" and how the ice sheets advanced click here). This is one of the reasons why northern lakes have relatively few species-- fish species are still moving back up into the upper Mississippi River basin and northern lakes from their Pleistocene refugia. It is also why populations of fish have complex patterns of genetic relatedness-- genetic relatedness between different populations depends upon how each population moved into the region (which particular river it came from), what barriers are present (waterfalls, isolated lake basins) and how long they have been isolated from other populations of Walleye. This makes Walleye populations genetically diverse. It also means that it is important to maintain this diversity at the landscape level in order to make sure the species can survive in a changing environment-- which is a challenge for fish hatcheries in the region.
For a map and detailed account of the genetics see:
Landscape genetic patterning of Walleye Sander vitreus: Vicariance, postglacial dispersal and spawning philopatry