Pre-spawn females hold back on nearby deep lake points, shoals, and dropoffs, but are eventually drawn upstream as rivers warm. Prime spawning habitat is located below falls, rapids, dams, along current edges, in eddies, behind boulders, in tributary creeks, and along rip-rap and rubble shorelines. River walleye are typically long and slender, but can be chunky and fat in early spring before they spawn. Not all of Ontario is open to walleye fishing at this time of year, so check area-specific regulations before wetting a line. Even in open areas, keep in mind that big, egg-laden females are prime breeders and most of the ones you catch should be handled carefully and released.
Smaller males are more abundant and better in the pan anyway.
Besides dictating when walleye spawn, water temperature influences where you'll find them. In early spring, usually they're in the warmest water available. Current and wind play a part in circulating warmer or colder water. River narrows and inlets can trap warmer water and concentrate walleye. I seldom carry a thermometer but can feel the difference in temperatures when handling bait and tackle.