As the fall weather approaches the water cools and the weeds start to die. When weeds die they absorb oxygen out of the water as they decompose and produce dirty methane-sulfate bubbles that float to the surface and capture a hydrogen molecule that releases sulfur, which is poison to fish in high concentrations. This is such small concentrations but still annoying to the fish. So they take off in to open waters or up rivers where there are not such high levels of sulfur. This also includes fresh wind-blown waters at weed beds from prevailing winds.
Walleye swim upstream and hang in deep pools or back moving currents near both sides of rapids. In this situation the best bet is to use a float with a minnow or a worm. Rapalas and Thundersticks work well too when casting in slower currents and back-eddies. Jigs may leave you snagged.
Many Walleyes go out in to the open water and stay suspended in 10-25 feet of water in the fall. Trolling with “Deep Down Husky Jerks: and Rattling Fat Raps are favored by many Walleye fishermen during this time as well. While not as exciting if you are in a good populated area of fish. Use a depth finder and determine the best depth for the atmospheric pressure. If the pressure falls very low, the Walleyes may stop feeding all together however if the pressure starts rising the Walleyes will start feeding aggressively.
It is known that many large females come close to shore at night in the fall between 10 PM and 3 AM. This is a perfect time to try trolling with a gloating Rapala in 2-3 feet of water or troll along rocky areas. Use a worm or a live minnow for shore casting.