Why are walleye described as becoming much more aggressive in the fall season?

Every calorie becomes crucial as they prepare for the winter season.

The behavioral shift observed in walleye during the fall is metabolic and survival-driven. As water temperatures begin to drop significantly from summer highs, the fish become highly motivated to feed aggressively because energy conservation is paramount for surviving the impending winter period; therefore, every calorie consumed is extremely important. This heightened predatory drive is often amplified by the fact that baitfish also tend to concentrate in localized, warmer pockets of water, providing concentrated feeding opportunities for the predators along windy shorelines.