As cold weather rolls in from the North, the surfaces of reservoirs and lakes cool, making their water heavy enough to sink and mix with cooler water in the thermocline below. Wind encourages the mixing, and eventually the thermocline narrows, then disappears. As cooled water from the surface sinks to the bottom, debris bubbles up to the surface, accompanied by hydrogen sulfide and other gases produced by disintegrating plants, releasing a musky or sulfurous smell.
Fishing gets difficult under such conditions, but fortunately, Turnover lasts only about a week on any one lake. Once the lake or reservoir has turned over, the fall Coldwater Period begins.
Coldwater Period
Water temperature: Cool, declining to cold
Fish mood: Moderately active to inactive
By the time Turnover is complete, a reservoir or lake’s water temperature is usually in the 50°F range. Fish have abandoned their summer behavior and it’s getting cold out there. This is when many anglers choose to end their bass fishing year.
But the Coldwater Period can yield the biggest bass you’ll catch all year, so don’t stow away your gear too quickly. Outstanding catches can be had when you locate groups of bass. Largemouths respond to changes in their habitat by aggregating around the remaining cover in their world. On natural lakes, green weed patches— coontail, pondweed, water lily and milfoil—survive until late in the season and can be found on steep, sloping structure. Before they move onto these slopes, bass that have spent summer buried in shallow weeds first move onto flats with weed clumps in 4 to 10 feet of water. As waters cool further into the mid-40°F range, they move onto or near drop-offs. Once bass move onto drop-offs, they can shift depth without having to move far laterally. Such areas become fall and winter sanctuaries for large ¬populations of bass.
In reservoirs, bass aggregate in creek channels and along the outside edges of weedy flats. These locations make them readily accessible to anglers. If shad school deep offshore, bass stay deep, too.
As long as water temperature remains in the 50°F range, largemouths may continue to feed aggressively, chasing lures. Slow your presentations toward the end of this period: Cold-blooded fish slow down as the water cools. But you can catch bass until the day a lake freezes.
