~by Rick Olson~
Walleyes are directly affected by this naturally occurring, seasonal phenomenon, and can make for some of the toughest fishing conditions you’ll face during the entire open water season.
As water temps reach their summer high, a layering process occurs, with the end result being an upper warmer layer, and a lower cooler layer, separated by a quickly changing narrow band, known as the thermocline. This deeper, cooler, bottom layer, can quickly become totally void of oxygen, and will eliminate any use. Trying to pull fish from dead water can be a complete waste of time.
If you know a thermocline exists, you would be well served to concentrate your efforts, at the thermocline, and shallower. The exception would be an extremely clear lake, where you have a thermocline, and a separate, deeper, oxycline.
Finding out whether or not a particular lake has a thermocline set up, is a relatively easy task. With a good liquid crystal graph, you can actually see the narrow band that indicates the layer separation.
Modern Fish finders display density of objects, as well as changes in density, which makes up a thermocline. The upper warmer layer, is less dense than the cooler bottom layer. It’s this change in density that will show up on an electronic graph, and it looks like a constant, narrow band.
Some lakes are so shallow and windswept that they may never thermocline. These lakes ”roll over” every time you get a decent wind, and the temperature remains relatively consistent from top to bottom, throughout the entire season.
Periods of flat dead calm conditions, combined with the heat of summer, push surface temps into the range of bathwater. But that’s as far as it goes, and will last until the next good wind mixes everything up. What happens then? Do the fish experience the same negative effects that the fall turnover brings? Absolutely not!
It’s not just the fact that a lake will turnover, that causes tough fishing conditions, but more likely due to the rapidly dropping water temperatures. The body temperature of a fish is subject to its environment, and rapid changes in water temp can shut fish down, and it may take some time for their body to adjust.
The turnover usually coincides with the first hard frost of fall, but not always. Some years, the change is so gradual that it becomes difficult to pin down. One of the indicators to look for, is water temperature.
When the surface temperature drops into the lower sixties and upper fifties, you’re in the turnover zone. Walleye activity can range from bad to good, depending on how severe, and how quickly water temps cool off. A gradual slide can make for better fishing. In that case, you can probably continue using presentations that have been effective, like trolling crankbaits and spinners.
Late summer and early fall can be one of the best times to work the shallow rocks with Shad Raps. The Shad Rap is the most effective crankbait for working shallow structure there is. By design, the bait has a perfect fish attracting wiggle, we like great fall colors, like fire tiger and crawfish.
Spinners can remain effective until the temps dip below sixty degrees. Spinners, trolled over sparse weed flats, along deep weed lines, and along any potential fish holding structure, can be extremely productive. While spinners are usually associated with a harness and crawler setup, don’t overlook a spinner and minnow combo. A spinner, with a single long shank hook, is the way to go. The long shank can be run through the mouth of the minnow, out the gill, and slid into the tail, adjacent to the anal vent. This technique will help keep the bait alive, and fresher, much longer than other methods.
If the daytime bite proves to be too tough, or nonexistent, you may have to concentrate your efforts after dark. Spinners trolled over the tops of green weeds, can be surprisingly productive. Besides the top and the deep edge, anglers on a night run should not overlook the inside edge. Walleyes will often move into extremely shallow water, especially at this time of the year. A spinner weighted down with nothing more than a split shot, may be just the ticket for inside ‘eyes.
Another top technique, for fishing after dark, is trolling a shallow running, minnow shaped crankbait, over rock bars, reefs, and shorelines. The key is to keep a bait close to the rocks, without constantly dragging the bottom..
Much of the late summer and early fall action can occur after dark, and even when things get tough, like during the fall turnover, there still might be a few walleyes that will surrender, for anglers willing to give up a little sleep.
Another option, would be avoiding the negative effects of the turnover by trying to find a lake that hasn’t turned yet, or one that already has, and had a week or two to settle down. The first ones to go are the shallow lakes, as they have less mass, and cool quicker than the deeper varieties. There may be as much as two weeks difference, or more, as to when it all begins, and ends.
The final option is to not go at all, but what fun is that? Fishing is fun, even when it’s tough.
Dealing with the fall turnover can prove to be a real challenge, and overcoming tough conditions can be extremely rewarding.