By Ken Schultz
There’s a chill in the air, and some significant changes are occurring or are about to occur. In the fall, a major change in some lakes is the turnover, a phenomenon that is especially noticeable in bodies of water that have significant depth and layers of markedly different temperature. This is generally large lakes and reservoirs.
If you only fish occasionally, you may miss the changes that occur and simply find on your next outing that the lake is quite different than it was on your previous visit, and perhaps harder to fish. But if you fish a lot you’ll probably observe some of the things that happen. Either way, fishing may become poor for a short while during the turnover, but quite good afterward.
Why and How Lakes Turn
Here’s what happens in the actual “turnover”: When the average air temperature is lower than the water’s surface, the temperature in the upper zone declines and mixing takes place. Cold water is more dense than warm water, so newly cooled surface water sinks to deeper levels. This causes a mixing of the water throughout the zones. Eventually the zones disappear. When the
water column mixes completely, the temperature is virtually the same from top to bottom.
Complete mixing may take several weeks to occur, or it may occur very quickly. A severe cold front can drop surface water temperature dramatically, perhaps even 10 degrees, virtually in a day; this hastens turnover. Wind may play a role in the turnover process, too. Wind doesn’t actually cause turnover, but some biologists have written that wind aids the mixing, and show it in accompanying diagrams.
In any case, mixing often causes new turbidity in the water for a while. You may also notice suspended leaves and other detritus in the water, which is the result of decaying bottom matter that was in the lower zone being dispersed through all levels.
Where smaller and larger lakes exist in the same general area, smaller ones may turn over before larger ones, or the speed with which they turn over may be quite different. Thus, where there are lakes relatively near each other, fishing in one can be much better or much worse than in another. Since fishing is often poor directly following turnover, if you have options as to where to fish, try to determine what the status is of those places you could visit.
Once things have stabilized, the aftermath of fall turnover is improved fishing. Baitfish activity can be stimulated as the result of nutrient or plankton dispersal, and many fish, bass in particular, will be shallower than they had been when the water was warmer. With the shallows cooling, fish move into areas where greater numbers of them are more accessible.
Go natural. In many instances, the water in lakes also becomes clearer after the fall turnover. When selecting lures, consider a natural-looking appearance. Plug patterns that look like shad (or alewife or shiner), bluegill, yellow perch, golden shiner, or crayfish, depending on the environment, are good bets rather than those that are more exotic or suggestive.
Go bigger. With baitfish being generally large in size, this is also a good time to fish larger size lures than you may have been using previously. Unless you’re also angling for panfish, try plugs that are one-third to a half-ounce in size, and minnow plugs that are 4 to 6 inches long rather than smaller.
Try topwater. Floating-diving minnow-bodied plugs make good surface lures, especially for morning fishing, and suspending models are good for subsurface stop-and-go twitching. Popping or chugging surface plugs are likewise good, especially in lakes with lots of baitfish activity. Bass may load up on schools of baitfish, sometimes on weedy flats; then, a quick-working, water-spitting surface plug produces marvelous strikes.
Try cranks and jigs. While spinnerbaits that are slow-rolled over objects or dropped along deeper edges of cover may be productive at this time, I prefer crankbaits and jigs for deeper probing. Try a jig-and-pork where the bank is steep, especially if there’s rocks or riprap, and pitch it along shorelines that have logs and treetops near deeper water.
Also...Don’t forget points or overlook deeper water when things have not stabilized, since fish may be roaming. Trolling is a good bet if fish are scattered, though many bass anglers don’t try it.
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