Fishing tips: Catching fish around the challenging “fall turnover”

Autumn is a great time to catch some actively feeding fish, but too many fisherman avoid the lakes around fall turnover. Learn about and understand turnover so you can continue having success throughout the fall.

So what is turnover and why does it happen? 

During the summer the warmest water rises to the surface. Sun and the wind warm this water, and it contains ample oxygen. As you descend through the water column, you’ll hit the thermocline – the line where water becomes dramatically cooler. Oxygen levels will also decrease beneath this line. Above the thermocline – in the warmer layer that fish biologists call the epilimnion – fish survive comfortably in the oxygen-rich water. Below that line (the hypolimnion) low oxygen levels discourage fish from living there. Decomposing organic matter at the lake bottom contributes to the low oxygen level.

Water is at its heaviest at 39 degrees, so as the surface temperatures drops to around 50 degrees, that top layer of water becomes heavier and wants to sink. Lakes can take a few days to turn or it can happen over night. A cold front, cold rain, or a heavy wind can increase the turnover rate. 

When a lake turns, the surface water falls and the now-warmer water from the bottom rises. The bottom water can carry sediment and decomposing organic matter, thus creating smelly and dirty looking water. But the highly-oxygenated water from the surface falls to the bottom, thus spreading oxygen throughout the lake.

How does this affect fishing? For any angler who ventures out on the water during the cooler temps it can be a make or break time. Finding fish right after turnover can be challenging; however, pay attention to what’s going on, and you can adjust and still catch fish. 

A few years ago, I was fishing on a lake during the turnover. Throughout the day, the water became dirty and the odor from rising lake sediments grew stronger. While using my trolling motor to adjust my position, it created a normal swirl on the surface. The difference this time? It didn’t stop. The prop had disturbed the surface water enough, and it began to fall causing a couple small swirls on the surface. It didn’t seem unusual at first, but after several minutes, I grabbed my phone and caught an 11-second video of what I’d been watching for minutes. Despite the lake’s discombobulated nature and tough bite that day, we caught a few walleyes and northern pike.

Bass, pike, perch, bluegills, walleyes… all may need time to adjust to turnover, but usually the reason you’re not catching fish post-turnover is because you’re fishing the same spots as you were before. Everything has changed! The flipping of the epilimnion and hypolimnion layers dispersed oxygen throughout the lake. Baitfish are willing to seek deeper depths, and when their forage goes deep, so do the sportfish. You’ll find post-turnover walleyes down to 80 feet deep. Be careful fishing for them, because hauling up fish then releasing them from those depths can result in dead fish, but just know that where there is food, predators follow. 

Bottom line, don’t get stuck fishing just weedlines and shallow points. Also seek deeper structure and pay attention to your sonar units to locate these fish.

Not all lakes turnover simultaneously. Small shallow lakes that cool quickly will turnover first, then deeper lakes will follow. If you want to avoid fishing lakes during or near turnover, seek deeper larger lakes, then switch to smaller lakes post-turnover as they will stabilize first.

Good luck fishing and stay safe!

 

Click HERE to see more tips and tactics by Jason Revermann.

 

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