Autumn is a great time to catch some actively feeding fish, but too many fishermen avoid the lakes around fall turnover. 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. The decomposing organic matter at the lake bottom contributes to the low oxygen level.
Water is at its heaviest at 39°, so as the surface temperatures drop to around 50°, that top layer of water becomes heavier and wants to sink. Lakes can take a few days to turn or it can happen overnight. A cold front, cold rain, or 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.
Fishing with Racer, and his parents Wendy and Barry from Texas this week, proved to be productive this week. Trout are loving this weather.
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