Seasonal Turnover relates to the exchange of surface and bottom water in a lake or pond. This annual recycling program happens twice a year. There’s spring turnover and fall turnover and summer stagnation in between. From spring to fall, warmer water goes from the top of the lake to the bottom and cooler water moves from the bottom to the top.
Summer Stagnation
During the summer, the sun heats water near the surface of lakes, but it doesn’t sink. Eventually a condition called “stratification” builds up, putting a well-defined warm layer of water over a cool one.
Fall Turnover
With the arrival of fall and cooler air temperatures, water at the surface of lakes cools, becoming almost as heavy as the cooler bottom water Strong autumn winds move surface water around, which encourages mixing with deeper water This is fall turnover. As mixing carries on, lake water becomes more consistent in temperature and oxygen level, allowing fish to move around freely.
Water Temperature and Turnover
Each fish has a different range of water temperature in which it could survive. Although fish can’t always find the exact temperature they prefer, they’re usually found in water close to that temperature. By mixing a knowledge of preferred water temperature and lake turnover, you can kind-of-sort-of predict which fish will be in a particular part of a lake at a special time of the year. Fishes that like warmer water will be surface feeders in the summer and bottom feeders in the fall. And fish that like cooler water will feed deep in the spring and on the surface in the fall.