Seasonal Lake Turnover
Turnover refers 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.
An understanding of turnover, combined with knowledge of what kind of water a particular fish likes, can make you a real fishing genius and give you great insight on when to fish and where to fish for the best results. As always, good luck.
Once the ice is out, the water on the surface of a lake starts to warm. When it reaches 39 degrees it begins to sink and is replaced by cooler water from below. This exchange continues until the water temperature is constant in the entire lake. Early in this process, fish will stay in the shallow areas of the lake where the water warms up faster, and where the first plant growth of the spring occurs.
During the summer, the sun heats water near the surface of lakes, but it doesn't sink. Eventually a condition known as "stratification" develops, putting a well-defined warm layer of water over a cool one.
Fish like the cooler water, but they also need the higher oxygen levels found in warmer water. So they'll migrate to an area right between the two levels of water called the thermo cline. The thermo cline can occur between 2 and 10 feet in depth, depending on the size of the lake.
It's best to find a point or some other form of structure that extends out from the shoreline and slopes gradually down into the thermo cline. This should be a good place to fish because the fish often school in this zone because they can find warmer water, but have quick access to deeper, cooler and safer water.
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 promotes mixing with deeper water. This is fall turnover.
As mixing continues, lake water becomes more uniform in temperature and oxygen level, allowing fish to move around freely. Fish can be difficult to find as long as these conditions prevail, usually continues until the weather turns cold, chilling the lake's surface.
Water Temperature and Turnover
Each fish has a different range of water temperature in which it can survive. Although fish cannot always find the exact temperature they prefer, they are usually found in water close to that temperature. By combining a knowledge of preferred water temperature and lake turnover, you can roughly predict the best time to fish, and which fish will be in a particular part of a lake at a particular time of the year. Fish 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. But don't hold us to this. Fish are always tough to catch.
Learn when are the best times to catch trout. Follow these guidelines on our next page to maximize your fishing endeavors.