Winter and Spring

This time of year is when one of waters greatest features comes into play. Water is most dense at 4°C, but freezes at 0°C. The freezing water is less dense and rises above the dense 4°C water. This property allows the water column to freeze from the top down and keeps the lake from freezing solid. During this time the warmest water is at the bottom and the less dense water that isn’t frozen yet is in-between it and the ice. The fish can still move into the depths, and will likely be associated near deep structure. The deeper water will provide more stability and large groups of fish may be found on one structure.  Then the part that everyone in the north has been waiting for, as air temperatures begin to rise the ice melts.

After the ice melts the spring turnover occurs, and the water column is all one temperature again. The air temperature begins to warm and after a few warm windless days the water column begins to divide into two distinct layers again. This brings those big mama’s back in from the deep and their metabolism begins to speed up. The fish start getting active again and start fueling up for the spawn.  The thermocline forms again and the difference in temperature and density between the two layers grows as spring progresses to summer. That concludes a complete turnover of a lake for a year.

Believe it or not that was the simplified version; there are many other factors that can come into play. The lake can have a chemocline (a chemical difference that divides the water) , there could be a river flowing into the system, the lake could not freeze over, or another factor could disrupt the formation of the thermocline. The seasonal changes  in the turnover can affect what part of the lake that the fish will be holding in. During the summer the fish will not be located below the thermocline and during the winter they are more likely to be associated with the depths because of the warmer and more stable temperatures towards the bottom . I hope this helps you to understand why fishing can be so hard during certain times of the year and helps you plan your next outing.