The Underwater Seasons

Craig Sandell © 2006

During the course of the Musky season, every body of water undergoes changes in its water temperature as well as changes in the oxygen that is dissolved in the water. As the underwater seasons change, the Musky react to those changes driven by their need to eat and their need to breath. The successful Musky angler must tune into these changes. He/she must be prepared to be flexible with regard to lure selection as well as conducting a better evaluation of water and weather conditions. Late season fishing can be marked by drastic weather changes and dramatic changes in the condition of the water.

As the water begins to warm after the long winter months and as emergent vegetation adds oxygen to the water, Musky become more active and settle into their seasonal patterns.

For the greater part of the Musky season, most bodies of water are locked into the characteristic thermal distribution commonly referred to as the "summer thermal water pattern". The graphic shown here at the left demonstrates this summer thermal pattern. Water at the surface tends to change gradually in water temperature and tends to have higher levels of oxygen than the water layers beneath it. The thermocline is sort of like a buffer area between the warmer surface water and the cooler deeper water. The cooler deeper water tends to have the lowest level of oxygen during this period of time.

Musky tend to populate the upper water levels when they are active and the lower water levels when they are inactive. The hotter the top layer of water, the more likely Musky are to seek a comfortable temperature at greater depths. At these greater depths, they are less likely to be aggressively active.

As summer transitions to fall and the water looses its heat to the longer cooler evenings, the temperature difference between the thermal layers of the lake become less distinct. Most of the oxygen is still located in the surface layer of the water and Musky tend to be more active during this time. Typically this time is associated with late August and early September. Temperatures will vary depending upon the geographic location and the depth of the body of water so you should keep a close watch upon the water that you plan to regularly fish. The graphic at the right will provide you some perspective regarding this gradual shift in water temperatures.

Relentlessly, the seasons move on toward fall. The nights get cooler robbing the water of heat as the warming effect of the sun diminishes due to its lower position in the sky. The water temperature tends to equalize the temperature between the upper warmer and more oxygen rich layer and the cooler less oxygen rich lower layer. The thermocline is still in place but as you can see from the graphic at the left the water is on the verge of homogenizing into a uniform temperature distribution. This time is a prime Musky activity window but the window is very short lived. It is very difficult to accurately predict the exact time of this water temperature circumstance. You'll just have to trust to "luck" if you are trying to hit this period on the head.

Finally, the water succumbs to the persistence of the changing season and "turnover" takes place. The thermocline barrier disappears as the water temperature becomes uniform throughout the body of water. This is typically a very slow period for Musky activity. The blending of the oxygen rich upper water and the oxygen poor lower water causes the overall oxygen level to be less than what the Musky are used to having. The Musky require time to adjust to the new oxygen level as well as to the fact that they are "stuck" with a uniform lower water temperature. As you might suspect, this is not a good time to Musky fish. Every body of water will experience turnover on its own timetable so it is very hard to predict. If you plan to fish late in the season, you must "keep your finger on the pulse" of the body of water that you plan to fish.

The Musky soon acclimate to the changes in the water oxygen levels and the temperature. Around late September or early October the Musky put on their winter feed bag and take advantage of the seasonal movement of forage fish. This is typically the time when you have a better than average chance to tie into a 25 to 45 pound fish. This time of year, however, is not for the "fair weather" Musky angler. You can plan on the weather being wet, cold, snowy and generally miserable.

Hopefully, this article has shed some light on the mystery of turnover and its effect upon your chances to have a Musky encounter. As has been said in other articles posted on this website, Musky fishing has a large element of luck associated with any angler success. The best thing you can do is be prepared with as much information as you can muster about the water you are fishing and then trust in the "Musky Spirts" to favor your efforts.

NOTE: One should also remember that, depending on the spring warm up, pre-summer and Imminent-turnover are relatively the same water conditions.