October 3rd 2018:

To start with let’s look back at October 3rd! A tropical depression made landfall east of Louisiana and brought the first blast of cold weather to the lake. The lake water was hot hot hot from the long summer of high pressure and 100 degree days prior to this first blast of cold dry air. This was the first major cooling of the water and the first of 5 lake turnovers I counter. The turnovers took place through October into early November as I recall. The first one was the most widespread and resulted in dead fish scattered across the lake primarily the south shore and southeast shore lines. As you can imagine the fishing went for good to terrible. I mean maybe one fish a trip!!

Dissolved Oxygen:

To understand why one must look at oxygen levels in the water. There are to types of oxygen, captured and dissolved. The captured is the o in H2o and makes up the water molecule. This oxygen is not available to the fish, only the dissolved is. Following the October 3rd cold snap, which was unusually early the lake was hit with a least 4 more over the next 30+ days. Each was local within the lake boundaries. For example a customer and I went out hoping things had returned to normal. As we crossed over west point ( the long shallow main lake point NE of the discharge) we were hit once again with the rotten egg order. This is caused by decaying matter and bacteria in the lake bottom being uplifted by the turnover. A turnover is when the upper water level cools and becomes denser ultimentelly sinking to the bottom and the lower water coming to the top. The oxygen starved bacteria loves this and quickly sucks up most of the dissolved oxygen and the overall water column percentage of dissolved oxygen gets lowered. At least that my interpretation. Right or wrong, the net effect of a turnover is to reduce the dissolved oxygen available to the fish. After fishing the lake for all October into early November I came to think of it as the Bass having the “FLU!” They just didn’t want to eat, move, swim or do anything!! Usually a turnover lasts for a few days and things get better, but the back to back to back cold snaps coupled with the unusually hot water (it was 100 degrees at the third boat ramp at 5 in the evening in mid September!) helped promote multiple turnovers. I would place the dissolved oxygen at around 4 mg/l or stressful conditions for the fish.

Sonar Observations:

During the turnover period I observed several sonar anomalies.  For starters, the water column was cluttered with small reflections due to suspended debris within the water.  The shad were scattered early on and as the water quality improved formed  in horizontal layers, like a pancake.  I attributed this to the possibility that they were taking advantage of some good water with better oxygen content.  This was observed around 10′.  Also noted was the lack of shad balls and the juxtaposition of shad adjacent to the bottom.  Everything was just suspended and using as little energy as possible.  It was not until the end of the turnover around the first week of November that the shad balls started to form.  I interpret shad balls as a defensive mode due to feeding bass.  So to me this was a precursor to improved fishing conditions.

It’s On:

Moving forward from early November and December it was on!  The scattered debris was gone, the shad were in defensive balls and the bass were easy to spot on the sonar.  Consequently, the bass fed with a vengeance. I went from catching 1 fish a trip to 40 plus.  Other boats reported the same excellent fishing following the turnover.

Take Away:

Turnovers are a natural occurrence with most lakes and typically lead to slowing fishing.  The good news is that following them leads to excellent fishing.  I believe you can get the jump on other anglers by monitoring your sonar data and looking for the following.  1.  A clearing of the water column due to debris settling.  2.  Horizontal suspended layers of shad as the oxygen levels return.  3.  Formation of shad juxtaposed to the bottom and finally shad balls.  All this can indicate that the poor fishing is about to end and it is going to get good again, real good!

Good Luck
Pete Dodge