Written by Adam Broughton.
Later summer fishing is typicall pretty tough: bait is plentiful and mature and water temps are hot and low in oxygen. So fish are well-fed and lethargic; a bad combination for anglers. But then temps start to cool off and fishing improves dramatically. While many people are headed to the woods or watching football, fishing die-hards are enjoying some of the best fishing of the year.
Lakes start to turn over and fishing is tough again. Sometimes, downright terrible. After the turnover, the bite improves, but nevertheless, many anglers simply opt out during this time. So what are the signs of turnover? Can you fish DURING the turnover and have success? What strategies should you know about fall turnover? Here is our advice...
What Exactly is the Turnover?
Only lakes that stratify in the summer will have a fall turnover, and conditions have to be favorable in order for a thermocline to be established. The “turnover” is when the summertime thermocline breaks up and warm water near the surface mixes with cooler water underneath. This event is triggered every fall when air temperatures cool water temperatures and cause the thermocline to become unstable. Wind-induced currents and wave action mixes the thermocline away, during which time the entire water column may be mixed; top to bottom.
Characteristics of Lakes with Thermoclines
Lakes that form thermoclines in the summer are typically deep (40+ feet), non-flowing and stable. With quality sonar, you can often “see” the thermocline if you increase the sonar sensitivity to the maximum setting. What you actually see are dust particles suspended in the density change.
Lanier, Allatoona, and Hartwell are examples of lakes that regularly have a distinct thermocline, typically around 35-40 feet deep. On very deep lakes, such as Carter’s Lake, the thermocline will be deeper, say 60-70 feet.
Characteristics of Lakes without a Thermoclines
This is what lakes look like in the winter. Water temps and oxygen levels are uniform from the bottom to the surface. Lakes that do not ever establish a thermocline will look like this year-round. Lakes such as these that never stratify are typically flat and/or have moving water.
Chickamauga, Nickajack, and Guntersville do not stratify in the summer, and subsequently do not have a fall turnover.
How You Can Tell
No single piece of information will definitively say “The lake is turning over right now”, unless that sign is exceptionally strong. But if you see several indicators together, you can easily conclude that a turnover is present. Here are the key indicators:
- Surface temps fall below 74° give or take a few degrees.
- Rising Gas Bubbles – Methane gas trapped in the bottom siltation will often be released with the shifting temperatures. During a strong turnover, the release of gas can be impressive, with pockets of streaming gas bubbles visible over much of the surface of the water. If you don't see gas bubbles on the surface, you can certainly see them on your sonar. Rising gas bubbles look like steadily rising lines, like this:
- Stagnant Odor – The water near the bottom of the lake has been sitting on decomposing plant and animal matter all summer. During the turnover, this water rises and mixes with the surface water. As a result, you can often smell a mild sulfur odor during turnover.
- Bits of Debris on the Surface – Along with the rising water comes bits of moss, rotting leaves, and other debris. Normally, you will only see a few pieces here and there, but it will be obvious that they are out of the ordinary.
- Water Color Change – During the turnover, suspended plankton and green-water algae will be mixed and disbursed, often discoloring the water. Some anglers describe it as “funky green”.
- Little or No Fish Activity – Oxygen levels are typically very low during the turnover, which is the #1 contributing factor as to why fishing is so tough during this time. A lack of fish activity can often be blamed on the turnover.
- Time of Year – The fall turnover usually happens as early as late September, but typically early to mid October in the south. It will be several weeks earlier in the northern states.
There is a Time and a Place
An important characteristic of the turnover is that not all parts of the lake turn over at the same time. Shallow water, such as creek arms and lake pockets, will turn over earlier than the main lake. Depending on conditions, you may be able to fish one or the other and avoid “turning” conditions completely. For example, if you start fishing up the lake in river arms and see bubbles, smell muck, and see debris on the water, then get out of there and make a run to the lower end of the lake where the water is still stratified.
Another suggestion might be to go to another lake altogether. If you know that your local lake is amidst a turnover event, then you might make a run to a more remote fishing option where thermoclines are never established, such as in a river. Some Georgia fishermen will run to nearby states to explore other fishing options.
Strategies for Fishing the Turnover
Fish Shallow – The earliest signs of the turnover is often fish activity near the surface of the water. Topwater fishing can be excellent at this time of the year, and it is well worth exploring topwater strategies. If the lake is known to have Blueback Herring in it, topwater strategies may be productive throughout the day.
Fish Deep – Fish in the “middle” depths suffer the greatest effects of the turnover. If you aren’t locating fish near the surface, try exploring the deepest depths of water near summertime holding areas. Vertical jigging spoons used at the mouths of creeks or on breaks near main-lake points can be very productive. Grubs and drop-shot rigs are also good choices. Typical “deep” depths range from 40 to 60 feet deep.
Cover a Lot of Water – Put your trolling motor on high and keep moving. If you get a bite, spend a few minutes exploring the area, as fish are likely to be moving together in small groups. If you don’t pick up additional fish, put the trolling motor back on high and get moving again.
Clear vs Dirty – Dirty water absorbs light more so than clear water, and most of that temperature absorption is in the first few feet of the water column. So if you have a segment of the lake with dirty, non-flowing water, the turnover will happen later in that area relative to where water is more clear or where there is more current or wave action. However, stained water that is a result of rain runoff may be much, much cooler.
Rain and Creeks – Dry ground temperatures and rain will be cooler than lake temperatures. So when you have rain in the fall, the runoff into the lake will be cooler. This cool water sinks quickly and mixes the thermocline layers. The same goes for creeks: they dump cool, heavy water into a lake and cause the turnover to occur relatively earlier. A heavy rain in the fall can often trigger a dramatic turnover event, provided conditions are primed for it.
If you suspect that you are late in the turnover, you might look for these areas, as they will be stable and fully mixed. If you suspect that you are early in the turnover period, you’ll want to avoid these areas and fish elsewhere.