Fishing the Thermocline

Jasper Johnson “Hook Up”

In an earlier article we talked about the dog days of summer being here and that it’s that time of the year when you need to go deep. In this article we are going to talk about the lures and tactics needed for this doldrums in the year’s fishing.

When the water gets hot the fish move down, we all know that. There are the exceptions, but in tourney fishing the majority often rules. We have all heard, or read about, the Thermocline and how the fish will move in hot weather down to that comfort line in the water and suspend right at that comfort zone. The Thermocline is not the bottom; it’s that level of water that is somewhere between the bottom and the surface where the warm water of the top layer meets the cool water of the lower depths. This level also holds the highest level of oxygenated water. When the top gets really hot it depletes the levels of oxygen in the water in most reservoirs. Likewise, the oxygen is also reduced in the waters below the Thermocline to the extent that fish cannot survive. 

So how do you find that comfort zone called the Thermocline? Well, as I stated in my last article, this is when it’s very important to know your depth finder and how to use it. Most of the newer depth finders have the capability to show you the Thermocline but not all of us have even tried to read it on our depth finders. The color variances in the newer depth finders is what is used to determine that depth and unless you have played with your depth finder a lot you may not even know what you are seeing when you do see that white zone. Most of the newer depth finders also allow you to turn on fish ID and set up the actual size of the fish you want displayed. Generally there are three sizes you can set up, Large, Medium, and Small, or a combination of these. I always set mine to Medium and large because I’m not looking for small fish. However, we also know that both Largemouth and Smallmouth bass follow their forage, which is shad in most Texas reservoirs, and most shad fall in the small category on your depth finder. So, there are pros and cons to not having small set up on your depth finder. However, you should also be able to identify shad pods in both down and side imaging easy enough not to require the small fish ID. 

So what should we do?? 

Well, what I do is pay more attention to what depth the fish are grouped in. Say you’re sitting in 40 feet of water and your depth finder shows the majority of the fish on the screen at 18-25 feet. You can almost bet that that is the Thermocline and the fish are stacked up in that line for their comfort. I’m sure you have also read many times that suspended fish are the hardest to catch and that it takes a lot to inspire them to feed.

Now how do we inspire those fish to get hungry and bite your baits? 

Well, the first thing you have to do is look at your arsenal of baits and determine what you have that can reach that depth. Yes, there now are some crank baits that can get down that far, but not many. Yes, a heavy spinnerbait can be counted down and slow rolled through that zone if you know, and have taught yourself, how to count them down. Yes, swim baits can also be counted down and then slowly retrieved through that level. Yes, swim jigs can also be done that same way. However, one of the most overlooked baits that can also reach that level is the “slabs”. It can be thrown out, aloud to sink to the bottom then raised to the depth of the fish and jigged up and down within that level and hopefully inspire the bite. 

One thing to remember is that fish also become accustomed to seeing baits and will ignore those that they have learned will bite them. So what to do since there are so few types of bait that will get you in that Thermocline zone? Well, use your imagination! When you get bait from your favorite tackle store there are probably 10,000 others that have also been sold to fishermen just like you. Get in your tackle room and change it up some to make it unique to you and the fish. However, also remember that all baits are supposedly balanced to operate at their peak from the factory so if you add something to one side you have to add the same to the other side or it’s not going to work properly as it comes through the water. Likewise, if you add some plastic trailers to bait it may also throw off the balance and render the bait useless. Keep in mind the balance of the bait and play with them until you achieve success. Add something and take it out and test it. If it doesn’t work, don’t give up keep trying until you succeed. Patience is the name of the game in bait modifications.

Well, I hope this has given you food for thought and some ideas that can get you on the fish this hot summer. If you have any questions and or comments please send them to and I promise I’ll get your questions addressed. Let me see the pictures of those bass you catch using your modified baits fishing the Thermocline. Now go catch a big’un!

Copperas Cove Leader Press

2210 U.S. 190
Copperas Cove, TX 76522
Phone:(254) 547-4207