The summer heat always brings out tons of fisherman that don’t fish the rest of the year. Many anglers associate summer with fishing and rarely fish outside of the spring or summer.
Of the four seasons, the summer is one of my least favorite. It’s a great time for really whacking-n-stacking a ton of channel catfish easily.
The fishing can be great but the whole “scene” on the lakes and reservoirs in the summer leaves a lot to be desired. That’s everything from the masses of water ski boats and jet skis to fighting the summer heat, especially here in my home waters. Each and every summer I wish I had access to a big river system that I could fish.
The brutal summer heat causes some changes in lakes and reservoirs that don’t have moving water.
If you live in an area where the water warms significantly these lakes and reservoirs will develop a thermocline.
There’s a long drawn-out explanation for a thermocline that’s super scientific but here’s what you need to know…..
- Lakes and reservoirs that don’t have current will typically develop a thermocline in the heat of the summer.
- The thermocline is a layer of water towards the bottom that has no oxygen or very little oxygen.
- Fish can venture below the thermocline to feed but they can’t stay there for extended periods of time.
- Thermocline plays a significant role in how you approach fishing for catfish in the summer. Not only where you fish but the techniques you use as well.
How To Find Thermocline On Your Sonar Fishfinder
I’ve covered a number of tips recently on choosing and using fishfinders. Following these videos, I had a number of questions about using a sonar fish finder to find the thermocline so I wanted to take the opportunity to answer these questions and walk you through the process.
If you’ve got a sonar fishfinder you should have no problem locating the thermocline in lakes and reservoirs assuming it exists and you’ve got your fishfinder installed and set up correctly.
You can use any of your sonar types (2D, DI, SI) to find the thermocline but I prefer to use my down imaging sonar first (but the 2D sonar is a good alternative).
To locate the thermocline on your graph you’ll need to venture out to water that’s deep enough for a thermocline to exist. This will typically be water that’s deeper than 21 to 22 feet.
Once you’re in the deeper water, go to your down imaging or 2D broadband sonar screen and drive in a slow straight and watch for a line in the lower part of the water column running across your sonar screen.
You may see some fish on the sonar unit below this line here and there. It’s not uncommon to see fish suspended just above this line also. That “line” you’ll see is the thermocline.
If you don’t see this line on your screen then begin increasing the sensitivity setting slowly until the thermocline appears.
I walk you through the whole process in the video above and show you some “real-time” fishfinder views from my Humminbird Onix 10 onboard my SeaArk ProCat 240 so you can see exactly what the thermocline looks like and how the adjustments impact the view.
It’s a simple process once you understand what you’re looking for and how to make the thermocline appear on your screen. It’s also a good general rule that if you can’t see the thermocline on your sonar screen without increasing the sensitivity you’re probably running your sensitivity too low!