Stratification time again

June 29, 2013

As the water approaches the upper 80s stratification of the water column occurs on most of our area reservoirs. This stratification creates a layer of water where most of the fish will congregate to survive.

Many of our area waters are starting or have been stratifying, and therefore it is a good time to discuss this phenomenon once again.

The thermocline is a layer of water somewhere within the water column where the warmer upper waters are prevented from mixing with those at a deeper depth. This barrier prevents the interchange of nutrients between the two areas, which creates essentially two separate environments in the water shed.

In a water column that is stratified, the thermocline is an area between the warmer water up to the surface called the epilimnion and the cooler water below called the hypolimnion. The epilimnion is the upper layer that stays relatively mixed and the temperature is relatively constant throughout its region.

The thermocline is generally a relatively shallow region between the epilimnion and the hypolimnion where the temperature change is relatively large. The hypolimnion is the lower layer of water whose temperature is relatively constant.

Life is scarce in this hypolimnion region, as sufficient food and oxygen may be in short supply.

The thermocline is important to angling because it represents the deepest, coolest, oxygenated water for the fish to survive in. It is where most species migrate to and stay in during hot water conditions except for transient feeding activities.

Different lakes will have different levels where the thermocline exists, but different areas on the same lake may have different levels where the thermocline exists. Generally, most sonar graphs will show the thermocline. You may have to increase the intensity to see it, but it will show it as a dark area resembling constant debri/clutter.

Consult your instruction manual as they usually have pictures of what a thermocline should look like on your graph. Many of us striper fishermen using live bait will find the thermocline real quick when you realize that your live bait dies quickly at certain depths.

The thermocline on Granbury usually develops around 20 to 25 feet down. Lake Proctor develops the shallowest thermocline I have ever seen. At times on Lake Proctor som times on the top 10 feet of water can hold fish. Deeper and cooler lakes usually develop thermoclines at deeper depths.

This thermocline can change with the influx of fresh water or heavy wind, which can mix up the water. As long as the water stays warm and continues to heat, this thermocline will most likely be present. Some shallower lakes or ponds apparently may never develop a thermocline.

Use your electronics to locate fish. The thermocline will congregate fish at one level, making it generally easier to find them.

Now getting them to bite is another story. Try several different patterns and different sized baits. Stressed out fish may be more apt to hit a small bait.

If you troll, set your depth right at the thermocline. You may be able to find active fish by running your baits all along the thermocline level until you can find an active fish. Don’t be afraid to chum the water with diced shad as this may bring on the bite where nothing else will.

Concentrate your efforts around this thermocline in the summer, and your chances for catching fish will most likely improve.


Lake Granbury is currently about 7 feet low and water temperatures are around the 83-84-degree range. Some shallower creeks will be much warmer.

Sand bass fishing continues to be excellent on slabs and spinners. Sand bass up to 18 inches in length are possible. Black bass fishing continues to be good on many areas of the lake.

Squaw Creek water temperatures are approaching the middle 90s due to the power plant. Some good black bass catches near deeper structure on the upper ends have been reported on deep diving crankbaits and texas rigged worms.

Summertime hybrids are heating up at Benbrook, Lewisville, Proctor and Bridgeport. Live shad is the best option for these hybrids.

Fished Proctor this past weekend and the hybrids are good to 8.5 pounds. At least that was biggest caught in my boat on that day.

Possum Kingdom striper have been slow. However, a few good catches have been reported on live bait. A 22-pound fish was caught near Bluff Creek, and some other good catches were reported near the state park.

Whitney sand bass are good, with an occasional striper being caught on deeper ledges and channels near Whitney Creek and the Island.

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Category: Sports Archived