Hot Sun… Cool Bass

The hot mid-day sun reflection shimmered like fluorescent streaks on the lake’s surface.

My fishing pal and I idled slowly towards the back of the heavily shaded, narrow and winding creek channel. I was certain my body was experiencing a core meltdown as I headed for a heavily shaded, sandy point for a brief respite from the blistering rays of the mid-day sun.

During the long, hot days of summer bass prefer the thermocline water layer. If the water surface temperature is 75 degrees, the thermocline layer can be anywhere from 50 degrees to 70 degrees.

Opening the cooler and handing me a bottle of ice-cold thirst quencher, Mickie Bohlmann and I squinted at the heat waves rising from the water on the main lake, saying a small prayer of thanks for the ancient tree-lined channel. As we sat enjoying a long sip of water in the cool shade, my fishing partner said, “I love to fish in the summer. But why do you think it is the bass are so much harder to catch during these long, hot days than they are at any other time of the year? It seems like they just disappear.”

Turning to me she said: “Oh, tell me, great and knowledgeable fish shaman, what do you think?” I almost dropped my coveted bottle of quencher.

One of my best friends, and a frequent fishing buddy, who is considered one of the local resident experts on the lake we were fishing, was asking me what I thought? I gazed at her in amazement for almost a few moments before answering. I could tell from the expression on her face that she knew what was coming.

Hot Weather: Where Do Bass Go?
I pulled myself straight up in the seat, sat my bottled water down, and with my best, Doug Hannon, bass-professor voice, said: “Why Mickie Marie, I’m surprised at you, they go where it’s cool — naturally.”

Mickie had seen this look, and heard this voice, on more than several occasions, so she settled back in her seat and prepared for one of my frequent dissertations on fish behavior.

Clearing my throat, “Hummmmmmph?..” I said, “Where do the bass go in hot weather, you asked? Like you and I, my dear old pal, bass seek comfortable surroundings.”

And so the lesson began.

Most reservoirs, other than northern lakes, stratify into distinct layers in the summer. And there is a definite like between bass behavior and water stratification. These three layers of water are called the epilimnion, thermocline and hypolimnion. The epilimnion is the upper warmest layer, and the hypolimnion is the deepest, coldest layer of water.

As summer wears on, the temperature of the water in temperate climate-zone lakes increases to a point where fish find the warm water of the epilimnion intolerable. If the surface temperature of the lake is 75 degrees, the epilimnion layer will be 70 degrees to 75 degrees, too, and much too warm for bass.

Bass during the long hot days of summer prefer the thermocline water layer. If the water surface temperature is 75 degrees, the thermocline layer can be anywhere from 50 degrees to 70 degrees. The thermocline layer also has more oxygen and an available food supply.

The hypolimnion layer is the colder water on a typical lake, but is almost devoid of oxygen because of plant and animal decomposition. If the surface temperature is 75 degrees, then the hypolimnion will usually be anywhere from 39 degrees to 55 degrees.

The Thermocline Layer
I glanced over at Marie just to see if she was still paying attention. She looked a little sleepy, so I began hip hop singing to the rhyme of the ancient angler: “Thermocline, Oh, Thermocline?. You are such a friend of mine?. . You hold the fish I’m looking for?. What bassin’ friend could ask for more?”

Mickie started awake, but I couldn’t understand what she was mumbling under her breath. Ignoring her mumblings, it was suggested that she pay closer attention to what I was saying. “Since the thermocline holds the greatest concentration of oxygen during the dog days of summer, it’s more than likely where you’re going to find bass.”

The lesson continued.

The thermocline can be found by measuring the water temperature at various depths with a recording thermometer. You’ll find that the thermocline layer will be of varying temperatures, cropping an average of 1 degree for each 1.82 feet of depth in the warm months on the average or typical, lake. Since this layer of water is closely related to temperature it can be determined by two factors: size of the lake, and action of the wind.

The size of the lake is important because the larger the body of water, the lower the thermocline and related strata. Other factors in determining the thermocline depth, or existence, include the physical environment of the lake, and rains and streams entering into the lake. If the lake is extremely shallow, there may be no thermocline at all. Too, heavy vegetation in some lakes can affect the depth, or existence, of the thermocline.

Wind action also affects the lake’s thermocline. For instance, if a lake runs north and south, the south end may be protected, or sheltered, by high bluffs or cliffs. If a heavy south wind blows, it will affect the south end of the lake very little and the thermocline will remain basically unchanged. But, the north end of the lake, which is unsheltered, will feel the full force of the wind and the thermocline on the north end will drop.

During late spring, when the lake is being warmed by the change in atmospheric temperatures, the sun warms the surface and the wind circulates this warmth from the surface to deeper areas. This circulation is usually maintained throughout the summer.

The thermocline is a level stratum. Being stable, it is close to, or on, the bottom over shoals and some shallow areas, positioned above the deeper holes. In lakes with gradual dropoffs from shore, the thermocline is one of the most important feeding areas — in the upper stratum — for bass. It is well to remember, however, that in very shallow lakes the thermocline may be absent.

Bass like the thermocline layer because of oxygen content and a plentiful food supply. They will leave the stratum only to feed. Therefore, the most active feeding periods for bass during the summer months will be at dusk and dawn. It is during these periods of the day that frogs, insects and other small creatures are most plentiful on shore, otherwise, the bass will have to depend on minnows, crayfish and aquatic insects found in the thermocline as their primary food supply.

Hot Summer Lures
During the dawn and dusk hours, a small lifelike topwater plug can usually entice a strike, but when the sun comes pouring across the horizon you’ll want to consider deep-diving lifelike plugs or plastic worms in the shad or crawfish colors. A bass spends most of its time at home during the hot summer months.

Home is usually found at the top of, and into, the thermocline in an average lake. And if you want to catch a bass, you have to practically ring its doorbell. Even then, it might refuse to answer. Without physically seeing its home, consideration of temperatures and weather conditions are necessary in determining the homeless.

Bass habitually move and feed in water temperatures that range from 70 degrees to 75 degrees, or more typically, 70 degrees to 72 degrees. There have been previous reports that bass feed in much colder water; however, they seldom feed in any water colder than 50 degrees.

In relation to the thermocline, bass will usually select a home within the upper part of the thermocline in the warmer half of the year. This is especially true of a typical lowland reservoir from late spring into fall, although variations above and below the preferred temperatures may occur in certain waters. In such cases, the depth of the actual home may also vary.

While you may find a bass at home, where it spends the majority of its time during the summer months, its feeding occurs outside its house or in a close area directly adjacent to it. The shallows and directly adjacent areas are the areas where most bass will do its feeding. This area between the home and shallows is known as the feeding route. All sizes of bass can be caught on the feeding route, and in the shallows, which is located near the lake’s bottom in those areas.

All sizes of fish can be caught on the feed, but the really big fish do not travel as far from home, or as often. The feeding route nearest home is the area of most feeding, most of the time, and especially most of the time for bigger fish. Bass are known to feed over weed beds and other obstructions that are five feet to 30 feet below the surface out in the middle of the lake.

Because they stay close to home — and security — the boundaries for a shoal of bass will not vary greatly and you’ll find that only the smallest fish will move into the shallows to feed. Bass caught in very shallow water are normally yearling bass in the foot-long class, or smaller.

The exact reason for the movements of bass, from the home over the feeding route are due to several factors; the most obvious being the movement of large numbers of forage fish and the related change in temperature during the summer months.

With a self-satisfied smile and what I felt was an exemplary explanation on the link between fish behavior and water stratification, I turned towards Mickie to see if she had absorbed my lesson on where bass go, and why during the dog days of summer. She was slumped in her seat, sound asleep!

If you want to catch those dog-day bass I hope you haven’t made the same mistake.

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