Thermocline's (need info) :)

[WhiteMike1018]

So as I was reading in a book about a day ago I remember:

"Lakes that stratify will form a thermocline"

First, do thermoclines happen on every lake?

How does this affect the fishing? Fish above it ? or under it?

I also read a lot about pros seeing the thermocline on their depthfinder and fishing it accordingly, Ive looked for this and never found it, maybe because there is no thermocline in the lakes I fish?

The deepest lake I fish regularly is about 140 acres in size. It is an old sand mine pit that has a lot of deep points and standing timber, the deepest depth ive registered so far was 37 feet. Does this lake have a thermocline?

Thanks -Mike

[Low_Budget_Hooker]

The thermocline is a layer of water, temp related but dissolved oxygen and other factors also come into play.

Yes it will affect the fish below, in or above it.

You need a high end color graph that is designed to mark temp layers.  I'm clueless w/ the freshwater finders but my Furuno would show them perfectly, but again, that's a $5k unit.

It can be found in lakes that stratify (turn over) and in the ocean

I wouldn't stress on it, just fish

[reo]

We get them on Erie and the other Great lakes but I have never seen them in water less then 45' (total depth) so it is not really a factor for my bass fishing. It can be seen on "regular" fish finders but any type of 'fish ID' feature must be disabled. Shows up fine on my eagle fish mark 480. I would guess that it is a factor for the California type lakes where you are taking bass in DEEP water. On Erie the water below the thermocline usually has very little O2.

[George Welcome]

Mike,

Thermoclines occur in shallow as well as deep water. It is simply the area where a large temperature change occurs within a small distance. I have seen it in water as shallow as 6 feet, and of course in deeper water. Almost anyone that has swam in a lake has experienced passing though this change. Usually the majority of the water is below the thermocline.

In deeper water situations this can drastically affect the fishing as the DO drops as well as the temperature below a thermocline.

[Crestliner2008]

I fish a large (7 mi. x 15 mi.), deep, hill-land type reservoir here in MA (Quabbin). Some areas go well below 100'. The DNR says this lake stratifies and the thermocline sets up every year.

Three years ago, when I bought my boat, I had the marina install a Lowrance X-135. The book that comes with this unit clearly shows how you can set-up and "see" a thermocline. However, regardless with how I change settings, I've never "seen" a thermocline on this unit.

I think I agree with what has been previously said, in that you probably need a high-end, color unit to see and find it.

[Wayne P.]

"Horse feathers" about the high end units and color needed for thermocline locating. My Eagle Fishmark 320, Lowrance X70A, Lowrance 1240A flasher, and Humminbird flasher all show thermoclines-none of those are "high end" or color.

[Wayne P.]

Here is a low cost, low pixel count, monochrome, old Humminbird unit (LCR 4000 ) that shows and explains thermocline. Scroll dowm to page 31-----

http://www.humminbird.com/PDF/lcr4000.pdf

[Gatorbassman]

"Horse feathers" about the high end units and color needed for thermocline locating. My Eagle Fishmark 320, Lowrance X70A, Lowrance 1240A flasher, and Humminbird flasher all show thermoclines-none of those are "high end" or color.

Wayne I totally agree with you. If you turn your sesitivity all the way up you will be able to find the thermocline if there is one. It will show up as a cloudy section at a set depth. I have seen one as shallow as 8ft and as deep as 30ft. It all depends on what time of year it is, how hot it's been, water clearity, and many other factors.

Here are some BR articles on the subject.

http://www.bassresource.com/fishing/thermocline.html

http://www.bassresource.com/fishing/shallow_deep_fishing.html

http://www.bassresource.com/fishing/fish-locator.html

http://www.bassresource.com/fishing/hot_summer_fishing.html

http://www.bassresource.com/fish_biology/destratification.html

http://www.bassresource.com/fish_biology/water_quality_problems.html

[Muad Dib]

so say for example the thermocline is at 10 feet. should u be fishing at 10 feet or where. ?

[indy basser]

exactly, try to find a channel bend or ledge with cover that is shallower than 10 ft on top and deeper than 10 feet on bottom.  This allows the fish to move inbetween the cool and warm water as well as have a place to ambush prey.  Thermocline + structure + cover = tons of bass

[Brian_Reeves]

I really don't know about the whole thermocline thing.  I'd say that down deeper, where the water is cooler, I'd go with slower baits...which I do anyway to maintain bottem contact.  Carolina rigs and heavy jigs.  For shallow, hotter water, I'm burning spinnerbaits, jerking crankbaits, and swimming rage tails and ***, and flipping jigs.  Those are all faster.  So I guess I don't really pay it any mind.

[boatnik13]

I agree with Wayne P.!   I have located thermolcline with Bk / W depthfinders. In lakes under 40 ft. depths. I've used in the passt ie(Humminbird 2000, Lowrance X65, Garmin 160 ) and now Humminbird 3D in Black and White. The cold water layer will deflect a % of the signal and show up in diffrent ways but not as strong as objects. The 2000 showed a black line. The X65 used a gray shaded zone and the 160 showed up as a Lt.shade of gray with a blue type of filter to give it a blue haze on Bk/W screen.  In small lakes as originally talked about > I use dissolved oxgen meter to locate fish in summer over Thermo. anytime. As basser said > other items will pinpiont fish VS thermo alone. In lakes over 3000 acres . Ican see trolling the thermo. but not in smaller narrower lakes under 500 acres. In small lakes it depends on the head waters and rain fall amounts. They can change a lake water temp in hours.

[Crestliner2008]

Wayne P & boatnik13 - O.K., great...then tell me how you set your sonar to see it? I always set my ping speed at max and my chart speed at about 70%. My sensitivity is about 80%-85% normally. If I'm anchored I'll reduce the sensitivity and if I'm running, I'll increase it. I keep the ping & chart the same regardless.

What am I doing wrong?

[Wayne P.]

I see thermoclines without any adjustments of the sonar unit. Automatic setting for me. The older LCR units I have don't have ping speed adjustments and chart speed is not a factor in thermocline detection. With my flashes units, I set the sensitivity to show a double bottom echo so I can tell if a bottom hardness change has occurred.

[boatnik13]

Once again I agree with him and I know it sounds like a broken record but he who speaks first ( WAYNE ) is doing a great job! I also keep my depthfinders on factory set. I don't like steering away from them unless I 'm very intrested in structure but now I have aqua-vu to do the dirty work.  Now my 3D needs no adjustments and since I'm a map maker > I don't hunt fish or thermocline anymore. I also am looking at bottom composition and structure. I do record D.O. levels.

All my past finders have found thermo. on factory settings. You mentioned still fishing! I have to be moving I believe to get my best pictures. I'm in stained water all the time and dozens of lakes . Not all will post thermo. in the heat of summer and the ones that do show up are over 20 ft. depth and not extensive. I have found suspended Lmb in these area's that no one fishes just above the thermo at say 18ft. of 30 ft.  I don't remember what depthfinder you use> ??? Tell us.

[HesterIsGod]

Bass will not go below the thermocline usually, not enough dissolved oxygen. If you are able to locate the thermocline, just treat the top of it like you would the bottom of the lake.

[NBR]

You may be picking it up but not recognizing what you see. I have and Eagle 340p on the TM and an old Eagle Super Nav on the console. Both show the TC as a fairly narrow band that looks a lot like surface clutter. They need sensativity set at 85% or higher.

Maybe your lake doesn't stratisfy.

[Garnet]

I've seen termolclines  on every fishfinder I've owned but I deal with a lot of Lake Trout lakes. Current will stop the stratfication and hard wind driven currents. It's not likely a 37 ft lake will devlope thermolclines, springs might kept the bottom layer colder.

Again smallies are different than largies. Start at the level of thermolcline and work shallow. Smallies will be in open water waiting for Rainbows,Lake Trout and salmon to push bait up. So if theres no predtors and baitfish below the thermolcline skip this.

Garnet

[WRB]

So as I was reading in a book about a day ago I remember:

"Lakes that stratify will form a thermocline"

First, do thermoclines happen on every lake? No, however most bass lakes will develope thermocline(s).

How does this affect the fishing? Fish above it ? or under it? Bass are comfortable in warm water. During the summer water can get too warm; over 80 degrees and the bass will go deeper to find more confortable water around 70 to 75 degrees. Lakes that develope a thermocline; a layer of cooler water that changes temperature within a few feet, the bass tend to suspend within a few feet of the thermocline. Wind can create current and current mixes the water layers, this mixing can bend the thermocline deeper or in some circumstances it can dissapear for a few days.

I also read a lot about pros seeing the thermocline on their depthfinder and fishing it accordingly, Ive looked for this and never found it, maybe because there is no thermocline in the lakes I fish?

There has been some discusion on using your sonar unit to determine the thermocline depth. Most sonar units can be adjusted to show the more dense cooler water thermal layers, however you need to know what you are looking at. A good book for this is; Don Iovino's Finesse bass fishing and the sonar connection;

http://www.iovino.com/

The deepest lake I fish regularly is about 140 acres in size. It is an old sand mine pit that has a lot of deep points and standing timber, the deepest depth ive registered so far was 37 feet. Does this lake have a thermocline? Yes.

What you should be interested in is determining at what depth the bass and baitfish are holding. If you can meter the baitfish and bass, you should be able to determine at what depth around the lake the fish are holding. If the bait is around 20 feet deep around the lake and you see a few larger marks between 18 to 22 feet, then it's a good guess the thermocline is some were between that depth. Whats is important is the life zone where the fish are holding is the depth you should be fishing.

WRB

Thanks -Mike