Thermocline And What It Means For Fish

[ten_scoach]

I'm still learning the basics of lake fishing ....grew up river fishing. Can someone please explain to me what the thermocline means for fishing? My basic understanding is it is where the water with oxygen meets the water without and subsequently, where the fish are. Generally speaking what depth is this on tr? Would the be a good time to pull cranks through that zone? Lookin forward to what you all have to say about the subject!

[fishinwrench]

The whole thermocline business is just one element of reservoir fishing that you have to put yourself through. But don't burn up too many brain cells or waste too much time pondering over it.....cuz in the end you'll discover that you can't depend on thermocline based patterns so it really doesn't mean squat.

[Bill Babler]

Wrench is correct on most of what he posted. The White River Chain however is a totally different animal. The thermocline dictates almost everything for us here. The White River is a series of clear water impoundments that were created by daming the river system.

The thermocline is a compression of the water throughout the system that creates tailrace trout fishing below its dams. These deep clear water impoundments are much different than most places in the world.

Here we have stradification, rather than turnover. The colder water compresses and sinks. The lighter warmer rises and compresses the colder water, forcing it down. Here on the White River we are talking about lakes with depths that can range up to 200 plus feet in some locations. No matter the season 200 ft. deep water never turns over with top water it remains deep.

Here is an example Lake of the Ozarks water can move thru the entire Osage River system in 48 hrs. with the dam at Truman and the dam at Bagnell at capacity. Table Rock takes 30 days to move water from Beaver Dam to Table Rock day it is about the same distance. 100 miles on the Rock and 90 miles on Lake O.

The thermocline is not only an O2 break it is also a temperature break. The break is usually to 55 to 65 degrees. Fish love to hang out at that depth, along with the bait that also likes it. We now have a solid thermocline on the rock at about 32 ft. Surface temps are still however somewhat cool for this time of the year at 83 degree, and as the Wrench alluded to it is keeping fish in this zone as well.

Here the spotted bass love to hang at the cline. LM and Jaws will remain active at much shallow and warmer temps than the K's. The K's like that cool deep water near the cline, along with lots of Kitty's and of course most of all the walleye.

Good fishing on the rock can be found to both suspended fish and bottom fish at the thermocline and the best place to start is 22 to 36ft.

Hope this helps

Good Luck

[ozarksfishin]

Bill hit the depths right on the head, the best way to describe the thermocline is its like our air conditioner in our house. When it gets hot outside, we don't want to go out in the heat unless we have to. The Kentuckys will pile up in big schools this time of year in the thermocline and once you find em, you can usually catch decent numbers of em. At least that's what us guide types hope for on a daily basis!

[huntest]

Bill and Phil, that's what I found this morning. Kentuckys suspended at 32 to 35 feet in 60 fow....several spit up crawdads

[ozarksfishin]

Lots of Kentucky s right now at that depth. Most of em we have been catchin have been spitting up crawdads and shad everywhere.

[Guest Brian B.]

I remember reading fishing reports years ago- when Tablerock was four or so years out from the big fish kill. (LMBV)

I seem to remember Rick LaPoint showing images of some of the healthiest Spots I have ever laid eyes on- he was using higher end sonar and bridge pylons or whatever you call them.. Fishing the thermocline and the schools and just entertaining the hell out of his clients.

LaPoint I believe was his name- point being, yes for the spots anyway it plays a big role.

The air conditioning reference is very accurate too. Now at certain times of the year the oxygen levels above/below the th-line can be drasticallly different as well.

Next we'll probably get intoa discussion on lakes "turning over".. That gets hard to digest at first as well.

[Rodmaker]

What is the best way to identify the cline depth.?

[Guest Brian B.]

My cheaper depth finders have always marked them, now keep in mind some times of the year the line doesn't mark. As well as other times of the year.

But right now you should be able to mark it easily. I would suggest turning the fish I'd off, and the sensitivity up a bit, just turn it up in steps while you are in 30/40. Foot or so, it should start presenting itself in. Short order. You probably want the auto depth range on so you are not fiddling with adjusting ranges.

(Sorry about the darn periods/ Blackberry junk)

But my Lowrances and Eagles- heck even the old Hummingbirds 100 and 300TX's all marked without too much playing with the settings.

I have seen depth finders show false fish when it was apparently the thermocline. This was on really grassy lakes, I suspect somehow air bubbles were getting trapped with floating grass at the thermocline due to the temp difference.

In July you should mark it very well.

[Bill Babler]

The thermocline will read on most HDS Lowrance units as some what of a heaver darker screen or depending on the sensitivity level you are running as a second bottom feature. ie if you know you are in 40 ft.it will tell you 40 ft. but your bottom line will show "example" 32 ft. It can also look like a heavy dark reading starting at the thermocline all depending on your sensitivity adjustment. I am running 83 percent and can see it easily. It just shows as interference at 32ft. over depth. Heavy water.

We have discussed turnover on the White River. That is pretty much a done deal