Themocline Question

[FishingApprentice]

I'm relatively new to bass fishing and trying very hard to learn. I fished in earnest last Summer for the first time. This Summer I'm trying to get more serious: watching videos, reading books, buying equipment, etc.

I was hoping some of you more experienced folks could tell me if I understand the thermocline and its implications rightly. As I understand it, the fish will (virtually) never be below the thermocline. So, by figuring out the thermocline depth, I can rule out fishing (hopefully) some large chunks of the lake. If fish are in an area of the lake whose depth is greater than the thermocline, they are "suspended over deep water". Am I on track so far?

A few weeks back, I set out to find the thermocline in my local lake. Following the prevailing advice, I set the fish finder's sensitivity very high and watched for a line to appear. Hmmm, but alas, no line.

Figuring my fish finder was not high-end enough, I bought three Vexilar Deptherm thermometers, tied them two feet apart to a rope that was 22 feet long, and dropped them into 30 feet of water. The readings said it was 80 degrees at 20 feet down. Incredulous, I repeated. Unless those thermometers are outrageous and habitual liars, the temperature is about 78 degrees at 22 feet, 80 degrees at 20 feet, 82 degrees at 18 feet, and the surface temperature is about 84 degrees.

Does this mean there is no thermocline? I'm more confused than when I started. Am I reading the wrong articles about thermoclines?

[Lund Explorer]

Usually, you'll see a bigger temp difference than just the couple of degrees you're seeing, but it is possible as so many thing determine the depth where a thermocline forms, if at all.

It may have to do the the length of time you left the probes down.  Or, you may have to drop them deeper as 30' seems rather shallow.

Not bass fishing related, but the thermocline in parts of Lake Michigan (for salmon fishing) is approach 90'-120' this summer.

[Glenn]

Here ya go!

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

[WRB]

To quote Catt "location + timing + presentation = bass.

The thermocline can affect 1 part of the equation "location". Bass need food and water with sufficient DO and survivable temperatures.

The old saying; find the food and the bass will be close by, is good to remember.

Using your sonar unit, look for baitfish or bass and note what depth level you see them. If you can meter the thermocline, then you will know the maximum depth the bass should be and what the life zone is; the depth where the baitfish are located. Bass prefer to hold near the thermocline, when a thermocline has developed. However suspended bass near the thermocline are not always the active feeding bass you want to catch. Active bass will be close by the prey they are feeding on.

WRB

[Tucson]

Here ya go!

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

Good article, thanks for the link.

[Wayne P.]

I was on the water yesterday and saw on my sonar display what looked like a thermocline around 20'. The max depth in that part of the lake is 31' and I was sitting in 22'. I checked the temp on the bottom and it was 61 degrees, at 15' it was 74 degrees, and at the surface it was 88 degrees. On the display the very beginning of the sonar returns was at 13' and the thickess return was at 20'. That gave me the pattern for that part of the lake. I fished the structure elements at the 12'-15' level. Caught a couple dozen bass doing that.

[Raul]

Thermocline = suspended bass, nope I don 't think so, thermocline = sometimes suspended bass, sometines not is more likely.

It 's important for you to know how to differentiate what you see on the screen and what it 's telling you, let me put you an example, in my neck of of the woods bass live in the same lake where you can find carp, bluegills, minnows, tilapia; from those species the one most resistant to low oxygen levels are carp, carp can survive in water with oxygen levels of around 3 ppm, bass and other species prefer more oxygenated water ( 3+ ppm ). Depending on the depth of the lake a phenomena like a thermocline may or may not be present, some lakes present it others don 't , and where it can be present it may not be visible on the screen, what tells me there is a thermoclin is the distribution of the fish in the water column, if I don 't see any fish below a certain depth and the climate pattern is associated to the climate patterns that create the phenomena of thermocline it 's safe to suppose there is a thermocline even though it doesn 't appear in the screen.

Let 's say that as I roam through the lake I see fish up to a certain depth and don 't see fish below that depth I suppose there 's a thermocline, now I know that carp are more tolerant to low oxygen levels, to me any deep fish I see on the screen is a carp, so if the deepest fish I see is, for example, 15 ft deep I won 't fish anything below 15 ft, surface to 15 ft is ok, below that, there 's no point in me wasting my time, and to make it even more specific, I won 't fish below 13 ft. So from all the surface and depths of the lake I have reduced the search by a lot.