Thread: Scientific Thermocline (lots of pics)

Originally Posted by DoubleGobble00

Two reasons come to mind. That being oxygen and temperature... I am sure all fish have a preferred temperature kind of like us. We can live outside in 100 degree weather but we prefer 70 degree weather inside our house. Also, the more oxygen the more active they can be so it makes sense that the less active fish are deeper in the cool waters just to be sluggish. Maybe they have their bellies full and just want to sit in there easy chair a while and be comfortable.

I assume the thermocline would be stronger (greater change in temp over less depth) and closer to the surface when you have several days with little to no wind. The wind seems to be the greatest mixing factor... Also, when you have some very windy days the thermocline would be weaker and deeper.. Does that make sense?

DoubleG

Yep, temp matters, as does proximity to cover, especially objects that provide alot of shade, and a nearby food source.

Here's something that I can't remember being said--the depth of the thermocline can vary in different portions of a lake. It'll be stronger and establish earlier further from rivers and other water sources and in shallower portions of the lake. Once established, it can take alot to break it up--thus the famous fall turnover that happens when surface water cools and sinks below the thermocline, eventually mixing the water sufficiently to destroy the thermocline. I don't think a few days of wind will do it, as wind essentially just affects the first few feet of water and most thermoclines set up at least 10 feet deep or deeper. That's also why you seldom get a thermocline on very shallow lakes (I'm talking 10' or less average depth)--the wind won't let it set-up.

Lot of good info here, thanks guys

I have never seen a thermocline here on Ky Lake.

Thermoclines normally occur in lakes with little or no water movement. Since Kentucky RLake is more a River Lake you probably won't see a Thermocline. I rarely see them on Truman Lake in Missouri when we have normal releases do to the amount of inflow and outflow of water. There are clines but not Thermoclines.

True; we've got them on river lakes in Ohio right now, because we haven't had enough rain or water flow to prevent it (dam flow is very low and water levels are actually dropping a bit).

Very good info. I don't turn my switchfire on set the sensitivity pretty high to get the thermocline.

Very good read....there are some smart guys on this site.

One of the most difficult things to figure out is if is a Water Density Change, Temperature Change or actual Thermocline (Absence of Dissolved Oxygen). The easiest way is to see where the fish and baitfish are since they can't live in low oxygen leaves very long. If they are above the Cline you might very well have a Thermocline.

Some would say this image has a Thermocline...I doubt it because the presence of fish below the line...



or this Humminbird Side Image...



Sometimes it's plankton and microscopic organisms rising in the water column.

Great read guys. Alot of good info. Fished-out, thanks for chiming in on the river lakes. I fish one of those OH lakes you speak of, EF, and always wondered why some summers the fish will be found deeper than.....well....this year. Guess it's the presence or lack of a strong thermocline from year to year. I guess I always assumed that since the lake was always "moving" that a true thermocline wasn't there. This is the first year I've payed much attention to it really. This post clears up a lot of questions. Definitely needs to be made a sticky.

Doug is correct about seeing fish below the cline. Here is what made me want to do this study. This was taken a few weeks earlier



Now are you confused??? LOL