Thermocline--??

[Fish on]

Easy question- what is it? How do you detect where it is on the particular lake? How do the fish relate to it?

[Skyman]

Your fish finder will usually pick up the thermocline. It'll be a bar running across your screen at the same depth no matter where you are on the lake. It looks like bubbles or baitfish but it continues across the whole screen.

Around here we generaly get two thermoclines. The first major will be from 15' to 25' down and the second minor will usually be around 40'. When scuba diving the thermocline is strange. Sometimes the sediment will float on top of the top thermocline. You think your on botom but you can swim through it and down another 20 to 80'.

[MuskyDave]

Skyman gave a good explaination of finding the thermocline. The best way to explain it, is that it is the seperation between oxygenated water (warmer) and less oxygenated water (colder). It sets up in lakes in late spring/ early summer and can range in depth from 15 to 40 feet or more depending on the water clarity.
The other part of your question, how fish relate to it is this. There is less oxygen below the thermocline so fish that suspend will set up above it. This also is a good way to find it, by how low the fish are suspending. This will show by their location in open water, and the depth they are found. Very few, if any, fish will be under the thermocline because of the limited oxygen at those depths.
The thermocline also turns upside down in the winter. In which the warmer water is lowered to the bottom and the colder water moves up to the surface. This is called turnover in lakes. When this occurs in lakes the fish then can be found at lower depths in the lake then during the pre-turnover periods.
This is my understanding of the thermocline, and I hope it helps with your's. If I have missed or not touched on something, I know there are very knowledgable people on here that can help to clarify anything that is still not understood.

Good luck and remember CPR saves Muskies to grow.

[Sponge]

One thing to remember too is that on larger lakes, especially w/ wind, the thermocline may be different in certain places on the lake. Your finder can help there also. The above posts were great answers; I also watch to see where most of the fish are suspended.

[esox14]

Another thing with finding it on your finder make sure your not in Auto.. To find that line you have to get in manual and start your sensitivity at 50 and turn it up slowly till you see that line. Get where all the fish are suspended first and you'll see it. Depends whether you have a newer finder or not though too.

[MuskieKid]

Good info. here - Thanks