In the image the thermocline appears to
go all the way to the bottom. Is this possible
or is there something I’m missing?
Thanks
SH
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In the image the thermocline appears to
go all the way to the bottom. Is this possible
or is there something I’m missing?
Thanks
SH
I'd be fishn and hanging round that 16fow area for sure......
Thermocline, as i understand it, isn’t a line but a separation of layers and yes, it will go deep. Low oxygen below keeps everything active above the layer and almost nothing below. Try this; put on a minnow and let it down 10 feet for 5 minutes. If it doesn’t catch a fish and screw up my demonstration, it will still be alive when you bring it up. Next put a fresh minnow on and drop it say 3 to 5 feet below the line on your graph for a few minutes. I’ll bet it comes up dead. It did when I tried it. No oxygen. If you’re trolling cranks, try to stay 2 or 3 feet above it and you’ll find fish when you find bait. Worked well for me in the TN summers.
I’d be trying to run along that ridge. Seems most of the time in the Summer, the fish love to hang out right at that point where the thermocline starts and stops.
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Is the drop-off a creek channel? Reason I ask is that on one of the lakes I fish I found an almost identical scenario and it was "within" the edges of a small creek channel (if that makes sense). Looked liked a thermocline layer but shouldn't have been one within the current of the channel, or at least I don't think it would.:dono
I have been scuba diving and encountered some serious thermoclines before and they are just as described. The water in the top of the water column is warm (~80 degrees F) and quite full of fish life. The thermocline itself is a fairly distinct sort of hazy line, where the visibility is blurry from the separation. The water below the thermocline can be downright chilly (~50 degrees F) and it is absolutely devoid of fish.
Several years ago I did a few technical dives to a downed Blackhawk helicopter that was in around 60 feet of fresh water and the thermocline was at around 22 feet. The water was comfortable above the thermocline, but bone chilling cold below. Visibility was bad, but worse at the mix line. After 25 minutes at the wreck I was losing feeling in my fingertips, the bare skin below my mask was numb, and it was time to go. On the way up there was a school of crappie holding on a submerged treetop off the bank a couple of feet above the thermocline.
Jim
interesting discussion!
does the thermocline show on DI better or worse?
Thermocline is readily apparent on di, and si, I don’t notice one being better than the otherQuote:
Originally Posted by river scum
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Here are my thoughts on the the OP image.
Im thinking that graph is showing only the top
portion of the thermocline. The bottom edge
of the thermocline is deeper than the 28.8 ft
shown on the graph, therefore we would have
to move out to deeper water to see the
bottom of the thermocline and the cool layer
of water underneath it.
SH
Good subject,
Hey Redge. Can you show an image
Of thermocline on si?
Thanks SH
I noticed what I now think is the thermocline on my home lake on my new Helix 8. This is the first unit I've had that has DI and SI and I could see the feature on both. This is a shallow lake and the deepest point I've found so far is around 23 feet. Is there a minimum depth at which a thermocline would form? Also, I assume that the thermocline could show up in different areas of the lake, but in areas that are deep enough for the separation to form?
This is a good thread.
If there is no water movement it can form pretty shallow, usually will not form in a main channels that has frequent movement like from hydro-generation and such. I had jug lines out one year about 50 yards from the channel set at 20 and pulled up 4 dead cats all around 5 lbs. but the channel was pulling water so it can be a very fine line as too where it is and where it isn't.
Quote:
Originally Posted by Sickle Hook
Thermoclines from when the density of hot water and cold water differ. The change in water temperature occurs rapidly in a a short depht change. Water will be warmer at the top and slowly cool down as you go deeper. When you hit the thermocline the water temperature and density will change rapidly within a ft or two. Unless there is a current the thermocline will separate the bottom water from the surface water.
As I diver I've hung in the water column vertically with my head above the thermocline and my feet below the thermocline. I required a full wet suit when diving belong the thermocline in freshwater lakes in the hot summer months. I also liked to dive off the diving boards and would often dive down to the bottom of the lake. It was very cold on the bottom and when coming back up you could easily feel the water warming up above the thermocline. Some lakes have two thermoclines. Some at 12 ft and the other at 25 ft or so. It depends on the water quality and the depth of the lake. Now running waters mix the water up so that thermoclines don't always form.
Some of the old stripper pits that I used to dive in where 60 ft deep and had a thermocline at around 25 ft and below that depth, the water was dirty and orange colored. We never went below the thermocline in that pit. It was clear for 100 ft at times above the thermocline and all the fish were swimming above the thermocline. Lots of sunfish swimming around 10 to 15 ft deep way above the thermocline.
The thermocline is not very thick. It's where the temperature of the water changes by more than a few degrees in just a foot or so of water depth. So the thermocline does not extend way down to the bottom. That area below the thermocline is called the hypolimnion. The area above is called the epilimnion. Most aquatic fish life lives above the thermocline during the hot summer months. After the thermocline breaks up and the oxygen mixed down into the hypolimnion again then fish can enter the deepwater again dn spend time down on the bottom of the lake in the cold winter months.
Quote:
Originally Posted by tstone
All you can tell is that the transducer was over shallow water and moved out over deeper water. It could have been the shoreline or a creek channel edge or an underwater hump or island. Unless the OP gives us more information about the area he was going over we won't know for sure.
If there is a strong current there won't always be a thermocline as the current will mix the deeper water with the surface waters and break up any thermocline.
I was just moving out from the shoreline to deeper water.Quote:
Originally Posted by Moveon
Thanks
SH
I’ll try and get one this weekend!Quote:
Originally Posted by Sickle Hook
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Attachment 351409 You can see some faint lines on the SI here...it was on auto that's why it's at 300 feet.
Can you give us your thoughts on
What’s happening in the OP image? Is it
a thermocline? I’m here to learn.
Thanks SK
Quote:
Originally Posted by Moveon
Another factor to ponder is that moving water will not have a thermocline, regardless of the depths. I fish a large reservoir and have never marked a thermoclone. Not to say that one doesn't exist, but I've read a lot about it and reservoirs where water is constantly moving will not thermocline. Same for rivers. I could be wrong, but this is what I've read over the years.
Thanks TK. Very interesting. Nice finder you got there.Quote:
Originally Posted by Central Minn
SK
I would think that is probably true about rivers because we catch catfish from 30 -50 ft deep in the summer.
But, what about sloughs that have depths of 12-20 ft?
So when somebody says the fishing will pick up when the lake rolls over with reference to thermocline, what is meant by that? Anybody interested in a pair of Cannon Mag 10s, (cheap). Lol
Quote:
Originally Posted by Crestliner08
Generally if there is a lot of water flowing though the reservoir and it's a small reservoir you are right. There are many kinds of reservoirs. Some are deeper than others. There are highland reservoirs and lowland reservoirs and some inbetween.
I fish a small 8000 to 10000 acre reservoir called Patoka Lake. It will form a thermocline in the hot summer months. It's an earthen Dam across the Patoka River which is a small river. Not a lot of current flows though the dam most of the summer. The flow rate though the dam depends on the water level in the reservoir and the water levels down river and the amount of rainfall.
If you are referring to "turn over" .... that's when the warm water above the thermocline gets a layer of colder water on top of it, causing the layer of colder (heavier) water to drop down thru the layer of warmer water .... essentially mixing the two. The faster and deeper the cold water layer forms, the deeper the turn over mixing will occur .... and that can stir up the bottom silt/muck, causing the lake water to turn brown to almost black (& let off a sulphur odor).Quote:
Originally Posted by yobuck