Percy Priest (elecronics question)

[brian graves]

In the summertime I really enjoy "night fishing" for crappie. An issue reading my sonar when looking for fish plagued me last year as well as again this weekend.

From the surface down to around 15 feet the sonar was FULL of red/blue. I had to adjust the sensitivity WAY down to get rid of it. Below 15 feet was normal. I belive it has something to do with hotter water and the thermocline. It seems anytime I run into that, that I never catch any fish. I ran all over looking for schools of crappie and never found any.

I'll try and take a screenshot next time. I was wondering if anyone else had that issue. I also wonder if it has something to do with me not catching any fish. when I can read my sonar/DI normally, I find and catch crappie. Not this past weekend.

[Dakota]

Hmm I haven't run in to that before? Yes screenshot it for sure next time.


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[TNBronzeback]

Yeah thats a new one on me too.
Surface clutter/clarity adjustment?
All the manufacturers call thier settings something a little different. Clutter, noise, rejection, ect.
If its just on top, it should be just a setting if your unit is working properly.
Thermocline will show up starting in like 30' or so on priest (depending where you are at) and extend deeper.
Either that or you keep finding the motherload of bait on the surface and its throwing your unit off. Lol.
In all seriousness though, if the bait is thick, it will throw off your depth sounding.
Yeah get some pictures next time. Alot of really good electronics guys on here.

[snowman]

I had the excact same thing last week...surface to 5 to 10 feet down

[Heiny57]

That could be bait if you are in coves or shallower water. I anchor over deep known hot spots and set out light. Then turn off sonar because it goes nuts with solid bait below.

[brian graves]

I'll be back out this weekend and look for it. Its really wierd. Its not baitfish. It was at 15 feet and as the water heats up it seems to go up the water column. Last year around August it was at around 10 feet.

It shows up even on my down-scan (HDS Gen2). on the down-scan/structure scan it looks like tiny bubbles.

I do believe its the thermocline. If I drop a minnow below it, they are dead within 30 seconds to a minute. Its crazy.

Heiny57, I've seen the same thing when anchored. I actually keep my sonar on to know how deep the bait ball is, and fish below it.

[Travis C.]

http://www.ultimatebass.com/bass-fishing-forum/index.php?topic=101221.0

Maybe this will either rule in or out the thermocline theory.

[Farley]

My guess is thermocline, thought I've found it to be slightly deeper than the depths you are seeing.

[TNBronzeback]

From what was described below and having and understanding of what thermocline is, i dont see how it could be thermocline. Thermocline is the distinct "line" created in the water where there is a difference in temp and oxygen levels. occuring in summer months where the surface is warmer and progressively gets colder as you get deeper. when i launch out of Long Hunter, i see the thermocline layer in that cove and depending on time of year and temp, its usually around the 20'-ish mark for example. so with that being said, your screen would be clear until the water gets deeper for the fish finder to pick up the thermocline layer, which would show up as you described as almost solid-full color. but if you are saying it starts at the surface, i dont see how that is physically possible since the colder water will be deeper.
i attached a google screen shot of a thermocline layer. you can see the hard line around the 20ft. mark and extends deeper meaning lower temps and less oxygen.
just my 2 cents on the subject. im no expert. lol.

[brian graves]

Travis, I ran across that thread when doing some web research. Thats exactly what my screen looks like, except mine's INVERTED. Its crazy. I see the high feedback/cloudy from 0-15 foot of water.

I'm wondering if I have some wonky setting on my Lowrance HDS Gen2, but I've been all over the web trying to modify the settings, etc... I've changed several around.

It looks just like this on both SI and Sonar, except inverted.
http://i238.photobucket.com/albums/ff167/WayneP_photos/Sonar%20Shots/3thermo.jpg

[agelesssone]

What you are seeing is the thermocline.
It has set up early on Priest because we have little to no flow of water on Priest due to lack of rain.
Turn down the sensitivity on your graph, I didn't notice what brand you are using but if it's a HB, pu the setting on clear mode, not max.
The thermocline is normally at 18-20 ft. Right now it is setting up about 15 ft due to lack of water flow.
Live bait will die when it is dropped into the thermocline due to lack of oxygen there.
Usually only carp, catfish, and gar will inhabit waters of the thermocline.

[deezelteck]

Have you tried a factory reset? Installed the latest updates? Make sure you backup all way points before doing either.

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[brian graves]

Well here's what I see on my Lowrance Gen2 HDS.

[FloatNFish]

I have noticed this at times as well. I always assumed it was small organisms moving in the water column during different light conditions. Anybody have any thoughts on this? I've never paid enough attention to it (I don't night fish much) but if this is what it is it will likely be more intense during a new moon and less intense during a full moon. See if it correlates over your next couple night trips. Also found this after a quick Google search: https://en.m.wikipedia.org/wiki/Diel_vertical_migration

[FloatNFish]

When I have noticed it there is a distinct change in sonar picture over a fairly short period of time with all the same settings on the graph.