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Posts: 1245
Location: Madtown, WI | I posted this on another board but thought I would open it to a bigger crowd....
OK, I was reading one of the articles in Esox last night on turnover and it got me thinking. This is totally BS theory but might be something to it.
Title….Turnover…the Oxygen affect.
We all know that below the thermocline the oxygen levels are extremely low, and not suitable for muskies. We also know then when turnover begins, this low oxygenated water starts to mix with the upper, oxygenated level. We also know that organic material is brought up from the bottom and mixed in as well. Organic rotting material uses up oxygen as it decomposes.
So as the oxygenated level begins to get diluted with low-oxygen water, and oxygen scavenging organic material, the overall level of oxygen in the column diminishes. This is greatly affected by the wave action that will speed up the dissolving of more oxygen (more surface area with waves). The waves also facilitate mixing and diffusion of the oxygen lower in the water column where the levels are mixing and the oxygen levels have been diluted.
So how does this affect fishing and why does fishing “suck” during turnover.
The oxygen depleted layer and the organic, oxygen scavenging material mixes with the oxygenated layer and lowers the overall oxygen levels in the water, especially deeper in the water column where wave action has less affect on the mixing action. The wave action intensity increases the rate of turnover and stabilization of oxygen levels. But, like last year, were we get a good stall…you might have lower oxygen levels, higher up in the column, longer then normal. Fish then do two things. One, they move shallow to get to more oxygenated water, or two, become inactive as their bodies react to the lower oxygen levels.
Still with me!
Now to me this theory on the surface makes sense. Few things thought that I would need to determine via research…and I am not interested enough to do the research!
1. When the layers mix, how low is the net O2 levels?
2. How long does it take for the O2 to diffuse down into the water column to replentish the O2 levels…with no mixing…with wave mixing.
3. How much O2 does the organic material use up?
4. Is this flex in O2 levels (If it even exists) affect the muskies?
The scary part is this can all be calculated…and at one point when I had more brain cells (Pre-alcohol days) I could have taken a stab at this….so one of you smart college kids get on this!
OK…Thoughts????
Cory | |
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Posts: 2515
Location: Waukesha & Land O Lakes, WI | This may sound simplistic, probally because I try to keep things as easy for myself to understand as possible.
When a lakes turns, its a drastic change.. drastic change, like a weather change, effects fish. Its my opinion that when fish get a spooking or encounter a drastic change they look for more oxygen. I've always had decent luck by going right to shallow weeds (and perferably as deep into them as possible) to find fish. Rivers and river mouths have always been good as well because they produce alot of moving oxygen and food.
I'm not a chemist, I don't play one on TV nor I didn't stay at a Holiday Inn Express last night. You can take all the O2 level mumbo jumbo and toss it. Common sense tells you that a lake is turning, when its turning the areas of least turmoil and most oxygen are going to be the best fishing areas. Its worked for me. | |
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Posts: 1245
Location: Madtown, WI | Well I guess I was going at the WHY part of it....not that we need to think in these terms on the water...more of a mental exercise I guess...The theory was getting at WHY it causes fish to go shallow...
I am with you though....go shallow...find the O2...find the fish... | |
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Posts: 32958
Location: Rhinelander, Wisconsin | OK, real quick for now:
1) The actual Turn Over period can be as little as 1 or 2 days if the temps drop fast enough. Keep in mind it's oxygen 'rich' cooling surface water displacing the water below the thermocline, as colder water sinks, warmer water rises, and the oxygen level shoud pretty rapidly replenish to an acceptable level as the column mixes and normal waves/currents occur. Algae and other decaying material will be dispersed throughout the column, unless you have a heck of a bloom on the surface which doesn't seem to stop the fish from getting right up into the pea soup, as I have seen on Pelican and Sabaskong Bay during the turnover 'bloom'. Also, muskies can and do tolerate low D/O levels better than many might think.
2) The traditional 'tough' turnover period has been considered to be after the temps stabilize top to bottom. I have always felt this is a big a factor as anything, as there is no temperature zone to search out throughout the system because temps are the same almost everywhere, except for the shallows which cool rapidly at night if temps fall hard, and warm quickly during the day if it's sunny. I look for shallow warmer waters like reeds on the windy shore (vegetation helps hold the temps up some and wind into those reeds pushes in the warmer surface waters from the sunny day before and the night wasn't bitter cold) if that situation exists after turnover first, then go to traditional primary break structure where the temps will be at least stable and the cover and prey I seek available.
3) Suspended fish will still be there if the prey is still there. Where there is food....
4) Some muskies spent the warm water period ( at least up here, where the temps never reached a critical point) suspended above the thermocline level, and some on the breaks, and some in the slop anyway, so there isn't any reason to search for them in the really deep, hard to cover water here in Northern Wisconsin because I can't troll. I pay more attention to light penetration, cover, and shadow, and fish where I think my coverage percentage will contact the most fish as a total presentation.
Nutshell, I agree with GMG on where to look first. If the lake is actually turning over, I go to a local river. Once temps hit the 50's again, it's go to the food and to the cover, and fishing high percentage water for me. | |
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Posts: 1023
Location: Lafayette, IN | Keep in mind that the "compost" at the bottom of the lake has already largely decayed/ decomposed. Oxygen depletion throughout the water column during turnover because of rising sediments would not be a real consideration on most bodies of water. Weeds seem to remain viable through turnover until ice-up. They wouldn't factor in much either I'd guess ("guess" being the operative word here).
Thoughts??? | |
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Posts: 8867
| I always figured that since the thermocline is now gone and the lake has de-stratified that the fish are just scattered throughout the water column, and since all the sediment/goop/etc. is suspended in the water that the fish just have a difficult time seeing food. You know, like shakin up a snow globe -- just scatters all the baitfish and everything... | |
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BS Theory on Turnover