Fall turnover

[singingdog]

My favourite smallie lake turned over in the last couple of days. I was out Sunday and it was 65F and clear, clear, clear. I could spot boulders in 18' of water, and see depth changes just from the colour change of the water. They were hugging bottom, but still hitting.

 

I got out for a bit yesterday: 62F and about 4' of visibility. The fish either moved or had shutdown. I couldn't buy a bite, even on the regular hotspots. Looking forward to the post-turnover bite.....that's when the big ones start hitting.

[Jigger]

Thanks for the update sd. Post turnover is the best time of year IMO.

[Peps]

when would post turn over occur?

[Raf]

i suspect what you saw was not turnover - it's still a little early. i notice a lot of lakes turn around thanksgiving when temps hit 50s. perhaps big wind mixed the water up a little.

 

post turnover is any time after that happens.

Edited September 21, 2011 by Raf

[singingdog]

when would post turn over occur?

 

Depends on the weather, but it can happen within a couple of days of the lake turning over. Once the visibilty comes back a bit, and the temps stabilise, the fish will start to develop more of a pattern.

[msp]

Im looking forward to the fall feedbag but not looking forward to winter.I wish that fall lasted longer.

[fishindevil]

i was brook trout fishing last weekend up near the edge of hali forest and alqonquin park and there was still a nice thermal cline down at 20-25 ft with temps in the 62 degree range no turnover up there yet..?????

[eman]

how do you class turnover? when the surface water temp is cooler than the deep.

 

Why does it go murky....dieing vegitation?

 

 

[Terry]

turn over is as it sounds

the water near the top becomes colder then the water near the bottom

 

and as we know heat rises so the warmer water on the bottom moves tot he top bringing all the debris that was on bottom making the water dirty and even outs the temps

[Jigger]

From what I understand,its more of a mixing and restabilyzing of the water column. The dirty water can be a sign and, like others have said, it seems early. Rethinking it, theres usually a more drastic swing in temps. Water is most dense at 4degC, i believe. Thats roughly 39degF. Once that mix happens, the water temps are uniform for the most part. Once the debris in the water clears, you can bet that the water has started stratifying again. Geez, i hope that description is accurate! If any of that is inaccurate, please let me know! Could be what singingdog is seeing is the start of the turnover period?

[bushart]

Maybe---just guessin here---with the record high warm temps we had this summer---the lower water column temps were higher than normal----so it would'nt take too many cooler nights to cool off surface temps to actually get below the bottom temps

 

Maybe this will be a more regular occurence with global warming---ok Go!!!

[Harrison]

Thanks for the heads up.

 

I look forward to two turnovers this time of year. Fall and Apple.

[jedimaster]

Turn over starts when the Epilimnion(upper warmer in the summer) layer hits 50 degrees. Its at this point where the natural water movement will allow it to start to mix with the water in the Hypolimnion Layer(lower cold water at roughly 40 degrees)

 

To my understanding this is what the result is in the fish. The lowest layer in the summer actually has the highest density and the lowest abilty to hold absorbed oxygen. This is what pushes fish shallow in the summer(minus certain cold water species like lake trout. They suck up the lowe O2 content in favour of the colder water.

 

During the turnover (when the surface temps reach 50 degrees) the water starts to turn over. The bottom water starts to rise (generally on the West End of the lake first as this is the natural flow of the lake due to prevailing winds). Surface water goes east, bottom goes west and up. You get the dirty water, as well you will get a sulfur smell from all the rotting debris in the bottom of the lake producing methane. The fish are pushed deep to get away from methane rich water. This shuts the fish down as they they are now in new areas, new temps and new o2 content water.

 

Once the turnover is done, and the water stabilizes. The bottom water is now clean of methane and is oxygen rich, the fish continue to move deep and go on the fall feed bag and are very active as they have adjusted to the new water temp, are in highly oxygenated water low in methane. Often fish will clump together in schools that don't normally (like largies)..

 

Anyway thats what I was told some time ago, and it kinda makes sense.

[kickingfrog]

Cold water has an increased capacity to hold dissolved oxygen.

 

The bottom of a lake that stratifies (yes at about 4 degrees C) can and does hold a great deal of dissolved oxygen but due stratification this D.O. cannot be replenished until the lake turns over in the fall.

[jedimaster]

Sure, eitherway less o2 deep in the summer, lots of o2 after the turnover in the fall.

 

Cold water has an increased capacity to hold dissolved oxygen.

 

The bottom of a lake that stratifies (yes at about 4 degrees C) can and does hold a great deal of dissolved oxygen but due stratification this D.O. cannot be replenished until the lake turns over in the fall.

[LucG]

This is a very interesting topic. The first time I've ever heard about "the turnover".

 

Its nice to know why the fish go on a feedbag in the fall.