Let's Talk Thermoclines And Turnover

[Catt]

Thank you Roger!

I aint getting into this one again, do a site search

[MacP]

Therefore, even if fish were disposed to seeking specific

water temperatures (they are not), it would be inaccessible.

 

Roger

 

 

They may not seek specific temperatures, but they do react differently at certain temperatures.  I'd also add that fish DO seek more comfortable waters at certain times of the year.  In the summer, the deeper you go, the cooler it gets.  In winter, if the water temperature gets low enough, water molecules arrange themselves differently than you would think.  Warmer water is less dense.

 

A link:

http://faculty.gvsu.edu/videticp/stratification.htm

[RoLo]

They may not seek specific temperatures, but they do react differently at certain temperatures. 

[WRB]

To me water temperature is important to cold blooded fish like bass. Water temperature impacts their annual life cycle, spawning and natural distribution. For example Florida strain largemouth have a lower tolerance to water colder than 45 degrees and that limits distribution.

Look up Cold Shock and the stress that sudden water temperatures have on fish in general. Large die offs have occured as a direct result of sudden cold water thermal shock, it can be very stressful to warm water fish like bass.

To say bass will not seek cooler water during the summer if DO are OK and prey is available differs from my experience. Small bass may not relocate, some big adult bass will move when water temps approach 80 degrees or more and move deeper to the thermocline depth. Cooler water can absorb higher levels of DO then warmer water, plus pelagic fish tend to be deeper near the cooler water.

Keep in mind that cold water heavier until is 39.4 degrees, then it gets super saturated with DO and becomes lighter' floating toward the surface and freezes at 32 degrees.

Tom

[Nitrofreak]

Thanks guys !!!

 

Learning a lot , Rolo , catt , looking for that conversation you two had about this I guess from a previous thread can you point me in the right direction please

[RoLo]

Thanks guys !!!

 

Learning a lot , Rolo , catt , looking for that conversation you two had about this I guess from a previous thread can you point me in the right direction please

[WRB]

Rolo,

We have one lake in SoCal that reports the oxycline depths at various areas throughout the lake. Big Bear lake located at 7,000 feet altitude has both a good trout fishery and decent smallmouth/LMB population. The lake is a little over 7 miles long. the dam biult in 1890 and raised in 1903, old lake and not deep, about 35' aversge, 70' at the dam. BB freezes in the winter and the water may reach 70 degrees mid summer. This lake fits your thermocline-oxycline definition being 2 separate depths coming together late summer. BB also has a aeration system at the dam and tends to have strong westerly afternoon winds to help with aeration. Large weed beds in shallower areas.

Most of our bass lakes are highland class, deep structure lakes that are far different than Big Bear. I believe BB is similar to lakes in the northeast.

Tom

[ColdSVT]

This thread needs to be a sticky...good good info!

[RoLo]

 

Rolo,
We have one lake in SoCal that reports the oxycline depths at various areas throughout the lake. Big Bear lake located at 7,000 feet altitude has both a good trout fishery and decent smallmouth/LMB population. The lake is a little over 7 miles long. the dam biult in 1890 and raised in 1903, old lake and not deep, about 35' aversge, 70' at the dam. BB freezes in the winter and the water may reach 70 degrees mid summer. This lake fits your thermocline-oxycline definition being 2 separate depths coming together late summer. BB also has a aeration system at the dam and tends to have strong westerly afternoon winds to help with aeration. Large weed beds in shallower areas.
Most of our bass lakes are highland class, deep structure lakes that are far different than Big Bear. I believe BB is similar to lakes in the northeast.
Tom

[WRB]

Turnover

Lakes that ice over may have a turnover when the ice melts and in the fall, lakes that stratify durning the umber may turnover in the late fall. A turnover means the upper layer of water quickly mixes with the lower bottom layers.

This occurs because the upper layer out weighs the lower layer and the layers switch places; the bottom water comes up to the top. When this happens bottom decaying debris come up along with a distinct odor of rotten eggs or sulfur smell and floating pieces of decaying stuff. The water then continues to mix for about 2 weeks until it is homogenous or the same temperature top to bottom.

Most bass lakes cool slowly in the fall and turnovers may not be abrupt, however a turnover occurs.

How does this impact bass fishing? The water temperature changes, the DO level change, the baitfish and other prey all relocate because their environment has changed. After about 2 weeks the lakes settles down and bass can be anywhere at all depths depending on the prey distribution, aquatic growth, wind and water temperature. Tough sledding during turnover periods.

Tom

[mod479]

 

It shows up on my Mark-5x with a bit of messing with the settings. As you can see, those fish are below the thermocline and feeding on a school of baitfish above it. The layer is about ~3-4' thick and down just above the 40 foot mark. 

[mudkart]

Actual data showing both a thermocline and oxycline.

[J Francho]

I aint getting into this one again, do a site search

 

The goal here is to distill this info into one thread, not debate.  Though any discussion of points made is certainly welcome, especially if it can be backed with links or research.

[Nitrofreak]

Turnover

Lakes that ice over may have a turnover when the ice melts and in the fall, lakes that stratify durning the umber may turnover in the late fall. A turnover means the upper layer of water quickly mixes with the lower bottom layers.

This occurs because the upper layer out weighs the lower layer and the layers switch places; the bottom water comes up to the top. When this happens bottom decaying debris come up along with a distinct odor of rotten eggs or sulfur smell and floating pieces of decaying stuff. The water then continues to mix for about 2 weeks until it is homogenous or the same temperature top to bottom.

Most bass lakes cool slowly in the fall and turnovers may not be abrupt, however a turnover occurs.

How does this impact bass fishing? The water temperature changes, the DO level change, the baitfish and other prey all relocate because their environment has changed. After about 2 weeks the lakes settles down and bass can be anywhere at all depths depending on the prey distribution, aquatic growth, wind and water temperature. Tough sledding during turnover periods.

Tom

[RoLo]

It is my understanding that the fish , particularly bass , will for the most part suspend during this transition , do they just get comfortable when their environment changes as such ? , understandably there are many reasons bass will suspend , this turnover period is when it is most noticeable for me .

[DRH2O]

Further reading (warning maths and graphs!)

 

http://jmp.sh/v/W6me4ORBfpxrvLMfKPnD

 

I don't know how to rotate PDFs, if you save the images you should be able to read the document easier.

[WRB]

Bass suspend about 90% of the time, it's the reason they have air bladders. When bass are resting, not swimming, they are suspending at various depths depending on the depth they are acclimated to.

During the turnover the bass will be at similar depths they were before the turnover, they slowly reaclimate to new depths where baitfish are located.

Are you calling bass suspended in the mid water column "suspended"? Bass suspend in the mid water column off shore to rest throughout the summer months, inactive and difficult to catch. After a turnover the bass may suspend off shore for a longer period of time and remain inactive until everything settles down. I know from personal experience the bite is difficult to figure out right after a lake turns over.

Tom

[Mainebass1984]

Once fall turnover occurs up here in New England the fish become very predictable. Its my favorite time of year to fish. The tend to congregate leading to some fast fishing. Its one of the best times of the year for big bass in New England.