[Capt. Lou]

This can happen in any inland lake , it has very little to do with temps but generally a lack of oxygen is the culprit . This varies in lake to lake your northern lakes like finger and gt lakes dissolved oxygen is available much deeper .
There is a lot of reasons for this variation in lakes which I won't go into here .
Local lakes all have depleted oxygen levels sans Round Valley and some other clearer water lakes that allows sun to penetrate and vegetation to grow and provide oxygen . In lakes wirh less clarity vegetation will not grow and thus no oxygen is made .
Fish locators have become the norm in locating thermocline but I can do the same with an electronic thermometer . If u know the temp range of the fish your after then just use thermometer to locate that depth , outline its thickness , fish within or above and your now fishing in correct water at least .
Once thermocline forms it will not break,but it will bend so the leeward lake side in wind will ride up, while the windward will push down , this occurs on larger lake primarily after several days of a heavy blow from a certain direction.
Early spring using your therometer or Ff with thermo you can locate these warmer water shorelines and get into fish quicker .
If you ever fished early spring on the Great Lakes you would quickly realize that even a couple of degrees in temp,could on any given day mean success or failure
Not many anglers downtemp locally Great Lakes guys live off those numbers, since many species such as offshore steelhead favor temp up and down and generally don't stage off shore
This outline is generally for trollers but bait fisherman can tap,into these methods and should to add a few fish to the cooler .