Temps under the ice

Might try this ice thing out more this year, and got me thinking about water temperature. Understand the open water period in lakes, then turnover, but through winter, does it stay pretty consistent in the lakes?

Cold water sinks, and turnover happens typically well before the water is ice ready, so do most lakes turnover a couple times? Perhaps even when there’s early ice? Lets say the surface is 40 when she turns, then that bottom when mixed might be 45ish? It certainly gets colder after that. How much denser is 32 than 45 degree water, and would that make a turnover even happen? Perhaps the cold just trickles down, and evemtually everything normalizes then that basin bite jumps off? Anyone else ponder these thoughts and what are your conclusions? Does this even make sense?

Then it’s in to figuring out weeds and what they do, what kinds die, dormant, go away, which ones will now hold baitfish, I’m just getting used to summer tactics and throw in all this shtit a guy gets a headache.

A lot depends on the depth of the water and whether there is a current or not. Deep water seems to “layer” a little but nothing like the same water that is not covered with ice.

I have a submersible thermometer that is used for taking stream water temps. Its got a nice loop on the top of the barrel that I can hang on a hook. When I find active fish I like to see what the water temps are where the bite is happening and will take a minute to drop the thermometer down to that level and get a reading, then drop it to the bottom and again just under the ice so I can see any differences. The readings can be interesting and a guy can be surprised by what the water temps are a foot below 2 feet of ice.

H2O is most dense at 39 degrees. So typically your coldest water should be at the top, under the ice. It should then be 39 degrees at the deepest spot. Like Tom said current will change things and could definetly make some areas better than others.

If it were me, I’d drop a lure down the hole before I spent time measuring water temp.

biggill wrote:

H2O is most dense at 39 degrees. So typically your coldest water should be at the top, under the ice. It should then be 39 degrees at the deepest spot. Like Tom said current will change things and could definetly make some areas better than others.

Do you guys feel that in most lakes come ice, where there aren’t streams/rivers flowing in, or if there are the flow this time of year is so low it can be negligible come the main basin?

Does ice make current? I mean if you get a cold snap and you see ice forming rapidly that’s alot of water underneath possibly getting displaced.

I like the thermometer Tom. Although with Biggill I’d certainly pick off all the willing biters first, it would certainly be good to know not only that the spot is good, but why its good as well dropping it down and taking some readings. One more piece to the puzzle.

I think oxygen levels are more important under the ice than water temp. I don’t feel that in my experience water temp has ever had much of an effect on fish behavior in the winter time under the ice. At least for the species of fish I fish for…

Dissolved oxygen is directly related to water temperature. Warmer water, relative to being cold in the first place, carries more dissolved oxygen than the colder water.

Something a lot of people do not know or forget is that different fish species extract oxygen from water easier [better] than others. Some fish can exist in relatively oxygen poor water. With the average temperature down deep in Lake Superior running at around 44 degrees, oxygen should be of short supply yet Lake trout will often be found at depths well over 200 feet. The Sissowet strain of Lake trout in Superior have been found at depths over 600 feet.

Oxygen is a part of the equation just like water temperature is. But water temperature’s role here covers more than just the fish a person is after. It also plays an integral part in the forage base that many of these fish eat. Available light, the amount of light offered on a day to day basis also comes into play with much of the forage base. Winter fishing is a whole different animal and when trying to sort thru an aspect of ice fishing to learn more about that aspect it is not at all unusual to find that the aspect you are studying has ties to several other things that together play into the whole of the scheme of things.

This makes my head hurt… I’m going to stick with looking at structure and punching holes to find fish, possibly unsuccessfully lol. I’ve been out of college too long to read the textbook Underwater Conditions Under the Ice and Their Relation to Modern Freshwater Fish! Don’t overthink it!