Interpreting water quality information

[hovermn]

I was reading the MN DNR lakefinder write up on a lake that stated water quality was very poor and that fish spend the majority of time in shallower water, around 10' or so. Would the opposite hold true in the winter? Would deeper water hold fish? How should I interpret this info for ice fishing? I believe it's a combo of toxins in the lake, and O2 levels.

Maybe they wouldn't hold in the deepest holes, but would O2 levels be higher in deeper water during the winter months?

[hovermn]

Sorry, I mean to say that they spend time in shallow water mid summer when O2 levels drop.

[Religion_Of_Fish]

My understanding is this: Basically fish will hold in the upper layers in summer because there is a thermocline. Denser and more oxygen depleted water will be in the bottom layer of the thermocline, especially in lakes with lots of week growth, algae blooms, urban runoff, etc. In the summer you can typically find the thermocline, if there is one, on your electronics. In the winter there is no thermocline after fall turnover and the water is pretty mixed so fish are capable of moving throughout the water column, although if it is a particularly deep hole, water at the bottom of that hole may be a third layer that never mixes and has no oxygen. Fish are capable of moving around but are more likely to be following their food source, so if you find what the fish eat, you will likely find the fish.

If you can find sources of oxygen, ie green weeds, inlets with open water, these are probably your best bet rather than looking deep.

Not that fish aren't ever deep, as you are probably aware crappie will often suspend over deep holes with soft bottoms (again, it's all about a food source) and fish such as walleye can most often be found deeper during the daytime. But the pressure change from pulling a fish up 30 feet will often times kill them anyway so I tend to fish shallower. Fishing lake trout is a bit different since they have the ability to adjust to the pressure better.

[hovermn]

Thanks for the info. On regular lakes, that's the theory I stick with. However, in this instance, poor water quality is specifically called out, as well as a depth of which fish don't travel deeper than during the summer (max depth is 28 ft, few fish below 13 ft)

I'm just curious if things would "flip" during the winter months with the lake turning over.