Turnover and it's effect on fishing patterns

[Lals]

I am guessing this is going to happen this week for the Metro. It seems for bass fishing, the patterns really don't change much with turnover but as the water gets colder (below 50 degrees) then it is for me more finesse but I know people have a lot of success with lipless cranks with temps even below 40 degrees which kind of blows my mind... Any opinions?

[mwal]

I do not think its turn over time yet. It does not occur till surface temp hit 39 dgrees. That is when water is heaviest the surface water sinks mixing all water in the lake eliminating the thermocline and oxygen dead zones. After turnover I have caught walleyes very deep and very shallow on the same day. Seems they can be everywhere. I tend to switch to larger suckers and chubs for bait. Trolling at night can also work with balsa cranks like Rapalas

Mwal

[TruthWalleyes]

Bingo. Got a ways to go yet. Water temps where i was fishing this weekend was 61.

[Hester]

Bingo. Got a ways to go yet. Water temps where i was fishing this weekend was 61.

I had about the same. 62-63 degrees

[RK]

Thank God for turnover. If it weren't for turnover, what would fishermen blame bad fishing on between September and November?

I can't think of any natural process that fisherman misunderstand as badly as they misunderstand turnover.

Turnover is very complex dynamic process, with so many variables it's hard to begin to identify them all. It varies from year to year and lake to lake and even within different areas on a large lake (different parts of Lake of the Woods turn over at different times, for example). As a result, how - if at all - it affects fishing varies just as much.

Some years, if there is a weak thermocline or a gradual cool-down, turnover can be so drawn out it's barely noticeable. On the other hand, if there's a hard thermocline, a rapid cool-down at the right time and with the right conditions can turn lakes over literally over night.

There's also no hard and fast rules about either temperature or timing. Turnover can occur at almost any temperature (although for most alkes around here most years it's somewhere in the low 50s). It's a function of thermal resistance to mixing, so it's not correct to say it doesn't happen until the water is at its most dense. Mixing starts when water at the surface becomes cooler than the water below it and sinks, creating convection currents. At some point thermal resistance is broken down by that current and can be accelerated by wind, other current, etc., and you have turnover.

How much thermal resistance there is depends on how stable the stratification is, mass, etc. A few summers ago we had a cool summer that led to very weak thermoclines and a fairly narrow range of min/max temperatures (low thermal resistance) within the epilimnion. Lots of lakes turned over during a late August/ early September cold snap, and barely anyone noticed.

Turnover is also very hard to detect without taking temperature profiles at depth. A lot of the things we identify as being evidence of turnover - crud floating on the water, dingy water, a funky smell - can sometimes happen concurrent with turnover but are also possible due to independent processes like decaying plant matter that increases fertility and triggers a late season brown algae bloom, for example. You see those phenomenon even on lakes that don't stratify and therefore never turn over in the first place.

(BTW - lakes turn over in the spring too, although it's more of a turn up than a turn over...)

Bottom line for me I guess is I don't worry too much about it. If I think a lake is turning over I look for stability, which usually means shallow water or isolated basins like bays, etc, or look for hard cover like rushes, wood, docks. Beyond that it's so unpredictable in terms of timing, duration, severity, etc., that it's almost impossible to account for in a rational way.

Doesn't stop my from blaming it when I lay an egg this time of year though.