My hunch is that many of our reservoirs and lakes are icing out as I write this (e.g. Am. Falls) or will soon ice out in the next few weeks. I would like to know more about the timing of "turnover" in Idaho's reservoirs following ice out and how fishing is affected. The information on the internet says that fish basically quit biting for about 2 weeks following "turnover".
I am using the word "turnover" to describe the phenomenon in which the water temperature profile inverts from the winter stack-up to the summer stack-up. Apparently there is oxygen depleted water on the bottom of the reservoir during the winter and "turnover" mixes this water along with bottom scum thereby creating a temporary fish lockjaw.
Hopefully, we can create a database for when the best (and worst)fishing occurs with respect to ice-out for SE Idaho places like Am. Falls, Bear Lake, Pali
es, Chesterfield and wherever else folks are interested in. I don't know how long after ice-out that it takes for this "turnover" to happen nor whether the fish stop biting at all let alone how long they quit biting.
Feel free to respond on here or by Private Message as you deem appropriate.
FR
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I have never noticed spring turnover on Pali
es but I did see it last fall..early October
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In my experience turnover can happen anytime in the first month after ice off. I'm not sure about the thermodynamics, but my understanding is if you get a pretty good windy day to stir up some water, it will turn over. I'm not exactly sure that the fish don't bite, but I think the cloudy water and abundant aquatic life being stired up make fishing more difficult.
That's my .02 cents.
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I believe in the turnover phenomena but it depends on the lake. The deeper lakes with a muddy bottom are the worst because the bottom gets stirred up and visibilty goes down. I do not believe that fish quit feeding it is simply that you have to put the fly, bait, lure right in the fishes face so they can see it. I always like fishing the edge of the ice as it draws back. I do not know the scientific reason why the fishing seems to be good for a couple of weeks along the edge ice, but it always seems to work for me. I have heard the fish scoop up bugs and stuff trapped in the ice as it melts?[crazy]
Windriver
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Thanks people. My successful experience trolling has been at Pali
es on the day of ice out in which the fishing was very good. It was good before ice out - fishing from the Indian Creek end during the period of recession but the ice out day was memorable.
I don't remember that type of action during American Falls ice out - at least not from the trolling aspect. It does seem like trolling there picks up in late April and May but my memory is a bit cloudy there. I think fate delivered ice out at A.F. the last couple days so us weekend warriors missed it.... It would have been a bit dangerous in a boat anyway with the winds that we had. Well, there may still be ice in the bays and hopefully that will keep the turnover suppressed for the weekend....
I hit Chesterfield last year as the ice receded and got skunked.
FR
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I googled lake turnover and it explains that water is most dense at 39 degrees. this is the temp of the water under the ice. When the ice melts this dense water sinks, less dense water replaces it at the surface and warms . the shallower the lake, the faster it happens. I think some lakes reach a point of the same temps at all depths, thus fish at all depths,thus harder to catch. At least the the excuse I'm using this year !!!
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Jacksonlaker,
Yes, I researched the turnover deal myself and you are correct about water being most dense at 39 F.
I am no expert, but based on what I read, the stable configuration both summer and winter will put the 39 F water on the bottom since it is most dense. The difference is that in winter, 39 F water is warmer than the remainder of the water profile (or certainly warmer than the ice at the surface and the water near the ice). The opposite would be true in summer where you have the coldest water on the bottom - that could be 39 F on the bottom or warmer since water becomes less dense with increasing temperature starting with 39F. It would typically become incrementally warmer as you head toward the surface during the summer.
The one report that I read said that after ice-out, there is a period where the surface water warms to 39 F and the middle is cooler and the bottom is 39 F, so density-wise you temporarily have a sandwich with lighter water caught in between. It takes wind or some other disturbance to make the top water shoot to the bottom where it mixes and displaces enough of the low-oxygen bottom-water to junk up the lake.
It makes my head hurt to think too much about this because it is pretty confusing. It is not clear why the 39F water on the surface does not slip down, one molecule at a time (water is a fluid after all), but there are enough people swearing to the phenomenon that I assume they have a solid basis for saying so. It sounds like water is pretty unique in that most other substances have their peak density on the bottom end of the temperature scale rather than in the middle. I guess we are lucky that water is the way that it is or there would be no ice fishing.
FR
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