Researchers from Ohio tested the overwinter survivibility of white crappie. They discovered that only 47% of all young white crappies survived whenever water temperatures dropped lower than 39F for at least one week. This compared to 97% survival when water temperature never became colder the 39F. Addtional research found that neither large size nor feeding level (energy reserves) significantly influenced winter survival. Crappies that winterkilled had similar energy reserves to those that survived. They assumed extreme cold caused chemical inbalances that led to winter kill. Ref: Trans. Amer. Fish. Soc. 132:977-987. Cold northern winters: the importance of temperature to overwintering mortality of age-0 white crappies by A.B.McCollum, D.B.Bunnell, R..A.Stein. Via, In-Fisherman Jan 2006, R. Manns-Bits&Pieces.
This contributes scientific information to the theory that supercooling of the water by bottom aeration during cold winter temperatures can contribute to severely stressed fish.
Thanks, Bill. I certainly wouldn't be surprised is other cetrarchs such as LMB, SMB, BG, RES, etc. share similar stress problems. According to Dave Willis possibly YP, WAE, and NP may not be as susceptible. This is pretty important stuff for anyone who lives in northern latitudes. Very, very interesting!
Bruce :
I have seen a number of articles that note high winter dye off rates in northern waters of BG and LMB yoy probably as a result of starvation (not enough body lipids) to survive the prolonged cold temps. While not the same as Bill's info it is just another result from long cold winters.
Can anyone comment on what water temps should be under an ice surface? I've used my Aquavue camera on some bodies of water (sans aeration), and the temps were always right around 39 F.
Is that the norm?
If the water column is stable the water should be 32 degrees at the interface of ice/water. Then the temps should gradually increase until they hit 39 degrees near the bottom. 39 degree water is heaviest (most dense). I believe this is what Theo posted last winter.
I would think that temp extremes would have even more drastic results in warm weather climes. Sort of like the "rate of change of change" thing.
DD :
It is a good thing that water temps. do not make as wide of temp. swings as air or all my fish would be dead. One day in Dec. it is 85 and kids are out in shorts playing football the next day its 15 with 2 in. of ice. I think your temp. swings are worse than ours and with low water from drought it could catch you in a hurry.
Good post, Bill!! I hadn't seen that paper yet, and I haven't gotten my January In-Fisherman yet!! So, you are a great advance warning system!
DW - R.Manns had another excellent discussion in the same magazine section about long term growth rates of Florida strain LMB. This longterm study (17 yrs) was conducted by Texas Parks and Wildlife Dept.(Austin) and printed in 2003 as: Management Data Series No. 210; author R.G. Howells. Do any of you Texans know how I can get a copy of this report?? I would sure like to read the entire article.