Pond Boss Forums INTRO Questions & Observations Winter Kill ?

Can winter kill still happen even it you airate? Had my pond for 9 years and this is the first time i had a large amount of dead fish once the ice melted. The only ones i seen that were dead seemed to be the biggest ones. perch suckers and large blue gill. pulled out at least 15 fish that were dead. Didn't see any signs of live fish but i think it is too early for them to be active up north .

Damone, from threads I've read here, yes, you can have a winterkill with aeration present. I am absolutely not an expert on the topic, but remember reading some accounts from this past winter and our recent thaw where people who aerated had kills. There are probably a number of factors involved in analyzing what caused the kill, but one thing I've read is that aeration may create a kind of supercooling effect in the water that can have an adverse impact on some of your fish.

I hope I'm not way off base with these thoughts and look forward to reading what the experienced folks have to say as it's an interesting topic for me as a future aerator.

Hang tight for a qualified answer!

I don't know if I'm qualified but I have learned a few things the hard way!

I believe I've stressed fish with too much winter aeration but it's never caused me a complete winterkill or even close to it. My biggest pond is about 1/2 acre for whatever that is worth.

One thing to keep in mind is 99 percent of all fish kills are due to a lack of oxygen. So logically aeration, even too much, would not eliminate oxygen.

In most cases where you have a complete winter kill or almost complete winter kill, D.O. levels dropped to critical low levels due to one, some, or all of the below:

1.) Significant snow cover for an extended period of time, which blocked out oxygen production via photosynthesis. Usually the shallower ponds are more at danger as they have less of a reserve of oxygen saturated oxygen just before ice up. If there is no photosynthesis and significant snow cover it's only a matter of time before that reserve gets used up.

2.) A pond that has had a build up of sediments and decomposed matter for a period of several years or longer with either insufficient break up of the stratification, or no break up of stratification at all via a bottom diffuser(s). (During summer stratification.) This results in anerobic decomposition on the bottom vs. aerobic which creates toxic gases like hydrogen sulfide, and of course ends up using oxygen under the ice.

3.) Extensive macrophytes going into winter that die and use up oxygen as they decompose under the darkness of snow cover.

4.) Too many fish could use up oxygen faster with the above conditions, but it's only speculation on my part.