3/4 acre pond, 10' deep, western N.Y.

I had some really nice bluegills in my pond, probably 40 or so real lunkers along with quite a few smaller ones, some perch and last fall I introduced 20 young lmb.

Ran the aerator 24/7 all winter, just like last winter. This spring it appears that every one of my big gills didn't make it. Just finished scooping them out of the pond along with a few smaller ones. Haven't found any lmb or perch dead.

I was thinking that maybe they were just old and over fed and without being fed all winter, they just couldn't make it. What scares me is tonight while scooping out the corpses, I saw a medium (6") gill dying in shallow water. He looked fine but obviously wasn't going to make it.

I tested the water with my little test kit and nothing seems to be bad, ph, nitr.,ammonia ok. Any ideas of what's going on and what I should do?

Oh, the water all comes from rain or a swamp out back like it always has and nothing has changed with that. No runoff from fields or anything.

Tyler, have you had an especially frigid winter? One possible drawback to winter aeration is that it may eliminate a thermal refuge for the fish.

Yes, Anthro, it was a cold winter. But would the fish continue to be dying now that the ice is gone?
What should I do next winter to ensure I don't have a repeat performance?

Thank you for responding.

Tyler

One possibility is that the pond turned over.

your aeration is running now? Shallow or deep?

If you run in the winter you want it to be in shallow water 3-4FT. Main idea is just to keep the lake from being snow covered. The ice helps retain some warm water but the snow blocks sunlight which if left for an extended time is not good.

Depending on your weather now I don't think you need to run any aeration right now in NY

I think that 33 degree water on the bottom killed them, due to winter aeration.

I have the aerator in about 6' of water. It's about 20' off shore. I was worried about this but last year had no winter kill using the same setup.

I guess I'll have to set it in shallower water and perhaps not run it constantly next winter. I unplugged the aerator last night. Hope I end up with some of the bluegills left.

It's funny that I don't see any perch or bass carcasses or maybe I will later.

Thanks for the comments and suggestions everyone. I appreciate it.

Tyler

I'm struggling that aeration induced super chilling caused the kill. If I understand correctly, the fish died after the ice was gone and only the BG died. Also, the winter aeration was only in one small area and not in the deepest water.

My understanding...A spring turnover occurs when the surface water temp warms to 39 degrees(the temp where water is the most dense)and starts sinking. This water then mixes with the bottom water that is low in DO and high in nutrients and moves that "bad" bottom water up to where the fish are residing. This "turnover" can happen very quickly given the right weather conditions like a rapid warming air temp and/or a "warm" rain (rain warmer than 39 degrees). This mixing (turnover) of top and bottom water will continue until the entire pond reaches 39 degrees. It is my understanding that it is not unusual for only one size class and species to be impacted. This happened in a lake near me a couple years ago. The only fish that died were all the large gizzard shad and they pretty much all died in 24 hours or less. The entire shore was lined with big dead shad.

Fall turnovers also occur and are similar in that as the surface water cools to 39 degrees in the fall it sinks and causes a similar mixing with bottom water.

Tyler,

Did your kill occur shortly after or during a significant warmup and/or rain event?

Bill D

By their various states of decomposition, I would say that most died mid winter and just a few look recent. Our ice has just gone off here in the last week and a half.

Saw another one in the last stages of life this a.m. Looked to have some white growth around his mouth, almost like a fungus. Otherwise a nice looking 6" gill.

Ah, ok. I misunderstood. I thought they all died after the ice was gone.