Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations Potential Winter Trout Kill

Hi all,

I have a 1 acre pond in Ontario, Canada. It is about 16 feet deep all around, as it used to be a quarry. Two years ago, I stocked it with 80 brown trout. They have been doing fine, although I don't usually see them. This summer, the surface aerator broke early on, and for the entire hot summer, there was no aerator while it was being fixed. The ice froze in December and was quite thick until around the end of March when it started to melt. Most of the ice was covered in thick snow, although one area was shovelled to make a skating rink. There were a few areas around the shore with small amounts of open water where pipes with groundwater were outflowing. Basically, I don't think there was a lot of oxygen for the fish, unfortunately, although it was the same this winter as every other since I've had them, with the exception of the aerator missing. Anyway, I noticed this weekend that there were a few dead fish in the small shallow areas I can see. There were about 3 in total, but I assume there are a lot more dead ones I can't see. I also saw about 2 live ones. I am wondering what I should do about this and if the dead fish will have a negative effect on my pond? How can I see how many fish are remaining? Any advice would be much appreciated.

Thanks,

Adam

Hi Adam. Sorry for your troubles. You should find the links from a member named "wbuffetJr". He is a graduate of the school of hard knocks for raising trout in a tough winter environment, and has posted lots of detailed, fantastic information on what he's done to keep trout alive with and without aeration.

Aside from that, other pondmeisters (and our professional mods) have noted many fish that die sink, and are never seen. Personally, I would rake out as many dead ones as you can. The decaying fish can add a lot of unwelcome chemicals/nutrients to your water chemistry.

But, on the positive, you've seen some live fish, so this confirms it wasn't a complete kill off. Perhaps the survivors will benefit from the lack of competition and thrive on the abundance of (extra) forage.

The two main options IMO to determine how many remaining fish are via hook & line survey vs. seine or shock survey. Shock (electrofishing) survey would be ideal, but isn't always available in your area (or in the 'pond budget').

First off let me say that I am FAR from an expert!! I have been getting my butt kicked at my place for years.

I am not sure how much reading on here you have done about Winter aeration. So you may know some of this.

I would say it is a safe bet that there are many more dead than what you can see.

Keeping a hole open in Winter is CRITICAL.

Worst case, if aeration goes down again shovel off more snow and get down to the ice. Sun can get through the ice and nature will make some DO for you. You can even shovel in strips and not have to clear an entire area though I would imagine the more cleared the better. Unfortunately this is not a viable option for me.

The good thing for you is that you saw some trout and that means you didn't have a total kill. It would be interesting to know if they survived due to the cleared off area for skating.

I may have lost all my fish AGAIN this year. The war continues....

Thanks so much for your response. I will definitely try to do a survey to see how many fish are remaining by using a rod and reel, since I don't have access to electrofishing equipment. I will take a look for the member you mentioned as well.

Thanks for your response. Having a pond that freezes over is certainly a challenge. I will try to get an aerator in as soon as possible, hopefully within the next two or three weeks. In the meantime, I will try to remove as many trout as I can, but it is hard since the pond is very deep. May I ask what you do in the winter to try and keep your fish alive? Do you keep a hole, and, if so, how?

I have been trying really hard to keep a hole open for 5 years now!

I have yet to be able to keep a hole open through an entire Winter yet. I built a stand alone solar system to power the aerator and our cabin up there. I have not yet been able to beat my condensation freezing up issue. Will be making changes and testing again this year. I have only had SOME fish survive one Winter. Not sure if any lived this year or not.

I do keep the aeration running all Spring, Summer and Fall though.

Hi Fyfer123,

Have a look at this thread:

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=504951&page=1

Haha I didn't want to bore him to death reading all that!

I will say I have to imagine Fyfer's conditions will be easier to keep a hole open than mine! I still have 4' or 5' of snow on the ground right now!!

I don't honestly know a safe way to keep a hole, as we go on the ice often, so I wouldn't want any chance of anyone falling through. I think clearing snow is the best option for me, as well as aerating for as long as possible.

Thanks, I will take a look.

That's a crazy amount of snow? May I ask where the pond is located?

You'll probably find some discussion in the PB archives on winter aeration and recommendations to place at least one diffuser in shallow water (say 1-3 feet). This would still allow some oxygen exchange to occur, and provide at least some increase in diffused oxygen (DO) in the water column. There is also discussion regarding 'super cooling' that may occur with winter aeration, and that is minimized by the diffuser being in shallow water. The kicker (in your case) is that trout are much more tolerant of cold water (and actually need it).

Mr Cody might chime in on that part, or maybe wbuffetjr.

I ran my shallow diffuser this winter, opening ~ a 30 foot hole. I have 3 dogs and ice fish often, and we didn't have any troubles. We stayed a good distance away from the edge of the hole (say 30-40 feet).

Our pond is at 10,000' elevation so "Winter" is much longer for us there.

As far as keeping a hole open safely, I am with Dr. Luke. I think you could have a diffuser in 3'-4' of water for Winter and rope off an area area around it so people couldn't get near it. Maybe don't shovel any snow anywhere near the hole so there's a clearly defined area to stay away from. Even if someone did get near it 3' of water wouldn't be near as dangerous as 16'.

Bill Cody has mentioned several times clearing the ice will work. I would do both at our place if I could.

I had my water down to 33.5 F degrees at one point in 2018. Not sure if that was the lowest temp or not. I had SOME fish survive that Winter for the first time ever. It is my understanding that super-cooling the water isn't a concern with trout.

Bottom line is if your aeration goes down, get it back up and going asap! I don't think there is a pond fish that is more sensitive to DO than trout!

You should look up posts by MNFISH also. He has done a TON with Winter aeration in Minnesota.

I will look into that, thank you. I am trying to find a way to aerate safely in the winter.

Yeah, adding an diffuser seems like a good idea. I am sure it would be safe if I do what you said. Why can't you have a diffuser running all winter in your pond? If your not going on it much, I assume safety is not a huge concern. I will also take a look at the user you have suggested.

I tried with one windmill first and it couldn't keep a hole open through the entire Winter. I then added a second eve bigger windmill and it had the same result as the first one. Then I built a solar system to power the cabin and run aeration. First year with it I didn't have my airlines run correctly and they filled with condensation,froze up and shut me down. This year we were able to run a 1/2HP pump all Winter, but it didn't have enough horsepower. The plume was to weak and couldn't cut through all the snow and ice. Will be running a 1HP pump this Winter.

I have access to power all winter, so I wouldn't encounter the same problems as you. I am going to look into some winter aeration solutions. I am also going now to try and retrieve as many dead find as possible and take stock of how many survivors there are. I appreciate everyone's help.

I would suggest putting your pump as close to the water as you can get it. Run the shortest airline you can and try to make it go straight down into deep water.