EXPLORING THE NIAGARA FRONTIER: Winter kill — coming to a pond near you

The winter of 2010-2011 was not a kind one for local landowners who have bass ponds on their property. Most ponds in eastern Niagara County froze over on Thanksgiving and didn’t thaw again until Easter. We weren’t blessed with the periodic thaws and rains that keep smaller local waters ice-free or a little open on occasion in the winter months.

The winter of 2010-2011 killed many a trophy bass 

like this one. Expect more of the same this year. 

(PHOTO CONTRIBUTED BY BOB CONFER)

That ice cap resulted in significant winterkill and many disappointed anglers that spring as carcasses of fish, large and small, washed up on the shores of those ponds. The ponds on our farm were especially hard hit – our walleye population was completely decimated and trophy-sized bass in excess of 5 pounds littered the shore.

It was really heartbreaking…you do everything you can to manage a decent recreational fishery for your family and then Mother Nature has her own plans.

In the years since, ponds faced with that adversity had recovered. But, it still takes a while to grow trophy bass in this area. They were finally getting there again.

But, as landowners were getting close to remaking their fisheries, this winter happened.

This hasn’t been such a drawn-out freeze over (most local ponds didn’t glaze until Christmas this winter), but the severity of the cold, the depth of the ice and the amount of snow cover atop the ice all mean that a winterkill is in the cards, and one that will likely rival 2011’s and maybe put it in the same league as 1977’s, which was noted for absolutely destroying what was an awesome pike and bass fishery at Ringneck Marsh in the Alabama Swamps.

What is winterkill?

Fish, like all animals, need oxygen. The oxygen that they breathe in from the water comes from two sources: The byproduct of photosynthesis of algae and weeds growing in that body of water and the oxygen that enters the water from the air.

Winterkill occurs when ice and snow together cover a pond and prevent both of those from occurring.

Ice cover will, of course, prevent oxygen from entering the water from the air and wind agitation. And, unfortunately, we’ve had ice on local ponds non-stop for almost two and a half months now.

But that’s not the primary cause of winterkill. If it was, most Niagara County ponds would have significant die-offs every year.

It’s the snow that’s the killer. Unlike a normal winter (whatever “normal” may be), we’ve been besieged with a lot of snow. Most ponds have been buried under snow for 6 weeks now and, especially in open farm country, many have 2 to 3 feet of drifting on top.

That snow depth prevents sunlight from entering the pond. Sunlight is necessary for photosynthesis which still occurs even in the coldest months. So, when the plants can’t get what they need, they don’t grow (and create oxygen) and then they die. Plant decomposition then consumes the oxygen that was needed by the fish.

The fish suffer and die a miserably slow death. Basically, they suffocate.

How to prevent winterkill

Winterkill can be prevented, allegedly, with small commercially-available windmills. But, they don’t work well in frigid winters like this as their wheels freeze over with ease.

Some folks also suggest that you periodically run a small outboard motor for a few hours at a time every few days. With wind chills in the -30s and the likelihood of freeze over on a daily basis, that’s also an impractical option.

Good pond management can also cut down on winterkill rates by ensuring there is not too much plant life in your pond (which consumes a lot of oxygen when it dies). To do that, you would have to use a weed rake in the summer and/or introduce grass carp to the pond (which we haven’t found to be very successful). But, you can’t remove all plant life, because you still need those oxygen producers to do their thing in the winter.

What to expect this year 

This winter has been bad, so it follows that the winterkill will be, too.

It’s more than likely that you already have a lot of dead fish in your pond. But, you won’t know it until two or three weeks after ice out. Their corpses are somewhat preserved by the cold water now, but as the water warms and oxygen is introduced to the water from the air, decomposition will speed up, the fish will become buoyant and they will wash up on shore.

Their bodies will be white, maybe even fuzzy, which is a fungus created by their rotting.

Smaller, shallower ponds without deep holes and a high density of plants and bass and panfish will be especially hard-hit. It will affect dozens of private ponds across the area and many public ponds that you might fish in Eastern Niagara County --- like the pond at Royalton Ravine Park, those in local golf courses, and the various ponds and marshes in the Tonawanda Wildlife Management Area.

If you are a fisherman it will be yet another depressing event from a depressing winter. This spring and summer, fishing might not be the cure for cabin fever that you had hoped it would be.



+Bob Confer lives in rural Gasport where he expects fish bodies to be piled up like cordwood. You can follow him on Twitter @bobconfer or email him at bobconfer@juno.com.


From the 05 March 2015 East Niagara Post