As cooler temperatures start to move in and we plunge into the winter season, your lake or pond is going to enter into its winter stratification period. During this period of time, generally from late November to early April, cooler water is actually near the surface of your lake or pond, in the form of ice, and warmer waters remain near the bottom closer to the earth’s crust. As many of you know, this is opposite to what we see during the summer. A strong winter season accompanied by a layer of thick ice can lead to issues with your waters. Throughout the winter your lake or pond can actually start to lose precious dissolved oxygen below the ice where bottom waters are cut off from the atmosphere. Prolonged periods of thick ice, accompanied by a layer of blanketed snow cover, will stress fish and can lead to a winter fish kill.
Multiple factors are taking place in this situation. As we know our fish cannot survive in ice, and as the oxygen levels become depleted, fish find themselves compressed into a layer of water that isn’t frozen and has high enough oxygen to sustain their metabolic function. Winter can be very stressful on our fish especially in older waterbodies where oxygen consumption from decomposition is more pronounced.
In mild winters, in which ponds do not freeze over, the likelihood of a fish kill is lower than in cold winters, but nature can sometimes be difficult to predict. In northern climates a diffused bottom aeration system can been seen as an insurance policy to help protect your fishery investment over the winter season. A properly aerated pond is constantly circulating water from top to bottom preventing the formation of thick ice and allowing for efficient oxygen exchange year-round. Our staff is well versed in aeration design and implementation, if you have any concerns about your pond heading into the winter season, we would be happy to put together an aeration design for you.
Cater L Bailey, Aquatic Biologist AQUA DOC Inc.