The Wolter Report Feb. 9 2017
Max Wolter, DNR fisheries biologist, Hayward: Once again, in early 2017, we find ourselves in the midst of strange weather patterns. The little snow we had covering the ice on frozen lakes in northern Wisconsin essentially disappeared due to wind and warm weather. So – what does it mean for fish when there is no snow cover on the ice? From a biology standpoint, it can generally be good. Like terrestrial plants, aquatic plants need light to produce energy. This is true under the ice as well. Light penetration decreases when even 4-6 inches of snow covers the ice. It is under these conditions that plants and algae start to use more oxygen than they create and oxygen levels start to drop, creating the risk of winterkill of fish. Some have experimentally tried manually clearing snow from the ice to promote winter fish survival, but in general, most do not consider it feasible. It would mean keeping about 15 percent of a lake’s surface area snow-free for almost the entire winter, including periods when it may not be possible to drive plow trucks on thin ice. Up to this point in time, the lack of snow cover on the ice for the first two months of winter 2017 points to good oxygen conditions for fish.