Free & Clear. In winters with limited snow cover on the ice, winterkill is not a concern. However, in snowier seasons like this one, anglers keep a close watch, especially on those smaller waters that have been covered for several months. Simonson Photo.
By Nick Simonson
By meteorological standards, we’ve made it through the worst of winter. Just like the hottest days of summer come in late July and August, a few weeks after the solstice, winter’s coldest stretch often comes in the final days of January. Then February brings with its shortened calendar the idea that March isn’t far away, and spring is just around the corner. However, what happens in the coming weeks is often telling in regard to the survival of both fisheries and wildlife. Winterkill for fish and lack of habitat for wildlife are often top-of-mind for anglers and hunters this time of year. One we don’t have much control over, the other there’s a lot we can impact.
Low O
For anglers, winterkill is often a concern, especially for those shallower prairie potholes which now sustain fishable populations of perch, pike, and walleyes through expanded management of the growing opportunities provided by a generally wetter cycle over the past 30 years in the region. When oxygen levels dip below two parts per million, that’s when fish begin to feel the effects of the lack of the vital dissolved gas. When thick ice and snow covers the surface of a frozen lake – as is often the case at midwinter – those remaining plants cease to provide oxygen through the process of photosynthesis, which requires direct sunlight for them to absorb carbon dioxide and release oxygen into the water for fish to effectively breathe. This slowing process is also compounded by the fact that oxygen levels decrease in smaller waters over the winter as plant materials break down as part of the normal cycle of decomposition after they die off.
Larger bodies of water don’t often face the challenge of winterkill. Lakes with depths greater than 20 feet are usually spared from fish kill events but can still suffer partial winterkills in shallower areas such as bays or lobes that are off the main body. Reservoirs, which typically do have some water movement even in winter, are generally safer from these events as well. Those smaller prairie waters with no major inlet or outlet that get buried in snow are typically of the greatest concern. While it is often hard to detect a winterkill until the ice breaks up and dead fish are found floating on the wind-blown side of a spring lake, anglers can sometimes smell it in the water when they punch late season ice holes. Throughout February is when many fish and wildlife agency teams do their sampling to survey for any potential adverse impacts winterkill may have each year.
Nowhere to Go
On the flip side of the coin, heavy snows of early winter have hung around, effectively extending the season from late fall to the current midway point. In addition, large snow events across the region have impacted the places that both upland and big game can go to stay warm and get out of the elements. Lighter habitat, such as CRP plantings, grassland acres and pastures have long been buried by that heavy snow and are effectively useless for cover at this point. Heavier options such as cattail sloughs, brush lines and even coniferous tree plantings has also been impacted by this season’s snowier start. These occurrences have greatly reduced the places both pheasants and deer can go in the cold, or alternatively have made finding shelter a bit more difficult, requiring the expenditure of more energy to get from their resting spaces to any remaining food sources such as fields or browse.
Unlike winterkill, however, where sportsmen and conservationists really can do nothing more than wring their hands and hope for the best under the water, habitat is something we can have an impact on. By working to improve set-aside programs and increasing awareness, effectiveness, and affordability of marginal land preservation options for operators, hunters can rest more assuredly on those cold winter nights that their favorite game have a better chance of making it to spring. On top of that, preserving cattail sloughs, swampland and marginal lowland acres also helps limit spring flooding as these natural sponges absorb, slow down and help purify spring’s meltwaters, providing benefits not only to the wildlife that call them home, but also to the people that live downstream.
As we come out of winter’s trough, it’s important to keep an ear to the rail and an eye on the resources we hold dear. While winterkill events may be out of sportsmen’s control, advocating for better habitat, supporting politicians who sponsor programs that foster it, and working to bring awareness of these options to the general public and their huge benefits for both wildlife and people will take at least half of the worry out of midwinter…in our outdoors.