Ask DNR fisheries biologist Max Walter: What goes into lake classifications?

The Wisconsin DNR fisheries program has been working on integrating a new lake classification system into our management. We assign each lake in the state a lake class based on its physical and fisheries characteristics, and anglers might want to familiarize themselves with a number of these classes.

About half of our lake classes have the designation of ‘simple’ fisheries. This means they have fewer than four different game fish species present. For example, a fishery that has largemouth bass, northern pike, and panfish is a simple fishery. A lake with four or more game fish species present, such as muskies, walleyes, and two bass species, is a ‘complex’ fishery.

Within the simple and complex groupings there are more specific categories that have to do with the temperature and clarity of the lake. For example, in the ‘complex-cool-dark’ lake class, you’ll find lakes with four or more game fish species (complex), cooler than average temperatures, and darker than average water. Moose Lake is a local example of a ‘complex-cool-dark’ lake. An example of a ‘simple-coolclear’ lake is Silverthorne Lake near Seeley.

There are a handful of other lake classes for special circumstances.

The ‘two-story’ lakes that can support cisco are in their own class. ‘Trout ponds’ are classed separately as well, and lakes that frequently winterkill or have other issues fall in a ‘harsh’ class. Lakes with a strong riverine influence are in a ‘riverine class.

Understanding what makes lakes different and what makes some lakes similar is very useful for management. Anglers might also benefit from understanding these differences. Fisheries and possibly fishing methods and timing will differ among lake classes, but more on that in a future edition.