Wisconsin Fish Tales

It was a real eye opener for those of us who fish Wisconsin’s waters last week when retired DNR fisheries biologist Frank Pratt spoke at the UW Center for Civic Engagement. He told us how our changing climate already affects the fish in our rivers, lakes and streams, and what is yet to come. The news could hardly have been worse.

Careful monitoring and diligent record keeping reveal that the waters our fish live in are warming. Numerous factors determine just how much, but the temperature rise ranges between half and one and a half degree Celsius – as much as almost three degrees Fahrenheit. Seems small, but for the fish and other denizens of the deep – and not so deep – it can be critical, even deadly.

Add to that the fact that our September temperatures now resemble what used to be August’s, and that spring ice-out on our lakes is trending earlier, and an even grimmer picture emerges. This is especially true for walleye, brook and lake trout, big northerns, whitefish and cisco. Cisco are greedily eaten by large walleye, northern and musky providing the nutrition these fish need to reach record breaking size. If the prey goes, as Frank sees it, so go their predators, and the cisco are indeed going.

For some fish, like the trout, whitefish, cisco and larger northerns it’s pretty simple; their inability to handle warmer water is the problem. By the end of this century they’ll be gone. If we want them, we’ll have to go to Canada. Their populations are already dropping in much of Wisconsin.

For the walleye it’s a bit more complicated. Sum it up by a comparison with what’s happening to coastal waterfowl. Due to warming waters, when the young need food the food is not there, so during the increasingly frequent early spring ice-outs whole hatches of baby walleye starve and are lost. As a consequence, our favorite walleye lakes are becoming bass, panfish and catfish lakes.

As Frank put it, those bass, bluegills, catfish and carp are the winners. Being warm water fish, they are thriving and will continue to do so. While that might be good news for some anglers it is not so for the walleye. This warm water advantage spells even more trouble since bass prey on smaller walleyes; a double whammy.

As for solutions? Dramatically cutting our use of fossil fuels was high on Frank’s list; driving electric, going renewable and eating locally grown food. He also encouraged keeping that lawn and its oxygen depleting nutrients away from the water with wide plantings of shrubs, native plants and trees along the shoreline. For anyone serious about climate change these were not idle suggestions.

“Of course if brook trout, cisco and walleye are gone by the end of the century,” said Frank, “it is likely that our great-great-grandchildren won’t have time for fishing anyway. They’ll be busy fighting to survive on too hot a planet.”

Regardless of how we feel about climate change, Franks data is real, undeniable. Hard facts, among a myriad of other hard facts that portend big trouble from a changing climate. The question is whether or not we – you and I – will take his research and that of his colleagues around the world seriously enough to act now before it is too late.