I don’t really know what the rationale is; but my guess is that it has to do with VHS. In WI, our regulations state that all minnows have to be obtained from a licensed bait dealer. Live fish cannot be transported away from any body of water.
We can use any fish that we catch as bait, but it needs to fit size requirements and also daily-bag limits. Which means, we can only use it on the immediate waters we’re fishing on.
What is really fishy though (excuse my pun), is that we can use dead fish as bait, provided they were not frozen or refrigerated as part of the preservation process.
To me, this says that I could go to any cesspool in the state, pull out the most disease-laden fish I can find, and use it as bait on a pristine water (as long as I don’t put it on ice).
That scenario is extreme. Unfortunately, If I want bullheads or chubs for flathead fishing, I need to buy them. Dealers for those two types of bait aren’t anywhere near my house or the landing I use. So this limits me to fishing with suckers in a river whose tributaries contains both chubs and bullheads.
(If anyone knows a bait dealer between River Falls and Osceola that sells chubs or bullies, drop me a line).