Most likely you caught a River Redhorse, and big one at that. Congrats! The spines on the nose were tubercles, which the males have during the spawn.
Hopefully the bar owner will take a long walk off a short pier…
Consequences for killing a protected animal in WI are $2,000-$5,000 , loss of hunting/fishing privileges for 3 years and possibly 9 months in prison.
The DNR wanting a species killed thing seems to come up every once in a while, I cannot find any time (even in the past) when killing native species was condoned by the DNR. Rarely do they even condone killing non-natives.