Utah Chubs

Wondering why under the record fish section the utah chub is listed as no longer legally harvested. That seems to be the same classification as sturgeon. They are all over the place in the Palisades where I fish. I think the next state record is in there. I don't know of anyone that keeps chubs but would like to try for a big one to get into the record book. Again wondering why it says that you can't harvest them. Thanks for your time.