If you check the dnr website, all of the info you need is right there for your viewing pleasure. lol www.mi.gov/dnr . but i believe the walleye season closes march 15th upper and lower peninsula. and i believe you must remove shacks on or before march 31st at midnight for the upper peninsula.
March 15 is the last day for walleye. Shack has to be off of UP waters March 31. Michigan / Wisconsin boundry waters March 15. Northern lower peninsula is March 15. But if conditions warrant shanties to come off earlier, those dates are useless.