Lakes with Northern Pike and Muskellunge possession
seasons the last Sat. in April – Nov. 30:
BARRY: Thornapple L. (from McKeown Rd. to Barger Rd.) minimum size
on muskellunge is 50”. LENAWEE: L. Hudson VAN BUREN: Bankson
L., Brownwood L., and Round L. (Keeler Twp. T4S, R16W, S13).

Im pretty sure it mean's the season is closed. All regulation's and season date's are based on the fact that if you plan on keeping a fish or not.

The DNR can't just say well you can fish for musky as long as you don't keep any… who's to know if people actually still are keeping fish illegally then?