Barry Conlon's second-half penalty secured three vital points for Grimsby in their battle to avoid relegation from the Football League.
The on-loan striker slotted in the winner in the 81st minute after Anthony Charles had handled.
Grimsby keeper Wayne Henderson pulled off two first-half saves from Justin Cochrane and Kirk Hudson.
Peter Bore hit the bar for the Mariners after the break before Conlon finally broke the deadlock.
Grimsby: Henderson, Stockdale, Bennett, Atkinson, Widdowson, Llewellyn (Bore 37), Hunt, Sweeney, Hegarty, Conlon, Akpa Akpro (Proudlock 77). Subs Not Used: Lund, Heywood, Forbes.
Booked: Atkinson.
Goals: Conlon 82 pen.
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