The Mariners started on the front foot and went ahead in the fourth minute when Matt Simon headed in Stefan Nigro's cross.
Simon went close again soon after, while Josh Nisbet and Alou Kuol were denied by Victory goalkeeper Matt Acton.
They were made to pay for those missed chances shortly after the half-hour, when Callum McManaman curled into the top-right corner from 15 yards after a Jake Brimmer free-kick had been cleared into his path.
Jacob Butterfield went agonisingly close to a stunning stoppage-time winner when his long-range half-volley was pawed away by Mark Birighitti.
The result means the Mariners remain three points adrift of Melbourne City at the A-League summit, having played two games more than the league leader.
Victory, meanwhile, is in 11th, two points ahead of bottom side Newcastle Jets.