Tommy Palliser said Thursday that two hunters from Inukjuak village reported the water had opened up around the area where the cornered whales had been bobbing frantically for air.
Locals said the mammals had been trapped around a single, truck-sized breathing hole for at least two days.
Palliser says villagers had been planning to launch a rescue operation Thursday.
But he says the winds seemed to shift overnight, pushing the floating ice further away from shore to open up the water.
Mayor Peter Inukpuk had urged the Canadian government to send an icebreaker.