"The likelihood of finding survivors is no longer there,"McGuire told a televised news conference in the Newfoundland capital of St John's.
The pilot had reported mechanical trouble before the crash.
The passengers and crew were wearing suits designed to help them survive for up to a day, but McGuire said they had been in the water longer than that.
"The (families) are aware that the 24-hour period for survivability in the emergency suits has now passed ... they are distraught," he said.
The helicopter sank about 65km southeast of St. John's.
Rescue officials are handing the case over to the Transportation Safety Board (TSB), McGuire said.
The TSB was set to launch an operation to lift the cabin up to the surface, according to investigator Mike Cunningham.
The first step would be to inspect the wreckage using remote controlled equipment, he said.