The deaths of 10 more pilot whales after a stranding on Stewart Island have taken the toll to 22.

Department of Conservation spokesman Tom O'Connor said most of a group of 54 whales in the shallows of Maori Beach yesterday had moved out to sea and a pod of about 100 offshore appeared to be moving away from the area.

The 10 died before rescuers could head them back to deeper water.

The whales began beaching at Maori Beach, about 7km from Halfmoon Bay, on Thursday afternoon.

DoC began assembling a squad of 100 volunteers yesterday morning.

Mr O'Connor said the call for helpers received a great response and volunteers were keeping vigil in case the whales returned.

Volunteers had a difficult day, with unsettled weather and cold temperatures.

"The water is very cold, the weather is overcast and so it can be very demanding on people.

"We've got to watch that they don't work themselves to exhaustion."

Mr O'Connor said large-scale whale strandings were rare on Stewart Island and none had been recorded at Maori Beach.

Almost 300 pilot whales died two years ago after beaching at isolated Doughboy Bay, a large inlet on the island's west coast.