A pod of about 80 whales was found stranded at Spirits Bay, 200 miles northwest of Auckland, the second mass beaching in the area in two months. While 25 of the whales were already dead, the Department of Conservation called in 100 volunteers to help the remaining mammals survive.But the department's Carolyn Smith said only 24 of the whales remained alive by Thursday morning, although it was difficult to gauge the exact number of dead because some carcasses had floated out to sea.

"It's pretty cold and arduous for the people on the beach trying to save the whales," she told Radio NZ. Ms Smith said heavy swells and high seas were making it impossible to refloat the whales at Spirits Bay and the department was considering using trucks to move them to a more sheltered beach about an hour's drive away.

Last month, 63 pilot whales stranded themselves near Kaitaia, about 50 miles away. Only nine survived. Scientists are unsure why pilot whales beach themselves, although they speculate it may occur when their sonar becomes scrambled in shallow water or when a sick member of the pod heads for shore and others follow.