Rescue workers are racing to help nearly 200 pilot whales stranded on New Zealand's South Island, officials said on Friday. The stranding has left 24 whales dead while 100 volunteers turned up at the Farewell Spit in New Zealand's Golden Bay to help refloat the whales stuck on the beach. The Department of Conservation (DOC) called off the effort and volunteers will return Saturday morning to keep the whales comfortable until high tide, when they'll try again. DOC's Andrew Lamason said it could take days to refloat more of the whales. "We've had plenty times in the past where the pods have gone out to sea and turned around and come back again," Lamason said. "We're preparing for a big few days." Scientists are not sure what causes pods of whales to strand themselves, according to Lamason, but said there have previously been numerous strandings at the stretch of beach in Golden Bay.