Around 100 volunteers are working frantically to save what is left of a pod of stranded pilot whales near Nelson this morning.
Yesterday the Department of Conservation worked through the day to rescue 198 pilot whales, which had become stranded six kilometres along Farewell Spit at Golden Bay, near Nelson.
Last night the rescue operation was scaled down, although some volunteers kept watch of the beach overnight.
Andrew Lamason of the Department of Conservation (DoC) said the whales were now stranded back towards Triangle Flat, which made access to them much easier.
There was around 100 volunteers at the beach now, some of whom had been there since 5.15am, Mr Lamason said.
"We've got volunteers out there and we have been directing more people out there. We have been receiving a lot of calls, we are down to about 60 whales still alive, and needing assistance.
"We have been asking people if they can head out with buckets, spades and any old sheets they might have."
Mr Lamason said of the 198 whales which were initially stranded, 70 had died by 11pm yesterday and he expected that number to rise.
"We have lost quite a few overnight... We have one of our guys searching along out on the Spit now and he says that he's finding dead whales out there.
"So whales that have been re-floated, they've swum out, come back in to different spots, and died on the beach."
Mr Lamason said if they were unable to successfully rescue the whales, euthanasia would be considered.
"It's something that we are definitely considering. All the efforts at the moment is getting them back re-floated into high tide, that's coming at around 6pm.
"If we get to a situation where it looks like they are unduly suffering then we will have a discussion with the guys on the ground who know best and then come to a decision.
"Right now our focus is still on getting them out."
Mr Lamason said the whales were all upright and in good condition.
"[Volunteers] are working hard and we reckon we have a reasonable chance.
"But if they re-strand or their health rapidly declines there is that other option."
To have a good chance of survival, stranded whales needed overcast or rainy conditions, but Farewell Spit had experienced dry, sunny conditions yesterday.
However, today the weather conditions "were good for whales", Mr Lamason said.
"It's overcast and we haven't got any wind to speak of although we might have a bit out at the Spit. It's generally pretty good for whales but it will make it challenging for people working out there."
He said most pilot whales in the pod, which included adults and juveniles, were probably closely related.
"It's like a hapu or a village," he said. "It's a whole mixed family group."
Mr Lamason said the geography of Golden Bay meant it was often the site of strandings.
"It's a big, shallow hook. Things come in, they get disoriented, and unfortunately we end up with a lot of dead whales."
Mr Lamason said local iwi would perform karakia on the dead pilot whales.
After that, the creatures would be tethered at mid-tide and nature would "take its course" as happened when three stranded sperm whales were towed to another part of Farewell Spit to decay away from the public in November.
The cause of strandings remained a mystery.DoC said it was plausible pilot whales' echo-location was not well-suited to shallow, gently sloping waters as they usually preferred steep areas such as continental shelf edges.
"Another theory points to pilot whales' highly sociable behaviour - when one whale loses its way and strands, its pod mates may swim to its aid," the Department said on its website.
Mr Lamason said people who wanted to help the pilot whales should arrive at Triangle Flat between 8am and 3pm today.
He said people should come prepared, and bring wet weather gear, sunscreen, food and water.
DoC was installing portable toilets at Triangle Flat.