There are concerns that a number of whales rescued after stranding at Farewell Spit today could re-strand themselves overnight.

About 416 pilot whales stranded this morning on the narrow stretch of land, the Department of Conservation said, and about 100 of those had been refloated by armies of volunteers during the day.

About 50 whales were thought to be still at sea, but as of about 4pm, DOC estimated 80-90 whales had res-stranded on the beach during the day after being rescued.

About 276 whales have died.

High tide overnight Friday will take place about 10.30pm, but because it will be dark, rescue teams have ruled that it is too dangerous to work with the huge animals in pitch black conditions.

The next available high tide is on Saturday morning about 11am, and rescue efforts are likely to begin once the whales become buoyant about 10.30am.

More than 500 volunteers turned out to help, many of which are coming back again on Saturday morning - DOC says that at this stage no further volunteers are needed.

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Live Updates:

5pm: 1 NEWS Now's live coverage of the stranding has now concluded. We will continue to bring you stories from Farewell Spit as they emerge, and will have more coverage when rescue efforts resume tomorrow morning.

4.20pm: Project Jonah General Manager Daren Grover says many of the 50 whales refloated today are reluctant to head into deeper water and are milling around the low tide mark, perhaps unwilling to leave their social group. Mr Grover told 1 NEWS there are deep concerns they could re-strand themselves overnight. The conditions at Farewell Spit are becoming increasingly cold and windy and focus is now turning to planning tomorrow's effort. Volunteers will be pulled off the beach as light fades tonight, as working with black whales on a dark beach in dark water is very dangerous, Mr Grover said. The first refloating efforts are due to begin tomorrow morning about half an hour before high tide when the remaining whales become buoyant about 10.30am or so.

3.40pm: The Department of Conservation has given updated figures on the Farewell Spit stranding. It says a total of 416 whales were stranded, and 50 whales have now been refloated and are out at sea. About 80-90 are still alive on the beach, and about 276 whales have died.

3.20pm: 1 NEWS reporter Emily Cooper, who is at Farewell Spit, has posted a video showing just how many dead whales are at the site.

3.15pm: Massey University is sending a scientist to perform necropsies on some of the deceased whales in order to find out if a disease or trauma was behind the stranding. Dr Stuart Hunter says the animals are insulated with a lot of blubber, so they will decompose quickly and time is of the essence. Their goal is to find out if there is an underlying reason for the stranding.

3.00pm: The next high tide is at 10.40pm tonight, but experts say it is too dangerous to try to refloat whales at night, so the next attempt will have to be at high tide about 11am tomorrow morning.

2.50pm: A mother and daughter who travelled from Nelson to help save whales have named one of them Echo, and are hopeful of its survival. Watch the video below.

2.20pm: The surviving whales are split along the beach, Project Jonah says. They are encouraging volunteers to read this guide before heading for Farewell Spit.

1.45pm: The next high tide at Farewell Spit is at 10.45pm - about 9 hours from now. Low tide is is about 4.40pm and volunteers will be pulled out of the water at sundown for their safety. Volunteers are being rotated by Project Jonah co-ordinators to keep them from getting too cold.

1.41pm: Louisa Hawkes of Project Jonah says she has never seen a stranding this big before. "This is quite emotional - it's encouraging to see the number of people who have come out to help ... We're going to give these whales the best chance we can ... Thank you to everybody who has come out to support us, particularly locals and medics who have driven some distance - it's really great to see everybody come out here to help the whales."

1.35pm: Update: About 45 whales have now been refloated, with volunteers forming a "human chain" to discourage the whales from coming back ashore. Blankets have been laid over the surviving whales, and they are being kept wet, and trenches are being dug around the whales to keep them comfortable.

1.30pm: The stranding is within walking distance of a popular cafe, and locals are joining forces with a number of tourists who have come down to take a look.

1.25pm: The area where the whales have stranded is a relatively high spot of Farewell Spit, and whales are known to usually strand further down the spit. This makes rescue efforts much more difficult.

1.05pm: Harrowing footage is coming in of whales making sounds of distress as volunteers try and keep them wet and comfortable.

12.55pm: This stranding is the third largest since records began in the late 1800s.

Around 70 per cent of the 400-odd whales that stranded died, but most of those who remained alive were successfully refloated.

12.30pm: Our cameraman Sam shot these images of rescuers wading in water, trying to move the surviving whales out to deeper water.

12.25pm: It's currently a waiting game for rescuers, who are desperately hoping the surviving whales won't restrand on the outgoing tide.