The Department of Conservation (DoC) says conditions are too rough in Golden Bay to monitor by boat a large pod of whales at risk of stranding.
In one of the biggest strandings in the country's history, nearly 700 pilot whales beached themselves on Farewell Spit, near Golden Bay, from Thursday evening, and 300 died.
Earlier this afternoon, DoC staff were monitoring a pod of about 200 pilot whales milling around in the sea below the base of Farewell Spit at Taupata Point.
The area in western Golden Bay is near Puponga, which was south of the site of the weekend strandings.
DoC said staff would monitor the situation from the shore, as the tide was going out.
A woman currently at Farewell Spit, Jo Wheaton, said the beach was closed as the clean-up was underway to deal with hundreds of whale carcasses from the previous strandings.
The dead whales on the beach at Farewell Spit had holes poked in them this morning in an attempt to prevent the carcasses from exploding, or drifting out to sea, as they decompose.
DoC spokesperson Andrew Lamason said there was a risk the carcasses would blow up as gas within their bodies built.
"They swell up - there's a lot of bacteria going on in their stomach - and the gut actually comes out of the animal and then blows," he said.
"This morning we'll be getting people down there basically poking holes in them, letting the gas out of them. Hopefully that makes them a lot less buoyant and less likely to drift off."
Mr Lamason said it was a job "like popping balloons", but protective gear would be worn to avoid any potential injuries to workers in the hazardous zone.
He said they would use a range of knives and special, 2m-long hypodermic needles to deflate the carcasses.
Most of the whales were clumped together, he said, which made the job a bit more straightforward.
DOC was also considering building a fence around them to keep them from washing out to sea and into beaches in Nelson and Kapiti Coast.
Hundreds of people braved challenging conditions to help refloat the surviving animals since the beachings. They battled chilly weather and sharks attracted by the decomposing carcasses. Stingrays also appeared on the tidal flats.
DOC will attempt to determine the cause of the mass strandings - the largest ever recorded on mainland New Zealand.
Biopsy samples would be taken from the dead whales and analysed.