"In the heat, the whales can explode, but we've taken steps to prevent that," Trish Grant, a spokeswoman for New Zealand's Department of Conservation, told CNN.
"Our staff has been puncturing the dead whales, using an implement that releases the gas (inside their carcasses) that someone local has built for us."
Excavators will be used to move the dead whales further up Farewell Spit in Golden Bay, which is on the tip of New Zealand's South Island, to a location in the nature reserve that's not open to the public.
From Friday to Sunday, around 400 whales died on Farewell Spit, the conservation department said in a statement. It's the third largest mass beaching of whales
in the country's history.
Grant told CNN that the department had spent Monday monitoring a pod of whales still in the Golden Bay area from the coastline amid concerns that they would also beach themselves.
"We've finished for tonight, but we'll resume our searches tomorrow. The whales are still in the Golden Bay area relatively close to shore and there's a risk that they could strand overnight," Grant said.
Whales were first spotted in the water late on Thursday night, by a department staffer, before being found on the beaches of Farewell Spit Friday morning.
Hundreds of volunteers joined the rescue effort.
Farewell Spit is considered to be a whale trap due to its shallow water, said Grant.
The largest whale stranding event in New Zealand took place in 1918, when 1,000 whales stranded themselves on the Chatham Islands. The second largest was in Auckland in 1985, when 450 ended up on a beach.
Grant said that many factors can be involved in whale beachings.
"Sometimes it can be caused by a diseased member among them - because they have strong social bonds, if one of them gets in trouble, the rest can follow," explained Grant.