Experts say the run of whale strandings in Golden Bay may be connected to weather patterns.
The latest stranding, on Monday, resulted in three long-finned pilot whales being left to decompose on Farewell Spit.
Mammal collection manager for Wellington's Te Papa Museum, Anton van Helden, said scientists were unsure what caused whales to strand but believed it could be related to weather patterns.
A Tasmanian study showed there was a local correlation between mass strandings and weather cycles, he said.
Individual strandings happened all year round but mass strandings tended to occur around New Zealand during November, December and January, when the sea was warmer, he told the Nelson Mail.
The whales could be driven in while on the hunt for seasonal food, or to give birth, or it could be that one or two animals in a pod were ill and drew the remainder of the mammals inshore, he said.
Meanwhile, overseas experts said a snowstorm might have contributed to the death of nine whales and 24 dolphins after becoming stranded on Cape Cod in Massachusetts last year.
And the United Nations and marine experts said naval manoeuvres and submarine sonars in oceans are a new factor among many threatening dolphins, whales and porpoises that depend on sound to survive.
Researchers found that a stranding in the 1990s of 12 Goosebeak whales in the Ionian Sea, around Greece, coincided with Nato tests of an acoustic submarine detection system.
Other Goosebeaks were stranded off the Bahamas in 2000, and experts linked that to military tests.
Tests on the bodies of seven whales that died near the Canary Islands in 2002 found haemorrhages and inner ear damage, which experts said was caused by high-intensity, low-frequency sonar used in the area.
In Tasmania, disease, the drive to stay with a sick pod member, and confusing underwater topography were all theories regularly put forward to explain the heartbreaking sight of beached whales dying lingering deaths on Australia's beaches.
Animal welfare organisations have been lobbying for years to restrict military sonar, which is used to locate submarines and other underwater objects.
They have documented dozens of cases of mass whale strandings and deaths around the world that they say are associated with sonar blasts, which are thought to disorient marine mammals and can cause bleeding from the eyes and ears.