Almost 200 whales have died in Australia and New Zealand this week in a series of mass strandings that have left scientists baffled.
A lone hiker stumbled upon 145 pilot whales stranded on a remote beach on Stewart Island, NZ, on Saturday.
Rescuers found two pods sprawled across the sand, the bulk of them lifeless. Half were already dead, while the rest had to be euthanised.
Two days later 10 pygmy killer whales washed up on Ninety Mile Beach in NZ. Four of the six have miraculously been rescued after workers and volunteers from the New Zealand Department of Conservation (DOC) transferred them to a nearby beach and refloated them back out to sea.
DOC spokeswoman Abigail Monteith said the whales were swimming about 400m offshore late yesterday afternoon.
"DOC would like to thank everybody for their hard work over the last few days in the rescue of these pygmy whales and we are hopeful that the six whales that have been refloated will remain at sea," Ms Monteith said.
In another incident, 27 pilot whales and one humpback were found on a small beach in a Victorian national park yesterday.
It is understood most of them are dead, with the handful that are currently clinging to life unlikely to survive.
Whales bearing themselves in scores is an obscure phenomenon, and one that scientists still scratch their heads over the evolution of scientific marine research.
Pilot whales are historically the most common species of whale to beach in mass numbers.
The largest documented stranding of pilot whales was in 1918 with up to 1000 whales found beached at the Chatham Islands, 800km east of the South Island of NZ.
DOC claims the most common explanation about mass whale strandings is that their echolocation – the way they communicate – is not very effective when it interferes with man-made sonar.
This forces them into a depressed state and affects their ability to find their way back into the sea.
Other theories are much more devastating.
Some marine biological studies have claimed that they are also beaching their own in trouble.
Injury, water pollution, navigational errors and changes in the weather are also blamed as reasons why whales may beach themselves but these tend to be more distinct cases as opposed to mass strandings.
DOC said in response to the recent NZ stranding that it was still unclear why whales beach themselves – adding that solo strandings are common but mass events are rare.
"Marine mammal strandings are a relatively common occurrence on New Zealand shores, with DOC responding to an average 85 incidents a year – mostly of single animals," a DOC statement read.
"Exactly why whales and dolphins strand is not fully known but factors can include disease, navigational error, geographical features, a rapidly falling tide, being chased by a predator, or extreme weather. More than one factor can contribute to a stranding.
"A number of strandings occurred on New Zealand shores over the weekend, but these events are unlikely to be related."
One sperm whale was found beached in Northland, NZ, at the weekend, as well as a pygmy sperm whale in Ohiwa, NZ.