About 500 pilot whales have died after becoming stranded on two beaches on islands off New Zealand, officials said.
Two “super pods” beached themselves on the Chatham Islands, which are located about 800 kilometres east of New Zealand’s main islands and are home to about 600 people.
None of the stranded whales could be rescued, with some of them euthanised, the Department of Conservation said.
The department said 232 whales stranded themselves on Friday at Tupuangi Beach and another 245 at Waihere Bay on Monday.
Daren Grover, of non-profit whale rescue group Project Jonah, called the incident “heartbreaking”.
He said whales searching for food around the Chatham Islands can find themselves going from very deep to shallow water very quickly as they approach land.
“They rely on their echolocation and yet it doesn’t tell them that they are running out of water,” Mr Grover said.
“They come closer and closer to shore and become disoriented. The tide can then drop from below them and before they know it, they are stranded on the beach.”
The deaths come two weeks after about 200 pilot whales died in Australia after stranding themselves on a remote Tasmanian beach.
“We do not actively refloat whales on the Chatham Islands due to the risk of shark attack to humans and the whales themselves, so euthanasia was the kindest option,” said Dave Lundquist, a technical marine adviser for the conservation department.
Mass strandings of pilot whales are reasonably common in New Zealand, especially during the summer months.
Scientists do not know exactly what causes the whales to become stranded, although it appears their location systems can get confused by gently sloping sandy beaches.
The whale carcasses will not be buried or towed out to sea because of the remote location of the beaches, but will be left to decompose, Mr Grover said.
“Nature is a great recycler and all the energy stored within the bodies of all the whales will be returned to nature quite quickly,” he said.