As many as 145 pilot whales have died after becoming stranded on a remote beach in New Zealand on Saturday evening.

A hiker at Mason Bay on the remote Stewart Island discovered the two pods of the whales, which were located approximately a mile from each other.

Roughly half of the whales were already dead by the time they were found, leaving officials from the New Zealand Department of Conservation with the “heartbreaking decision” to euthanize the remainder.

“Sadly, the likelihood of being able to successfully re-float the remaining whales was extremely low,” said Ren Leppens, the department’s operations manager. “The remote location, lack of nearby personnel and the whales’ deteriorating condition meant the most humane thing to do was euthanise.”

NEW ZEALAND DEPARTMENT OF CONSERVATION Almost half of the whales were already dead by the time they were discovered.

The stranding of marine mammals is a relatively common phenomenon on New Zealand’s shores, according to a statement from the DOC.

Indeed, a number of whales ― including 10 pygmy killer whales, two of which have died ― became stranded on the country’s shores over the weekend. Two sperm whales, including one female pygmy, also died over the weekend in separate incidents.

NEW ZEALAND DEPARTMENT OF CONSERVATION Officials made the decision to euthanize the remaining whales.

As previously reported by HuffPost, nearly 700 whales washed up on the South Island’s Farewell Spit in 2017, in what became the third-largest whale stranding since record-keeping began.

Of those that were stranded, almost half were declared dead.

There’s not exactly a clear-cut answer as to why marine mammals become stranded. A multitude of factors, including navigational errors, sickness or extreme weather, can be involved, according to the Australian National Geographic.