Up to 145 whales are dead after stranding themselves on a beach in New Zealand over the weekend, wildlife officials said.

The whales were found Saturday on the remote Stewart Island beach, which is also called Rakiura, according to a statement from New Zealand's Department of Conservation. Half of the whales were already dead when they were found, and the rest were euthanized partially due to the condition they were found in, the statement said.

“Sadly, the likelihood of being able to successfully re-float the remaining whales was extremely low. The remote location, lack of nearby personnel and the whales’ deteriorating condition meant the most humane thing to do was to euthanize," Department of Conservation Rakiura manager Ren Leppens said in the statement. “However, it’s always a heartbreaking decision to make.”

Meanwhile, the department was appealing to the public for help saving another eight whales that stranded themselves in a likely unrelated incident on Ninety Mile Beach, on the opposite side of the country.

Two of the pygmy whales had already died, but the remaining whales were moved to Rarawa beach, where they were being held in a stream. The Department of Conservation asked volunteers to help with the re-floating of the whales.

The New Zealand Department of Conservation said it responds to about 85 stranded marine mammal incidents per year. While relatively common, they usually involve a single animal, the department said.

"Exactly why whales and dolphins strand is not fully known but factors can include sickness, navigational error, geographical features, a rapidly falling tide, being chased by a predator, or extreme weather," the Department of Conservation explained.

Nearly half the world’s whale and dolphin species are found in New Zealand.