About 80 whales and dolphins were stranded Monday on a remote southwest Australian beach, and most of them died before rescuers could reach them, conservation officials said. Volunteers and government officers struggled to save about 25 that were being battered by rough seas in Hamelin Bay in Western Australia state, the state Conservation Department said in a statement. The rescuers were trying to stabilize the mammals before freeing them from the sand and guiding them back to sea, it said. It was the latest mass beaching of whales in Australia. Strandings happen periodically in Tasmania, in the southeast, as whales pass during their migration to and from Antarctic waters, but scientists do not know why it happens. It is unusual, however, for whales and dolphins to become beached together. The department said the group of false killer whales and bottlenose dolphins became stranded early Monday morning on a stretch of beach about 4 miles (6 kilometers) long.