More than 100 long-finned pilot whales stranded along the shores of Western Australia on Thursday have returned to the ocean, while 29 died on the beach, wildlife officials said.
Officials were working to remove the 29 whales that had died on the beach, Pia Courtis, a regional wildlife officer with the Parks and Wildlife Service for Western Australia, said on Thursday in a news conference posted by the agency on social media. The agency planned to take biological samples and measurements from the dead whales for research.
After marine officials and volunteers had helped the other whales back out to sea, boats were on the water and a spotter plane was monitoring the area to ensure they did not return to shore.
The four pods of 160 pilot whales were spread across about 1,640 feet of beach at the Toby Inlet, near the town of Dunsborough, in Western Australia on Thursday morning, local wildlife officials said, in a statement on social media.
Photos shared by the wildlife service on Facebook showed rows of whales lying on the shore as crowds gathered to see the mass stranding.
The rescued whales had moved farther offshore on Thursday and were last seen traveling north, the wildlife department said.
“So far, so good — they haven’t made it back to shore, but we will keep monitoring them,” Ms. Courtis said.
Officials said they did not know what had caused the stranding, which included mostly adult females and a few calves. In general, experts have theorized that the causes for such strandings may include pods of whales following a sick, or stuck, whale and getting stuck themselves; the confusion brought about by undersea noise caused by humans; or an attempt to avoid predators.
Several mass strandings have unfolded in Australia in recent years.
In July, a pod of almost 100 long-finned pilot whales was stranded in the shallow waters off a remote beach in Western Australia. More than 50 died, and the rest were later euthanized.
One of Australia’s deadliest strandings took place in 2020, when 470 whales were beached on a coastline in Tasmania. Most of them died.
Pilot whales can grow to 24 feet in length and weigh up to 6,600 pounds. When pilot whales are stranded, rescuers are often in a race against time because once the whales are out of the water the weight of their bodies can crush their organs.
Pilot whales, which can be short or long-finned, are known for being social animals, and tend to live in large schools of hundreds of whales separated into close-knit pods of 10 to 20 individuals, according to the National Oceanic and Atmospheric Administration.
Experts said the mass strandings on beaches pointed to the whales’ strong social ties.