Dozens of pilot whales have died in Western Australia after a large pod became stranded on a beach Tuesday. Out of the more than 90 whales that were stranded, more than half have died as officials race to save the remaining animals. 

The ordeal started on Tuesday when a large pod of pilot whales, one of the largest dolphin species, was spotted huddling together in a tight group about 328 feet offshore. It was originally believed that there were between 60 and 70 pilot whales in the group at Western Australia's Cheynes Beach, but Western Australia's Parks and Wildlife Service later have raised that number to roughly 96. 

"What's happening right now," the Cheynes Beach Caravan Park posted on Facebook. "...We don't know! But look at this pod of whales only 100m off the beach." 

At first, the pilot whales were all huddled together, facing inward in a tight circle. They were soon after seen in a tight line, facing the same direction. And after a few hours, the park said they had "stranded themselves." Videos show dozens of the animals washed up along the beach, many whipping their tails in the low onshore waters in an attempt to free themselves back out to sea. 

The Parks and Wildlife Service quickly responded, but by 8:15 a.m. local time on Wednesday, the agency said that 51 whales had died. Roughly 45 pilot whales remained alive, and video from the agency shows dozens of staff members and volunteers standing with the animals in the water as they prepared to lead them out to sea. 

"We're just going to try to gently herd them out of the bay, away from the rocky point ... and into deeper water," Incident Controller Peter Hartley said, adding that volunteers will also be using kayaks and vessels to lead the pilot whales to safety. "...We've got to be optimistic in this game." 

Fantastic effort today from 250 registered volunteers, more than 100 staff from the Parks and Wildlife Service and other...

Posted by Parks and Wildlife Service, Western Australia on Wednesday, July 26, 2023

Officials and volunteers were successful at releasing the pilot whales on Wednesday – but not for long. 

"Sadly, despite best efforts from volunteers and Parks and Wildlife Service staff, the whales have re-stranded further along the beach," the Parks and Wildlife Service said. "Veterinarians will continue to assess the re-stranded whales and advise of the most appropriate course of action to ensure the most humane outcome for the whales."

Whale strandings and other deadly incidents have been making headlines in recent months. 

It was recently determined that the world's most endangered whale species, the North Atlantic Right Whale, is even closer to extinction than previously thought after several individuals became stranded or entangled. And just days ago, the Faroe Islands' traditional pilot whale hunt came under renewed scrutiny after a cruise ship watched an annual hunt unfold. 

In the U.S., many have pointed to offshore wind development as reason for strandings in the Northeast, although experts have said that is not the case. 

Why do whales beach themselves?

Long-finned pilot whales live in large groups of hundreds of animals that divide themselves into "close-knit pods" of 10 to 20 whales, the National Oceanic and Atmospheric Administration says, and it's not uncommon for them to be huddled together. 

"At the surface, these whales will often display various active behaviors such as raising their heads above the surface or lifting their flukes out of the water and splashing them down against the surface," NOAA says. "They are also regularly seen resting or logging at the surface in a chorus-line or stacked formation and sometimes approach vessels moving at slow speeds."

The circumstances surrounding this particular stranding remain unclear. It could have been the result of them logging together and getting too close to shore, but in past pilot whale strandings, one of the animals being injured or ill has also played a role. 

In June, a pod of 55 long-finned pilot whales became stranded in Scotland. Sarah Dolman, a senior ocean campaigner for the Environmental Investigation Agency, said on Tuesday in that situation, post-mortem examinations showed one of the female pilot whales had difficulty giving birth. 

"This may have been what brought the pod ashore," she said of that incident. "Pilot whales live in incredibly sociable and strongly bonded groups. Often, tragically, when a sick or injured pilot whale comes ashore, the rest of the pod will follow."

In:
• Oceans
• Australia
• Whales

Li Cohen

Li Cohen is a social media producer and trending content writer for CBS News.