More pilot whales were found stranded on an Australian coast Wednesday, raising the estimated total to almost 500 in the largest mass stranding ever recorded in the country.

Authorities had already been working to rescue survivors among an estimated 270 whales found Monday on a beach and two sand bars near the remote west coast town of Strahan on the island state of Tasmania. Another 200 stranded whales were spotted from the air on Wednesday less than 10 kilometers (6 miles) to the south, Tasmania Parks and Wildlife Service Manager Nic Deka said. "From the air, they didn't look to be in a condition that would warrant rescue," Deka said.