Nine whales died on Monday after stranding themselves against a rocky breakwater on Australia's east coast, with experts working to herd the rest of their group out to sea.
About 20 long-finned pilot whales got into trouble in Bunbury harbour, 175 kilometres (110 miles) south of Perth, Western Australia's Department of Parks and Wildlife said.
"Nine long-finned pilot whales have died after congregating against the breakwater wall in Bunbury harbour this morning," it said in a statement.
"There are currently four whales alive on the adjacent beach and one whale in the shallows. The department is working to move these whales back into deeper water."
Six whales have already been herded back out to sea by small boats, it added.
The department said an aerial search of the area did not detect any more whales in distress.
Whale beachings are relatively common in Australia, but scientists do not know why they happen.
In 2009 a group of long-finned pilot whales, which can grow up to 6.5 metres (21 feet) in length, stranded themselves in Hamelin Bay, south of Bunbury, with efforts to save most of them failing.