Ninety surviving false killer whales that were stranded on an isolated beach in the Australian state of Tasmania will be euthanised, authorities have said.
More than 150 false killer whales, which are a species of oceanic dolphins, were found stranded in the island state's northwest coast near Arthur River, about 400km from Tasmania's state capital, Hobart.
Rescue crews attempted to save the whales that survived the ordeal, but unfavourable weather conditions and the remote nature of the site prevented the successful re-floating of the animals, the Tasmanian Parks and Wildlife Service said.
Reasons for the beaching are unclear.
"Our mass stranding events usually involve pilot whales. However these are false killer whales and it is our first large mass stranding of these animals in around 50 years," said Tasmanian Parks and Wildlife Service Liaison Officer, Brendon Clark, at a news conference.
False killer whales are an endangered species, can grow up to 6.1m long and weigh up to 1,361kg, and closely resemble larger killer whales.
They are found in all tropical and subtropical oceans, generally in deep offshore waters, according to the US National Oceanic and Atmospheric Administration.
