Wildlife officers have made the tough decision to euthanise 90 false killer whales stranded on a remote Tasmanian beach after failed attempts to refloat them.

More than 150 of the whales were found stranded near the Arthur River on the island’s west coast late yesterday, according to Tasmania’s Department of Natural Resources and Environment.

Parks and Wildlife Service Incident Officer Shelley Graham said unfavourable ocean conditions meant officers had decided to euthanise the remaining whales by firearm.

“The conditions for the next two days are forecast to be very similar to today and it’s really unfavourable for getting the whales out into the water, unfortunately,” Graham said.

“Following expert veterinary assessment, we have decided that euthanasia is necessary for animal welfare reasons.”

All remaining 90 whales will be euthanised, Graham confirmed.

“We [made] several attempts to relocate, to refloat this morning, but they just continually restranded, unfortunately,” Graham added.

PWS Deputy Incident Controller Kris Carlyon said the euthanasia will be humane.

“We use world’s best practice and it’s a very strict operating procedure that we go through to do that,” he said.

“We use specialised ammunition to do the job and make sure it’s effective so that we don’t have a worse case to deal with. We’ve done this often in the past.”

Aerial images showed the whales spread out along the beach, with some half-buried in sand.

Others were found trapped in shallow waters.

By this morning, only 90 were still alive, and while rescuers attempted to send two back out to sea, wind and rough seas meant they immediately returned to shore.

It marks the known first mass stranding of false killer whales in Tasmania in 50 years.

Initial observations showed 136 whales were alive, however, the number has dropped to 90.

Tasmania Parks and Wildlife Service liaison officer Brendan Clark said the animals had been stranded for between 24 to 48 hours.

“Initial assessments indicate that refloating the whales will be difficult due to the inaccessibility of the site, ocean conditions and the challenge of getting specialised equipment to the remote area,” he said.

“While we have had previous success with mass whale stranding events on the west coast with refloating and rescuing whales, it’s important to note that the environmental and access challenges mean we will be unlikely to use those same rescue techniques.

“Animal welfare will be a priority in this response.” 

Authorities said it was unclear why the animals had been stranded.

Vets and marine biologists were on site to assess the surviving whales, Clark confirmed.

First mass stranding for species in 50 years

Mass whale strandings are not uncommon on Tasmania’s west coast, however authorities confirmed it was the first for false killer whales in Tasmania in 50 years.

Then, about two years later, another 230 whales became stranded on Ocean Beach.

Just 35 animals survived the stranding.