Why is Tasmania the site of so many massive whale strandings? This is what we know

Whales have stranded again in large numbers off Tasmania, with rescuers scrambling to get the animals back into deeper waters.

It’s estimated that about 230 pilot whales got into trouble in the shallow depths off Macquarie Heads, on the west coast – exactly two years after another stranding in the same location.

Wednesday’s event comes just two days after 14 young sperm whales were found dead on the coast of Tasmania’s King Island.

So why do these events keep happening, and is there something about Tasmania’s topography that makes whales more prone to stranding?

Most pilot whales on Ocean Beach have died.(Supplied: NRE Bag)

Two strandings in a week ‘unusual’

Simply put, the cause of whale strandings can often be a mystery – and at this stage, so is the situation unfolding at Ocean Beach.

With more information expected on Thursday, the Department of Natural Resources and Environment Tasmania (NRE Tas) said on Wednesday that their rescue efforts would be guided by the “comprehensive cetacean manual”, which has “been extensively revised since the 2020 mass stranding”.

NRE Tas said marine experts would “assess the scene and situation to plan an appropriate response,” but offered no insight into the cause of this event.

Marine expert Vanessa Pirotta said determining the cause of strandings was the million-dollar question.

“Whale strandings are a complete mystery,” Dr Pirotta said, “but what’s really unusual here is that this is the second stranding for this week.”

Pilot whale on a beach with a lifeguard taking care of it.
The social nature of the pilot whale species could have something to do with the numbers involved, experts say.(ABC News: Monte Bovilli)
Dr Vanessa Pirotta on a boat with a drone.
Vanessa Pirotta said it was difficult to pinpoint a definitive reason why the strandings are happening.(Delivered: Dr. Vanessa Pirotta)

She said that with pilot whales, which are very social animals, there were a few common theories about what leads them astray.

“So it could be mis-navigation,” Dr. Pirotta said, and adding environmental factors may also be involved.

“The fact that we’ve seen similar species in the same location at the same time returning in terms of stranding … could give some sort of indication that there may be something in the environment here,” she said.

“The reality is we just don’t know at this stage.”

Numerous whales stranded seen from above
The 2020 event at Macquarie Heads is considered Australia’s worst whale stranding ever.(ABC News: Cameron Atkins)

Herd mentality a likely contributor

After working for the Tasmanian environmental department in the 1980s and 1990s, retired veterinarian David Obendorf has seen a large number of whale strandings.

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