Why is Tasmania the site of so many large whale strandings? Here’s what we know

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Whales have again stranded off the coast of Tasmania in large numbers, with rescuers doing their best to get the animals back to deeper waters.

It is estimated approx 230 pilot whales got into trouble in the shallows near Macquarie Headson the west coast – exactly two years since another stranding in the same place.

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 susceptible to stranding?

An aerial view of hundreds of whales on a beach.
Most pilot whales at Ocean Beach are dead.(Delivered: NRE Tas)

Two strandings in one week ‘unusual’

In short, the cause of whale strandings can often be a mystery – and at this stage, that is the case with 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 its rescue efforts would be guided by the “comprehensive Cetacean Incident Manual”, which had “undergoed extensive revision since the 2020 mass stranding”.

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

Marine expert Vanessa Pirotta said it was the million-dollar question of why strandings occur.

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

Pilot whale on a beach with a lifeguard looking after it.
The social nature of the pilot whale species could have something to do with the numbers involved, experts said.(ABC News: Monte Bovill)
Dr.  Vanessa Pirotta on a boat with a drone.
Vanessa Pirotta said it was difficult to pinpoint a definitive cause for the strandings.(Delivered: Dr. Vanessa Pirotta)

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

“So one can be misguided,” said Dr. Pirotta, adding that environmental factors could also potentially come into play.

“The fact that we’ve seen similar species at the same time in the same place that repeats in terms of strandings… might give some kind of indication that there might be something environmental here,” she said.

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

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

Herd mentality a likely contributor

After working for the Tasmanian Environment Department in the 80s and 90s, retired vet David Obendorf has seen his fair share of whale strandings.

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