Whales have again become stranded off the coast of Tasmania in large numbers, with rescuers doing their best to get the animals back into deeper waters.
It is estimated around 230 pilot whales got into trouble in the shallow depths near Macquarie Heads, on the west coast — exactly two years from 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 which makes whales more susceptible to getting stuck?
Two strandings in a week 'unusual'
Simply put, the cause of whale strandings can often be a mystery — and at this stage, that goes for 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 their rescue efforts would be guided by the "comprehensive Cetacean Incident Manual" which had "undergone extensive review since the 2020 mass stranding".
NRE Tas said marine wildlife experts would "assess the scene and the situation to plan an appropriate response," but offered no insights on what had caused this event.
Marine expert Vanessa Pirotta said determining why strandings occur 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."
She said with pilot whales, which are highly social animals, there were a few common theories about what leads them astray.
"So one could be misnavigation," Dr Pirotta said, adding environmental factors could also potentially come into it.
"The fact that we've seen similar species at the same time in the same location reoccurring in terms of stranding… might provide some sort of indication that there might be something environmental here," she said.
"The reality is we just don't know at this stage."
Herd mentality a likely contributor
Having worked for the Tasmanian environment department in the 80s and 90s, retired veterinarian David Obendorf has seen his fair share of whale strandings.
While he hasn't been involved in this particular event, he said a factor that could come into play for strandings was the species being "herd whales".
"There are certain times of the year, and locations, that are prone to having a frequency of whale trappings," Dr Obendorf said.
He said the beach topography of Tasmania and tidal conditions could make an environment more susceptible to strandings, with both Tasmania and New Zealand well-known "hot spots".
"All that happens if whales, through their echo location, can't navigate a deeper water and get a confused echo signal.
"They may find themselves in shallow water and then put out distress calls… which leads to a pod stranding. These animals, because of their size, get embedded in the sand at the time when the tide is out and collapse in the sand."
The next time the tide comes in, he said, the animals are unable to right themselves and can then drown from taking in sea water.
Tasmanian coast close to ocean shelf
While strandings of the scale seen at Macquarie Harbour both in 2022 and 2020 are infrequent events, strandings as a whole are not, agreed department of Natural Resources and Environment wildlife biologist Kris Carlyon.
He said it was the unique topography of Tasmania that made it somewhat of a "whale trap".
"Our coast is very close to the shelf edge where it drops off, and a lot of these species forage in a deeper water off the shelf edge," Dr Carlyon said.
"Our bathymetry, the sort of coastal topography around Tasmania, is quite complex … so we've certainly seen mass strandings of pilot whales, of dolphins and sperm whales as well on King Island before, and all around north west Tasmania."
Teenagers looking for trouble?
When it comes to sperm whales — such as those found beached on King Island earlier in the week — Dr Carlyon said again a social element came into play.
"Sperm whales are really interesting. When the males reach sort of five, six years of age they do tend to peel off from the maternal group," he said.
"So they get kicked out of the group … they become a bit more independent.
"But the young animals, before they're big and sexually mature and can hold their own against the big breeding bulls, they tend to hang out in groups … like groups of teenagers hanging around together."
That's why, he said, for bachelor pod strandings, the common number of whales found tended to be between six and 20 animals.
"Often it is just simply misadventure."
Sightings of free-swimming or stranded whales and dolphins should be reported to 0427 WHALES.
Members of the public are asked to stay away from the rescue operation, as untrained volunteers can hinder proceedings.
