Pilot whales: mass stranding of a curious, social species at Macquarie Harbour

One of Australia's leading researchers into whale biology says mass strandings of pilot whales are not unheard of, given the species' curious and social nature that results in them travelling in large pods.

Dr Vanessa Pirotta, of Macquarie University, has researched whale behaviour for decades, and said pilot whales' nature made them more susceptible to such phenomena compared to other species.

There had been similar examples in Western Australia and New Zealand in recent years.

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While it was far too early to say what caused the stranding at Macquarie Harour on Tasmania's west coast, Dr Pirotta said there could have been a number of factors at play.

"There are many reasons why they potentially might strand," she said.

"One could be aero-navigation, they could have become startled by something, they could have been curious or, although largely an offshore species, they could have been predating on a species that drew them into this location.

"Pilot whales are incredibly social and are known to hang out in large groups, so to hear of a large pod like this, I'm not surprised. With them being very social and trusting of where individuals are leading them, that can result in them stranding."

Pilot whales travel in large pods, and are among the species most susceptible to mass strandings. Picture: Brodie Weeding

Pilot whales travel in large pods, and are among the species most susceptible to mass strandings. Picture: Brodie Weeding

Pilot whales are not migratory and can appear in Tasmania's waters at any time, with a widespread distribution throughout the Southern Ocean and as far south as Antarctica.

Parks and Wildlife Service's Marine Conservation Program is leading the rescue effort, but one-third of the 270 whales had already been confirmed to have died within the first day.

Marine Conservation Program wildlife biologist Kris Carlyon said most of the whales were inaccessible by vessel, making it a logistically challenging operation.

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He said pilot whale strandings were not uncommon in Tasmania.

"We have had multiple mass strandings of both pilot whales and sperm whales in a similar location," Dr Carlyon said.

"We're not quite sure [of the reason] - it could be that they have been drawn in to this area by feeding close to the coast, it could be simple misadventure by one or two animals because pilot whales are such a social species, it may have drawn the rest of the group in, we're not too sure at this stage."

Race against the clock to save as many whales as possible

The cool, wet weather in Strahan and the West Coast this week could help to prolong the time the whales could survive the stranding, however the situation could be different for each individual animal.

Dr Pirotta said the position that a whale was stranded on the sandbank was a key factor in how long they could survive.

"An animal over five-metres-long can weigh a couple of tonnes, and has probably never felt their own weight before. Their potential weight can crush them, they can overheat, many could die of overheating because they're so efficient at warming their bodies in a marine environment.

"Intense sunlight can be a problem.

An overlooker watches as efforts to save the whales get under way. Picture: Brodie Weeding

An overlooker watches as efforts to save the whales get under way. Picture: Brodie Weeding

"They're air breathing, so being on the land means they can still breathe, but depending on the position that they're stuck in the water, it's very important that their blowhole isn't obstructed."

While mass whale strandings are tragic events, they also play a role in gathering a greater understanding of whale biology.

Dr Pirotta said researchers could later use the stranding to increase human knowledge of whale genetics, diet and how well-connected the population was.

This story Are pilot whales their own worst enemy? first appeared on The Examiner.