The tragic news of more than 470 long-finned pilot whales stuck on shore had all our eyes glued to the Australian island Tasmania during the last week.
Only two days after the first pod of around 270 animals had been discovered in Macquarie Harbour on Monday, reports of a second, equally large group stranded only a few miles away emerged. Officials believe them to be part of the same pod that was washed up differently with the tide. Though the location made the approach incredibly difficult, 60 volunteers and local officials were able to quickly rush in and attend to the situation. By Thursday, at least 70 animals had been rescued successfully with only 20 remaining onshore that were assumed to be well enough for rescue. Four more were too weak to be released and had to be euthanized. By Saturday, the last rescue efforts ceased with “Tasmania’s west coast now clear of live whales”. The statement released by the Tasmanian government confirmed that 108 long-finned pilot whales had survived the stranding and had been refloated successfully. 350 are estimated to have succumbed to the stress of stranding and died on the sandbanks.
Biologists now hope that the released whales will reform as a group and return to safer waters. Meanwhile, the focus has shifted to remove the carcasses from the bay. Since leaving the bodies on the shore might cause them to start bloating and drifting, they might become a navigation hazard, attract predators, or even pose a health hazard. Different strategies for the removal are now tested with burials and towing them out to sea on the forefront.
What caused the whales to strand initially is still and will most probably remain unclear. Pilot whales are a deep-diving species that is mostly found in deep waters. Their navigation system of echolocation is therefore not made for the shallow waters and might have left them disoriented when they came too close to shore during a feeding session. As they are very social animals that live in big groups, they are prone to mass stranding. The distress of a small percentage of animals stuck on sandbanks might have caused the others to investigate and consequently get stuck as well.
Historically, pilot whales have been part of the biggest mass strandings reported globally and especially in the area. With Tasmania as a hotspot for such incidents with 80% of Australia’s whale strandings occurring here, pilot whales have been involved in the five biggest ones. The current event was even worse than the previously biggest Australian mass stranding of 320 pilot whales in West Australia. While both of these are considered to be due to a natural cause, the largest ever stranding event of 1000 pilot whales in New Zealand in 1918 was assumed to have followed seismic and sonar exploration.
Sample reports covering the incident can be found under the following links:
- On the pilot whales’ biology and possible stranding causes: https://www.theguardian.com/environment/2020/sep/25/tragedy-in-tasmania-what-are-pilot-whales-and-why-do-they-strand-themselves
- On removing the carcasses: https://www.bbc.com/news/world-australia-54307815
- On the situation after the final rescue mission: https://www.bbc.com/news/world-australia-54275771
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