Humans searching for answers on whale beachings for more than 2000 years

US scientist did CT scans of dead pilot whales in Tasmania, writes SIMON BEVILACQUA

Dead pilot whale at Macquarie Harbour on Thursday. Picture: STEVE BELL/GETTY IMAGES

ARISTOTLE is said to have been the first person to study whales.

In the fourth century BC, the legendary scholar from Ancient Greece worked with fishermen in the Aegean Sea, recording and analysing whales, dolphins and porpoises and wrote up his findings in his seminal, History of Animals.

In it he noted: “There is some doubt as to the reason why they cast themselves on the land, for they say that sometimes they appear to do this without any cause.”

More than 2300 years later, researchers on Tasmania’s West Coast, where about 400 pilot whales stranded and died this week, are wondering the same thing. Why?

After two millennia of consideration — from great minds like Aristotle and other thinkers of Ancient Greece, like Theophrastus, Plutarch and Herodotus, all the way to modern scientists armed with the technology of CT scans, biopsies, global weather and ocean data, and digital data-crunching abilities the likes of which the world has not seen before — we’re still in the dark.

There is, however, no shortage of theories.

German scientists collated the dates of sperm whale strandings in the North Sea between 1712 and 2003 and compared this with data of astronomers’ observations of sunspots. They found more strandings occur when the sun’s activity is high — of 97 strandings over 291 years,

90 per cent occurred at a similar sun cycle. The scientists speculate that since changes in solar radiation affect the Earth’s magnetic field, whales may use a magnetic sense of orientation like pigeons and may be disorientated by flux in the geomagnetic field.

Another theory, popular with Australian and New Zealand researchers and raised this week in relation to the Macquarie Harbour beaching, is that social bonds play a role.

Professor Darlene Ketten

Pilot whales are members of the dolphin family and are highly social, living in family pods of 20 to 100. The theory goes that gently sloping sandy beaches can send echolocation clicks away from, rather than back to, an animal. And when one in a pod gets in trouble in the shallows, the others follow out of family bond. This theory is used to explain why some whales returned to the deep by rescuers turn around and head back to the pod.

Sound is critical to whales. Loud sound has long been used by humans to herd them. Aristotle wrote of a fishing method using “a loud and alarming resonance” that would induce dolphins “to run in a shoal high and dry … on the beach and so … catch them while stupefied with … noise”.

Similar fishing methods are used today in the Faroe Islands, near Scotland, and in the Taiji dolphin drive in Japan.

Sonar from depth- and fish-finders have been reported to bring whales to the surface and change their behaviour.

In recent decades the use of military sonar for detection of submarines has been involved in strandings. Navies began using mid-frequency active sonar in the 1960s. Since then, researchers have recorded at least 12 strandings of beaked whales that coincided with naval exercises, and 27 others near a naval base or ship.

Mass strandings of beaked whales in the Bahamas in 2000 and in Greece in 1996 were investigated and followed by expert panel reviews that concluded military sonar use in the vicinity of the beachings debilitated the animals and precipitated the strandings.

Beachings at Madeira (2000), the Canary Islands (2002, 2004), Hawaii (2004), Madagascar (2008) and Greece (Corfu 2011, Crete 2014) involved sonar from military, industrial and research vessels.

Professor Darlene Ketten is an American neuroethologist, who has travelled the world using biomedical imaging to study the condition of the inner ears of stranded whales. She came to Tasmania in 2005 to do CT scans and to teach researchers her methodology.

Her scans of beaked whales over the years often revealed blood deposits in the inner ear and haemorrhaging in the fluid of the subarachnoid spaces around the brain.

Prof Ketten says similar injuries in humans would not be fatal nor cause permanent hearing loss, but could be temporarily debilitating.

However, Prof Ketten says pilot whales, such as those beached this week, are different to beaked whales.

“Concerning pilot whale strandings, there is something very important to keep in mind: pilot whales are notorious for large mass strandings for unknown reasons,” she said.

“This has been true for centuries, based on reports in community records around the world. There is no question beaked whales have stranded in relation to military sonar exercises, but that has not been shown for pilot whales.”

In 2005, 130 pilot whales beached and died at Marion Bay, near Copping on the Forestier Peninsula. At the time the HMAS Huon and HMAS Diamantina were searching offshore for the anchor from the Dutch vessel Heemskerck, lost during Abel Tasman’s visit to Tasmania more than 360 years ago.

The Royal Australian Navy confirmed both ships used short-range, high-frequency active sonars in the search, but denied their use had a role in the strandings. Local experts agreed the navy sonar had not played a role, pointing to the fact whales often beached in the area and that surfers knew it as The Boneyard because whale bones could be found poking from the sand.

For the record, I asked the navy whether there had been any sonar exercises in the vicinity of the West Coast strandings this week, but it did not respond.

The US Navy announced in July it was starting 1818 hours of active sonar training in its Mariana Islands testing centre, near Guam, in the western Pacific, which should be in full swing now. But, of course, Macquarie Harbour is a long, long way from Guam.

Could there, however, be a link with the US’s Guam sonar tests and the bizarre sight of two humpbacks in a crocodile-infested river in Kakadu National Park recently? It’s a long shot, but stranger things have happened.