DNA research reveals a twist in the legendary tale of Eden's killer whale 'Old Tom'

Evolutionary biologists have decoded the genetic lineage of a famous orca that worked alongside whalers in Eden early last century.

Before his death in 1930, "Old Tom" led a pod — "the Killers of Eden" — that helped humans hunt baleen whales.

The orca patriarch and his family were rewarded with the lips and tongues of the resulting prey.

The ritual was known as the "Law of the Tongue".

Now, fresh research has added a surprise twist, courtesy of Old Tom's skeleton, which has long been on display at the Eden Killer Whale Museum.  

It began with lead researcher Isabella Reeves, a Flinders University and Cetacean Research Centre PhD candidate, who took samples from the jawbone and teeth to Norway.

There, she did the lab work with Professor Andrew Foote, a leading killer whale geneticist, to sequence Old Tom's DNA.

"We only had one shot to actually extract the DNA, so we needed the best facility and the best guidance to do the lab work," Ms Reeves said.

Ms Reeves and her team compared Old Tom's DNA with samples collected from killer whales around the world forming a representative global dataset.

While Old Tom and his pod shared a common maternal ancestor with other orcas from Australasia, the North Pacific, and North Atlantic oceans, most of his genetic variations did not match any other living population. 

These results suggest that the killer whales of Eden are likely to have become extinct sometime after Old Tom's death in 1930.

His DNA is most similar to the modern-day orca of New Zealand, but still is very distinct from any killer whales that live today.

As part of the study, researchers collaborated with traditional custodian and Thaua elder Uncle Steven Holmes, who said his people's bond with the whales dates back many generations.

Mr Holmes says while much knowledge has been lost since European colonisation, there are stories of his ancestor Budgenbro, or Chief of Twofold Bay, singing songs to the pod, calling them towards the beach, and he was even known to ride on their backs.

“I don’t know how the connection started, and I’d like to know how this connection all came about,” he said.

“How was this friendship born? How did we become bonded?

“Even though they are not here anymore, we still live by the ‘Law of the Tongue’.”

According to killer whale researcher John Totterdell, there are other examples of relationships between orcas, whalers and First Nations people in Alaska, British Columbia and northern Europe.

But he said the "extraordinary mutualistic relationship" between the Eden orcas and local whalers was the most significant in the world.

While pods of orcas pass down their hunting strategies through the generations, the legendary collaboration with Eden whalers ended with the deaths of Old Tom and his family. 

Old Tom is believed to have starved to death after losing two teeth during a struggle over a baleen whale carcass with local man John Logan. At the time of his death, Old Tom was almost 7 metres long and weighed a hefty 6 tonnes.

John Logan is said to have been wracked with guilt over his role in Old Tom's demise, and after the famed orca's carcass drifted ashore, Mr Logan funded the construction of the Eden Killer Whale Museum.

Collections manager at the museum Angela George says while news of the possible extinction is saddening for the town, the study has put to bed rumours that Old Tom may have been female.

"Some of the results are quite surprising," she said.

"Old Tom didn't always behave the way a male is expected to behave, which has always raised questions around his gender.

"The story is very much a part of the Eden narrative — whether you lived in the whaling era or not, it is very much a part of the town's identity."