Eden’s killer whales: helping human hunters
WHEN SHE WAS JUST 13 years old, zoologist Dr Danielle Clode was enthralled by the legendary stories of Eden’s killer whales. Surveying the still waters of Twofold Bay, on the NSW south coast, from the crow’s nest on her parents’ gaff-rigged yawl, she would will a distinctive black fin to cut through the water’s surface.
She wasn’t the first to be intrigued by Eden’s killers, which between 1840 and 1930 helped whalers hunt baleen whales by herding the doomed giants towards the waiting whaleboats. But by 1981, when Danielle was 13, it seemed the killers were long gone. Now, decades later, and based at Flinders University, she has returned to Eden to delve deeper into the hamlet’s unusual whaling history.
The pod that made the town on the NSW south coast famous has long since moved on, leaving only a museum and rusted whaling station as evidence of the partnership. “The killer whales became legend in Eden and stories spread of their prowess,” Danielle says.
Whaling in Eden took off in 1828, but it wasn’t until 1844 that stories of the peculiar behaviour started to emerge. Eyewitnesses talked of orcas (Orcinus orca) prowling the entrance of Twofold Bay for migrating humpback, blue, southern right and minke whales.
Killer whales help whalers hunt their targets
Using the unique geography of the bay, the waiting orcas would ambush whales that were vastly bigger than themselves – ripping at fins, diving over their blowholes, and forcing them into shallower waters for the whalers to finish off. Once a whale was dead, they’d feast on the lips and tongue, leaving the rest of the carcass for the whalers.
Over the years baleen whale numbers plummeted, and by the time when Eden’s whaling operation shut down in 1929 orcas were rarely seen. More than 80 years on, it is difficult to know whether the hunting partnership was real. Accounts from the time suggest it was – eyewitnesses described killer whales ‘tail-flopping’ and breaching to attract the whalers; others claimed the predators towed the whaleboats to the flailing whales by tugging ropes with their teeth.
Danielle says the relationship was probably mutual exploitation. “Obviously the killer whales seem to have evolved a particular style of hunting that suited the geography of Eden, whereby they drove the baleen whales into the bay and used the shallow water to capture them,” she says. “The whalers added a new dimension to that, and could kill the baleen whales much quicker.”
As detailed in the updated edition of Danielle’s book Killers in Eden (published in 2011 by Museum Victoria), similar hunting behaviour – working in groups, taking on roles, biting fins, flinging themselves over the blowhole – has been observed in modern-day pods of orcas attacking migrating grey whales in the North Pacific Ocean. “The killer whales themselves may have disappeared from Eden, but the behaviour of their relatives in other oceans gives us an insight into how and why this seemingly remarkable association between human and whale developed,” she says.
Killer whale populations differ on eating habits
Indeed, modern genetic analysis is helping scientists home in on killer-whale family histories, hunting styles, morphology, and prey specialisation. Cetacean biologists are finding that the killer whale is not one uniform species, as previously thought, but rather, that some populations are picky eaters with sophisticated hunting methods to match their tastes. In recent years, three killer whale types have been identified off Canada’s west coast – those that hunt salmon close to shore, highly mobile transients that eat mammals, and largely mysterious ‘offshores’. In the Southern Ocean it’s a similar story: since 2007, three Antarctic killer whale ecotypes have been identified – one that eats herring and mackerel, a mammal hunter, and a dwarf form – and it’s believed there are more.
It’s still not clear where Eden’s orcas fit into this picture. Museum Victoria palaeontologist Dr Erich Fitzgerald, who compiled the latest whale evolution data for Danielle’s book, says it’s possible that they were mammal-hunting specialists. “That’s consistent with the idea that Eden’s killers were similar to those [highly mobile] transient, mammal-hunting killer whales that occur off the Pacific coast of North America,” he says.
Killer whales don’t hunt alongside humans in Eden anymore, but pods are now seen chasing humpbacks off the NSW coast. Danielle says she’s glad they’re coming back: “We talk about the Eden killer whales disappearing, but I suspect that they didn’t disappear or die, they just moved offshore – and new generations of the particular family, or pod, are still patrolling the east coast, just the way they did in those early days.”
Source: Australian Geographic, Issue 105 (Nov – Dec, 2011)