While the past couple of weeks have been nothing short of amazing with a diversity of marine life having been sighted in the Bremer Canyon, we have been patiently awaiting the arrival of the largest of the odontocetes (toothed whales), an iconic deep-sea predator, the sperm whale.

Sperm whales are generally sighted in the area throughout our season, but usually start to arrive in numbers from mid-March onwards. We haven’t sighted a single sperm whale in the area this year, until today, and we definitely weren’t expecting it to happen the way it did.

We arrived to the hotspot today to find members of Split Tip’ pod spread throughout, foraging. Noosa and Loupy surfaced close to our vessel but spent only short intervals on the surface before slipping down below. In hopes of finding another group more interested in interacting with us, we headed westward, toward the S-bends. We hadn’t made it far before Sara and Cookie’s pods were sighted, tracking east, back toward the hotspot. We tracked with them until they joined Split Tip’s pod, embarking on long foraging dives as they scoured the area for prey.

Then, with a large splash at our 1 o’clock, everything changed. The orca began to pick up speed and surge out in front of us, clearly in pursuit of something big.

Skipper, Craig, immediately put the Alison Maree into gear to keep up with the frontrunners, including matriarch, Cookie. Behind us, dozens of orca surged from the west, all headed in the same direction as we were. Cheers came from the deck as 4 orca erupted simultaneously from peaks in the swell, as a unit. With the ability to travel at speeds of up to 60km/h it took them no time to catch up. The orca had pushed up toward the continental shelf into only 80 metres of water, which is far shallower than the usual 1000+ metre depth zone where they’re usually found.

Given beaked whales are most commonly on the menu for the Bremer orcas, everyone was on the lookout for a small dorsal fin and long slender body, characteristic of beaked whale species, to emerge from the surface ahead of the killers. Instead, what we saw left our jaws gaping. The unmistakable arched back and tail of a sperm whale.

As we approached the commotion, the shock factor rose when we realised the sperm whale was in the company of four others, one much smaller than the others and believed to have been a juvenile.

As we approached, the group of sperm whales appeared distressed and exhausted, huddled in a tight group, poking the tips of their heads out of the water and letting out heaving blows as they tried to regain their breath. Members of Split Tip’s pod including Wonks and Flapper swam tight circles around the huddled sperm whales who were thrashing their tails around to fend off the predators.

The head of one of the larger adults emerged from the surface, with its mouth wide open, displaying its powerful toothed bottom jaw.

Then, a large dark bubble rose to the surface amongst the huddle, believed at the time to have been blood. Historically, it was thought that sperm whales, due to their size, herding behaviour and strong toothed jaws were not vulnerable to killer whale predation. However, killer whales have since been known to attack sperm whales, often targeting females and calves rather than males, which are typically more aggressive. Females under attack have been observed forming defensive circular formations referred to a ‘rosette’, to protect young calves or injured adults which are kept in the centre. The mood onboard became solemn as we processed what may have just unfolded in front of our eyes – had the orca really just taken down a sperm whale?

But something was off. One of the killer whales began tail slapping off our port side and the others quickly moved off from the sperm whale huddle. We followed suit, conscious of causing any further stress to the animals or any interference. Then matriarch, Split Tip, emerged, circling our vessel with a small chunk of meat in her mouth which was thought to have been a chunk of sperm whale and the cause of the dark bubble seen only minutes earlier.

The orcas stayed in the area for some time, but kept their distance from the sperm whales who remained tightly huddled. We desperately scanned the surface for scraps of meat or an oil slick… but nothing. Eventually, we began tracking west again with members of Split Tip and Alki’s pods, in hope of finding more clues as to whether or not the events that had just unfolded had in fact been a successful predation.

But the orca continued on along the shelf edge, in shallow water. A few females, including Kalimna, surfaced with small chunks of meat in their mouths, but questions arose as to whether it was perhaps something like squid, rather than mammal meat, given orca have been known to harass sperm whales and to steal chunks of giant squid from them.

Unfortunately though, the mystery meat remains just that, a mystery. Given we only capture glimpses of the story as it unfolds on the surface, what happens below can only be speculated, meaning the day ended with a myriad of unanswered questions burning in everyone’s minds. However, after closer analysis of the photographs, video footage and behavioural observations recorded during the chaos of today, while we are unable to confirm whether the event was a predation, it seems unlikely. What was originally thought to have been a bubble of blood exploding on the surface, has since been confirmed as faeces. Sperm whales are known to defecate when threatened, referred to as emergency or defensive defection. The cloud of diarrhoea created when the whale waves its tail through its poo acts to deter predators and in this case, seemed to work! Given their faeces appear reddish in colour, due to their diet consisting of 90% squid, it’s no surprise it was easily mistaken for blood. Regardless of the outcome, the orca put on an intense pursuit which showcased their power and elite hunting techniques, allowing them to herd the ocean’s largest toothed predator into the shallows. But it seemed that today they were no match for the defence tactics of the sperm whales whose incredibly strong bonds helped them to withstand an attack from the ocean’s apex predators.

Events like this are rarely witnessed, let alone documented, with only a handful of accounts having been recorded globally, and will always remain an immense privilege and a reminder of just how wild these animals and this place are.

What a remarkable day in the Bremer Canyon!

Photographs captured by onboard photographers, Jodie Lowe and Machi Yoshida. Blog written by Marine Biologist, Jennah Tucker.

-Naturaliste Charters