Members of the Pacific Whale Watch Association (PWWA) caught a rare view of aggressive activity between two giants of the sea on Thursday, when a large group of transient Bigg's orcas squared off with a pair of humpback whales over the course of a few hours.
Capt. Joe Zelwietro of Eagle Wing Tours spotted a group of about 15 killer whales being "unusually active" in the Juan de Fuca Strait, a stretch of the Salish Sea between Vancouver Island and Washington state, shortly after 11 a.m. PT, the PWWA said.
A few minutes later, Capt. Jimmy Zakreski of B.C. Whale Tours noticed there were two humpback whales in the middle of the group of orcas, the association said.
"Around these parts, it's very common for us to encounter orcas. It's also very common for us to encounter humpbacks," said PWWA executive director Erin Gless in an interview.
"It is not very common for us to encounter them in the middle of a brawl."
During the three-hour encounter, which happened around 40 kilometres east of Victoria, observers say the mammals breached, slapped the water with their tails and made loud vocalizations before they finally disappeared into the fog.
"I'm still trying to wrap my head around it because it was absolutely unbelievable," said Mollie Naccarato, a captain and naturalist with Sooke Coastal Explorations on south Vancouver Island.
"At first the orcas seemed to be chasing the humpbacks, but then when there was space between them, the humpbacks would go back toward the orcas."
Gless says the orcas were seen circling the two humpbacks and occasionally nipped at their flippers and tails.
Territorial or predatory?
Bigg's orcas feed on marine mammals such as seals, sea lions, and porpoises, but do occasionally hunt larger prey, she said. That's in contrast to the northern and southern resident orca groups, which feed mostly on fish.
"Orcas are the only natural predator that humpback whales have in this region," Gless said. "Even though humpback whales can get to be the size of a school bus, a group of very experienced hunters can attack [them]."
Gless says there was some debate among whale watchers who witnessed Thursday's interaction as to whether the behaviour was territorial or predatory.
Some believe the killer whales were acting strangely because they were irritated about the humpbacks being on their turf, while others thought the group of orcas showed a few of the typical trademarks of a group hunting approach.
"We saw some of that splashing around ... getting on top of the back of the humpbacks as they were trying to breathe," she said.
The humpback whales involved were identified as BCX1948, known as Reaper, and BCY1000, known as Hydra.
Reaper is at least four years old and has been matched to winter breeding grounds off Jalisco, Mexico; Hydra, an adult female, has been matched to breeding grounds in Maui, Hawaii, where she's given birth to at least three calves.
Gless says nobody saw how the conflict was resolved because it was particularly foggy when both sides swam off. A few groups will be back out on the water Friday, trying to spot the two humpbacks to see if they made it out alive.
Gless says the orcas' behaviour wasn't entirely out of the ordinary but it's an encounter whale watchers have rarely witnessed, especially not up close.
"We really got to see something spectacular," she said.
But it could become more common as the populations of both species continue to grow, she added.