An epic half-an-hour struggle between a blue whale and about 60 orca is the second rare display of predation behaviour seen by the animals off the Great Southern coast in two weeks.
Naturaliste Charters Whale Watching had taken a boat full of passengers to their “hot spot“, about one-and-a-half hours off the coast of Bremer Bay on Thursday.
Marine biologist Pia Markovic was on board, and immediately noticed the tell-tale signs something was on the move.
“As soon as we got there, we could see some white surging and some splashes on the horizon,” she said.
“We saw orca, pilot whales and dolphins, and they were all surging … they were all going in the same direction.
“We know that that behaviour generally means predation is happening, so we know that something ahead is going on, or something is out there calling for back up.”
Sure enough, Ms Markovic spotted an oil slick on the surface of the water and the boat started following where the animals seemed to be headed.
On their way to the disturbance, Ms Markovic noted about three separate pods of orca that all seemed to be going in the same direction.
The boat spotted the juvenile blue whale just after 12pm, and saw a struggle was underway.
“We kept bunny-hopping up further ahead and then when we got to the blue whale, there were about 10 orca physically holding onto it,” she said.
“The blue whale was already missing chunks and that would have happened just before we got there.
“It was clear they were either going to try and drown it, or they are going to try and take parts of it and make it bleed out until it dies.”
For around half an hour, the boat watched as the orca systematically herded and forced the 15-metre juvenile blue whale underwater, while ripping chunks off it as it struggled.
“At one point they did go in for the underbelly,” Ms Markovic said.
“Of course that’s where all the main organs are, so there was a lot of blood – bright red fresh blood – in the water.
“At one point one of the big males came through and hit it square in the back, and there would have caused a serious internal bleed as well.
“It had blood coming out of its mouth and it was just thrashing around the surface for quite a while.
“It was pretty quick from when we started seeing the slick, to when they put it down underwater the whole thing was about half an hour.
Ms Markovic said she had warned the passengers about how gory the experience may be, but all the tourists on board chose to watch the display.
“This was a really lucky encounter for the passengers to see,” she said.
“From what we’ve been able to find, we think it’s the only third time this blue whale predation has been observed in the world.
“People do get upset when animals are being hunted but everyone was really understanding when we spoke to them about it.
“They got that it’s nature, it has to happen, and they’re orca and that’s what they do there isn’t any sound anyway so that may have helped.
“A lot of it happens below the surface, you don’t see all of it.”
Ms Markovic said it was key for Naturalist Charters to let people know what they had seen, so they could start bringing more people onto tours and educate them about the animals and ecosystem of the Bremer canyon.
She said it was important to get their research vessel out as much as possible so they could continue documenting the orca in the area.