There was high drama at 12 Mile Reef, Bermagui on Tuesday when a pair of feeding orcas became involved in an apparent pitched battle with a pod of extremely agitated humpback whales.
Exactly how the killer whales and three humpbacks were interacting is unclear at this stage, but a sample of chunks of blubber found on the scene will be sent for analysis.
Pods of humpback whales were passing my fishing boat all morning, heading north on their migration. Then around midday, while fishing 25km offshore, I noticed a commotion not far away and some odd behaviour by a pod of whales.
The whales were swimming fast back and forth and slicing between were the tell-tale killer whale dorsal fins. The whales seemed agitated and even swam toward and around my boat.
There was a solid oil slick and chunks of what appeared to be blubber on the surface, being fed on by birds. Eventually the pod regrouped and continued to swim north at pace.
The killer whales however loitered in the same area for at last half an hour and could have been feeding on something below.
I was able to bring on board some of the blubber that I have retained for identification purposes. It was amazing to watch the two orcas and the humpback pod interacting in such an excited matter and then to hang out with the orcas for some time while they were up to something.
Where the blubber came from is unclear and could even be from a dolphin, given that a huge pod was seen in the area shortly before by fellow recreational angler Kevin Facey.
“The wake just goes to show how agitated (the whales) were. I was on the 12 Mile until 11am. A large pod of dolphins were racing about in all directions,” he recalled.
“At that stage I thought they were feeding on bait fish. I also noticed several large splashes that I thought were migrating whales, although after your recount, I now belief they were the orcas. I left the area still wondering what was going on. Now I realise that the main ruckus was just about to happen. There were close to a hundred dolphins spread over a large area. They were in smaller groups of five or six travelling at pace in all directions.”
The account of the whale and orca interaction and sample was great timing, as funding for diet analysis in killer whales has just been awarded to a collaboration of researchers.
David Donnelly is a marine researcher, specialising in cetaceans, and manager at Killer Whales Australia, formerly Australian Orca Database.
The other partners in the new research project are the University of Tasmania and MIRG (Marine Information and Research Group Australia), a WA-based organisation.
Mr Donnelly said the Bermagui sample would be added to a collection of other killer whale samples from previous strandings and also prey samples.
“This is an incredibly important collaboration that will greatly increase our understanding of the species,” he said. “As you know, sightings of killer whales and especially their behaviour does not happen all that often.
Mr Donnelly said based on the photos, the two killer whales looked to be Type A females with no prominent dorsal cape visible and the eye patch not overly large.
“I can see some nicks in both dorsal fins, so we should be able to ID if they're in the catalogue. They both look to be female, though the larger fin could be what we call a sprouter or young male,” he said.
He said his colleague Ben Sellers at UTAS was very happy to do the analysis of the blubber sample as part of his studies.
Fatty acid analysis can reveal past feeding on a trophic level and the likely ecosystem that the prey item frequented, and genetic analysis of the skin should get down to species.
And the good news is that the National Parks and Wildlife Service in NSW on Wednesday agreed to facilitate the transport of the sample to Tasmania through its Narooma office.
I kept and froze two samples measuring 6 by 6cm. Mr Donnelly said the sample colour looked like humpback but it was difficult to be sure. Dolphin blubber is usually around 3cm thick.
He was in the process of attempting to identify the two orcas, based on nicks in both dorsal fins and the shape of the cape and eye white markings, so he should be able to ID them if they're in the catalogue.
Eden whale watcher Peter Whiter congratulated me on a great experience. “If the orca were predating a humpback, then it's very likely, given the increase in their numbers, that we will see more of this in our waters.”
The humpback highway was certainly in full effect, with a steady of stream of individuals and pods swimming past the boat again on Wednesday, as I fished inshore waters south of Bermagui.
The analysis of the sample is exciting news and I will bring you updates as they develop.
The whales didn't seem injured, but the again there is a lot of whale - it was almost like the whales stumbled upon them feeding on the dolphin and both parties were not happy - that's just one theory and probably proved wrong by the sample!