Humans did a pretty good job of turning physical nets to their advantage in scooping fish out of the ocean. Now, we’ve perhaps gotten a little too good at it, with overfishing being a prevalent threat to many oceanic species. We’re not the only ones who have utilized nets as a means of feeding, mind, and recent footage caught off the shores of Australia shows a group of humpback whales proving just that.
Rather than using some string looped over a hoop, these amazing marine animals were observed using air bubbles as a way of gathering up prey. The incredible footage, published in the journal Aquatic Conservation and captured by a citizen scientist with a drone, captured a mass super-group of humpback whales practicing bubble-net feeding off the New South Wales coast in 2020. The observation marks just the second time humpbacks have been spotted in the southern hemisphere, and the first time they’ve been seen feeding this way off the shores of Australia.
First, a quick explainer. Bubble-net feeding sees a group of whales hunting cooperatively with the help of strategically blown bubbles that close in on prey such as fish and krill. By manipulating the prey with these nets, the whales can work together to make feeding easier. It’s been seen among humpback and Bryde’s whales but isn’t necessarily exclusive to these cetaceans, as it’s possible we’ve just not been around to witness it among other species.
It was previously considered to be the case that most hunting by humpbacks occurred while they were in the northern hemisphere, following a “feast and famine” model that sees them fasting when migrating to the calving grounds in the southern hemisphere. It’s possible, however, that this observation could join others in proving this theory wrong, and that humpback whales actually do hunt outside of the known feeding grounds. As the study authors write in their paper, there’s a pretty simple reason as to why we might only be finding this out now.
Humpback whales were among those targeted when whaling was in its prime, obliterating the population and pushing it to near extinction. Changes in law and policy, as well as painstaking conservation work, has fortunately seen their numbers return to near pre-whaling figures. It’s quite likely, then, that we will continue to see “unprecedented” behaviors among these whales now that there’s actually enough of them around for us to catch them in the action.
Beyond making for some magnificent footage, why are we so interested in watching what whales get up to and where anyway? “Whales play important an important role in the ecosystem of the ocean because they feed in one area and poo in another,” wrote lead author on the study Dr Vanessa Pirotta in their article published in The Conversation. “This action – known as the 'whale pump' – moves nutrients around the ocean. Their poo feeds tiny organisms, such as plankton, which are eaten by krill, and then eaten by whales.
“Seeing these super group feedings highlights changes in our marine environment we might not have otherwise been aware of.”