Tag Archives: whale watching tasmania

Super-Groups of Humpback Whales & Bubble-net Feeding

New paper published about the formation of ‘super-groups’ of Humpback Whales and bubble-net feeding in East Australian waters

Large groups of Humpback Whales came together to feed along the south-east coast of Australia, including here in Tasmania.

The last Humpback Whale migration south, between September and November 2020, has really been something special. Not only in Tasmania, but all along the south-east coast of Australia.

We’re excited that we had the opportunity to contribute photographic evidence of the formation of ‘super-groups’ of Humpback Whales as well as ‘bubble-net feeding’ behaviour to a scientific paper that got published two days ago. The paper by Vanessa Pirotta, Kylie Owen, David Donnelly, Madeleine J. Brasier, Robert Harcourt is titled: First evidence of bubble-net feeding and the formation of ‘super-groups’ by the east Australian population of Humpback Whales during their southward migration. If you are interested, you can access the full paper here. It’s definitely worth a read! 🙂

Super-groups of Humpback Whales feeding in Tasmanian waters.
Humpback Whales feeding in close proximity of each other.

First recorded evidence of bubble-net feeding by Humpback Whales off Tasmania and East Australia

Dr. Maddie Brasier, who is one of the co-authors of the paper and also our ‘in-house’ marine biologist has put together why this publication is another important step towards ensuring the conservation of Humpback Whales in Tasmanian and east Australian waters, so read on:

Pirotta’s paper includes three accounts of bubble-net feeding within Tasmanian waters, all three of which were recorded by Wild Ocean Tasmania. 

What is bubble-net feeding?

Bubble-net feeding is when Humpback Whales expel air underwater to create a ring of bubbles around their prey. They then lunge towards the surface inside that ring of bubbles, engulfing a massive mouthful of food. Bubble-net-feeding can be performed by single individuals or multiple animals lunging into the same bubble-net. All observations of bubble-net feeding by Wild Ocean Tasmania in the 2020 summer season involved single individuals. 

To create the bubble-nets, Humpback Whales turn tightly whilst expelling air. Humpbacks can do this, because their huge flippers are edged with tubercules. These fist-sized bumps contain one hair follicle that is connected to a series of sensitive nerves. The tubercules increase lift and decrease drag as they swim through the water. These physical features make them incredibly hydrodynamic and more agile than other whale species. 

Prior to the observations recorded in Pirotta et al. bubble-net feeding in the Southern Hemisphere had only been formally documented in Antarctica. These new observations are really exciting, and we feel incredibly lucky to have documented these events in Tasmanian waters. 

A single Humpback Whale bubble-net feeding in Tasmania – Screenshot of drone footage

Why are these observations important?

It was believed that Humpback Whales followed the “feast and famine” rule whilst migrating, feeding only in their polar feeding grounds, then fasting on migration and in their sub-tropical calving grounds. We now know this is not the case, with many records and sightings of Humpback Whales feeding during their migration in previous years, including many Wild Ocean Tasmania sightings here in Tasmanian waters.

Feeding during migration, also referred to as supplementary feeding, suggests that there is a need for Humpback Whales to supplement their energy supply outside of their summer feeding in Antarctica. Supplementary feeding may become increasingly important as our Oceans change. Flexibility in feeding practices is important for a species’ ability to adapt to changing Ocean conditions such as increased temperatures and nutrient availability. As temperature and nutrients influence the Ocean productivity, this can ultimately affect the distribution and abundance of prey species for larger marine species like Humpback Whales.

It is also possible that specialised behaviours such as bubble-net feeding may be increasingly observed as the East Australian Humpback Whale population continues to recover from industrial whaling. Such behaviours may have been present prior to over-exploitation, but are only now reappearing and being observed.

Several Humpback Whales feeding together

What does this mean for Tasmanian waters?

At present we do not fully understand the importance of Tasmania as a feeding ground to Humpback Whales and other cetacean species. However, by investigating how environmental variation and population dynamics can influence the feeding of Humpback Whales in Tasmanian waters, it will help us predict how future Ocean change may influence whale populations. This could also provide evidence for more effective management to reduce threats to Whales during known feeding periods. 

The observations in Pirotta et al. were primarily from citizen scientists and highlight the importance of observing and recording our wildlife. In Tasmania you can contribute your whale sightings to the Tasmania Fluke Project (email your photos to madeleine.brasier@utas.edu.au or to Wild Ocean Tasmania), or report your sighting to the DPIPWE Marine Conservation Programme. So get out there and tell us what you see!

Ever watched a Whale eat?

Looking into the mouth of a Southern Right Whale

A skim-feeding Southern Right Whale on our Seal & Ocean Expedition.

Have you noticed that the Ocean has changed colour in Tasmania, from a clear blue to a deep green? The water appears to be a bit murky or ‘soupy’. This is caused from billions of microscopic algae and shrimp-like animals. These tiny drifting organisms are food for some of the largest animals that live in the Ocean.

A few days ago, we had the pleasure of watching a Southern Right Whale have it’s lunch on our Seal & Ocean Expedition. The Southern Right Whale is a member of the ‘Baleen Whale’ family. These Whales don’t have any teeth and feed by filtering food through 220-260 baleen plates that are up to 2.8 meters long and hang from each side of their upper jaws.

Looking into the mouth of a Southern Right Whale. You can clearly see the baleen hanging from the sides of the upper jaw.

Unlike the Humpback Whales that would often undertake some spectacular feeding displays, Southern Right Whales swim with a steady open-mouthed movement through prey swarms, trapping their prey in their baleen bristles, while also filtering water out of their mouth (see photo above).

To the disappointment of the researchers, there was no poo that we could have sampled, but we are very eager to collect some samples during the Whale season to help the scientists with their work, so they can analyse how Baleen Whales stimulate microbial communities through nutrients released in their faeces.

Follow us on Instagram to stay up to date with our conservation projects and wildlife sightings!

And if you are traveling to Tasmania this season and would like to learn more about why whales are so important for the Oceans health and life on Earth, then come and join one of our tours. We’d love to have you on  board!