Burrunan dolphin (Tursiops australis)
What do we know about the Burrunan dolphin
Bottlenose dolphin (Tursiops species)
Prior to Dr Kate’s discovery, two different species of bottlenose dolphin were known world-wide, the common bottlenose dolphin (Tursiops truncatus) and the Indo-Pacific bottlenose dolphin (Tursiops aduncus).
The common bottlenose (Tursiops truncatus) is distributed all over the world. T. truncatus are large animals, growing to 4m in length. Commonly found offshore, they have a dark grey colouration along their dorsal side and flanks, and a lighter underside. Common bottlenose dolphins have a curved dorsal fin, and a short, stubby rostrum.
The Indo-Pacific bottlenose dolphin (Tursiops aduncus) is widely distributed throughout the Indo-Pacific region, including Northern Australia. This species is smaller than the common bottlenose, being 2m – 2.5m in length. T. aduncus has a lighter grey pigmentation, with spotting on the ventral side, a long rostrum, and a triangular-shaped dorsal fin.
Which dolphin is it?
While dolphins were commonly seen throughout Victoria, especially in Port Phillip Bay and the Gippsland Lakes, no one knew which species they were; T. truncatus or T. aduncus. The dolphins in Port Phillip Bay and the Gippsland Lakes shared characteristics with both of these species; they had a curved dorsal fin and a stubby rostrum similar to T. truncatus, but were also smaller and lighter in colour similar to T. aduncus. These dolphins also possessed characteristics that were unique, including a distinct tri-colouration with a darker grey on the dorsal side, a lighter grey along the flanks extending over the eye, and a whiter colour on the ventral side. These dolphins were commonly referred to as ‘Southern Australian Bottlenose’, without any formal classification.
It was then Dr Kate asked the question: ‘What species of dolphin inhabits Port Phillip Bay?’. Using genetics as a tool for identifying cryptic species, Dr Kate begun by taking genetic samples of dolphins within Port Phillip Bay and the Gippsland Lakes, along with accessing historical museum records. Expecting her results to identify the Port Phillip Bay dolphins as either T. truncatus or T. aduncus, Dr Kate was surprised that her findings did not match either of these species. Not only that, her findings indicated the dolphins within Port Phillip Bay and the Gippsland Lakes were unique and unlike anything else in the world! So began the journey of dolphin discovery!
Where does the name Burrunan come from?
The discovery of the Burrunan dolphin was an amazing scientific journey but there was still the matter of coming up with the name for the new dolphin species. Dr Kate was in charge of coming up with the dolphin’s name, she wanted something that was reflective of the dolphin’s history and had a significant meaning.
Working with VACL and the Boonwurrung elders, we searched through the historical record and found “Burrunan” was a named used to describe dolphins through Aboriginal narrative.
Burrunan is the Aboriginal name given to dolphins meaning “name of a large sea fish of the porpoise kind” used in Boonwurrung, Woiwurrung & Taungurung languages*.
One of the only two known Victorian resident populations of Burrunan is in Port Phillip Bay where the Boonwurrung people have documented their existence for over 1000 years.
*Thomas W (1834) William Thomas Papers, Manuscript 214. William Thomas Papers, Manuscript 214.
Where are the Burrunan dolphins found?
The Burrunan dolphin are only found in Victoria, Tasmania and South Australia. Recently there has been genetic confirmation of the Burrunan genetic type found in Western Australia, however little is know about there presence or numbers in WA waters.
The species is characterised by small, isolated and genetically distinct populations. In Victoria, Port Phillip Bay hosts a resident population of only 120 Burrunan dolphins, whilst in the Gippsland Lakes there are only 65 resident Burrunan dolphins!
So unlike the other two Tursiops species, they are incredibly restricted to a very small part of the globe, and show little migration of mixing between the different populations. These factors make the conservation and future protection of the species crucial.
What do I do if I see a Burrunan dolphin?
If you see a Burrunan dolphin (other dolphins, seals or whales) you can log your sighting via our TrakMM page. These sightings allow us to put important ‘dots on the map’. Community sightings contribute to our Citizen Science program and allow us to know where the dolphins are, even when we are not there!
Many eyes on the water and reporting the sightings make a huge difference in our understanding of movement patterns.
If you’re on the water, please adhere to the Marine Mammal Regulation by remaining 100m away if on a powered and unpowered vessel (ie boat, SUP, kayak) and 300m if you’re on a jetski. This allows the dolphins to choose to interact…or not! If they do approach you, slow down and keep your track.
Identifying individual Burrunan dolphins
MMF researchers use the dolphin’s dorsal fin to identify each individual dolphin. Identifications are based on the naturally occurring nicks and notches found on the dolphin’s dorsal fin, usually on the trailing edge of the dorsal fin, and those markings act like a ‘FINgerprint’. They are born with ‘clean’ fins and gain nicks over time via social behaviour or human-induced causes, such as boat-strikes and nets.
When we undertake our boat-based research, we collect thousands of images of the dolphins, then back in the MMF office, we have a strict protocol for processing the photos, so that we can tell which dolphins has been sighted across the seasonal survey period. We also collect underwater footage (via GoPro). From the video footage we can also assess the fin ID but it is also useful for identifying gender, mother/calf associations and behaviour.
Employing this technique, variables, such as population size and trends, survivorship and calving rate can be measured. This provides a baseline for future efforts in conservation and management of these resident population and the species as a whole.
Adopt your very own Burrunan dolphin!
You can adopt your very own Burrunan dolphin! By adopting a dolphin, you are helping our researchers get out on the water to collect crucial scientific information that can be used to help us better understand and protect the Burrunan dolphins!
You can choose a male or female from either the Port Phillip Bay or Gippsland Lakes populations! We will keep you updated on your Burrunan dolphin, along with updates across the entire MMF Team.