Burrunan dolphin (Tursiops australis)
The Burrunan dolphin (Tursiops australis) was formally described as a new and separate species in 2011 by MMFs Founding Director Dr Kate Robb (Charlton-Robb) and colleagues, based on multiple lines of genetic and morphological evidence.
Since then, numerous other studies exploring the entire genome, including Dr Kate’s current genomic study, have validated the Burrunan as a separate and valid species. Further to this, the Burrunan has now been identified as the most ancestral node for all ‘bottlenose’ dolphins worldwide, with the split dated at 1.03 million years ago!
With only two known resident populations in Victoria (Port Phillip Bay and the Gippsland Lakes) we have been able to have the Burrunan listed as ‘Critically endangered’ under Victoria’s Flora and Fauna Guarantee Act.
Our applied research programs, education and outreach initiatives are designed to ensure the Burrunan are better understood and protected for future generations to enjoy!
What do we know about the Burrunan Dolphin?
Prior to Dr Kate’s discovery, two different species of bottlenose dolphin were known worldwide, 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.
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 began 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, but 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!
The Burrunan dolphin (Charlton-Robb et al. 2011) is thought to be restricted to southern and south-eastern Australia, with distinct and genetically isolated populations across the known range (Charlton-Robb et al. 2011; Charlton et al. 2006; Charlton-Robb et al. 2015; Moller et al. 2008; Pratt et al. 2018; Bilgmann et al. 2007). Though the species classification is contested by some (Committee on Taxonomy 2019; Jedensjo et al. 2020), a larger body of evidence now exists, further validating the Burrunan as a separate species to the common and Indo-Pacific bottlenose dolphins (T. truncatus and T. aduncus, respectively), using mtDNA regions (Omerus et al. 2015), concatenated mtDNA/nuDNA sequences (Gray et al. 2018), the mitogenome (Chehida et al. 2020; Horreo et al. 2019; Lee et al. 2019; Moura et al. 2013), the time-calibrated molecular phylogeny of Certiodacyla (Zurano et al. 2019), and more recently with differences in the species karyotype (Brookwell et al. 2021). The species classification has been accepted by Museums Victoria and re-classification of Burrunan dolphin specimens is currently underway (W. Longmore, Collections Manager: Birds and Mammals, pers. comm.). The species has also been listed on ZooBank, the official registry of Zoological Nomenclature, according to the International Commission on Zoological Nomenclature (ICZN), and is listed in major databases including the World Register of Marine Species and World Cetacea Database.
In October 2021 after a thorough assessment by the Scientific Advisory Committee, following the International Union for Conservation of Nature (IUCN) Red List Categories and Criteria guidelines, the Burrunan dolphin was listed under Victoria’s Flora and Fauna Guarantee Act 1988 (the FFG Act) as ‘Critically Endangered’.
The assessment is based on the Burrunan dolphin’s known life history, population size and decline, geographic range (extent of occurrence and/or area of occupancy), and threats. Only described in 2011 and originally listed under the FFG Act in 2013, it is concerning to see the upgrading of the listing from ‘Endangered’ to ‘Critically Endangered’.
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 name 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 is 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 known about their 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.
How do you tell individual dolphins apart?
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 have 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 the conservation and management of these resident populations and the species as a whole.
How MMF is working to protect the Burrunan?
In order to establish greater protection and conservation for our unique Burrunan dolphin, we need to bridge the gaps in our current knowledge about this new species by addressing a number of data deficiencies. Greater scientific knowledge underpinning the correct management and conservation of this species is crucial. With no data, there is no incentive for action, and without action, we can have no conservation.
Introducing ‘Project Burrunan’; MMF’s flagship research project.
The specific aim of this project is to investigate the biology, population size and structure, and threatening process impacting the endangered Burrunan dolphin. With only 120 Burrunan resident to Port Phillip Bay and 65 resident to the Gippsland Lakes, the need to better understand these populations and the wider species is crucial. These populations have significant conservation concern due to their low levels of genetic diversity, close proximity to urban, agricultural and residential settings, and high exposure to various anthropogenic threats.
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 reporting any sightings make a huge difference in our understanding of movement patterns.
If you’re on the water, please adhere to the Marine Mammal Regulations 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.
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.