Project Burrunan

Burrunans leaping ©MMF

Project Burrunan

Project Burrunan is MMFs founding flagship project…a crucial conservation project. As one of only four new dolphin discoveries world-wide since the late 1800s, the Burrunan dolphin (Tursiops australis) is endemic to southern and south-eastern Australian waters (Charlton-Robb et al. 2011). The species was described using skull and external morphology in addition to numerous genetic regions, consistent with recommendations of the Workshop on Cetacean Systematics (Reeves et al. 2004) and the Unified Species Concept (De Queiroz 2007). The completion of the entire mitochondrial genome (maternally inherited DNA molecule) analysis and full Tursiops (bottlenose dolphins) species assessment further validates the Burrunan as a distinct species, falling outside the Tursiops lineage (Moura et al. 2013). In addition, it was found that the Burrunan stemmed from the deepest ancestral node (Moura et al. 2013), correlating this with geological records provides an explanation for possible divergence of 1.07 million years ago, suggesting that the origin of the Tursiops genus may be coastal habitats of Australasia (Moura et al. 2013, Charlton-Robb et al. 2014).

The formal naming of the species is just the tip of the iceberg. MMF’s Project Burrunan is the only research program of its kind in Victoria, with a special focus on the newly described dolphin species, this research aims to protect and conserve this charismatic and endemic dolphin for future generations to enjoy. However, 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.

The Burrunan is now listed as ‘Threatened’ under the Victorian Flora and Fauna Guarantee Act, however in accordance with the IUCN Red List and the Australian EPBC Act, this recently described species will be classified as ‘data deficient’. Given its limited range/occupancy, small population size and significant threats, the species would be considered for classification at the ‘threatened’ level.

Two coastal Victorian populations are recognised, Port Phillip Bay and the Gippsland Lakes (Charlton et al. 2006, Charlton-Robb et al. 2011, Charlton-Robb et al. 2014). Port Phillip Bay has an estimated population size of 80-100 animals (Dunn et al. 2001), whilst the Gippsland Lakes has an estimated population of 65 animals; however in winter the numbers increase to 128 suggesting possible seasonal immigration (Henderson, Charlton-Robb et al. submitted; Charlton-Robb et al. 2015). Current genetic research shows the Victorian Port Phillip population is distinct from the Gippsland Lakes and Tasmanian population/s (Charlton-Robb et al. 2015) and that these populations are in-turn distinct from the South Australian populations (Möller et al. 2008), however we know little about the actual migration pathways or potential barriers to movement and gene flow. Outside of these main regions, it is also unclear whether there are additional populations of the Burrunan.

The Burrunan dolphin exemplify small isolated populations susceptible to numerous threats, including commercial and recreation fisheries, tourism, anthropogenic contaminants, shipping, gas and oil mining exploration with seismic activity (in Bass Strait) and environmental change. However, given the lack of knowledge regarding the actual distribution and possible migration of Burrunan, management and mitigation of these threats is difficult.

For the first time we have been able use biopsy samples collected from free-swimming dolphins and compare the levels to deceased beach-cast dolphins (Monk, Charlton-Robb et al. 2014). This current research into heavy metals levels in the Burrunan from coastal Victoria primarily found that deceased animals had significantly higher concentrations of mercury than live animals and therefore it was concluded that mercury was contributing the majority of the toxicological burden on these dolphin. Samples examined in this study were pre-2009, prior to several environmental impacts in both Port Phillip Bay and the Gippsland Lakes (ie dredging and severe flooding & inundation event, respectively). In addition, genetic variation is crucial to the long-term survival of a species through its role in enabling species to adapt to environmental change. Low levels of genetic variation are seen in both mitochondrial DNA and nuclear markers in Victorian and Tasmanian Burrunan populations (Charlton-Robb et al. 2011, Charlton-Robb et al. 2015).

The Burrunan is now listed as ‘Endangered’ under the Victorian Flora and Fauna Guarantee Act, however in accordance with the IUCN Red List and the Australian EPBC Act, this recently described species will be classified as ‘data deficient’. Given its limited range/occupancy, small population size and significant threats, the species would be considered for classification at the ‘Endangered’ level. As yet no Action Plan has been developed for the Burrunan dolphin in Victoria. Greater scientific knowledge underpinning the correct management and conservation is crucial.

Aims of Project Burrunan

The specific aims of the project is to further assess the species distribution and range, gain better estimates of overall population size, assess the level of gene flow between the discrete populations and also assess the potential migration pathways. In doing so, we will have a better understanding of potential ‘hot spots’ and ascertain if there are additional populations of these species. The Victorian resident Burrunan populations inhabit two very different habitats (large salt-water embayment and fluctuating estuarine brackish environment), it is therefore difficult to extrapolate and identify other likely important habitats for these species. This research will also investigate the presence and habitat use of the Burrunan across coastal and offshore regions of Victoria, a crucial aspect of Australian EPBC Act and international IUCN Red listing. This will allow further investigation of habitat preferences and highlight areas of importance for the species.

This study will provide the first formal population estimates (size and structure) for the only two known resident populations of Burrunan in coastal Victoria, through an abundance modelling technique known as capture-recapture. By photographically identifying individuals on several occasions through time within a population it is possible to model abundance variables. The identifications are based on the naturally occurring nicks and notches found on the dolphin’s dorsal fin. 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.

In addition, this is the only research being conducted approved to collect biopsy samples from free-swimming Burrunan dolphins. One biopsy sample collected from free-swimming Burrunan dolphins will allow genetic analyses (using the skin portion of the sample) and diet and/or toxicological analyses (from the blubber portion). By assessing the dolphins DNA, we can determine the gender of the animals, effective population size (those contributing genes to the next generation), kinship relationships, genetic diversity, migration rates and populations stocks.

The exploration of newer genetic technologies will allow the phylogenetic affinities of the species to be further assessed (as a putative generic name has been assigned T. australis). In addition, given the complex nature of delphinid species world-wide, the utilisation of next generation sequencing (NGS) technologies may allow better insight into evolutionary processes associated with such species complexes. This research will further solidify Australian genetic research as world-class and add to the growing international interest in the use of NGS technologies.

This small but important sample from living populations, coupled with fin identification, uses a multi-disciplinary approach encompassing studies on population & conservation genetics, gene expression, population structure & modelling, toxicology, diet (via fatty acid analyses) food web analysis and behaviour of Burrunan dolphins across Victoria.

To support Project Burrunan please see our Partnership Program or Donate today.

Comments (2)

  1. Randall Lee     August 17, 2017 at 5:16pm

    I am curious if you have any info on the foraging range of the Gippsland Lakes Population. I have seen them feeding outside Gippsland Lakes Entrance and wondered how far they forage, or if indeed they do have seasonal migration patterns

    • Kate Charlton-Rob     November 15, 2017 at 11:03am

      Hi Randall, the resident Gippsland Lakes Burrunan dolphins do venture out of The Entrance and forage offshore. We have conducted focal follows of a resident pod that was 3 nautical mile offshore and the next day back near Tambo Bluff. There is also genetic link to Burrunan dolphins in Tasmania (with every mtDNA haplotype in Tasmania matching one from the Gippsland Lakes). We hypothesise there is gene flow with the annual winter migration from Tasmania to the Lakes, which is mainly male mediated, as we see the same ‘winter’ transient males in the Gippsland Lakes year after year.

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