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Dissertation
Investigating dolphin population connectivity in southeast Queensland
Doctor of Philosophy, University of the Sunshine Coast, Queensland
2026
DOI:
https://doi.org/10.25907/01081
Abstract
Dolphin studies in southeast Queensland (SEQ) are sparse, with long-term research efforts focused predominantly in the Moreton Bay Marine Park (MBMP). Eighteen dolphin species have predicted ranges across SEQ waters, including the data-deficient, unprotected coastal waters of the Sunshine Coast (SC) where no studies have been conducted to date. This thesis aims to assess connectivity between the Great Sandy Marine Park (GSMP) and SC, a component of SEQ waters, examining whether these regions support distinct dolphin populations or exhibit spatial overlap and gene flow across wider SEQ. Opportunistic boat-based surveys from 2022-2025 investigated dolphin species presence, spatial connectivity, social structure, genetic connectivity, and predation risk. Five species were sighted, with resident Indo-Pacific bottlenose dolphins (Tursiops aduncus, ‘Near Threatened’ IUCN Red list) and Australian humpback dolphins (Sousa sahulensis, ‘Vulnerable’ IUCN Red list) occurring throughout the region. Photo-identification revealed 943 individuals across the five species. An analysis of the resident species’ home range revealed species- and location-specific patterns. In the GSMP, T. aduncus exhibited larger home ranges than S. sahulensis, while the opposite pattern occurred on the SC. Importantly, no spatial or social connectedness was observed across regions, indicating these two populations were socially separate. Social network analysis of individuals sighted ≥5 times (n = 192) indicated these delphinids employed fission- fusion dynamics. Socially connected networks for both species showed individuals exhibited high gregariousness, were also highly clustering, and multiple communities were identified within each region. The occurrence of some mixed- species associations also identified. Subsequent genetic analysis using single nucleotide polymorphisms from biopsy and stranded T. aduncus samples (n = 43) confirmed that two populations exist in SEQ, with limited gene flow between regions and high levels of relatedness within each population; however, connectivity via intermediate populations in unsurveyed areas such as eastern K'gari is possible. An assessment of predation risk via shark bite scar analysis identified tiger sharks (Galeocerdo cuvier) and white sharks (Carcharodon carcharias) as the primary predators in SEQ; species known to spatiotemporally influence the population dynamics and habitat use of cetaceans. S. sahulensis exhibited higher scarring than T. aduncus, and GSMP individuals faced greater predation risk than SC dolphins. These findings reveal year-round S. sahulensis and T. aduncus residency in the SC, previously undocumented outside marine park boundaries. By establishing baseline data on species-specific spatial hotspots, characterising social structure, genetic connectivity, and predation risk, this thesis revealed distinct populations in both protected and unprotected waters in SEQ, emphasising the need for tailored marine park zoning and enhanced protection in currently unprotected waters.
Details
- Title
- Investigating dolphin population connectivity in southeast Queensland
- Authors
- Georgina Hume - University of the Sunshine Coast, Queensland, School of Science, Technology and Engineering
- Contributors
- Bonnie Holmes (Principal Supervisor) - University of the Sunshine Coast, Queensland, School of Science, Technology and EngineeringAlexis L Levengood (Co-Supervisor) - University of the Sunshine Coast, Queensland, Centre for BioinnovationKathy A Townsend (Co-Supervisor) - University of the Sunshine Coast, Queensland, School of Science, Technology and Engineering
- Awarding institution
- University of the Sunshine Coast, Queensland
- Degree awarded
- Doctor of Philosophy
- DOI
- 10.25907/01081
- Organisation Unit
- School of Science, Technology and Engineering
- Language
- English
- Record Identifier
- 991252199802621
- Output Type
- Dissertation
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