Doctoral Thesis
Fine scale connectivity of the sandbar shark, Carcharhinus plumbeus, along the Western Australian coast
Doctor of Philosophy (PhD), Murdoch University
2023
Abstract
The overriding theme of this thesis is connectivity in Indo-West Pacific carcharhinids. I review the results of relevant previous studies and identify general connectivity patterns and knowledge gaps, including a lack of dedicated tests for genetic structure along contiguous coastlines. I describe how I assessed fine-scale connectivity in the sandbar shark (Carcharhinus plumbeus) on the continental shelf of Western Australia. This species is exploited in many jurisdictions across its broad geographic range including Western Australia, where it is harvested in the southern part of the state and is also subject to traditional Indonesian fishing in the Timor Sea. An understanding of connectivity in sandbar sharks in this region is needed to ensure the sustainable management of these fisheries. My assessment was based on patterns of variation in 1,480 single nucleotide polymorphisms from the nuclear genome and 1,068 bp of the mitochondrial control region in sandbar sharks collected from five sites, one with a temporal replicate, spanning approximately 2,700 kilometres of coastline from Albany in the south to the Timor Sea in the north. I found no evidence of barriers to gene flow in either the nuclear or mitochondrial genomes, despite conducting a range of high-power statistical analyses. I also analyse the size distribution of individuals to refine our understanding of size segregation in this species in this region and evaluate an unsuccessful attempt to track the movements of individuals in the study area via satellite tagging. Although the genetic data suggest that sandbar sharks form a single biological stock off Western Australia, the species’ size segregation highlights the importance of ongoing management to minimize the likelihood of growth overfishing in the south of the state. Management also needs to recognise that the stock extends into the Timor Sea where unmanaged Indonesian fishing may impact sustainability in Western Australian waters south of this location.
Details
- Title
- Fine scale connectivity of the sandbar shark, Carcharhinus plumbeus, along the Western Australian coast
- Authors/Creators
- Brenton M Pember
- Contributors
- Jennifer Chaplin (Supervisor) - Murdoch University, School of Environmental and Conservation SciencesNeil Loneragan (Supervisor) - Murdoch University, Centre for Sustainable Aquatic Ecosystems
- Awarding Institution
- Murdoch University; Doctor of Philosophy (PhD)
- Identifiers
- 991005609665807891
- Murdoch Affiliation
- Centre for Sustainable Aquatic Ecosystems; School of Environmental and Conservation Sciences
- Resource Type
- Doctoral Thesis
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