PhD project: The causes and consequences of growth variation in Pacific fishes

Opportunity Type: 
Student Opportunity
Closing Date: 
Sunday, September 15, 2019

School of BioSciences, University of Melbourne

The Pacific Ocean covers 46% of the Earth’s water surface and provides ~60% of global fisheries catch. Natural ENSO cycles dominate Pacific climate, oceanography and biology, but vast regions are now warming faster than the global average due to climate change. A PhD project is available to explore how these natural and anthropogenically driven changes affect the growth of key marine fishes from across the Pacific Ocean, and what this means for future fisheries productivity and marine conservation.

Fishing and anthropogenic climate change induce similar trait responses in fishes, despite being underpinned by very different mechanisms. Fishing can affect the phenotypic diversity of harvested stocks through the selective removal of, for example, the biggest or oldest individuals. Likewise, warming has been implicated in ‘shrinking fish’ and shifts in phenology. Whilst the mechanisms driving warming-induced trait changes are debated, empirical observations increasingly show that both fishing and warming often lead to ‘faster’ life histories characterised by rapid juvenile growth, early maturation, smaller body size, and reduced life span.

Disentangling the relative importance of fishing and warming can be difficult in marine systems where long-term observational or experimental data are often sparse. This data gap can be filled in part by reconstruction of growth histories of individual fish from examination of the growth increments in their otoliths ("ear bones"), in which annual deposits are laid down, similar and analogous to tree rings. This information remains an under-utilised yet potentially powerful resource.

The successful applicant will collaborate with fisheries scientists and research partners from across the Pacific to generate otolith-based growth biochronologies. Future directions could include the application of novel growth models to assess adaptive capacity in populations to future warming and harvest, the development of environmental proxies based on otolith inorganic or organic chemistry, and assessing how growth changes impact on fisheries productivity.

The student will need to obtain an Australian Postgraduate Award (APA) scholarship at the University of Melbourne (or be competitive for an international postgraduate scholarship: IPRS, MIRS; worth $30,600 pa. pro rata). Thus, a first-class honours or master’s degree, and/or evidence of publishing in international peer-reviewed scientific journals will be essential. Information regarding University of Melbourne scholarships and admission processes can be found here: This PhD will contribute to a larger Australian Research Council funded project awarded to the supervisory team.

We seek applicants with an excellent appreciation of general ecological/ evolutionary theory, a strong quantitative background, and experience with the programming language R. Experience working with otoliths or related growth-increment data will be advantageous. The project is based in Melbourne, but some overseas travel may be required for sample collection and international collaboration during the project. As such, we seek a highly motivated student with a proven capacity to work independently, as well as successfully engage with external research partners and industry stakeholders. The preferred starting date for this project is early-2020.

Closing date for expressions of interest is 15th September 2019 for both international & domestic applicants. Please submit a cover letter outlining your interest in the project, your academic transcript, and CV with contact details for two referees to: John Morrongiello, School of BioSciences, University of Melbourne., Please contact John for further information.

Supervisory team:
John Morrongiello, Uni. of Melbourne
Bryan Black, Uni. of Arizona
Steve Swearer, Uni. of Melbourne