Properties and applications of aquatic species size-distributions

Principal supervisor


  • Name: Shane Richards
  • Email:
  • Position and School: Senior Lecturer, School of Natural Sciences
  • Name: Pia Bessel-Browne (CSIRO)
  • Email:
  • Position and School: Research Scientist, CSIRO

Project Description

Natural populations consist of individuals that at any given time vary in their body size. The shape of body size distribution in a population can inform us about population status and species properties, but most analyses to date are based on theoretical predictions without extensive validations with empirical data. Many size-based ecological and fisheries models assume that the maximum body size of a species is fixed in space and time, yet empirical data suggests that species body sizes vary extensively across temperature gradients. Moreover, experimental evidence suggests that that intra-specific body size distributions could be described with a consistent shape, but conditions under which this occurs remain unclear. This project aims to investigate statistical properties of intra-specific body size distributions in fishes and other aquatic ectotherms using a extensive global and regional empirical datasets across ecological and human impact gradients (underwater visual surveys, fisheries surveys, citizen science, angler reports, and others).

The project has three main objectives:

1) Identify and quantify intra-specific body-size distributions using empirical datasets of fishes and aquatic invertebrates (copepods, rotifers) that span ecological and harvesting gradients. Assess whether temperature and harvesting induce consistent responses in the properties of size-distributions (e.g., mean, variance, skew).

2) Conduct population and community-level simulations to explore species physiological parameters and ecological conditions under which theoretically predicted size distributions are consistent with empirically observed distributions, assessed in objective

3) Develop quantitative tools that take observed body-size distributions when the number of observations is limited and estimate population status. Apply the tools to citizen science-based data sets (e.g., angler data, natural history observations) that are becoming increasingly abundant with advances in detection and monitoring technology.

The PhD scholarship for this project is provided through Audzijonyte’s ARC Discovery project and CoSE as well as a QMS top up of $5K for 3.5 years and OSHC.

Authorised by the Executive Director, Institute for Marine and Antarctic Studies
June 21, 2022