Oral Presentation AFSS/NZFSS Joint Conference 2019

Movement patterns of whole fish communities throughout a wet-dry tropical river in northern Queensland (#184)

Michael Venarsky 1 , Ben Stewart-Koster 1 , Edward Boone 2 , David Crook 3 , Jonathan Marshall 4 , Glenn McGregor 4 , Cameron Schulz 4 , Stuart Bunn 1
  1. Griffith University, Nathan, QLD, Australia
  2. Department of Statistical Science and Operations Research, Virginia Commonwealth University, Richmond, Virginia, USA
  3. Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory, Australia
  4. Water Planning Ecology, Science Division, Queensland Department of Environment and Science, Brisbane, Queensland, Australia

Species movement is the “glue” that binds populations together by facilitating gene flow and dictating habitat (re)colonization. However, despite decades of research we understand the movement patterns of very few species which limits the understanding of the relationship between species movement and ecosystem structure and function. In this study, we explore the movement patterns of fish communities throughout the Mitchell River catchment in northern Queensland. We combine a catchment-wide strontium isoscape (87Sr : 86Sr) that accounts for temporal variation in Sr isotope composition with fish otolith microchemistry analyses to delineate the movement patterns of whole fish communities (gobies to barramundi) throughout the river catchment (upper to lower reaches). We have sampled twenty-one sites from which we collected 1030 fish otoliths from twenty-six species whose body size ranged from five to ninety centimetres standard length. To date, 754 otoliths have been analysed, showing that the number of movement events per individual ranged from zero to fifteen. However, the majority of fish (~75%) moved either zero or one time(s) over their lifetime, with the majority of these movements occurring in the sub-catchment of birth. Importantly though, the probability of movement was not consistent during an individual’s lifetime, with the majority of movements occurring early in life. Thus, our preliminary results suggest that the fish communities throughout the Mitchell River catchment consist of a mix of stationary (short distance) and mobile (long distance) individuals, with stationary individuals generally dominating population abundance and mobile individuals representing a small proportion of the population.