Standard Talk (15 mins) Australian Society for Fish Biology Conference 2022

Regional and inter-regional fish movement responses to river discharge (#24)

Jason Thiem 1 , Brenton Zampatti 2 , Ben Fanson 3 , Ivor Stuart 4 , Lee Baumgartner 4 , Chris Bice 5 , Gavin Butler 6 , Luke Carpenter-Bundhoo 6 , David Crook 1 , Doug Harding 7 , Kate Hodges 8 , Wayne Koster 3 , Jarod Lyon 3 , Zeb Tonkin 3 , Ian Wooden 1 , Ryan Woods 8
  1. New South Wales Department of Primary Industries, Narrandera Fisheries Centre, Narrandera, NSW
  2. CSIRO Land and Water, Adelaide, SA, Australia
  3. Department of Environment, Land, Water and Planning, Arthur Rylah Institute for Environmental Research, Heidelberg, Melbourne, Victoria, Australia
  4. Charles Sturt University, Gulbali Institute for Agriculture, Water and Environment, Albury, NSW, Australia
  5. SARDI Aquatic Sciences, Inland Waters and Catchment Ecology Program, , Henley Beach, South Australia
  6. Department of Primary Industries, Grafton Fisheries Centre, Grafton, NSW, Australia
  7. Department of Regional Development, Manufacturing and Water, Brisbane, Queensland, Australia
  8. Department of Environment and Science, Ecosciences Precinct, Brisbane, Queensland, Australia

Movement of freshwater fish throughout the environment is essential for population persistence and is fundamentally linked to river hydrology. In this study we collated fish movement data comprising a time series spanning several decades from existing i) telemetry, and ii) otolith datasets, to analyse regional (>5 km) and inter-regional (>100 km) fish movements in relation to river discharge in the Australia’s Murray-Darling Basin. Data were compiled for two native freshwater fish species, with a combined sample size of 2696 individual tagged golden perch (Macquaria ambigua) and Murray cod (Maccullochella peelii), and a separate sample of 1126 individual otoliths. Telemetry data indicated that event-based river discharge metrics had a significant positive effect on the probability of regional movement of both species, although the effect size was substantially smaller for Murray cod. Analysis revealed that every 1-unit increase in standardised discharge was associated with a 4.86-fold increase in the odds of golden perch moving compared with a 1.44-fold increase for Murray cod. Similarly, otolith data revealed that river discharge had a significant positive effect on inter-regional movement (emigration/immigration) for both species. This effect was greater for golden perch than Murray cod and was mediated by fish age and location. While our sample size was limited for Murray cod, analysis of golden perch data revealed that every 1-unit increase in standardised discharge was associated with a 2.6-fold increase in the odds of emigration occurring. Our results demonstrate the value of integrating multiple datasets to broaden the spatial and temporal application and relevance of flow-movement relationships. In the context of managing water for the environment, we used the flow-movement relationships generated from the current study to predict regional and inter-regional movement under a range of flow scenarios to demonstrate the utility of this approach.