Assessing the Success of Environmental Flow Delivery Using Acoustic Telemetry Techniques

The Edward-Wakool River system in south-western New South Wales (Australia) forms a major anabranch of the Murray River. The system has high ecological value, excellent fish habitat and historically supported a diverse fish community. Increasing flow regulation has reduced flow variability and facilitated a fish community decline over the past 100 years. Restoration of a more natural flow regime was seen as a major tool to facilitate fish community recovery. To examine the responses of large bodied fish species to water delivery, Murray cod (Percithyidae), golden perch (Percicthyidae), silver perch (Terapontidae) and common carp (Cyprinidae) were fitted with acoustic tags. An acoustic array of 50 receivers was installed throughout the system to determine the extent of small and large-scale movements in response to flow delivery. The use of acoustic telemetry permitted real-time monitoring of flood runner use, movements between main channel, migration barrier impacts and identified refuge habitat once flows receded. Application of the Eonfusion software package further permitted consolidation of complex data into easily interpretable video files. The project is a rare example of how acoustic telemetry can be used in an adaptive management context to report on management objectives. Results are being used to inform a strategic adaptive management model for future watering events.