Monitoring fish movement can test the effectiveness of environmental flow releases when they are used to trigger spawning behaviour. Environmental flow releases have been used to enhance Australian grayling (Prototroctes maraena) spawning in regulated rivers in south-eastern Australia and resource managers require knowledge of the effectiveness on the conservation of this threatened species.

Australian grayling movement was monitored in the Thomson River, south-eastern Australia using acoustic telemetry to determine whether the species undergoes a spawning migration, where they migrate and timing in relation to environmental flow releases. Drift netting was used to verify whether spawning took place.

Adult Australian grayling undertook downstream spawning migrations (up to 140 km) to the lower Thomson River, coinciding with environmental flow releases.

The findings of this study support the use of environmental flow releases to trigger spawning migrations by Australian grayling. In addition, they provide managers of other species with an example of the potential effectiveness of environmental flow releases in triggering fish migration or spawning that can assist in rationalising this management intervention.