Horseshoe Bend Tunnel is four kilometres from Walhalla on the Thomson River. It was built in 1911 and 1912 to drain water from the Thomson at Horseshoe Bend to allow for alluvial mining of the river bed. It gained heritage status in 2002 (if you’re interested in the history of the tunnel, please download a copy of the Heritage Report part one and part two). Horseshoe Bend Tunnel now acts as an artificial fish barrier to the alpine regions. Flows have only gone round the bend two per cent of the time in the last 13 years. This has severely impacted upstream migration to the unreachable 85 km of habitat for migratory fish.
Fish migration is extremely important in the lifecycle of many of our native fish, including the protected Australian Grayling. The Grayling is listed as vulnerable under the Environment Protection and Biodiversity Conservation Act 1999.
About the Australian Grayling
The Australian Grayling is a small to medium-sized, slender, silvery fish with soft-rayed fins. It lives in south-eastern Australia, including Victoria, Tasmania and New South Wales.
The Grayling has a very short life span of 2-3 years and migrates throughout its life cycle between fresh and marine waters. Adult Graylings live in freshwater river systems. They move up and down the river looking for food and during autumn migrate to near the estuary to spawn. Its eggs are swept downstream towards the sea and the adults return upstream. The young fish remain in the sea for about six months before returning to freshwater.
In our region it can be found in the Thomson, Macalister, Avon, Latrobe, and Tarwin rivers.
The Grayling needs our help
Threats to the long term future of the Australian Grayling include
- artificial fish barriers (like Horseshoe Bend Tunnel)
- introduced fish species
- low river flows
- river regulation by dams
- nutrients in waterways
- its short and complex life cycle of needing to move up and downstream to reproduce