Re-establishing Murray crayfish in South Australia

In 2023, the Murraylands and Riverland Landscape Board, in collaboration with a number of partner organisations, undertook an ambitious trial to re-establish the virtually extinct Murray crayfish (Euastacus armatus) in the South Australian portion of the Murray River. As an iconic native species and of cultural significance to First Nation’s communities, protecting the future of the Murray crayfish is of vital importance.

Where did the released Murray crayfish come from?

As a result of the 2022-23 flood events, a number of Murray crayfish were rescued from black water affected sites interstate. Many of these crays were returned to the location from which they were found, but around 200 were retained for release in South Australia. Between being rescued and released, the crays were maintained in aquarium facilities in Mildura and Victor Harbour.

Murray crayfish can be aggressive and damage one another if held in close proximity, particularly if there are both larger and smaller individuals present in a tank. Tank numbers need to be limited and crayfish need to be provided with cover habitat options – anything from PVC tubing to clay plant pot or rock cave to hide in. Murray crayfish are omnivorous and will eat vegetables and meat, but while they’ve been held in captivity, they’ve demonstrated a real liking for carrots.

Both male and female crayfish were released, ranging in size from about 8cm up to about 30cm in length. Including crays of both sexes and in various life stages maximises the likelihood that the released cray will reproduce and develop a self-sustaining community.

Where were the Murray crayfish released?

That’s top secret information! We’re not disclosing details about the release site to give the crayfish the best chance of survival. What we can say is that the project partners have been involved in significant research which helped identify the most suitable locations for the release by understanding the conditions that crayfish prefer.

How did the Murray crayfish become extinct in South Australia?

For the last 40 years, the iconic Murray crayfish has been virtually extinct in South Australia. Altered flows caused by river regulation reduced the scale of suitable Murray crayfish habitat. In addition, over fishing by commercial and recreational fishers and pollution also resulted in the decline of the species.

While Murray crayfish do live successfully in locations along the River Murray upstream, human intervention is required to successfully re-establish the population in South Australia. This is because Murray crayfish have a very limited range, so it is unlikely that they will spread downstream naturally.

What happens after the Murray crayfish are released?

After the release, the Murraylands and Riverland Landscape Board and Nature Glenelg Trust will work with a number of partner organisations to monitor the released crayfish to ascertain their survival rate and learn more about their habits. Around 30 of the released crayfish were fitted with tracking devices which will help researchers to monitor their movements.

Monitoring will also be undertaken by rangers from the River Murray & Mallee Aboriginal Corporations (RMMAC) River Ranger team.

What should I do if I find a Murray crayfish?

If you happen to find a Murray crayfish while fishing or exploring the river, you should return it to the river and don’t tell people where you found it. You’ll be playing a role in helping to preserve the future of this iconic species for future generations.

Murray crayfish are recognised a protected species under South Australian law. Protected species must be returned to the water immediately. Anyone who takes or causes harm to a protected species may face heavy fines.

Who was involved in the project to release Murray crayfish back into the South Australian Murray River?

This initiative is a partnership between Nature Glenelg Trust, and the Murraylands and Riverland Landscape Board through funding from the landscape levies, with support from New South Wales DPI, OzFish, North West Aquaculture, Victoria Fisheries Authority, River Murray & Mallee Aboriginal Corporation (RMMAC) and PIRSA.