Stopping a torrent of tilapia in the Murray-Darling Basin

Stopping a torrent of tilapia in the Murray-Darling Basin

There are currently no known tilapia populations established in the Murray-Darling Basin, however, unless we are vigilant now, it is likely they will invade.   Tilapia are classified in the 100 worst pest animals, and one of the worst freshwater pest fish in the world by the International Union for the Conservation of Nature.  The best way to stop tilapia establishing in the Murray-Darling Basin, is for people not to move tilapia into the Basin in the first place. 

There is a high risk of a tilapia incursion into the Murray-Darling Basin with tilapia (Oreochromis spp.) populations established in four neighbouring catchments, including creeks within 10 kms of the Basin.  If tilapia become established in the Basin they are likely to survive across most of the Northern and Western Basin.  People are the major risk of translocating tilapia into the Basin.  Tilapia are mouth brooders keeping their eggs and fry in their mouth which means the eggs can survive for a very long time, even if the parent fish is dead.  People moving tilapia into the Basin dead or alive is a high risk for an incursion.

Tilapia map

Map of catchments with tilapia known populations

Tilapia Impacts

It is expected that an established tilapia population in the Basin, will:

  • Cause reduced water quality including increased blue-green algal blooms and winter fish kills.
  • Dominate refuge waterholes during droughts due to their ability to stunt growth and breed under harsh conditions.
  • Compete with native fish for food and space, excluding native fish from breeding areas and reduce the breeding success of many native fish species.
  • Predate on small native fish.
  • Disturb aquatic plants and increase the turbidity of the water.
  • Ultimately cause an additional impact on already stressed river systems and native fish, resulting in economic, social and environmental impacts to Basin individuals and communities.
Map of water suitable for tilapia  within the Basin

Map of water suitable for tilapia  within the Basin

The Murray-Darling Basin tilapia exclusion strategy

  • The strategy raises the community’s awareness of the risks and impacts tilapia pose to the Basin. Community members are trained to educate their networks not to bring tilapia into the Basin; the impacts tilapia will cause to the Basin, and; to identify tilapia and report them if they are ever detected.  Early detection of new pest fish outbreaks is vital to allow pest management options to be undertaken.  Please report any unusual fish sightings to the State Government through the Pest Fish Reporting tools
  • QLD DAF – call centre 132523 or daff.qld.gov.au
  • NSW DPI: (02) 4916 3877 or pests@industry.nsw.gov.au
  • Identifying tilapia:

The diagrams below are useful for recognising the difference between tilapia and our native fish.

 Tilapia have one continuous dorsal (top) fin with a pointed end

Tilapia have one continuous dorsal (top) fin with a pointed end

Native fish have a dent or break in their dorsal fin with rounded end.

Native fish have a dent or break in their dorsal fin with rounded end.

Tilapia with eggs in mouth

Tilapia with eggs in mouth

Tilapia fry flushed out of a tilapia’s mouth.

Tilapia fry flushed out of a tilapia’s mouth.

 

Project partners

This project is funded by the Murray-Darling Basin Authority and undertaken by River Health and Habitat Restoration in partnership with a wide range of Basin fishing clubs, community groups, schools and the community.

References

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Greg Ringwood

Greg Ringwood

Greg Ringwood is a fisheries scientist, with extensive experience in restoring native fish habitat and fish communities. Greg has worked on many river restoration and flood recovery programs across the Northern Basin, the Dewfish Demonstration Reach is the most high profile of these programs. Greg has worked on Carp management and preventing a tilapia incursion into the Basin since 2008. Greg also formally worked on the Native Fish Strategy in Queensland. Contact greg@rhhr.com.au
Greg Ringwood

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