Hunt for Tilapia continues in Mackay

A barramundi which is a natural predator of tilapia
Barramundi are natural predators of Tilapia and are currently being monitored in the Mackay Gooseponds. In June this year 1000 barramundi fingerlings were released into the Gooseponds to help control the Tilapia pest species. The release was a coordinated event, made possible by strong support and contribution from the local community, including key stakeholders – Reef Catchments, the Mackay Recreational Fishers Alliance and Mackay Area Fish Stocking Association.

Efforts to detect and control tilapia outbreaks in Mackay were recently renewed, taking a high-tech twist with the use of environmental DNA (eDNA sampling).

Trent Power, aquatic ecologist from Catchment Solutions, said the latest round of Tilapia sampling would focus primarily on the upstream and downstream waterways around the Gooseponds, as well as other potential at-risk areas.

“As well as the Gooseponds and adjoining waterways, we will extend the search to the Botanic Garden lagoons as this area is a likely hotspot for new incursions,” Mr Power said.

Samples of eDNA collected will be sent to James Cook University (JCU) where they will be analysed for the presence of tilapia DNA, providing a method of early detection.

“The team at JCU have developed primers which can amplify DNA markers specific to tilapia, allowing us to detect the presence of tilapia DNA in water samples,” Mr Power said.

“This technique is relatively new but has proved to be very sensitive, with the potential to detect tilapia at some sites where traditional sampling methods may not pick them up.

“The data can be used to assess current distribution and also to track movements in the tilapia population with follow-up sampling after the wet season.

“This information will also help us assess the predatory control trial (release of barramundi) in the Gooseponds which started in June this year, it would be very encouraging if tilapia DNA was not found.”

Samples will also be gathered with the use of an electrofishing boat to support eDNA findings and provide additional information on the native fish populations.

“As the name implies, electrofishing uses an electrical current to temporarily stun the fish which can then be scooped up and identified. It is important to use both techniques to provide the best picture of the fish community at each site. eDNA will be able to tell us if tilapia are present and electrofishing will allow us to determine species composition and size distributions,” Mr Power said.

He said it was critical the levels of tilapia in Mackay continued to be tracked and monitored.

“Tilapia are considered to be one of the worst aquatic pest species in Australia with a high potential to out compete our native fish species, so it is very important we have an accurate gauge of their movement,” Mr Power said.

“If you sight or catch a tilapia, we are asking people to ring Queensland Fisheries straight away to report the find on 13 25 23. If we can get the community on board to keep an eye out for tilapia and to report sightings, we have a much better chance of controlling the spread in Mackay and beyond.”

He said he applauded the level of community commitment so far.

“We would not be able to so successfully address Tilapia in the Mackay region without the support we have had from the community. The project has been a coordinated community effort, with strong support from key groups such as the Mackay Recreational Fishers Alliance and Mackay Area Fish Stocking Association. Very generous donations from members of the public were also received for the purchase of barra fingerlings”

Stop the Spread is a Reef Catchments Systems Repair program, with funding from the Australian Government and supported by the local community.