Environmental DNA (eDNA) survey of Tilapia infestations in the Fitzroy River Basin

Ojectives: Using environmental DNA (eDNA) to conduct a further survey of tilapia in the Lower Fitzroy Basin catchment. Outcomes: The results of the current survey support previous reports that tilapia are present at several locations throughout the Fitzroy Basin Catchment. Five sites tested positive for tilapia in the current survey including Rossmoya Road, which previously had low detection rates, Hedlow Creek and Eden Bann Weir that previously did not meet quality controls, as well as Lammermore and Ross Creeks that were surveyed for the first time using eDNA methods. The other five sites all tested negative for tilapia DNA. It must be noted a negative result does not confirm tilapia absence at a particular site. A negative result could be due to the DNA simply not being sampled due to low abundance or chance, or it could mean tilapia are not present at the site. All quality control measures (i.e. negative samples, equipment controls and negative PCR controls) were clear of contamination in the current survey. The successful result of zero contamination occurring strengthens the need to carry out eDNA surveys separate to electrofishing or other surveying methods where contamination from field equipment to eDNA equipment can easily occur