Rotenone key in wiping out aquatic pest

By Dale McNeil

Picture1 Speckled Livebearer 

A Speckled livebearer Phalloceros caudimaculatus removed from Willunga creek on South Australia’s McLaren Vale.

Two separate reports of a “strange fish” captured in the heart of South Australia’s wine country led to an investigation by scientists from the SA Research and Development Institute (SARDI). Follow up surveys verified the establishment of a new aquatic pest for the State, the speckled livebearer Phalloceros caudimaculatus. SARDI scientists and managers from Biosecurity SA, the EPA and the Adelaide and Mount Lofty Ranges NRM Board joined forces to wipe out this new infestation.

Picture2Dale Electrofishing

Too many to zap! Early investigations revealed abundant and widespread populations of the pest throughout the creek.

After a rapid but thorough consultation process including EPA and veterinary regulators, and preliminary scientific investigations, rotenone treatment was employed along several kilometres of stream running through agricultural and urban land in the picturesque Maclaren Vale. Follow up surveys for the past four years have verified that all pest fish have been removed during initial and rapid follow up spot treatments using rotenone. Dosage rates were tailored to the highly tolerant pest fish after tolerance trials were conducted by SARDI. The treatment also removed all pest carp (Cyprinus carpio), the only other species present.

Picture3 Rotenone

Rotenone mixing and application into Phalloceros habitat in Willunga Creek. Flowing runs and riffles, pools, subterranean drainpipes, trickles, front yards, back yard fishponds, dams and reed beds were all treated to complete the eradication.

Following treatment and follow up surveys, native mountain galaxias (Galaxias olidus) from the neighbouring tributary were translocated into the reach by the Local children at Willunga Primary School. Tadpoles, yabbies, frogs and turtles were removed prior to treatment and kept in aquaria before being returned to site following treatment.


Native Galaxias olidus ready to move next door to the treated tributary thanks to the children of Willunga Primary School.

With a principal threat to native fish now removed, other restoration activities s are free to proceed with less risk of failure. As part of a consultative partnership between local community, scientists, Biosecurity and Natural Resource Managers, rotenone treatment was an efficient and effective method of meeting State and regional management targets stating that new aquatic pest species will not be allowed to establish in South Australian catchments. Rotenone is a key part of this great success story and is one of the principal tools for maintaining and restoring native fish populations and abolishing aquatic pests.



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