CSI-style genetic fingerprinting finds native fish in unexpected place

The olive perchlet is one of several native species that have been found in unexpected places (image: Gunther Schmida).

STATE-OF-THE-ART genetic technologies are helping to solve riddles about native fish populations, according to a study released today by NSW Department of Primary Industries (DPI) and the University of Canberra.

NSW DPI Research Scientist Dr Dean Gilligan said the genetic “fingerprinting” project was led by the University of Canberra with input and support from NSW DPI Fisheries, Diversity Arrays Technology and the NSW Environmental Trust.
“Previously, when we discovered threatened fish populations in unexpected places, it had been difficult to determine whether they had always been there, whether they were a newly established population, or whether they had been introduced,” Dr Gilligan said.
“Fortunately those days are gone, because we can now trace the genetics of fish species to better understand where they come from.”
Dr Gilligan said the recent study applied these CSI-style technologies to recently discovered populations of Southern Purple Spotted Gudgeon on the North Coast, Olive Perchlet in the Lachlan Valley, and the Darling River Hardyhead in the Hunter Valley.
“We now know how important each of these populations of fish are and have the information we need to develop conservation programs to protect and recover two seriously threatened species of native fish,” Dr Gilligan said.
Some recent examples of successful genetic fingerprinting include:
Southern Purple Spotted Gudgeon on the North Coast
When Southern Purple Spotted Gudgeon were found in a small urban creek in 2012 by a student from Southern Cross University, it had been 38 years since they had been found on the North Coast. Using DNA analysis, the research team discovered that this population was natural and had been clinging on, undetected, in the tiny creek.  
Olive Perchlet in Lachlan Valley
Olive Perchlet had not been seen in the Lachlan Valley for 50 years, until one was discovered in 2007. The genetic fingerprint of these Olive Perchlet confirmed they were a natural population that had remained undetected for almost half a century. This population may be the last remaining one within the Southern Murray-Darling Basin. If protected and recovered, these fish could be used to repopulate the species throughout the Murray and Murrumbidgee Rivers.
Darling River Hardyhead in Hunter Valley
The small and inconspicuous Darling River Hardyhead was once widespread throughout the Hunter Valley in the 1980s, but none have been seen for 16 years. By analysing some of the few remaining Darling River Hardyhead in the Hunter Valley, using DNA and film clips of past populations, it was discovered the Hunter Valley stock have the same genetic makeup as those from the Namoi Valley. This indicates that rumours that Hardyhead were introduced into the Hunter Valley from the Namoi Valley in the 1970s may be true. It also reveals that if Hardyhead are to be re-introduced to the Hunter Valley, the Namoi Valley may the best place to source the fish. 
Southern Purple Spotted Gudgeon on the North Coast
A population of Southern Purple Spotted Gudgeon were discovered for the first time ever in the Hunter Valley in 2009. Prior to that, the closest they had ever been recorded to the Hunter Valley was in Lake Minnie Water – approximately 400km north. This represented a potentially massive range expansion for the species. In this case, the team’s analysis determined that the population has many genetic similarities to populations from the Central Queensland region between Bundaberg and Rockhampton. The team noted that they while it is unlikely to be a naturally occurring population, it isn’t a perfect genetic match with any of the known populations in that region either. 
For more information on threatened fish species, click HERE.

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