Abstract
Background
The Kangaroo River Macquarie Perch is a cryptic taxon that has been widely reported to likely constitute Australia’s first extinct fish species, this has however been suggested without dedicated and targeted survey and any qualification for the level of survey effort that has been undertaken. In this study we collate and review all of the historical sampling effort that has been undertaken within the historic range, along with presenting the findings of our recent surveys in order to determine if a sufficient level of sampling effort has been undertaken to determine without reasonable doubt that the last individual has died.
Methods
In 2025 targeted eDNA surveys of a 70km stretch of the Shoalhaven River where a sample was collected every river kilometre, in addition fyke netting net surveys were carried out at 3 discrete locations along the 70km stretch of river. Targeted eDNA samples where also collected from 10 tributaries of the Shoalhaven and Kangaroo Rivers. This follows on from an extensive eDNA sampling program that occurred in 2023 where 25 targeted locations were sampled across the Shoalhaven and Kangaroo River catchments.
We also collated and interrogated all of the historical sampling efforts within the catchment to quantify the level of effort and identify if any Macquarie perch detections have occurred.
Results
Data analysed to date show no detections of Macquarie Perch from either eDNA samples or recent conventional sampling methods. A review of past sampling efforts also did not reveal any detections of Macquarie perch.
Conclusions
Our finding provides further evidence that the Kangaroo River Macquarie perch taxon is now likely extinct and that exhaustive surveys in the known and expected habitats, at appropriate times throughout the species historical range over appropriate timeframes have been undertaken and failed to detect the taxon and it is therefore appropriate to declare the taxon extinct.