NSW Department of Primary Industries/Murray Local Land Services, $120,000
Dr Lee Baumgartner, Dr Luiz Silva, Dr Stacey Kopf, Daniel Svozil
Macquarie Perch, a threatened species, was once very prevalent along the Murray. However there has been a big reduction in its population with only one small population remaining in Dartmouth Dam, in the Victorian portion of the Murray catchment, and another [possibly] in Mannus Creek, in the NSW portion of the Murray catchment.
The initial aim of this project was to determine whether or not the populations of Macquarie Perch in Mannus Creek (one fish was found in 2009) had persisted following the failure of Mannus Dam in October 2010, and then a major flood event.
Researchers began their first sampling for Macquarie Perch in June 2017 at 15 sites - five sites upstream of Mannus Dam which has been reinstated; five sites immediately below the dam to Mannus Falls; and five sites from the falls to the Tooma bridge – a distance of about 65kms.
Coupled with the fish sampling was a habitat mapping assessment undertaken in November 2017 which collected data about all the different structures (pool size and depth, refuge habitat, woody habitat, riparian vegetation, pest plant species, and refuge areas) along the creek’s 65km length.
A second round of sampling commenced in February 2018.
Early indications are that the population of Macquarie Perch in Mannus Creek has persisted with over 30 individuals found in the reach below Mannus Falls. Both juveniles and recruits were found, indicative that the fish are probably spawning in the area and that there could be a self-sustaining population. The habitat mapping has also indicated habitat conducive for spawning. Macquarie Perch require a specific habitat type to spawn i.e. it generally spawns at the foot of pools with the fertilised eggs settling in riffles (a series of rocks that creates small cascades.)
The sampling has also indicated the presence of other eight fish species along the sampling area, including three natives (Murray cod, Mountain galaxias and River blackfish) and five invasive species (Redfin perch, Common carp, Brown trout, Goldfish and Gambusia). Special attention will be given to the distribution of Redfin perch in the area since that species prey on all different life stages of Macquarie Perch.
The researchers are analysing the habitat mapping data, correlating the presence/absence of Macquarie perch with habitat features. Once they have completed the analysis, it will provide a guide for identifying other areas that may have habitat features suitable for Macquarie Perch.
A progress report was submitted to the NSW DPI-Fisheries and Murray LLS with results from the first fish sampling.
Final Report: Silva, L., Pearce, L.,Mabon, S., Horta, A., Duffy, D., Kopf, S., Ning, N., Baumgartner, L. (2018) Macca's in the Manus, Macquarie perch refuge in the Upper Murray. ILWS Report 114
The expected outcome of this project is recommendations/management plan for Macquarie Perch for NSW DPI-Fisheries and Murray LLS that will help conserve the threatened species.
Dr Luiz Silva