June 8, 2023
Since 2021, ARI has helped evaluate the ecological and hydraulic performance of two fishways in northern Victoria. The fishways were constructed at Koondrook and Cohuna to reconnect 140 km of the Gunbower Creek with the Murray River. Improving fish passage is a core part of the North Central Catchment Management Authority’s Native Fish Recovery Plan.
ARI has carried out fishway trapping, boat electrofishing, and water level and velocity assessments. Preliminary trapping results (at Koondrook fishway) found that small-bodied and juvenile large-bodied native fish were moving through. The 2023 fish surveys at both fishways detected large accumulations of juvenile Carp and few native fish.
ARI’s work has identified possible refinements to maximise fishway efficiency. These relate to modifying fishway attraction flows, addressing low light levels under the bridge, and reducing build-up of debris and aquatic vegetation.
The monitoring also led to the fishways being closed to help prevent the large accumulations of juvenile Carp from moving into the Gunbower Creek. Additional sampling at both fishways is recommended following the dissipation of the juvenile Carp, as any additional refinements to the fishway operation will be relevant to native fish. This work shows the value of ongoing monitoring to allow adaptive management.
