Monitoring fish in the Koondrook-Perricoota Natural Flooding Event in 2016: Acoustic monitoring component
Duncan, M., Robinson, W. and Martin, K., 2017. Monitoring fish in the Koondrook-Perricoota Natural Flooding Event in 2016: Acoustic monitoring component. Report to Forestry Corporation and MDBA, 47p.
Koondrook-Perricoota Forest (KPF) is an extensive floodplain forest area adjacent to the River Murray between the towns of Gunbower and Barham. River regulation and the associated reduction of natural flooding of the forest have resulted in the decline in the health of the forest. To address this decline, water management infrastructure has been constructed as part of The Living Murray Initiative to enable the watering of the KPF. These structures were operated to water the forest for the first time from August to October 2014 and the fish response to the flooding was monitored. In the winter and spring of 2016, rainfall in the catchments of the Murray-Darling Basin resulted in widespread flooding and KPF received the largest flood since December 2010. This presented an opportunity to monitor fish responses to a natural flood that could potentially inform management of the watering infrastructure to maximise benefits to native fish. The main areas of interest were the movement response of large-bodied native fish and common carp, and whether the flooding triggered a large common carp spawning event in KPF, potentially providing a source of juveniles that could colonise the Murray River. Golden perch (n=12), silver perch (n=1) and common carp (n=44) were fitted with acoustic tags to enable their movements within and outside KPF to be tracked during the flooding. Most golden perch moved downstream away from KPF once water began to flow and moved into KPF once flooding commenced. The single silver perch tagged also moved downstream with the flood. These downstream movements preceded anoxic blackwater that resulted from the flooding, though dissolved oxygen levels were falling and may therefore have triggered this downstream movement to avoid anoxic blackwater. Alternatively, the downstream movements may have been associated with a spawning migration. In contrast, of the 42 common carp tagged outside KPF, 34 moved into the forest at some point during the flooding. Most movements into KPF occurred soon after floodwaters arrived. Some individuals continued through KPF to the Murray River and then moved downstream to Gunbower Creek or upstream towards Barmah-Millewa Forest. Twelve carp had their last detection within KPF; they potentially left KPF via an unmonitored connection to the Murray River, or remained in isolated pools, or died.