Murray–Darling Basin Authority Native Fish Strategy Strategies to improve post release survival of hatchery-reared threatened fish species Michael Hutchison, Danielle Stewart, Keith Chilcott, Adam Butcher, Angela Henderson



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Pre-stocking training

Fish were trained in groups of approximately 1400 (enough to stock one site) in 5000 L tanks provided with cover areas for fingerlings and a mesh screen permeable to fingerlings, but not to predators (Figures 11 & 12). One tank was used to train fish bound for soft release, and another identical tank was used to train fish bound for standard release. Predatory fish (one each of Murray cod, golden perch and spangled perch) were kept on one side of the screen. Predatory fish were kept in the tank for at least two weeks prior to introduction of fingerlings to ensure that they were behaving and feeding normally. Predators were provided with sections of PVC pipe to use as shelter and cover (Figure 12).


Training followed the same procedures as for the tank based validation studies except that all fingerlings remained in the training tank for three days. Untrained control fish were maintained in predator free 5000 L tanks. Densities of fingerlings in training tanks (pre-stocking) were almost three times higher than for the tank based validation training. For training to be a viable stocking tool, it must be feasible to train fish en-masse. A total of 2-3% of fingerlings were lost to predation over the three day training period.



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