Table 9.2 Summary of fish spawning responses to Commonwealth environmental watering. N/A = Not applicable to this watering action. Detailed findings are presented in Appendix D. Fish spawning and reproduction CEWO Water planning and delivery Monitoring and Evaluation questions and outcomes Flow component type Expected outcomes of LTIM Question Observed outcomes What information was Were appropriate flows and target/planned watering action (From the evaluation based provided to achieve the magnitude, duration, Water Use Minutes on? expected outcome? timing and/or and/or CEWO Acquittal inundation extent report CEW delivered from Could not be assessed To provide refuge from irrigation escapes hypoxic water for fish and other aquatic biota Recession and To influence different What did commonwealth NA (The watering actions N/A N/A late autumn/winter environmental occurred outside the time changes in rises that watering action in contribute to increased when equilibrium species may contribute to silver Yallakool Creek spawning activity of usually perch spawning. equilibrium species (e.g. To provide a number of Murray cod, river peaks at a time when blackfish? water temperature is What did commonwealth Environmental flow No eggs or larvae of High unregulated floods in suitable for silver perch environmental water delivery occurred outside golden perch or silver 2016-17 did not trigger spawning. contribute to the monitoring period, and perch were detected spawning in golden or ‘periodic’ To determine if level flow spawning therefore not be with targeted silver perch in Yallakool Creek rises timed with periods of species (e.g. golden and assessed. No evidence of fortnightly sampling, or the Wakool River. 23°C water temperature silver perch, bony herring) golden perch or silver which involved using Environmental flows occurred and no moon (dark night perch spawning was drift nets across the outside the monitoring period, sky conditions) has any found during the four study zones, from and therefore could not be influence on silver perch sampling period Sept to Dec 2016 assessed. spawning response. What did commonwealth Most opportunistic Monitoring abundance Watering actions on the flood environmental species spawned on the of larval fish using light recession did not specifically contribute to the spawning recession of the traps target spawning of of species’ coinciding with opportunistic fish, but occurred ‘opportunistic (e.g. small bodied fish) Commonwealth at a time when spawning of these taxa usually occurs and
Table 9.2 Summary of fish spawning responses to Commonwealth environmental watering. N/A = Not applicable to this watering action. Detailed findings are presented in Appendix D. Fish spawning and reproduction CEWO Water planning and delivery Monitoring and Evaluation questions and outcomes Flow component type and target/planned magnitude, duration, timing and/or inundation extent Expected outcomes of watering action (From Water Use Minutes and/or CEWO Acquittal report LTIM Question Observed outcomes What information was the evaluation based on? Were appropriate flows provided to achieve the expected outcome? CEW delivered from irrigation escapes To provide refuge from hypoxic water for fish and other aquatic biota Could not be assessed Recession and late autumn/winter watering action in Yallakool Creek To influence different changes in rises that may contribute to silver perch spawning. To provide a number of peaks at a time when water temperature is suitable for silver perch spawning. To determine if level rises timed with periods of 23°C water temperature and no moon (dark night sky conditions) has any influence on silver perch spawning response. What did commonwealth environmental contribute to increased spawning activity of equilibrium species (e.g. Murray cod, river blackfish? NA (The watering actions occurred outside the time when equilibrium species usually N/A N/A What did commonwealth environmental water contribute to ‘periodic’ flow spawning species (e.g. golden and silver perch, bony herring) Environmental flow delivery occurred outside the monitoring period, and therefore not be assessed. No evidence of golden perch or silver perch spawning was found during the sampling period No eggs or larvae of golden perch or silver perch were detected with targeted fortnightly sampling, which involved using drift nets across the four study zones, from Sept to Dec 2016 High unregulated floods in 2016-17 did not trigger spawning in golden or silver perch in Yallakool Creek or the Wakool River. Environmental flows occurred outside the monitoring period, and therefore could not be assessed. What did commonwealth environmental contribute to the spawning of ‘opportunistic species’ (e.g. small bodied fish) Most opportunistic species spawned on the recession of the coinciding with Commonwealth Monitoring abundance of larval fish using light traps Watering actions on the flood recession did not specifically target spawning of opportunistic fish, but occurred at a time when spawning of these taxa usually occurs and
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