Hydropower / Pumped Hydro Energy StorageProject Small Scale Hydropower Technologies Impact on Australian Native Fish
A final report on the impact of small scale hydropower technologies on Australian native fish species.
For many fish species, downstream migration is required to satisfy important life history requirements, such as feeding and breeding. However, river infrastructure (e.g. dams, weirs, hydropower turbines) can block these migrations. The provision of safe downstream passage of fish at these structures is therefore a significant challenge worldwide. Fish are exposed to a range of stresses when they pass river infrastructure that are not encountered in natural flowing, unregulated rivers. Two stresses that can combine to cause significant injury and mortality to fish are decompression (rapid, extreme drops in water pressure) and fluid shear stress (when water of differing velocities and direction intersects, causing distortion of fish).
Within the Murray–Darling Basin (MDB), many fish species undertake extensive downstream migrations as eggs, larvae, juveniles or adults. Passage through river infrastructure has been shown to affect their survival, but the relative contribution of different stresses (such as rapid decompression and fluid shear) to overall injury and mortality remains poorly understood. In turn, this makes it difficult to assess the risk associated with infrastructure projects, or to develop engineering and operation guidelines to reduce the risks of downstream fish passage.
This report details laboratory experiments that determined the tolerance of various species and life stages of fish from the MDB to rapid decompression (in hypo/hyperbaric chambers) and elevated fluid shear (in a shear flume). Fish were exposed to a wide range of conditions to model the probability of injury and mortality. Our ultimate goal was to determine critical thresholds for injury and mortality, and develop criteria to protect downstream migrating fish at river infrastructure. We hope these criteria can better inform policy relating to the development and management of mini-hydropower and irrigation infrastructure to protect downstream migrating fish.