Developing fishways for non-salmonid fishes: A case study from the Murray River in Australia
fishways, Murray River, fish passage, Australia, dams, weir, barriers, design, laboratory tests, vertical slot, fish density, perch, upstream, diel movement, swimming, swimming ability
Innovations in Fish Passage Technology
American Fisheries Society
In the last one hundred years there have been dramatic declines in the range andabundance of native freshwater fish in southeastern Australia. A major contributing factor tothese declines has been the inhibition or prevention of fish passage at more than 1, 500 damsand weirs. Additionally, the few fishways that were built at these barriers were based onsalmonid designs and were thus not suitable for the Australian fish fauna.To redress the situation, new fishways were designed and built based on laboratory tests withnative species using an experimental vertical-slot fishway. The present study concerns theassessment of one of these fishways at Torrumbarry Weir on the Murray River. The wide sizerange (120-600 mm) of fish ascending the fishway and the reduction in fish density below the weirafter the fishway was operational, indicated the success of the fishway. The dominant portion ofgolden perch (Macquaria ambigua) (Percichthyidae) and silver perch (Bidyanus bidyanus)(Terapontidae) migrating upstream were immature fish. Field experiments defined diel movementpatterns, ascent time, and movement through an experimental tunnel, and demonstrated that theswimming ability of one species in situ was greater than estimates from laboratory experiments.This study emphasizes the significance of four important steps in developing fishways: 1)identifying the species a life stages (and sizes) that are migrating, 2) testing these fish in anexperimental fishway, 3) designing and building the fishway, and 4) quantitatively assessing thefishway. Fishways for nonsalmonid fishes have frequently failed because steps 1, 2, and 4 havebeen ignored.