In Mediterranean climatic zones, climate change is altering weather patterns, with parts of Australia becoming increasingly arid, experiencing above average temperatures and fewer rainfall . Increasing aridity is leading to more frequent and longer water shortages, reductions in the size and number of natural permanent wetlands and decreased water stability in semi-permanent waterbodies. As human demands for water resources grow, increasing amounts of water are being transferred from natural systems and stored in various man-made waterbodies. The greater delivery of water for human use has led to increased variability and shortages of permanent water in many natural waterbodies, whereas water availability in anthropogenic waterbodies tends to be stable. Therefore, the permanency of water in man-made water storages suggests that they may form significant refuges for a range of aquatic biota.
Approximately 75% of water in the Murray-Darling Basin is diverted into expansive irrigation systems that deliver significant volumes of water for agricultural and other human uses. Historically, irrigation channels are perceived as waterways that form dead-end ‘sink-populations’, where larvae from natural recruitment are drawn into the channels and ‘lost’ from the natural waterway. However, any loss of larvae and, subsequently, juvenile and adult individuals, could be ameliorated by reconsidering the environmental management of these systems. For example, there is a growing number of recent studies that have found positive values of different types of man-made infrastructure. Therefore, fish that inhabit the channels only constitute a loss if they are left to die during regular channel maintenance operations. A total of 2053 fish of 11 different species were sampled during a fish salvage operation in 2020. These results included 1068 western carp gudgeon, making up the bulk of the captures, as well as 164 of the iconic Murray cod and 98 river blackfish.