Importance of irrigation infrastructure as refuge habitat for native fish

Due to the growing impacts of climate change, Mediterranean climatic zones are expected to become increasingly arid, with a greater risk of drought. As a result of this, natural wetlands will reduce in size, thereby limiting habitat availability for aquatic biota. Anthropogenic waterbodies such as weirs, dams, and irrigation channels, often provide stable sources of water and are likely to become increasingly important as a refuge for aquatic and terrestrial species. Irrigation systems, particularly the extensive systems in the Murray-darling basin, are a potential host to a variety of native fishes, but their utility as important habitat and refuge are yet to be examined.

This study describes the outcomes of an opportunistic sampling program associated with a fish salvage operation. Through this, fish assemblages were quantified in a 15 km system of main and lateral irrigation channels. A total of 2053 fish were sampled, made up of 11 species, including two threatened species. Of the 11 species, seven were native species and four were introduced. 137 Murray cod (Maccullochella peelii), 87 river blackfish (Gadopsis marmoratus) and 19 golden perch (Macquaria ambigua) were translocated from the irrigation channels, into nearby natural waters to boost natural populations. This study found that anthropogenic waterbodies have the potential to act as a refuge habitat with some species showing potential evidence of natural recruitment within these waterbodies. These results clearly demonstrate the capacity of these irrigation channels to provide a significant source of Australian native fish, both small-bodied and large-bodied species, for future conservation purposes. Man-made waterways are a source population of fish when they can be safely harvested and translocated from these waterways to boost biota in natural areas.