The rivers of northern Australia contain a high diversity and abundance of freshwater fishes, and are relatively undisturbed compared to similar systems throughout the world. There is, however, increasing pressure to use the region's water resources to support agricultural and mining development. It is imperative that we understand the ecological water requirements of key biota before any such development occurs.
This study assesses the importance of both wet and dry season hydrological flow components on juvenile abundance of key fish species. We utilised a standardised electrofishing dataset spanning ten years that has sampled the freshwater fish assemblage at a number of sites in the Daly River, Northern Territory. Results suggest whilst juvenile abundance in the early dry season of many wet season breeding species was related to the magnitude and timing of wet season flows, their subsequent survival to the end of the dry season was also highly related to dry season discharge and duration. Interestingly, the abundance of species which breed in the dry season was also related to both the previous wet and dry season flow conditions. This study emphasises the importance of both wet and dry season flows on freshwater fish recruitment patterns, and also the need to place species-specific flow responses in the context of their life history. Our work will assist in environmental flow management decisions throughout Australian tropical rivers.