“Fish need water”. A simple factual statement perhaps, however, when fresh water in Australia is increasingly a scarce and sought after commodity, how do we ensure that fish get the water they need? How does science determine how much water a fish actually needs? When and where its needed? For what purpose, and for how long? And when the water is delivered, how many fish does it support? These questions are now regularly being asked of Australian freshwater fish ecologists by water managers and policy makers.
Environmental flows (or environmental watering) is the deliberate release or management of water to maintain or improve the health of freshwater ecosystems. Since at least the early 1990s, environmental flows have been a key management tool in Australia commonly targeted at supporting native fish populations. Early efforts focused on maintaining minimum flows for habitat provision; but over time, more sophisticated strategies have emerged that utilise flow-ecology relationships to justify flows and support critical elements of a fishes life cycle (e.g. spawning and movement cues, food generation). Despite the scientific advances made, there remain significant challenges including, water scarcity and altered flow regimes due to climate change, water development in regions with limited ecological knowledge, expectations from degraded populations and implications of non-flow drivers on outcomes. Additionally, scientists are now evaluating the benefit of these environmental flows for native fish to justify public purse expenditure. This talk will outline how far we’ve come in the last few decades, and explore the challenges we face now and into the future.