The Australian Lungfish is an iconic species. It is an air breathing freshwater fish that may survive up to 100 years and has remained unchanged for 140 million years. However, young fish may not be reaching maturity, leaving an ageing population in terminal decline. We propose to use a novel method for exploring this threat. This method integrates radiocarbon ageing and conservation genetics to identify historical (pre-1950s) and contemporary trends in genetic variation and rates of successful breeding. Historical environmental data will be related to these trends enabling managers to prioritise intervention actions. This study will provide a unique method for the conservation of lungfish and other long-lived species.