Conservation research has predominantly focused on identifying where and why species or habitats are under threat. While this is a crucial first step, it does not tell us how to optimize the allocation of resources in order to conserve threatened biodiversity. The time is ripe to focus on identifying the key management actions needed to respond to multiple threats and emerging risks. Using state-of-the-art techniques in conservation decision science, priority threat management assessment, and expert elicitation, we seek to identify the most ecologically effective and at the same time, least costly management actions needed to ensure the long-term persistence of at risk biodiversity of the Fraser River Estuary. This estuary is the mouth of the largest salmon bearing river in the world and a stopover point for more than one million migratory birds. Many species on the estuary are at risk due to water pollution and loss of habitat resulting from industrial and urban development, exploitation of fish stocks, and climate change. This study region serves as a prime example of a complex system under siege from multiple threats but with limited scientific data. We show that such systems can be analyzed to generate management actions ranked according to estimated cost, ecological benefits, the probability of success. Importantly, this analysis can clarify what can and cannot be achieved for different levels of conservation investment, and can be used to leverage increased investment in conservation management
