Tiger sharks (Galeocerdo cuvier) are highly migratory, which makes it difficult to understand where they came from and how big their populations are. We are analysing tiger shark genomes (i.e., the complete set of all of their genetic material) to better understand their population size, structure, relatedness, and movement patterns across Australia. We are also using environmental DNA (eDNA) methods to detect the presence of sharks in a non-invasive way. By combining two different approaches we are hoping to advance knowledge of tiger shark populations while also developing new methods for monitoring their presence throughout Australian waters.