Movement of individual organisms is one of the most fundamental aspects of life and is crucial for developing an understanding of ecological processes to implement effective conservation strategies. The Speartooth Shark (Glyphis glyphis) is a threatened euryhaline species occurring patchily in rivers, estuaries, and marine waters throughout northern Australia and Papua New Guinea. Long term movement was monitored by a receiver array (up to n = 55) deployed in the Adelaide, South Alligator, West Alligator, and Wildman Rivers of the Van Diemen Gulf from 2013–2024. In total, 147 G. glyphis individuals from neonates to subadult were tagged with 2-, 3-, and 10-year acoustic transmitters and monitored for up to 3628 days. Movements of sharks were confined to areas based on specific habitat preferences. Speartooth Sharks demonstrated large-scale seasonal movements in response to environmental factors such as freshwater flow and salinity. These results will be used to inform policymakers about potential impacts of changes to river systems and inform key seasonal management areas. For example, limited geographic range and movements suggest that wet season water ‘harvesting’ may significantly impact this species.