The hilsa shad (Tenualosa spp) fisheries are one of the most important commercial fisheries in the Bay of Bengal region, being the national fish of Bangladesh, and playing an essential cultural and economic role in the lives of Myanmar people. More recently, the availability of Hilsa has declined across this region, due to a number of anthropogenic pressures, mainly intensive fishing and river obstruction by dams and barrages. Hilsa are known to be anadromous moving from the sea to the brackish or freshwater to spawn, however very little is very little is known about the lifecycle requirements of Hilsa in Myanmar waters and their migratory routes. River engineering and irrigation infrastructure is increasing in Myanmar rivers, wetlands and estuary systems and this has the potential to significantly negatively impact the Hilsa fisheries in Myanmar. With very little information on the migration patterns of Hilsa in Myanmar, it limits the ability for planning and positioning of infrastructure or remediation works such as fish passage. Leading on from other preliminary World Fish studies, Delta Flows is utilizing otolith microchemistry to determine the movements of adult Hilsa from the sea to the brackish or freshwater, where spawning might occur, and the movements of the juveniles back to the sea. Preliminary catch data has found adult Hilsa hundreds of kilometres inland including young-of-year, so it is suspected that at least a proportion of the population is spawning in freshwater. The next stage is analysis of the otolith microchemistry and this will help to better understand the lifecycle requirements of Hilsa in Myanmar waters, and improve informed decision making in relation to infrastructure planning.