According to FAO’s recent report, "The State of World Fisheries and Aquaculture 2022", rebuilding overfished stocks could increase marine capture fisheries production by 16.5 million tonnes and thus contribute to the food security, nutrition, economies and well-being of coastal communities. Scientifically assessed and intensively managed stocks have, on average, seen increased abundance at proposed target levels; in contrast, regions with less developed fisheries management have much greater harvest rates and lower abundance. This highlights the urgent need to replicate and re-adapt successful policies and regulations in fisheries that are not managed sustainably, and implement innovative, ecosystem-based mechanisms that promote sustainable use and conservation around the world. These regions with less developed fisheries management systems include parts of SE Asia, where complex multispecies fisheries make management difficult, as management models that have been successfully implemented in the global north are unworkable. As a result, major adaptations are required through the development of multispecies assessment criteria as the foundation stone of successful fisheries management systems for these regions and their fisheries to be able to contribute to the “Blue Transformation” through the effective management of all fisheries. This panel focuses on case studies from the Gulf of Thailand (Thailand) and Vung Tau (Vietnam), bringing together stakeholders currently involved in the development and piloting of multispecies assessment criteria to assess the sustainability of these complex fisheries and to identify and implement actions to close gaps through a time bound Fishery Improvement Project as a part of the MarinTrust Improver Programme. Panel members will discuss their drive to make changes in a complex ecosystem and the pitfalls and successes along the way as they move towards sustainable management systems and ultimately contribute to the wider vision of Blue Transformation.