Covering a water surface of more than 22,000ha in large, Tam Giang- Cau Hai lagoon in Thua Thien Hue province is considered as the largest lagoon system of Southeast Asian region. This is a remarkably coastal ecosystem where many aquatic species high in valuable economy are dwelling. In the Tam Giang - Cau Hai lagoon, the aquatic resources for catching and aquaculture are major livelihood of thousands fishermen's households. Nevertheless, this renewable bio-resources are at risk of depletion as a result of an exploitational process weaken in management and organization and lacking in scientific basement. As a consequence, some aquatic species are at risk of extinction, water bird populatios decreased in individual number etc. that has affected adversely the livelihood of Thua Thien Hue's lagoon-based fishermen. The matter of resource management in general and aquatic resource management in particular are always the top priorities of local authorities, scientists and fishermen communities in Thua Thien Hue's lagoons.