To assess the status of an ecosystem in an appropriate manner, theoretically we have to know its past trajectory and the present state should be evaluated as a point in the continuous trajectory. When preparing the chapter on the Yellow Sea and the East China Sea in the NPESR, it was evident that far less knowledge and information were available than were required to do the state assessment of YS/ECS ecosystem. The picture was fragmentary in terms of geographical, temporal, taxonomical and thematic coverage. A basin-scale picture was lacking, in particular, on nutrient cycles, benthos, fish species biomass and population dynamics, pollutants and their ecological impacts. There were also problems in synthesizing data due to differences in sampling and analysis methods among nations. With such holes, it was even more difficult to single out the causes of ecosystem change. Some of the gaps can be filled in the near future with new international projects in the region. One example is YSLME (Yellow Sea Large Marine Ecosystem) project supported by GEF (Global Environment Facility). Of the five working groups established in the YSLME project, four working groups’ activities are relevant to ecosystem status assessment; Fisheries, Ecosystem, Biodiversity, and Pollution. From proposed activities, historical data will be mined in a more methodical way. And basin-scale surveys are planned to collect up-to-date data of various variables. With better data coverage, a better theoretical development is desired.