Runoff from the Yellow River, the second largest in China, has historically nourished the fisheries resources in Laizhou Bay waters for a long time. However, a recent reduction in seasonal or annual outflow could lead to decline in nutrient flux and biological productivity. Our data from a series of comprehensive surveys in the above waters since 1982, showed that the 114 species of fish in the community were dominated by 66 warm-temperate species comprising 52.28% of total NED (Ecological Density of Number) and 57.06% of total BED (Ecological Density of Biomass). These fish averaging 14.48g, were much smaller than cold-temperate species. Therefore, the seasonal alteration in ecological density within the community could be differentiated into a November to next July cold group, characterized by abundant recruitment in estuarine waters, and an August to October warm group, characterized by congregation of maturing species for spawning. It was found that the spatial dynamics of e fish community in the studied area differed little among stations, and that numerical parameters were directly proportional to water depth. Although there were large seasonal variations in both species composition and ecological density in the fish community, japanese anchovy, Engraulis japonicus T. et. S, and hair-fin anchovy, Setipinna taty (V.) maintained and controlled the overall development of the nekton community in the waters.