Abstract: Total catch in the main river declined from 43×104 t to 8×104 t in 2011, with a reduction of 81%, while in contrast, since 1950s, total catches in Lakes Dongting and  Poyang fluctuated between 2-4 104 t, respectively. The impact of the Three Gorges Dam on discharge of the three outlets into Lake Dongting was limited, but it decreased the days  and amount of backward flow from the river to Lake Poyang. The inflow of water from the Yangtze River accounts for 30% of the total runoff of Dongting Lake, but only 0.1% in Lake Poyang. Therefore, for the maintenance of fishery resources (especially those fishes with drifting eggs) of the main river, Lake Dongting is much more important than Lake  Poyang. The decline of fishery resources in the main river was mainly the result of obstructions between the river and lakes, although overfishing has also contributed to this,  thus, it is difficult to have a fundamental improvement on the fishery resources in the Yangtze River even fishing is forbidden for ten years. If Lakes Poyang and Dongting are  isolated by dams, the fishery resources in the river will further decline, the extinction of the finless porpoise can hardly be avoided. Therefore, it is crucially important for  the maintenance of biodiversity in the Yangtze River to keep ecological connections between the river and both lakes.