Effects of fish stocking on the zooplankton community structure in a shallow lake in China

Changes in the zooplankton community structure in relation to fishery practices in Lake Donghu, Wuhan, China were examined. The number of Protozoa species increased slightly, whereas the number of rotifers and crustaceans decreased from the 1960s to the 1990s. The total annual average densities of zooplankton increased 15-20 times in the 1990s compared with the 1960s. This increase was largely attributed to Protozoa, which contributed 93.4% by number of the total zooplankton density in 1991. Cladoceran densities decreased markedly from 1987. Changes in densities of rotifers and copepods were not evident. Trends in zooplankton biomass were similar to density. Large changes in zooplankton community structure coincided with markedly changes in concentration of chlorophyll a and transparency in Lake Donghu in 1987. The year 1987 seems to be the threshold year when the zooplankton community structure changed considerably. These changes were related to continuously increasing fish stock biomass in the lake. It was suggested that fish stocking and fish biomass should be a better managed for improvement of the quality of the lake's environment.

SATELLITE REMOTE-SENSING PREDICTION OF JAPANESE PILCHARD FISHING GROUND IN THE HUANGHAI SEA AND THE EAST-CHINA-SEA

The thermophily, fishing season and central fishing ground of Japanese pilchard (Sardinops melanosticta) were studied by using satellite remote sensing (SRS) and other methods in Haizhou Bay and Tsushima waters during 1986-1990. A rapid prediction method of fishing ground is presented. Moreover, the results indicated that the thermophilic values of the fish stock are 11-20 degrees C and both fishing grounds are in increasing temperature process from the beginning to the end of the fishing period. The Japanese pilchards gather vigorously at the sea surface temperature of 15-17 degrees C. The water temperature is a key factor affecting the fishing season and the catch of the fishing ground. The increasing temperature process restricts the fishing season development and central fishing ground formation. The accuracy of 15 predictions made in the Haizhou Bay fishing ground is up to 91.3%, and 37 predictions made in the Tsushima, fishing ground shorten the fish detection time by 13.4% - 22% on the average.

Influences of the Fish-Mouth Project and the Groins on the Flow and Sediment Ratio of the Yangtze River Waterway

A depth-integrated two-dimensional numerical model of current, salinity and sediment transport was proposed and calibrated by the observation data in the Yangtze River Estuary. It was then applied to investigate the flow and sediment ratio of the navigati