STUDIES ON PRESENT SITUATION AND CHANGE TREND OF DONGTING LAKE FISHERY RESOURCES AND ENVIROMENT

The investigations in 1990-1999 show that:the fish species in Dongting Lake are similar to those in 1970s,but the population composition has changed greatly.Most of fishes are the lacustrine fishes including commom carp,crucian carp and Parasilurus sp etc,which take up to 86.1%.The proportion of the four major chinese carps is less than 10%,and the migration fishes(Coilia ectenes etc.)are very scarce.In 1991s the average catch is 39.7 thousand tons.In comparison with the past,the fishery yield increases,but most of fishes are 1-2 year old ones,and the preparing parent fishes are seriously scarce.The main reasons are water engineering,deposit silt,artficial enclosure,water pollution and over catching.