The field work of this survey was carried on from April to July 1981 duringthe breeding season of the "Four famous chinese carps" (Ctenopharyngodon idellus,Mylopharyngodon piceus, Hypophthalmichthys molitrix and Aristichthys nobilis). The results show that the locations of the spawning grounds of these fishes alongthe up and middle sections of the main stream of the Changjiang River is similar tothe work which was made in 1960s. In 1981, the total amount of the eggs spawned bythe four domestic fishes in the whole surveyed sections of the river is estimatedto be 173 hundred millions. It is only about 15.7% of that in 1960s, and indicatesthat the resources of these fishes in this river has been critically declined. At present, the proportion of the eggs spawned by these fishes in the ChangjiangRiver make a great difference in comparison with that in sixties. In the whole inves-tigated sections of the river, the egg's percentage of C. idellus is 59.8%, M. piceus,31.6%, A. nobilis, 4.7% and H. molitrix, 3.9% in 1981. But in the sixties, the egg'spercentage of C. idelllus is 40.9%, M. piceus, 26.1%, Ⅱ. molitrix, 26.1% and A.nobilis, 6.9%. The changes are remarkable. The structure of reproduction populations of these fishes in the Changjiang Riverhas been presented in simplification (or destruction). It appears as follows in the repro-duction populations: the body-size of parent fishes becomes smaller in common, thenumber of age-groups is reduced, the low-age-fishes appeare to be a dominant and theprimary sex-matured fishes constitute the majority. All of these are the obvious sym-bols of the declination of the resources. The investigation indicates that the resources of these fishes in the ChangjiangRiver has been seriously damaged and the total amount of the eggs spawned by thesefishes has sharply decreased. For the purpose to recover the natural resources or these fishes in the ChangjiangRiver, it is necessary to protect the natural reproduction conditions and rebuild themigration pathway and breeding places of these fishes. Seeing that the migratorypathway has been cut off by the water project at Gezhouba, we propose that thefacilities for a fish passage should be built on the dam.