AN ECOLOGICAL STUDY OF ERYTHROCULTER DABRYI IN LAKE LIANG-TZE

During the year 1956—1957,an ecological investigation of Erythroculter dabryi was undertaken in Lake Liang-Tze,Hupeh Province.The growth,breeding season,embryonic development, stomach content analysis,age composition of the catch etc.,form the chief items of the investiga- tion. Erythroculter dabryi is one of the predaceous fishes in the lake.It feeds mainly on shrimps and fishes of small size,such as Gnathopogon,Gobius etc.,while the young fish below 10 cm. in body length,is a zooplankton feeder,Bosmio and Cyclops being frequently found in its diet. Generally,the individual of one year old and about 12 cm.in standard length has attained sexual maturity.The ovary develops to the 2nd stage(according to B. A. МеЙн)and remains as such during the winter season.In March of the following year the ovary continues to develop to stage 4,until early in June,when the water temperature is 18° to 20℃.,then the eggs are laid in the littoral region of the lake,adhering to the aquatic plants. The embryonic development proceeds normally when the water temperature is between 23° and 28℃.,and the hatching occurs after one and a half days incubation.The fertilized egg fails to develop when the temperature is below 15℃.One and a half months after hatching,the young fish has grown to resemble the adult in appearance. The annulus formation on the scales is similar to that of the common carp,Cyprinus carpio, being the intersection of new circuli with the old circuli.Individuals of one to three years old form the chief component of the catch.