From March, 1983 to February, 1985, 436 specimens of the fish were collected from the middle and lower reaches of the Jialing River. The vertebra is used as the main material for the investigation. Meanwhile, 77 pieces of cross-section of their pectoral spines were made for comparison. The rate of coinsidence between both is 92.21 per cent. The time of forming annual rings on the centra, length-composition and age-composition of the catch have been approached in this paper. With computer, the optimal regres...