STUDIES ON GROWTH CHARACTERISTICS OF GYMNOCYPRIS PRZEWALSKII PRZEWALSKII

In this study,1175 samples of Gymnocypris przewalskii przewalskii,which were collected from the Qinghai Lake from May,2002 to July, 2003,were aged by determining the annuli of otoliths.Regressive body length was used to fix the Von Berta-lanffy function.Otoliths are good materials in age determination,which have relatively clear annuli and are unlikely to lose annuli because of absorption or erosion.Besides,the growth rates were calculated from the ages of these fish samples.The survey during the period from May to August showed that the sex ratio of males to females in the brood stock was 1166 to 1.This is consistent with the results of the statistics in the 60s and 90s of the 20th century. In all the brood stocks ,the body length and body weight of the smallest male individual at the age of 4 was 13010mm and 2810g,respectively,while the body length and body weight of the smallest female individual at the age of 5was 17010mm and 5110g,respectively.The age composition was from 4 to 11.The mean body length and body weight of female were bigger than those of male.The body length and body weight was in the relation of power function.The relationship of body length to body weight for the female was W=01000174譒2.49899,and that for the male W= 010000402譒2.75382.There was a significant difference in growth between the female and male.Their growth could be described by Von Bertalanffy equations Lt=55119301 1-e-0107112(t+013044)(female),Lt=682186881-e-0105304(t+014240)(male),Wt=123713431(1-e-010711(t+013044),/sup>)214990(female),Wt=256713242(1-e-010530(t+014240))217538(male).The inflection points for the growth of female and male were 12157 and 18167,respectively.Otolith described the growth of Gymnocypris przewalskii przewalskii well,scale and dorsal fin spine could not do better