Age Structure,Growth Characteristics and Life-history Pattern of Xenophysogobio boulengeri

A total of 405 specimens of Xenophysogobio boulengeri were collected from October 2010 to July 2011 in the upper reaches of the Yangtze River.The age structure and growth characteristics were studied by otolith,then the life history pattern was concluded by the method of fuzzy cluster analysis.The results showed that,the catch consisted of four age groups and individuals of age 1 to 2 groups were dominant,occupying more(83.70%).The relationship between body length and weight was described by formula W=5×10-6L3.294 3(r2=0.941 3,n=405,F=6 040.22,P0.01).The body length and otolith radius could be expressed as L=0.000 8R2-0.168 4R+42.504(r2=0.836 5,n=399,F=399.20,P0.01).The von Bertalanffy equations of the species were calculated by Lt=179.49(1-e-0.249 8(t+0.289 8)),Wt=133.18(1-e-0.249 8(t+0.289 8))3.294 3.The age inflection point of body weight was estimated at 4.48 years.According to the typical characteristics of r and k selection and the results of fuzzy cluster analysis,it was concluded that the life-history pattern of X.boulengeri tended to r-selection.Compared with samples of this fish from the study area in 2001-2002,the growth characteristics of them have changed in the upper reaches of the Yangtze River,therefore it is urgent to take protective measures for this fish.