Zoological Studies

Vol. 51 No. 7, 2012

Reproductive Biology of Schizothorax o’connori (Cyprinidae: Schizothoracinae) in the Yarlung Zangbo River, Tibet

Bao-Shan Ma1,2, Cong-Xin Xie1,*, Bin Huo1, Xue-Feng Yang1, and Shui-Song Chen3

1College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei 430070, China
2Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan, Hubei 430223, China
3Yangtze Valley Water Environmental Monitoring Center, Wuhan, Hubei 430010, China

Bao-Shan Ma, Cong-Xin Xie, Bin Huo, Xue-Feng Yang, and Shui-Song Chen (2012) The reproductive biology of Schizothorax o’connori (Cyprinidae: Schizothoracinae) was studied by examining 1126 individuals collected between Aug. 2008 and Aug. 2009 in the Yarlung Zangbo River, Tibet.  The population had a significantly higher proportion of females than males (X2 test, p < 0.05).  Using a logistic regression, it was determined that the standard lengths at 50% maturity were 304 mm for males and 389 mm for females; the ages at 50% maturity were 8 yr for males and 10 yr for females.  Based on the monthly proportions of macroscopic gonadal maturity stages and monthly variations in the gonadosomatic index, S. o’connori spawned over a short period, from Feb. to Apr. with a peak in Mar.  Females had heavier livers than males for a given eviscerated weight (ANCOVA, p < 0.05).  According to the size distribution of oocytes, S. o’connori appeared to show a high degree of spawning synchronicity.  The estimated values of fecundity ranged 8228-39,343 (21,190 6990) eggs/fish.  The relative fecundity ranged 6.2-22.2 (14.3 3.3) eggs/g of fish.  The fecundity of S. o’connori increased linearly with the standard length and total weight, but had no significant correlation with age.

Key words: Reproductive biology, Spawning season, Fecundity, Schizothorax o’connori, Tibet.

*Correspondence: Tel: 86-027-87286862.  Fax: 86-027-87282114.    E-mail:xiecongxin@mail.hzau.edu.cn