Preliminary Study on the Age and Growth Characteristics of Schizothorax macropogon

Schizothorax macropogon is one of the most important commercial species in the Yarlung Zangho River. We aged all the specimens and indentified growth characteristics by examining 293 specimens collected in the Yarlung Zangbo River during 2004 and 2006 based on dorsal fin ray sections. The specimen was formed by 14 age groups from age 2 to age 14 and age 16. The most proportion of the specimen were formed by individuals age 4 to age 6, accounting 74.85% to the total specimen examined. Sex ratio (female : male) was 1 : 0.881. The relationship between standard body length and weight was described by formula W = 0.018L(2.961) for males and W = 0.023L(2.904) for females respectively. Therefore, the growth of S. macropogon was in a constant speed which can be described with von Bertalanffy equation, L-t = 49.622[1 - e(-0.074(t + 4.017)), W-t = 2 034.48][1 - e(-0.074(t + 4.017))](2.962) for males and L-t = 65.676[1 - e(-0.053(t +3.305))], W-t = 4 520.633[1 - e(-0.053(t + 3.305))](2.904) for females. The growth inflexion points were 10.7 years and 16.6 years for males and females respectively with the corresponding standard body lengths 32.86 cm (male), 43.06 cm (female) and body weights of 600.31 g (female), 1 326.75 g (female)