Age, Growth, and Reproduction of Opsariichthys Bidens (Cyprinidae) from the Qingyi River at Huangshan Mountain, China

Age, growth, and reproduction of Opsariichthys bidens (Cyprinidae) from the Qingyi River at Huangshan Mountain, China. Zoological Studies 51(4): 476-483. The age, growth, and reproduction of Opsariichthys bidens were studied in a sample of 281 specimens from monthly collections made from May 2009 to Apr. 2010 in Qingyi Stream, Anhui Province, China. The sex ratio of this study population was 1: 1.18 (female: male), which did not significantly differ from 1:1. The oldest females and males were 5 and 4 yr old, respectively. The dominant age groups were 2 and 3 yr old in both sexes. Annuli on scales were formed in Feb. and Mar. No obvious sexual dimorphism was observed in the length-weight or length-scale radius relationships or in the total lengths back-calculated at each age for either sex. An inflection point occurred in the growth curves given by the von Bertalanffy growth functions for total weight. At this inflection point, females and males were 4.7 and 4.3 yr old, respectively. Both sexes reached sexual maturity at age 2 yr. At this age, total lengths of females and males were 118.1 and 126.5 mm, respectively. The temporal pattern of the gonadosomatic index corresponded to a spawning period that occurred from Apr. to July. Absolute fecundity significantly increased with total length and weight and significantly varied among age groups, whereas no significant variation was observed in relative fecundity in relation to body size. These life-history traits (e.g., the timing of annulus formation, young age structure, temporal pattern of gonad development, and early age at maturity) of O. bidens in the studied river are hypothesized to be tightly associated with features of the surrounding environment, such as local hydrological rhythms, unstable habitat conditions, and severe human disturbance.