AGE, GROWTH, AND MOTALITY CHARACTERISTICS OF PELTEOBAGRUS NITIDUS (Sauvage et Dabry) IN THE THREE GORGES RESERVOIR

Pelteobagrus nitidus is one of the dominant benthic fish species after impoundment in the Three Gorges Reservoir (TGR). To study its population characteristics, we sampled fishes (N=2477) from the lower, middle, and upper sections of the TGR from 2015 to 2016, and analyzed the age, growth, and mortality characteristics of P. nitidus. The average standard length (SL) of P. nitidus was (87.1±0.5) mm, and the SL showed no sexual dimorphism. The averaged SL (93.1±0.7) mm and averaged body weight (12.5±0.3) g of populations in the upper section were significantly higher than those of populations in the lower and middle sections. The otolith radius was significantly positive correlated with the SL. P. nitidus was composed of 1—6 ages in the TGR, and two aged individuals dominated the population (42.04%), and the age structures were different among sections. The SL and body weight (BW) relationship was: BW=5×10^–6 SL3.21, which exhibited an allometric growth pattern. The VBGF growth equations for the SL and BW were: L_t=132.2 1–e^{–0.67(t+0.27)} and W_t=32.3 1–e^{–0.67(t+0.27) 3.21}, respectively. Our results suggested that the growth inflection point of the BW was 1.5 age, and the fishing mortality coefficient was 0.61/a. The current exploitation of P. nitidus was 0.44, indicating that P. nitidus was in a state of mild development. The fullness index, hepato-somatic index, and lipid-somatic index showed similar spatial variation patterns, i.e., that values were the highest in the upper section. The fullness index was significantly positive with the hepato-somatic index or lipid-somatic index, suggesting that the three indexes were suitable for evaluating nutritional status of P. nitidus. Our study provides some scientific implications for the management of P. nitidus.