Temporal pattern and growth characteristics of Pseudobrama simoni at Jingjiang Reach of the Yangtze River

Abstract:

In order to reveal the population dynamics and growth status of Pseudobrama simony in the Yangtze River, a stow net, 40 m in length, 1.8 m in height and mesh size 1.86 cm, was set on Jingjiang wetland for the acquisition of 2 or 3 times a month from 2002 to 2009. The results showed that there were 73 960 fish belonging to 237 fish samples. In which, the P. simoni was 4 253 fish，accounting for 5.52 % of the total. The average catch number of P. simoni per haul was 19 while the maximum was145. Among the total 409 256.23 g of fish catch， P. simoni was 39 618.05 g，accounting for 7.67 %. The average catch weight of P. simony per haul was 180.08 g while the maximum was 1 714.6 g. Analysis indicated that monthly fish catch weight of P. simoni presented a Nonstationary Random Process. SPSS V13.0 software was used to construct the ARIMA model based on monthly fish catch data from January 2002 to December 2009 and ARIMA（1，0，0）（0，1，1）₁₂ model included an equation of (1－0.387B)（1－B¹²）lny_t=（1－0.555B¹²）e_t. The fitting precision of ARIMA model was 83.21%-93.90% from 2003 to 2009. Meanwhile, the biomass peak of P. Simony appeared from May to September, which was two or three months later than Hemiculter bleekeri , the first dominant species in the waters. The age and growth characteristics of the individual analysis for P. simoni collected in 2005 showed that the sex ratio of males to females was 2.3∶1 in the population. The males had three age groups from aged 1 to 3 and females only had two age groups from aged 1 to 2, significantly lower than the age structure of populations of Yao River and the Qiantang River. The Von bertalanffy growth equations of male were concluded as L_t=147.17×［1－e^{－0.1648×(t+3.2036)}］ , W_t=44.36×［1－e^{－0.1648×(t+3.2036)}］^2.785. The estimated parameters for Logistic growth function were L_∞=147.17 mm and W_∞=44.36 g.