Studies On Age, Grouth And Population Protecton Of Mystus Pluriradiatus In Yuanjiang River

We have collected 482 individuals of Mystus pluriradiatus from Yuanjiang River during June,2008 to July,2009. Studied the age and the growth characteristics, calculated the annual population size, and built the B-H model of Mystus pluriradiatus. According to these studies we made some strategies and measures for the population protection of Mystus pluriradiatus. The main results were summarized as follows:1. The age of Mystus pluriradiatus were identified by the age material, we deemed sectioned lapillus was the credible age material,and using asteriscus assisting with the sectioned lapillus in the high age groups was a precision and easy method to estimate age of Mystus pluriradiatus.2. There were 5 age groups in the age configuration from 1～5, the preponderant groups were from 1 to 3, taking 94.13 percent of the total; The average length was 140.7±38.2mm, range from 60mm to 277.6 mm; The average weight was 46.6±40.9g, range from 3.8 g to 275.0 g.3. The length weight relationship can be expressed by the equation The relationship between body length and sectioned lapillus radius can be expressed as the equation L=226.12(RO)-52.852 (R2=0.8434, n=145); The the VBGF equation of the body length and body weight were and and the growth parameter were:k=0.1993,t0=-0.4363,L∞=376.8653mm,W∞= 598.2410g; The inflexion point was 2.3 years; and at this point the body length and weight were 152.7mm and 51.4g.4. The total mortality coefficient Z of Mystus pluriradiatus in Yuanjiang River was 0.8566, the total mortality rate A=0.5607, the natural mortality coefficient M=0.3704, the natural mortality rate v=0.2424, the fishing mortality coefficient F= 0.4862, the fishing mortality rate u=0.3188, the E=0.5677. The biomass of Mystus pluriradiatus in the studing area was 7438.8 Kg by the LCA analysis.5. The B-H model was built for the Mystus pluriradiatus population protectipon.When tp=1, M=0.3704, k=0.1993 and F=0.4862, The yield per unit recruitment Yw/R=25.1g/ind. In the studing area, the average body weight Wy= 45.4g/ind,the average body length Ly=146.5 mm/ind., and the average age Ty=2.1a.6. We suggest the age of Mystus pluriradiatus in the studing area should be increased to 3a, reduce the fishers population and change the fishing method, do much more researches on the hydropower station's influence to Mystus pluriradiatus, and also on the proliferation and protection of Mystus pluriradiatus.