1.Key Laboratory of Ecological Environment and Resources of Inland Fisheries, Scientific Observing and Experimental Station of Fishery Resources and Environment in the Lower Reaches of Yangtze River, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, China；2. Wuxi Fishery College, Nanjing Agricultural University, Wuxi 214081, China
Abstract: The age, growth and morphological features were investigated in 362 samples ofPseudobramasimonicollected in Changshu section of Yangtze River from August to December of 2009 in order to reveal the population and growth status. It was found that the population ofPseudobramasimoniwas comprised of 3 age classes ranging from dominantl 1 year old individuals (accounting for 51.3%) to 3 year old individuals. The population ofPseudobramasimoniwas changed from 62.33 mm to 133.65 mm in body length, primarily between 75 mm to 110 mm, representing 75.41% of the samples. ThePseudobramasimonihad body weight from 3.70 g to 46.10 g, mostly between 3.70 g to 18.70 g accounting for 80.11%, with significant differences in body length and body weight and without significant differences in condition factor, body depth, head length and other 28 morphological features between female and male. The regression equation between scale radius (R) and body length (L)was expressed asL♀=391.67R4-2211.8R3+4609.7R2-4171.4R+1463.2(n=156,P<0.001，r2=0.6973)，andL♂=171.22R4-895.44R3+1719.8R2-1406.4R+486.47(n=178,P<0.001，r2=0.7821),while the regression equation between body length and body weight(W) was described asW♀=4.52×10-6L3.2901(n=156,r2=0.94),W♂=1.09×10-5L3.0915(n=178,r2=0.98).The growth characteristics of the fish were described by the Von Bertalanffy growth equationLt♀=142.31×[1-e-0.1125(t+8.3442)],andLt♂=153.73×[1-e-0.1024(t+6.8309)].The growth inflexion point was found to bet=2.24 year old in the female, andt=3.96 year old in the male, young tendency in the lower reaches of Yangtze River.
2014, Vol. 29 
