岷江切尾拟鲿的年龄结构与生长特征

Age structure and growth characteristics of Pseudobagrus truncatus in Minjiang River

以2012年11—12月和2013年4—5月在长江上游岷江河口区域采集的436尾切尾拟鲿（Pseudobagrus truncatus）为研究对象,以耳石为年龄鉴定材料,对其年龄结构和生长特性进行了研究。结果表明：调查样本由1～6龄组成,以2～3龄鱼为主,占统计总量的81.82%;切尾拟鲿随着年龄的增长,雌鱼和雄鱼之间的体重、体长差异逐渐明显,体重与体长呈幂函数关系,雌、雄鱼体长与体重的关系式分别为：W♀=2×10-4L2.3822（n=193,R2=0.904,P〈0.01）,W♂=2×10-4L2.4322（n=225,R2=0.884,P〈0.01）,表明雌、雄鱼均属于异速生长型。选用Gompertz生长方程拟合其生长,雌、雄鱼体长生长方程分别为：♀：Lt=785.78e-1.36e-0.59 t,♂：Lt=926.35e-1.84e-0.42 t;雌、雄鱼体重生长方程分别为：♀：Wt=438.62 e-5.61e-0.45 t,♂：Wt=559.64e-5.49e-0.41 t。雌、雄鱼体长生长的拐点年龄分别为4.18龄和4.75龄,体重生长的拐点年龄分别为3.09龄和2.21龄。研究区的切尾拟鲿显现出低龄化和小型化趋势;为可持续开发利用,建议捕捞规格限制在100 mm（10 g）以上。

The age structure and growth characteristics of Pseudobagrus truncatus were studied based on 436 specimens collected from Minjiang River, a Yangtze River＇ s tributary in November -December 2012 and April-May 2013. The results showed that asteriscus was a good material for determining the age of P. truncatus. The ages of the specimens ranged from 1-6 years. The dominated age ranged from 2-3 years, accounting for 81.82% of the total specimens. With the growth of age, the male appeared to grow at a faster rate and there were significant differences in growth patterns between males and females. The relationship between the body length （L） and the body weight （W） appeared as a power function relation, which could be expressed by formula W = 2×10-4L23822（ rt= 193, R2 =0. 904, P〈0.01 ） for females and W =210-4LZ＇4322（n=225, R2 = 0. 884, P〈0.01 ） for males, respectively. The Gompertz growth function was especially sui- ted to describe the growth patterns. The growth of body length and body weight of the female and male can be deseribed by the Gompertz growth equation as follows： α L, =785.78e-136-59t, S： L,=926.35e-s4-42; ： W,=438.62 e-561e-~＇45＇, 6： W,=559.64e-549e-41. The in- flection points of body length growth were 4.18 years and 4.75 years, and the inflection points of body weight growth were 3.09 years and 2.21 years for the female and male, respectively. Our results indicated that P. truneatus was at younger ages in the study area. In order to sustainably utilize the P. truneatus population, we suggest that only fish larger than 100 mm （ 10 g） could be harvested.