长江上游草鱼种群结构与生长特征

Population Structure and Growth of Ctenopharyngodon Idellus in the Upper Yangtze River

长江江津江段是连接三峡水库和长江上游干流的重要通道，2008-2010年对该江段的草鱼种群进行了调查，以了解长江上游草鱼的种群结构和生长特征，为其资源恢复和保护提供依据．结果表明，草鱼种群个体体长范围为75．0～880．0 mm，平均体长为438．8±221．4 mm，体质量范围为8．5～8900．0 g，平均体质量为2400．3±2426．2 g．资源群体的个体大小分布指数PSD＝50±6，PSD-P＝41±6，PSD-M＝4±2，PSD-T＝0，显示该江段草鱼种群中大个体偏少．该江段草鱼种群年龄由0＋～7＋龄构成，其中优势龄组为1＋～4＋龄，占种群数量的75．7％．草鱼体长（L）与鳞径（S）呈显著线性关系（L＝50．3671 S-32．0071），与体质量（W）呈显著幂函数关系（W＝5．8522×10^-5L2．8193）．用过渡的Von Bertalanffy 生长方程描述草鱼的生长规律，模型参数为L∞＝1029．1990 mm，W∞＝18216．2322 g，k＝0．1682，t0＝-0．2325，其生长特征指数φ＝5．25，生长拐点年龄为6．28龄．与历史资料相比，长江草鱼种群平均体长和生长性能均表现出下降趋势．三峡工程建设后，长江上游逐渐成为草鱼的重要栖息地和产卵场，应采取禁渔等措施，加强该江段草鱼种群及其生境保护．

Jiangjin section of the Yangtze River is an important ecological corridor connecting the Three Gor -ges Reservoir and the upper Yangtze channel .To understand the population structure and growth of Grass Carp （ Ctenopharyngodon idellus） in the upper Yangtze River and provide information for its resources restoration and conservation , investigations on Grass Carp population were carried out in Jiangjin section during 2008-2010 .The results showed that the standard length of Grass Carp in Jiangjin setion ranged from 75 .0 mm to 880 .5 mm with the average length of 438.8 ±221.4 mm, and the weight ranged from 8.5 g to 8 900.0 g with the average weight of 2 400.3 ±2 426.2 g.The proportional size distribution indices of Grass Carp were 50 ±6 （PSD）, 41 ±6 （PSD-P）, 4 ±2 （PSD-M） and 0（PSD-T）, which indicated that the upper Yangtze River had a size structure with less large Grass Carp .The age of Grass Carp ranged from 0 ＋to 7 ＋, and the dominant age groups were 1 ＋～4 ＋, accounting for 75.7%of the total individuals.The standard length （L） had a significant linear relation with scale length （S） （L=50.367 1 S-32.007 1）, and had a significant power function relation with weight （W） （W=5.852 2 ＆#215;10 -5 L2.819 3）.The growth of Grass Carp could be described by Von Bertalanffy growth model , where L∞ =1 029.199 0 mm,W∞ =18 216.232 2 g,k=0.168 2 and t0 =-0.232 5.The index of length growth per-formance （φ） of Grass Carp was 5.25, and the growth inflection age was 6.28.Compared with the previous data ,the average length and growth performance of Grass Carp population in the Yangtze River all showed a decline tend-ency.The upper Yangtze River has become an important habitat and spawning site for Grass Carp after the comple -tion of the Three Gorges Project and , therefore, measures such as fishing closures are suggested to be taken to con-serve the population and its habitat .