长江上游江津江段鲢种群的年龄和生长特征

Age and Growth of Hypophthalmichthys molitrix in Jiangjin of the Upper Reaches of the Yangtze River

三峡工程的建设对长江鱼类产生了显著的影响.为了解三峡工程建设后长江上游鲢的种群状况,根据2008-2010年在江津江段采集的149尾标本对鲢的年龄和生长特征进行了研究.采集到的鲢体长范围为95.0～860.0mm,平均体长为(451.1±171.6)mm,体质量范围为13.5～9 750.0g,平均体质量为(2 314.2±2 125.9)g.鲢鳞片上的年轮表现为闭合性切割和疏密特征,年龄结构由0+～5+龄共6个龄组组成,其中优势龄组为1+～4+龄.体长(L)与鳞径(R)呈显著的线性关系:L=139.841 2R+15.973 4;与体质量(W)呈显著的幂函数关系:W=1.876 7×10-5 L2.992 5.长江上游江津江段鲢为匀速生长类型,其Von Bertalanffy生长方程为Lt=1 036.974 8[1-e-0.188 2(t+0.216 5)],Wt=19 864.662 3[1-e-0.188 2(t+0.216 5)]2.992 5,其生长拐点年龄为5.80龄.尽管年龄结构和生长性能表现出一定的衰退趋势,但与湖泊、水库中的鲢种群相比,长江上游鲢种群仍然具有相对复杂的年龄结构和较优的生长性能.三峡工程建设后,长江上游已逐渐成为鲢重要的栖息地和产卵场,该江段鲢种群在4大家鱼资源保护中应该得到重点保护.

The Three Gorges Project is expected to greatly affect fish assemblages in the Yangtze River. To evalu- ate the present status of the population of silver carp （Hypophthalmichthys molitrix） in the upper reaches of the Yangtze River, we carried out a study on its age and growth characteristics based on 149 samples collected in Jiangjin section of this river in 2008-2010. The body length of silver carp ranged from 59.0 mm to 860 mm with an average of （451.1±171.6） mm, and the body weight ranged from 13.5 g to 9 750.0 g with an average of （2 314.2±2 125.9） g. The annuli in the scales were marked by the intersection of successive groups and the interspace between the sparse zones and the dense zones of circuli. The ages of the indivduals ranged from 0-＋ to 5-＋, and most of the individuls aged in 1＋ -4＋. The relationship between body length （L） and scale length （R） or body weight （W） could be expressed as L=139. 841 2R＋15. 973 4, W=I. 876 7× 10-5 L2992S The silver carp in Jiangjin section of the upper reaches the Yangtze River was of the uniform growth type, and its growth could be described by the Von Bertalanffy growth equations： L,：I 036. 974 8 [1-e 0.1882（t＋0.216s）], W,--19 864. 662 3[1-e -0.188 2（t＋0.216 5）]2.992 5 , and the growth inflection age was 5.80. In spite of a degradation tendency in age struture and growth performance of silver carp, its population in the upper reaches of the Yangtze River had a more complex age composition and better growth perform- ance than the populations in lakes and reserviors. The upper reaches of the Yangtze Rive has become an important habitat and spawning site for silver carp after the completion of the Three Gorges Project and, therefore, more attention should be paid to the protection of silver carp population in these reaches.