小江拟尖头鲌的年龄、生长、繁殖及其资源开发状况研究

拟尖头鲌(Culter oxycephaloides)属鲤形目(Cypriniformes), 鲤科(Cyprinidae), 鲌亚科(Cultrinae), 鲌属(Culter), 为中国特有鱼类, 分布于长江流域的四川、湖北、湖南等省的江河湖泊中。2013年47月以及1012月在三峡库区支流小江江段收集拟尖头鲌样本1741尾, 对其年龄、生长、繁殖及其资源开发状况进行了研究。结果表明: 所采集的拟尖头鲌包括5个年龄组, 其中23龄年龄组为优势年龄组, 占78.59% (N=425尾); 体长与体重呈幂函数关系, 表达式为W = 0.000007L3.10(R2=0.99, N=789尾), 其生长属于匀速生长类型; 采用von Bertalanffy生长方程分别拟合体长、体重与年龄的关系, 其表达式分别为: Lt=519.631-e-0.22(t+0.12), Wt=1806.081-e-0.22(t+0.12)3.10; 生长拐点年龄t=5.02龄, 此时对应的体长348 mm, 体重558.8 g; 绝对繁殖力变动范围为2038288430粒/尾, 相对繁殖力变动范围为54161粒/g, 体重与绝对繁殖力的关系以二次方程曲线拟合度最优, 其表达式为Fabs＝33462.08+0.11W-44.01W2(R2=0.49, sig.=0.020.05, N=31); Ⅳ卵巢卵径变动范围为0.06750.1325 cm, 平均值为0.1060 cm; 拟尖头鲌产卵类型为分批产卵类型; 小江拟尖头鲌的现有开发率为E=0.51/年; Beverton-Holt动态综合模型显示, 目前小江拟尖头鲌的Emax为0.40/年, E10为0.32/年, E50为0.25/年。根据研究, 目前小江拟尖头鲌的种群处于过度开发状况, 应采取措施, 加强其资源保护。  

STUDY ON AGE,GROWTH, REPRODUCTION AND THE STATUS OF RESOURCE DEVELOPMENT OFCULTER OXYCEPHALOIDES (KREYENBERG ET PAPPENHEIM) IN THE XIAO RIVER

Culter oxycephaloides (Kreyenberg et Pappenheim), which belongs to genus Culter, subfamily Cultrinae, family Cyprinidae, order Cypriniformes. They are a unique species in China and mainly live in the rivers and lakes of the Yangtze River Basin. Due to the impoundment of the Three Gorges Reservoir, the ecosystem of the upper Yangtze River basin especially the tributaries of the Three Gorges Reservoir has been profoundly changed. The Xiao River is an important tributary of the Three Gorges Reservoir, and the habitat of a variety of organisms especially fishes. According to the data collected in 2013, some sections of the Xiao River have become major spawning grounds of Culter oxycephaloides. Hence it is critical to investigate the age structure and the growth characteristics of Culter oxycephaloides, in order to better manage and protect this fish resource. In April-July and October-December of 2013, we collected 1741 individuals from the Xiao River of the Three Gorges Reservoir and conducted the fish biology and ecology study. Our 245 samples could be divided into 5 age groups, and 23 year-old individuals accounted for 78.75% of the total samples. The relationship between the body length (L) and the body weight (W) could be fitted as W = 0.000007L3.10 (R2=0.9, N=789). The Von Bertalanffy growth function was Lt=519.631-e-0.22(t+0.12),Wt=1806.08 1-e-0.22(t+0.12)3.10. The growth inflexion point of the body weight was 5.02 years, and the corresponding body length was 348 mm and the body weight was 558.8 g. The absolute fecundities ranged between 20382 and 88430 eggs per fish, and the relative fecundities were between 54 and 161 eggs/g. The eggs of mature females were 0.030.14 cm in diameter, with an average of 0.11 cm. Based on the frequency distribution plot of egg diameters, we deduced that the development of oocytes in the ovaries of Culter oxycephaloides was in a successive process and the female could spawn twice within a reproductive period. We compared the coefficients of the linear equation, the logarithmic equation, the quadratic equation, the Cubic equation, the compound equation, the power equation and the exponential equation, and found that quadratic equation best described the relationship between the body weight and the absolute fecundity (R2=0.49, sig.= 0.020.05, N=31). The exploitation rate of Culter oxycephaloides in the Xiao River was 0.51/year in 2013. The Beverton-Holt dynamic model indicated that Emax (the exploitation rate for the maximum yield), E10 (the exploitation rate at which the marginal increase of relative yield-per-recruit is 1/10th of the value at E=0) and E50 (the exploitation rate at which the stock is reduced to 50% of the original biomass) were 0.40/year, 0.32/year, and 0.25/year respectively. The comparison between Emax and the exploitation rate in 2013 demonstrated that Culter oxycephaloides in the Xiao River were excessively exploited in 2013. Therefore, the future fishing activity in the Xiao River should be strictly supervised in order to maintain and enlarge the population of Culter oxycephaloides.