中文摘要：

浅水湖泊牛山湖和月湖均位于长江中游武汉市境内,前者水质清澈、沉水植物茂盛,属典型的草型湖泊;后者长期受生活污水和工业废水排放的影响,水质恶劣、沉水植物稀少,属典型的藻型湖泊。文章选择这两个湖泊的共同优势鱼类——鲫（Carassius auratus）作为研究对象,通过比较两类不同湖泊环境条件下鲫种群结构和生长上的差异,评估人类活动引起的水环境改变对鱼类种群生存状况的影响。2006年春季（3—5月）,于牛山湖和月湖各采集鲫种群样本713尾和641尾,研究结果表明：（1）牛山湖和月湖鲫种群的全长频数分布经kolmogorov-Smirnov检验均符合正态分布,但前者的分布范围（63—271 mm）大于后者（72—191 mm）,前者的全长峰值（190 mm）亦大于后者（110 mm）;（2）牛山湖鲫种群的年龄组成（6个年龄组）较月湖（仅3个年龄组）完整,但月湖各龄鲫的全长均显著大于牛山湖（P〈0.05）;（3）两个湖泊性成熟鲫的雌、雄鱼比均随全长的增长而增加,即小个体性成熟鲫以雄鱼为主,大个体性成熟鲫以雌鱼为主,该现象在月湖更为明显;（4）牛山湖和月湖鲫全长–体重回归关系（W=a Lb）分别为W=0.00001 L3.060（R2=0.989）和W=0.000006 L3.246（R2=0.971）,协方差分析表明两个湖泊鲫种群的b值差异极显著（P〈0.01）;另一方面,月湖鲫种群各全长组雌、雄鱼的肥满度均显著大于牛山湖（P〈0.05）。作者认为影响牛山湖和月湖鲫生长和种群结构的主要因素是两个湖泊饵料组成和捕捞压力等方面的差异。

英文摘要：

Human activities have profoundly affected the environment and population structures of fishes in Yangtze lakes.In order to evaluate the effects of environmental degradation on fish population structure,a comparative study on population characteristics of crucian carp Carassius auratus between a eutrophic urban lake（Yuehu Lake） and a macrophytic suburban lake（Niushan Lake）,both in Wuhan,was carried out during March to May 2006.Fishes were collected and compared from the two different lakes,and the water quality was measured at the same time.Results showed that：（1） pH,conductivity,TN-N,TP-P and Chl.a of Yuehu Lake were higher than those of Niushan Lake.The numbers of total fish species and carnivorous fish species in the Yuehu Lake were fewer than those in the Niushan Lake.（2） The relative biomass of crucian carp in Yuehu Lake were higher than that in Niushan Lake,as per the multimesh gillnet catch per unit effort（CPUE） in Yuehu lake was higher.（3） Length distributions of crucian carp in both Niushan and Yuehu Lakes showed typical distributions when tested by kolmogorov-Smirnov,with a length range 63—271 mm（peak at 150 mm） and 72—191 mm（peak at 120 mm）,respectively.（4） The crucian carp in Niushan Lake had a more complex age structure with six age groups,while Yuehu Lake had only three,with age 1 representing the largest proportion of 89%.（5） The relationship between weight（W） and total length（L） has been represented by the equation W= aL b,where W=1＊10 5 L 3.06（R 2 =0.9893） in the Niushan Lake and W=6×10 6 L 3.22（R 2 =0.9649） in the Yuehu Lake.Analysis of covariance demonstrated that the length-weight relationship of crucian carp are significantly different between the two lakes（P0.01）.Meanwhile,the crucian carp in Yuehu Lake showed a growth advantage compared to those in Niushan Lake for fish condition factors of males and females from all of the three length groups in Yuehu Lake were all significantly greater than those in Niushan Lake.（6） A