中文摘要：

于2009年4月至2013年4月在额尔齐斯河流域进行7次采样,调查额尔齐斯河（中国段）鱼类感染四钩虫种类组成及其感染情况。分析四钩虫的种类组成、感染率、感染强度、平均丰度和方差均值比。结果发现,额尔齐斯河鱼类感染四钩虫共2种,分别为单肠四钩虫（Tetraonchus monenteron Wagener）和北方四钩虫（Tetraonchus borealis Mizelle et Webb）。单肠四钩虫仅见于白斑狗鱼（Esox lucius Linnaeus）的鳃部,其感染率从冬季至春季逐渐上升,达到最大值44.8%,夏季大幅度下降,冬季有所回升,单肠四钩虫在不同季节呈聚集分布。北方四钩虫仅见于北极茴鱼（Thymallus arcticus Pallas）的鳃部,因北极茴鱼属额尔齐斯河珍稀土著鱼类,数量少,故采集到的北方四钩虫数量十分有限。研究表明单肠四钩虫感染呈现明显的季节性动态变化,春季感染率最高,其次是夏季、冬季,与感染强度、平均丰度、方差均值比呈现相同的季节动态变化趋势。单肠四钩虫在白斑狗鱼不同体长组中方差均值比均大于1,表现为聚集分布,其中25～30 cm体长组方差均值比最高。

英文摘要：

An investigation on the Tetraonchus composition of fish species along the Chinese section of the Ertix River was carried out. According to the general methods of fish parasites,7 times of sampling survey were conducted along the Ertix River during the period from April 2009 to April 2013. The composition,infection rate and intensity,average abundance and seasonal dynamic change of Tetraonchus were analyzed. There were 2 kinds of fish Tetraonchus infection in the Ertix River,and they were T. monenteron（ Wagener,1857） and T. borealis（ Mizelle et Webb,1953）. T. monenteron was found only in Esox leucius gills. The infection rate in winter and spring increased gradually and to its maximum value of 44. 8%; it decreased obviously in summer but increased to some extent in winter. Seasonally,T. monenteron was distributed in an aggregated way. The T. borealis was found only in the T.borealis gills,so T. borealis genus was the valuable and rare native fish species in the Ertix River,the number is very small,and the collected samples were very limited. The study results revealed that there was an obvious seasonal dynamic change of T. monenteron infection,the infection rate was the highest in spring,and then in summer and autumn. The seasonal dynamic change trends of infection intensity,average abundance and variance ratio were similar. The variance-to-mean ratios of T. monenteron in different-length groups of northern pike in the Ertix River was higher than 1 and showed an aggregated distribution,in which the variance-to-mean ratios in 25- 30 cm-length group was the highest.