中文摘要：

2006－2012年在金沙江下游非倒灌区域的巧家江段进行了渔获物调查，对该区域的鱼类生物多样性和群落结构的年际动态进行了研究。5年共调查发现鱼类57种，隶属于3目8科42属。鲤形目3科33属43种，占总种类数的75．44％；鲇形目4科8属12种，占总种类数的21．05％；鲈形目2科2属2种，占总种类数的3．51％。长江上游特有鱼类20种，占总种类数的35．09％；其中长薄鳅（ Leptobotia elongata）列入中国濒危动物红皮书保护名录。2006、2008、2011和2012年之间的鱼类种类数（分别为36、32、37、37种）差异很小，均与2010年种类数（47种）有差异，但One-way ANOSIM检验差异在统计学上不显著（R＝1， P＝20％＞0．05）。除2010年外，调查区域的优势度在4年间总体上呈下降趋势，而Shannon多样性指数和均匀度呈上升趋势，丰富度则各年大致相当。聚类分析（ CA）和非度量多维标度（ NMDS）方法对5年间的鱼类群落结构的年际变化的分析结果表明：5年的鱼类群落结构可以分为2组，但One-way ANOSIM检验结果显示各组间无显著性差异（R＝1， P＝10％＞0．05）。 SIM-PER分析的结果表明，5年间丰度减少的种类均为喜流水性鱼类，而丰度增加的种类既有喜流水性的鱼类也有适应静、缓流水的鱼类。鱼类丰度在年份梯度上的变化不明显，各年间各种鱼类的丰度呈偏正态分布。研究结果表明，非倒灌区域的鱼类仍然受到流域内梯级电站修建的影响。

英文摘要：

The lower Jinsha River supports a rich fishery resource in the complex aquatic environment resulting from littoral gradients.Research indicates that the cascaded hydropower stations constructed on the lower reaches of the Jinsha River have profoundly affected the fish diversity and community structure in the impoundments but the influ-ence on non-impounded reaches is not yet known.Natural hydrologic conditions still exist in the Qiaojia section of the lower Jinsha River and it has become an important habitat for many fish species.This investigation analyzed the biodiversity and community structure of the fishery resource in the Qiaojia section, based on fish catches from 2006 to 2012, and examined the impact of the first phase of a hydropower construction project on fish resources in the non-impounded section.Field investigations were carried out Oct.10-25 of 2006, Nov.5-13 of 2008, Nov.20-29 of 2010, Oct.9-22 of 2011 and Nov.20-Dec.10 of 2012.Fish from catches were identified according to The fish of Sichuan, FAUNA SINICA, OSTEICHTHYES, CYPRINIFORMES, II and other literature resources.The full length, body length and weight of each fish were measured.A total of 57 fish species, belonging to 3 orders, 8 families and 42 genera, were identified in the survey area during the five year study period.Cypriniformes consisted of 3 families, 33 genera and 43 species and accounted for 75 .44%of the total species;Siluriformes accounted for 21.05%（4 families, 8 genera and 12 species）;and Perciformes accounted for 3.51%（2 families, 2 genera and 2 species） .Twenty fish species endemic to the upper Yangtze River were observed during the investigation, ac-counting for 35.09%of all species;among them, Leptobotia elongate is listed in the China red data book of endan-gered animals.Fish species identified in 2010 （47 species） were significantly different from species found in 2006, 2008, 2011 and 2012 （36, 32, 37, 37 species, respectively）, but one-way analysis of similarity （one-war ANO-SIM） indicated no signif