Lake anchovy, Coilia ectenes taihuensis, a kind of small-sized and zooplanktivorous fish was thedominant fish in Lake Taihu. The changes of the fish catch and the relationship with environmental variation werestudied, based on historical data from 1952 to 2004 and the studies from 2003 to 2005. The results were asfollow: ( 1 ) The catches of the fish increased from 640.5 t in 1952 to 21 221 t in 2004. Especially since 1994 theincrease had speeded up; (2) The age structure of the fish population was that 0+ individuals occupied only 33%in 1979 and 34% in 1980, but the figure increased to 99.04%±2.21% in 2003 and 99.08%±0.80% in2004; (3)0+ lake anchovy mainly fed on zooplankton. Cladocera, Copepoda and Rotifera respectively accountedfor 89.77%±13.69%, 7.84%±11.53% and 2.39%±4.95% of its diet. The conclusion was that, humanactivities such as the obstructed buildings between river and the lake, over fishing, environmental pollution andthe ecological characteristics of the fishes in Lake Taihu were responsible to the changes of catches and agestructures of the fish. With the fish catches increasing, there was the trend of zooplankton standing mass decliningduring October in the lake. So the increase of the fish catches might enhance phytoplankton development in thelake.%在太湖,随着鱼类总渔获量的不断增加和鱼类种类的不断减少,湖鲚(Coilia ectenestaihuensis Yen et Lin),一种小型浮游动物食性鱼类已成为绝对优势种.根据1952-2004年的统计数据和2003-2005年对湖鲚年龄结构和食物组成的调查,研究了湖鲚快速增加的原因以及与环境间的相互关系.结果如下:(1)在1952到2004年期间,湖鲚渔获量从1952年的640.5 t、占总渔获量的15.8%上升到2004年的21 221 t、占63.8%.尤其是1994年后湖鲚渔获量以每年1280.5 t的速度增加;(2)湖鲚种群年龄结构低龄个体呈现不断增加趋势.1979和1980年0+个体仅占33%和34%,而2003和2004年0+个体分别上升到99.04%和99.08%;(3)0+湖鲚主要摄食浮游动物.按照个数组成比例计算,枝角类平均占89.77%±13.69%、桡足类占7.84%±11.53%、轮虫仅占2.39%±4.95%.分析认为:江湖阻隔、过度捕捞、富营养化不断加重等人类活动以及太湖特有的鱼类生态学特点是导致湖鲚渔获量不断增加、年龄结构发生变化的根本原因.随着湖鲚数量的快速增加,在湖鲚生长期间太湖浮游动物现存量呈现相应下降趋势,这可能使太湖浮游植物更易暴发.
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