仔稚鱼在长江口沿岸碎波带的时空分布

The spatio-temporal distribution of fish larvae and juveniles in the surf zone of the Yangtze River estuary

2006年5月至2007年6月期间,对长江口沿岸13个站位点碎波带出现的仔稚鱼进行调查分析,以探明仔稚鱼在长江口沿岸的时空分布以及利用碎波带栖息生长的变化规律。研究结果表明,仔稚鱼在春末、夏季和秋初的物种数和分布密度较高,尤其以7月和8月最高,秋末和冬季碎波带鱼类的物种数和分布密度均较低,在3月最少,月变化规律显著。长江口沿岸生活着四种生态类型的仔稚鱼,其中包括分布在长江口的南支和北支上游的淡水性鱼类,分布在沿海水域的海洋性和河口性鱼类以及季节性出现于河口的洄游性鱼类。通过对碎波带仔稚鱼群落优势种的体长月变化进行分析发现,洄游性鱼类刀鲚和河口性鱼类鱼都是季节性出现在碎波带并利用其作为保育场和索饵场,淡水性鱼类太湖新银鱼常年生活在河口碎波带索饵育肥,而海洋性鱼类大海鲢等是大潮时被潮水输送至河口碎波带短暂生活,表明仔稚鱼利用碎波带的方式因物种而异。

To explore the spatio-temporal distribution of fish larvae and juveniles in the surf zone of the Yangtze River estuary,samples were collected monthly on the spring tide at 13 stations during May 2006 to June 2007.The species number and individual amount were the highest in summer especially in July and August and the lowest in late fall and winter especially in March.The investigation results indicated there were significant differences among the months.The freshwater fish were mainly distributed in the south branch of the estuary and the upper reaches of the north branch,the marine fish and estuary fish were mainly in the coastal areas,and the diadromous fish apeared in the estuary seasonally.The research on the length change of these four dominant fishes revealed that the selection of the surf zone by fish larvae and juveniles differed according to various species.The diadromous fish Coilia nasus and the estuary fish Liza haematocheila apeared seasonally in the surf zone.In addition,they made use of the surf zone as their nursery and feeding ground.Neosalanx taihuensis,the fresh water fish,lived in the surf zone all the year round while the marine fish including the Megalops cyprinoides were carried by the spring tide to the surf zone and lived there ephemerally.