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为了探明长江口南支刀鲚仔稚鱼的丰度和分布变化,2014年3-9月在长江口南支设置8个站点,采用大型仔稚鱼网(口径1.3 m,网目0.5 mm)在每月大潮期间按月进行表层水平拖网。共拖网91网次,采集刀鲚仔稚鱼1 270尾,体长范围为3.56~50.88 mm,发育阶段由卵黄囊期仔鱼期到稚鱼期。其中涨潮期间采集刀鲚仔稚鱼1 013尾,平均密度0.27 ind/m3,平均体长10.00 mm。其中St.8密度最高,达0.268ind/m3,平均体长为9.44 mm。退潮期间采集刀鲚仔稚鱼163尾,平均密度0.01 ind/m3,平均体长为20.08 mm。St.8昼夜调查表明,夜间采集刀鲚94尾,涨潮期间密度为0.056 ind/m3,小于白天涨潮密度,退潮期间密度为0.003 ind/m3,小于白天退潮密度,涨潮平均体长为13.86mm,大于白天;夜间退潮平均体长为22.01 mm,与白天相当。比较沿岸碎波带研究结果,长江口南支出现的刀鲚仔稚鱼个体较小,有必要加强对江面刀鲚早期资源漂流水域的保护。
In order to find out the abundance and distribution of larvae in the southern branch of the Yangtze River estuary, from March to September 2014, eight stations were set up in the south branch of the Yangtze Estuary. Large larvae (1.3 m in diameter and 0.5 mm in width) During the monthly tide monthly surface level trawling. A total of 91 net trawl, juvenile larvae collected 1 270 tail body length range 3.56 ~ 50.88 mm, the developmental stage from the yolk sac stage larvae to juvenile stage. Among them, 1,013 larvae were collected during the high tide, with an average density of 0.27 ind / m3 and an average body length of 10.00 mm. St.8 which the highest density, up to 0.268ind / m3, the average body length of 9.44 mm. During the ebb tide, 163 larvae of juvenile larvae were collected, with an average density of 0.01 ind / m3 and an average body length of 20.08 mm. St.8 day and night surveys showed that 94 daggers were collected at night and the density during the flood was 0.056 ind / m3, which was less than the daytime flood density. The density during the ebb tide was 0.003 ind / m3, less than the ebb tide during the day. The average body length of the floodwaters was 13.86 mm, The average body length of the nighttime ebb is 22.01 mm, which is equal to the daytime. Compared with the research results of the coastal wave zone, the juveniles of Daphniphoripopu young larvae appeared in the southern branch of the Yangtze Estuary are small, so it is necessary to strengthen the protection of the early driftwood of Daping River.