长江口南支仔稚鱼数量随潮汐变化的研究

The study on the amount changes of fish larvae during flood and ebb in the south branch of Yangtze River Estuary

2015年3月至2016年3月,在长江口南支江面上设置8个站位点,每月大潮期间用大型仔稚鱼网(1.3 m口径,0.5 mm网目)进行水平拖网,年间共拖网171网次,共采集仔稚鱼74 689尾,隶属于12科39种,5月到9月的丰富度较高,涨潮时的丰富度大于退潮,物种数以6、7月最多,密度以7月最高。贝氏(Hemiculter bleekeri,53.4%)为最优势种,其次为子陵吻虾虎鱼(Rhinogobius giurinus,12.65%),翘嘴鲌(Culter alburnus,8.38%),鳊鱼(Parabramis pekinensis,7.18%)、青鱼(Mylopharyngodon piceus,6.55%)和有明银鱼(Salanx ariakensis,4.63%)。涨潮时全年共渔获仔稚鱼39种,退潮时共渔获23种,并且各月份涨潮时的种类数均大于退潮时的种类数,St.6至St.8各站点涨潮时的密度均大于退潮时的密度。在St.7站位点进行中层拖网,在种类组成上与表层差异不明显,但多样性均不如表层。

To clarify the amount changes of fish larvae during flood and ebb in the south branch of Yangtze River Estuary,8 stations were set in the south branch of Yangtze River Estuary,and the trawling was performed in the surface monthly by a larval net（ 1. 3 m mouth-diameter,mesh 0. 5 mm） during March 2015 to March 2016. A total of 74 689 individuals were collected in the 171 trawls,belonging to 39 species,12 families. The richness during May to September is higher,while the richness is higher in the flood tide than the ebb tide. The species number during June to July is the highest,the density of fish larvae is the highest in July. Hemiculter bleekeri（ 53. 4%） is the dominant species,followed by Rhinogobius giurinus（ 12. 65%）,Culter alburnus（ 8. 38%）,Parabramis pekinensis（ 7. 18%）,Mylopharyngodon piceus（ 6. 55%）,Salanx ariakensis（ 4. 63%）. In the throughout flood and ebb tide survey,39 species were collected at flood tide,while 23 species in the ebb. The species number is higher at flood tide in each month,and the density of fish larvae is also higherat flood tide at each station of St. 6 to St. 8. The trawl was performed in the middle layer at St. 7,as the result,the species composition of fish larvae has no significant difference with the surface layer at St. 7,while the diversity is lower than the surface layer.