长江中游监利江段鱼卵及仔稚鱼时空分布

Spatial and temporal distribution patterns of eggs,fish larvae and juveniles at Jianli cross-section in the middle reaches of the Yangtze river

2010年5—7月对长江中游监利江段鱼卵和仔稚鱼的时空分布进行调查,共采集到鱼卵样品9494粒,仔稚鱼样品328422尾,分属8目15科43属51种。结果显示:5—7月鱼卵的平均密度为13.3 ind./100 m3,最大密度值87.8 ind./100 m3,主要集中在5月;5—7月仔稚鱼平均密度为61.8 ind./100 m3,最大密度值489.0 ind./100 m3,主要集中在6月下旬至7月上旬。经W符号秩次检验,在水平分布上,鱼卵密度在北岸、江心和南岸均存在显著性差异(P<0.05);仔稚鱼密度在北岸与南岸差异不显著(P>0.05),仔稚鱼密度在北岸与江心差异极显著(P<0.01)。在垂直分布上,表层和中层的鱼卵及仔稚鱼密度均没有显著性差异(P>0.05)。在昼夜分布上,鱼卵和仔稚鱼夜间分布密度大于白天,昼夜差异显著(P<0.05)。

Surveys for spatial and temporal distribution patterns of eggs,fish larvae and juveniles were carried out at Jianli cross-section in the middle reaches of the Yangtze river from May to July in 2010,A total of 9494 eggs,328422 fish larvae and juveniles,belonging to 8 orders 15 families 43 genera 51 species.the results showed that the average density for eggs and fish larvae and juveniles were 13.3 ind./100 m3 and 61.8 ind./100 m3,respectively.the density of eggs was higher on May,and the maximum was 87.8 ind./100 m3;the maximum density of fish larvae and juveniles was 489.0 ind./100 m3.It had significant difference that the density of roe between surface and middle cross-section in the horizontal distribution at two banks and middle area（P〈0.05）;There were significant difference in the horizontal distribution at north bank and middle area（P0.01）,and there were no significant difference at south bank and north bank（P〉0.05）.Yet it had no significant difference that the density of fish larvae and juveniles between surface and middle cross-section in vertical distribution at two banks and middle area（P〉0.05）.Our results ind.icated that it had significant difference in density of eggs,fish larvae and juveniles between day and night（P〈0.05）,the density of eggs during the day was lower than at night.