长江下游安庆段鳜属(Siniperca)仔稚鱼时空特征及影响因子

Spatial and temporal characteristics and influencing factors of larvae and juveniles of Siniperca in the Anqing section of the Changjiang River

为了解长江安庆段鳜属(Siniperca)鱼类早期资源现状,探究鳜属仔稚鱼时空特征及影响因子,于2018—2020年4—8月在该江段开展鱼类早期资源调查。结果表明:2018、2019、2020年鳜属仔稚鱼的首次出现时间分别为4月29日、4月30日和5月5日,早期资源发生的时间呈延迟状态;各年份仔稚鱼累计出现时间分别为44、54、68 d,出现频率分别为40.74%、55.67%、69.39%,累计采集数量依次为175、313、404尾,呈逐年上升趋势;各年份仔稚鱼高峰期出现时间分别为7月14日—8月6日、7月16日—7月27日和6月18日—7月20日,对应平均丰度依次为0.073、0.051、0.044 ind./m^(3);仔稚鱼丰度的空间分布存在差异,整体呈现出左岸(0.056 ind./m^(3))>右岸(0.046 ind./m^(3))>江心(0.026 ind./m^(3))的特征;相关性分析显示,仔稚鱼丰度变化同流量、水位及水温均呈显著正相关(P<0.05),与透明度呈显著负相关(P<0.05),仔稚鱼丰度的时间动态特征同流量、水温的季节变动模式相一致。研究表明,调查期间鳜属鱼类繁殖产卵的最适水温为25.6~29.2℃,水温梯度的改变刺激了其繁殖事件的发生,仔稚鱼绝对数量的逐年增多反映出长江安庆段鳜属鱼类的年际补充量得到稳步提升,资源恢复的形势向好。

In order to understand the status of resources of larval and juvenile Siniperca in the Anqing section of the Changjiang River,and to explore the spatio-temporal characteristics and influencing factors,an larval and juvenile fish resource survey was carried out from April to August,2018 to 2020.The results showed that the first appearance time of Siniperca larvae was April 29th(2018),April 30th(2019)and May 5th(2020),indicating a delayed occurrence time of resources of larval and juvenile Siniperca.The cumulative occurrence time of larvae and juveniles in 2018,2019 and 2020,was 44 days,54 days and 68 days respectively.The occurrence frequency was 40.74%(2018),55.67%(2019)and 69.39%(2020).The cumulative number of larvae and juveniles collected in 2018,2019 and 2020,was 175,313 and 404,respectively,exhibiting a time-dependent increasing trend.During the investigation,the occurrence time of peak abundance of larvae and juveniles was from July 14th to August 6th in 2018,July 16th to July 27th in 2019,and June 18th to July 20th in 2020.The corresponding average abundance was 0.073,0.051,and 0.044 ind./m^(3) in 2018,2019 and 2020,showing a time-dependent decreasing trend.Affected by hydrological dynamics,the spatial distribution of larval and juvenile drifting density in the Anqing section was different,showing the characteristics of the left bank(0.056 ind./m^(3))>the right bank(0.046 ind./m^(3))>the center of the river(0.026 ind./m^(3)).Spearman correlation analysis showed that the abundance of larvae and juveniles was positively correlated with the flow,water level and water temperature(P<0.05),and significantly negatively correlated with the transparency(P<0.05).The temporal dynamic characteristics of larvae and juveniles abundance were consistent with the seasonal variation pattern of flow and water temperature.The results of this study reveal that the optimum water temperature for the reproduction and spawning of Siniperca is 25.6 to 29.2℃during the investigation,and the change of water temperature gradient stimulates the occurrence of breeding events in Siniperca.The annual increase of the absolute number of larval and juvenile fish reflects that the annual supplement of Siniperca fish species in the Anqing section has been steadily enhanced,and the situation of resource recovery is improving.