三峡库区支流小江回水区鱼类早期资源状况

Status of Early Stage Fish Resources in the Backwater Area of Xiaojiang River in Three Gorges Reservoir Area

研究三峡库区回水区江段鱼类早期资源状况,为鱼类资源保护提供科学依据。2019年3-6月在三峡水库支流小江回水区用2种网具开展鱼类早期资源调查,以了解该区域仔稚鱼的种类组成、仔稚鱼密度的时间动态,并分析其与环境因子的关系。调查共采集到仔稚鱼9 499尾,12种,以太湖新银鱼(Neosalanx taihuensis)、中华鳑鲏(Rhodeus sinensis)、子陵吻虾虎鱼(Rhinogobius giurinus)、鲤(Cyprinus carpio)和鲫(Carassius auratus)仔稚鱼的数量较多;其中产黏沉性卵鱼类5种,产沉性卵鱼类4种,产漂流性卵鱼类2种,产浮性卵鱼类1种。4月下旬至6月上旬为仔稚鱼采集的高峰期,其中4月为鲤仔稚鱼密度出现的高峰期,4-5月上、中旬为鲫仔稚鱼密度出现的高峰期;底质类型、透明度和水温是影响所有种类、鲤和鲫仔稚鱼密度空间变动的最重要的因素。研究结果表明3-6月三峡水库水位的快速消落很可能是影响黏草产卵鱼类产卵孵化的关键影响因素,建议通过三峡水库的水位调度以及在库区支流回水区放置人工鱼巢来缓解该影响。

In this study,we investigated early stage fish resources in the backwater of Xiaojiang River,focusing on species composition,temporal dynamics of larval and juvenile density and their relationship with environmental factors.The aim was to assess the status of early stage fish resources in Xiaojiang River and provide scientific evidence for fish resource protection in the Three Gorges Reservoir area.Samples were collected using scoop nets and trawls from March to June in 2019 and water quality parameters,including water temperature,dissolved oxygen,pH and transparency were measured synchronously.A total of 12 fish species from 11 genera,5 families and 4 orders were collected,and the number of Neosalanx taihuensis,Rhodeus sinensis,Rhinogobius giurinus,Cyprinus carpio and Carassius auratus larvae and juveniles were higher than for other species.The number of larvae and juveniles collected peaked from late April to early June,with C.carpio larvae and juveniles peaking in April and C.auratus larvae and juveniles peaking in early to middle April and May.Substrate type,transparency and water temperature were the most important factors associated with spatial variations in larval and juvenile densities of all species,especially C.carpio and C.auratus.Furthermore,the rapid decrease of water level in Three Gorges Reservoir from March to June is likely the key factor affecting spawning and hatching of fish that spawn sticky eggs on grasses.To alleviate the impact,we recommend regulating the water level of Three Gorges Reservoir and placing artificial nests in the backwater tributaries of Three Gorges Reservoir.