三峡库区支流磨刀溪产粘沉性卵鱼类早期资源现状

研究磨刀溪变动回水区的鱼类早期资源，可为三峡库区重要生境、水生生物多样性保护提供科学依据。2019年的4-6月，在三峡库区支流磨刀溪变动回水区江段（新津乡-龙角镇）开展鱼类早期资源监测，以了解该区域鱼类早期资源种类组成、仔稚鱼密度的时间动态以及与环境因子的关系。结果表明，采集到的7种产粘沉性卵鱼类的鱼苗中，以贝氏?(Hemiculter bleekeri)、鲤(Cyprinus carpio)、鲫(Carassius auratus)为主；密度高峰期集中在4月下旬至5月中旬。磨刀溪新津口至龙角镇之间江段共分布有鲤、鲫集中产卵场4处。冗余分析(RDA)表明，饵料丰度、溶解氧和pH是影响鱼苗分布的主要因素。磨刀溪变动回水区江段是粘沉性鱼类产卵场的分布区域，三峡水库4-6月水位的快速消落，很可能导致鲤、鲫等产粘沉性卵鱼类资源的损失。建议通过短时期维持库区水位或在回水区放置人工鱼巢、恢复水生植被来减缓这种影响。

Status of Early Stage Resources of Fish with Sticky and Demersal Eggs in Modaoxi River, a Tributary of the Three Gorges Reservoir

In this study, we investigated early stage fish resources in the water fluctuation zone of Modaoxi River, a typical tributary of Three Gorges Reservoir, focusing on species composition, temporal dynamics of larval and juvenile density and their relationship with environmental factors. Early-stage resource monitoring was conducted from Xinjin to Longjiao from late April to June of 2019, and environmental parameters, including water temperature, dissolved oxygen, pH and water depth were measured synchronously. The aim was to assess the status of early stage fish resources in Modaoxi River and provide scientific evidence for habitat and fish species diversity protection in Three Gorges Reservoir. Among the total of 10 fish species collected, there were 7 fish species with sticky and demersal eggs, dominated by Hemiculter bleekeri, Cyprinus carpio and Carassius auratus. The density of larval and juvenile fish peaked from late April to mid-June. A total of 4 spawning grounds were found in the river section between Xinjin and Longjiao. Redundancy analysis shows that food availability, dissolved oxygen and pH were the critical factors affecting fish fry distribution. The water fluctuation zone in Modaoxi River is the primary area of spawning grounds for important economic fish species. The rapid decrease in water level in Three Gorges Reservoir from April to June is likely the key factor causing the loss of fishes with sticky and demersal eggs (C. carpio, C. auratus). To mitigate the impact, we suggest carrying out ecological regulation to reduce the daily variation range of water level, placing artificial nests and restoring aquatic vegetation in the backwater area of Three Gorges Reservoir.