三峡库区小江太湖新银鱼时空分布

三峡水库形成后鱼类群落结构发生了根本性的改变，浮游动物食性的太湖新银鱼（Neosalanx taihuensis）成为了库区优势种。为探究三峡库区太湖新银鱼种群生长规律，2019年1-12月，每月下旬在三峡库区小江6个采样断面使用银鱼捕捞专用拖网进行了调查，应用单位捕捞努力量渔获量（Catch Per Unit Effort, CPUE）测度太湖新银鱼种群的时空分布特征。结果显示，2019年太湖新银鱼在三峡库区小江的时空分布特征明显。时间动态上，太湖新银鱼种群生物量的周年变化为先升后降，3月开始迅速增长，在4月达到最高值（2080.08 kg/km2），随后逐步下降，7月捕捞旺季过后，生物量明显下降；空间分布上，太湖新银鱼春季繁育的稚幼鱼最先出现在上游的渠口和养鹿断面，之后下移，主要集中在高阳断面（867.16 kg/km2），其次是黄石和双江断面，而长江断面太湖新银鱼分布最少。研究表明，太湖新银鱼时空分布特征主要由种群繁殖特征及库区水文情势决定，其种群在4月快速增长，与小江5月蓝藻密度急剧上升可能存在关联。建议在种群快速增长前，对三峡库区小江太湖新银鱼的繁殖群体进行捕捞，尤其是在3月的渠口和养鹿断面，可以起到较好的控制效果。

Spatiotemporal Distribution of Neosalanx taihuensis in Xiaojiang River of Three Gorges Reservoir

Impoundment of Three Gorges Reservoir resulted in fundamental changes in the fish community structure and Neosalanx taihuensis, which preys on zooplankton, has become the dominant species. Understanding growth characteristics of the N. taihuensis population in Xiaojiang River will be helpful for managing N. taihuensis. From late January to late December 2019, monthly investigations of N. taihuensis were conducted at six sampling sections in Xiaojiang River using an appropriate trawl net, with five sections in the back water area of Xiaojiang River and one in the cove where Xiaojiang River flows into the Yangtze River. We analyzed the spatiotemporal distribution characteristics of N. taihuensis population, using catch per unit effort (CPUE), and explored the relationship of N. taihuensis population growth with blue-green algae blooms in the river. The objective was to provide scientific evidence for managing the N. taihuensis population and controlling blue-green algae blooms. During 2019, there was an obvious pattern in the spatiotemporal distribution of the N. taihuensis population in Xiaojiang River. Temporally, the biomass of the N. taihuensis population initially increased and then decreased. A rapid increase in biomass began in March, peaked in April at 2080.08 kg/km2 and then gradually decreased, especially in July after the fishing season. Spatially, N. taihuensis juveniles from the spring spawning first appeared in the Qukou and Yanglu sections, and then moved downstream to the Gaoyang, Huangshi and Shuangjiang sections. The highest N. taihuensis CPUE occurred in the Gaoyang section (867.16 kg/km2), and was lowest in the Xiaojiang River cove at Yangtze River ( 7.13 kg/km2). The spatiotemporal distribution of N. taihuensis population was primarily determined by the breeding characteristics of N. taihuensis and the hydrological regime in Three Gorges Reservoir. In Xiaojiang River, the rapid growth of the N. taihuensis population in late April may be related to the sharp rise of cyanobacteria density in May. Therefore, to more effectively control the N. taihuensis population, we suggest harvesting the breeding population in March before spawning leads to rapid population growth, especially in the Qukou and Yanglu sections.