长江如皋江段仔稚鱼资源现状调查分析

【目的】调查长江如皋江段仔稚鱼资源现状，探索仔稚鱼物种组成、生态类型、群落特征及仔稚鱼丰度时空特征，为长江近河口段仔稚鱼资源监测提供基础数据。【方法】采用鱼类早期资源调查方法对仔稚鱼进行采样调查，将仔稚鱼样品在Olympus SZX 16体视解剖镜下进行种类鉴定，对部分形态特征残缺难以辨认及不确定种类的仔稚鱼进行细胞色...

Status quo of fish larva resources in Rugao section of Yangtze River

【Objective】 To investigate the status quo of fish larva resources in Rugao section of Yangtze River，to explore species composition，ecological types，community characteristics and spatial and temporal characteristics of fish larvae abundance，so as to provide basic data for the monitoring of fish larvae resources in the estuary of the Yangtze River.【Method】 The fish samples were collected by early fish resource survey method，and the samples were brought back to the laboratory for species identification under Olympus SZX 16 stereoscope.The cytochrome c oxidase subunit 1（COI）gene sequence molecular identification were conducted for of fish larvae of species with incomplete or uncertain morphological characteristics.Abundance，relative importance index（IRI）and community characteristic values［Margalef’ s richness index（D），Shannon-Wiener diversity index（H'），Pielou’ s evenness index（J），Simpson’ s dominance index（λ），Jaccard similarity coefficient（Cj），Cody difference index（βc）］of fish larvae of each species were calculated.【Result】 A survey on fish larva resources was conducted in the Rugao section of the Yangtze River from May to August in 2021.During this period，a total of 69355 fish larvae were collected，belonging to 6 orders，8 families，40 species，among which 9 were dominant species（IRI≥100）and 9 were common species（100>IRI≥10），accounting for 85.01% and 12.97% of the total.Fish larva abundance ranged from 1.50 to 9668.17 ind/100 m3，with an average abundance of 502.74 ind/100 m3.The ecological types of fish larvae were divided in four ways:the fish larvae were mainly sedentary fish；most of them were demersal fish；they were mainly omnivorous，followed by carnivorous；and there were more fishes that produced adhesive eggs and drifting eggs.In terms of time，fish larva abundance peaked at the end of May（1490.48 ind/100 m3），and lowered in June，showing a positive correlation with water flow variation.Spatial distribution of fish larvae was affected by habitat，river morphology and flow velocity，and the abundance in the nearshore was higher than that in the middle of the river（714.55 ind/100 m3 in the north bank，615.58 ind/100 m3 in the south bank and 290.31 ind/100 m3 in the middle of the river）.Diversity analysis showed that D，H'，J and λ were 3.50，2.33，0.63 and 0.16，respectively.【Conclusion】 Compared with previous research results from 2018 to 2020，the number of fish larvae，abundance and community diversity characteristics in Rugao section of the Yangtze River increased significantly in 2021，and the early recruitment population of fish in Rugao section recovers well.