根据2013年对南沙西南陆架海域的4个航次底拖网调查数据，分析了渔获组成及生物多样性指数。结果显示，4个航次调查期间共收集并记录渔获物251种，其中鱼类202种、头足类16种、甲壳类33种，渔获种类夏季最多，冬季最少。根据计算相对重要性指数（ IRI ），短尾大眼鲷（ Priacanthus macracanthus ）、剑尖枪乌贼（Uroteuthis edulis）和多齿蛇鲻（Saurida tumbil）为优势种（IRI≥500）；深水金线鱼（Nemipterus bathybius）、蛇鲭（Gemphylus serpens）、黑（Lophiomus setigerus）、大头狗母鱼（Trachinocephalus myops）、带鱼（Trichiurus leptu-rus）、花斑蛇鲻（Saurida undosquamis）和长体圆#（Decapterus macrosoma）等为主要种（100≤IRI<500）。聚类分析表明春秋季的优势物种结构相似性较高。丰富度指数（ D）在夏季达到最高，冬季最低；多样性指数（ H′）夏季最高，最小值出现在秋季；均匀度指数（J′）秋季最低，其他3个季节变化不大；优势度指数（λ）秋季最高，夏季最低。%According to the bottom trawl survey data in southwestern continent shelf of Nansha area in different seasons of 2013,we analyzed the species composition and biodiversity indices. We collected 251 species,including 202 fish species,16 cephalopod species and 33 crustacean species. The total number of species of catch composition was the highest in summer and the lowest in winter. According to the index of relative importance( IRI),the dominant species were Priacanthus macracanthus,Uroteuthis edulis and Saurida tumbil,whose IRIs were higher than 500;the main species were Nemipterus bathybius,Gemphylus serpens,Lophiomus setigerus,Trachinocephalus myops,Trichiurus lepturus,Saurida undosquamis,Decapterus macrosoma,and so on,whose IRIs were 100~500. Cluster analysis indicates that the dominant species structure was more similar between spring and autumn. The Margalef richness index( D)reached the maximum in summer but the the the minimum in winter;the Shannon-Weiner diversity index( H′) reached the maximum in summer but the minimum in autumn;Pielou index( J′)reached the minimum in autumn,but there was little difference among the other three seasons;dominance index(λ )reached the maximum in autumn but the minimum in sum-mer.
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