黄海山东海域春、秋季鱼类群落结构

Community structure of fish resources in spring and autumn in the Yellow Sea off Shandong

为了解黄海山东海域鱼类群落结构现状,2006年春季(5月)和秋季(10月)在该海域利用疏目变水层双拖网进行了调查,共设置45个调查站位。调查数据根据各站位扫海面积和各鱼类可捕系数进行了标准化处理。利用相对重要性指数、等级聚类、非度量多维标度、相似性百分比、数量生物量比较曲线等方法,对该海域的鱼类群落结构及其空间分布与稳定性进行了研究。结果表明:调查共捕获鱼类61种,春、秋季各50种。春季优势种为玉筋鱼、方氏云鳚和鳀;秋季优势种为鳀和青鳞小沙丁鱼。群落组成以小型、低质种类为主,春季有18种,秋季有12种种类个体平均体质量小于10 g。根据聚类分析和非度量多维标度(NMDS)方法分析结果,黄海山东海域春、秋季鱼类群落均可划分为2个群落:近岸浅水群落(组Ⅰ)和远岸深水群落(组Ⅱ)。春季,组Ⅰ包括22个站位,组Ⅱ包括15个站位,组间差异系数为73.94%;秋季,组Ⅰ包括17个站位,组Ⅱ包括21个站位,组间差异系数为55.97%。B IOENV程序分析表明,鱼类群落与水深的相关性较好,春季相关系数为0.474,秋季为0.579。黄海山东海域春、秋季鱼类群落Ⅰ、Ⅱ的数量优势度曲线均高于生物量优势度曲线,W统计值均为负值,且春、秋季群落Ⅱ的W统计值均低于群落Ⅰ,鱼类群落结构处于严重干扰状态。

Fishery science and management are progressively switching their attention from single species to ecosystems,and increasing the need for research of fish community.Based on the data collected by trawl surveys in May and October of 2006 in the Yellow Sea off Shandong,fish community patterns such as species compositions and spatial pattern were analyzed.In the investigated area,35°00′-38°00′N,120°30′-124°00′E,45 sample stations were set up.The survey data were standardized by sweep area and capture coefficient.The capture coefficient was set to 0.55 for pelagic fish and 0.35 for near demersal fish and 0.25 for demersal fish.The index of relative importance（IRI）was calculated to determine the importance of the species.Species were defined as dominant species when IRI value is more than 1 000.Important species were defined for those IRI value being grealer than 100 but no more than 1000.The multivariate statistical analyses include cluster analysis,NMDS,SIMPER and BIOENV to analyze the pattern of community compositions.The species,whose cumulative biomass less than 0.01% or frequency less than 5%,were excluded from multivariate statistical analyses.The abundance biomass comparison（ABC）curves and W-statistic,generated by PRIMER,were used to analyze the communities＇ disturbed states.The results showed that a total number of 61 species belonging to 57 genera,37 families and 13 orders were collected,50 in springs and 50 in autumns.The dominant species were Pacific sandeel（Ammodytes personatus）,Japanese anchovy（Engraulis japonicas）and fang＇s blenny（Enedrias fangi）in spring,and were Japanese anchovy and Japanese sardinella（Sardinella zunasi）in autumn.The important species were Pacific cod（Gadus macrocephalus）in spring,and were yellow croaker（Larimichthys polyactis）,silver pomfret（Pampus argenteus）,Pacific sandeel and rednose anchovy（Thrissa kammalensis）in autumn.The fish communities were predominant by little,low-valued species.In spring,the average body weight of 18 species was no more than 10 grams,and 12 species in autumn.The fish community in the survey waters can be grouped into two assemblages through the clustering and NMDS results.The group Ⅰ,which contains 22 stations in spring and 17 stations in autumn,was in the coastal waters near the land and the group Ⅱ,which contains 15 stations in spring and 21 stations in autumn,was farther away.The dissimilarity between group Ⅰ and group Ⅱ was 73.94% in spring and 55.97% in autumn.The relationship between fish community pattern and water depth was dominant through the BIOENV program.The abundance curves were above the biomass curve and the W-statistic value was below zero in all groups in spring and autumn.We can conclude that：（1） There were many reasons for the low level of species of this survey,but overfishing and environmental degradation were the important one.（2） Fish community can be grouped into two assemblages according the water depth,but there exists no clear border between them.Most species existed in the two assemblages simultaneously.（3） The fish community in the Yellow Sea off Shandong was seriously disturbed.Miniaturization of fish community was serious.