中文摘要：

依据2009年冬季、2010年春季和夏季在南日列岛西南部海区3个航次的渔业资源综合调查资料,通过对南日列岛西南部海区鱼类资源密度及分布特征、体长、体重、幼体比、优势种、相对重要性指数以及优势种对鱼类总数量的贡献,讨论了南日列岛西南部海区鱼类数量变化及其与水团变化之间的关系。结果表明：春、夏、冬3季鱼类重量密度分别为601.26kg·km^-2、2599.60kg·km^-2和730.36kg·km^-2;尾数密度分别为17.3×10~3尾·km^-2、255.00×10~3尾·km^-2和22.6×10~3尾·km^-2;平均体长、体重和幼体比分别在春季、冬季和夏季为最高,分别为14.95cm、49.76g和81.72%。春季主要由产卵群体组成,多为规格较大的成鱼;夏季由索饵群体组成,多为规格较小的幼鱼。鱼类数量的平面分布与福建近海不同季节水团的变化有关,春季鱼类聚集在闽浙沿岸水和海峡暖水交汇的外侧海域,夏季鱼类多聚集在营养盐丰富,沿岸流控制的近海海域。各季节鱼类数量分布特征与优势种分布基本一致。

英文摘要：

To detect the relationship between horizontal distribution of fish assembles and water masses or between seasonal distribution of fish assembles and water masses,three fish trawl surveys were conducted in the southwest waters of the Nanri Islands in December 2009 and in April and August 2010.Density and distribution pattern of fish assemblages,body length,body weight,juvenile ratio,dominant species,index of relative importance,and contribution to the total number of dominant species were analyzed in the study.The results showed that fish densities in terms of both weight and number were higher in summer（2599.60 kg·km^-2,22.6×10~3 ind·km^-2） than those in spring（601.26 kg·km^-2,17.3×10~3 ind·km^-2） and winter（730.36 kg·km^-2,22.6×10~3 ind·km^-2）.The average body length of fish was the highest in spring（14.95 cm）,while the average body weight was the highest in winter（49.76 g）.The proportion of juvenile was the highest in summer（as high as 81.72%）.The variation in distribution pattern and biological parameters of fish assembles was probably associated with spawning and forging activities of fish.For example,it was mainly composed of spawning adult assembles in spring,while foraging juveniles were predominant in summer.Distribution pattern of fish assemblages was related to the seasonal variation in water mass and food availability in the coast water of Fujian.Fish densities were higher on the offshore side of Zhejiang-Fujian coastal water and Taiwan Strait warm current water.While in summer fish was more abundant in the nearshore region where food was particularly abundant.The distribution pattern of fish assemblages was consistent with the distribution pattern of dominant fish species.