浙江南部近海鱼类粒径谱特征

为了解浙江南部近海鱼类群落粒径结构的时空特征、季节变动及其影响因素,基于2019年4个季节的渔业资源调查数据,利用粒径谱、多维尺度排序等方法,研究了鱼类粒径谱特征及其时空变动.结果表明,全年Sheldon鱼类粒径谱形状大体为单峰型,鱼类粒级介于?2～11,最高值出现在6～7粒级,以小型鱼类为主.四季Sheldon鱼类粒...

Fish size spectrum characteristics in offshore waters of southern Zhejiang Province

In order to improve the understanding of the spatio-temporal characteristics, seasonal variation and influencing factors of size structure of offshore fish communities in southern Zhejiang Province, we studied the characteristics of fish particle size spectrum and its spatiotemporal variation by means of particle size spectrum and multi-dimensional scale sorting based on the seasonal fishery survey data in 2019. The results show that the shape of annual Sheldon fish size spectrum was generally unimodal, and the size class ranged from-2 to 11, with the highest biomass occurring in the size classes of 6-7, mainly small fishes.The Sheldon fish size spectrum was basically unimodal in four seasons, and there were seasonal differences in the peak and maximum biomass corresponding to the size range and species composition. The fitted curves for the normalized fish size spectrum were all dome-shaped, and the curvature ranged from-0.18 to-0.09, with the maximum in winter(-0.09) and the minimum in spring(-0.18), indicating that the fish biomass was most vulnerable to external disturbance in spring but relatively stable in winter. The results of multidimensional scaling demonstrate that the fish community in this study can be classified into four subgroups in winter and spring, and three subgroups in summer and autumn. The analysis of size spectra by subgroups shows that the nearshore fish community is much affected by external disturbances than the far-shore fish community. In general, the fish community off southern Zhejiang Province is in a disturbed state, which may be related to environmental factors, seasonal migratory and sedentary fishes, as well as the closed fishing periods and fishing activities.