苏北浅滩沙脊潮沟地形对鱼类分布格局的影响

为研究苏北浅滩沙脊潮沟海域地形特征对鱼类群落分布格局的影响,根据2011年5月(春)和2010年11月(秋)在苏北浅滩中部海域渔业资源调查的资料,采用方差贡献和回归分析的方法,通过对中部海域沙脊潮沟处鱼类生物学特征、资源密度、优势种相对重要性指数以及优势种对鱼类总数量的贡献的分析,讨论苏北浅滩沙脊潮沟地形对鱼类分布格局的影响。结果显示,鱼类空间分布差异与潮沟系统的地形地貌有关,春季潮沟外侧海域是小黄鱼、鰐等洄游性鱼类的渔场,潮沟海域是洄游性鰐和方氏锦鰑的渔场位置,沙脊海域是赤鼻棱鰒等非洄游性鱼的渔场。秋季鱼类空间分布仅与潮沟系统沙脊地形相关,沙脊海域主要是大银鱼的索饵场和越冬场。鱼类数量季节变化还与鱼类产卵洄游和生长相关。春季重量密度(16.08 kg/km2)大于秋季(10.74 kg/km2),而秋季尾数密度(16.3×103尾/km2)大于春季(5.36×103尾/km2)。春季鱼类规格较大,与部分成鱼具有到这一海域进行产卵洄游的习性有关,而秋季同种鱼则以幼体居多,且优势种个体小,与秋季部分鱼类幼鱼在此处索饵和育幼有关。总体上,苏北浅滩沙脊潮沟海域特有地形,使得这一海域春季是鱼类的产卵场,夏秋季是育幼场,因而在渔业上具有重要的意义。

Distribution pattern of fish community in Northern Jiangsu shoal in relation to bathymetry and tidal creek of sand ridge

Based on the data from scientific fishery investigation in the waters of middle Northern Jiangsu shoal in May 2011 and November 2010, respectively, using the methods of variance and regression, the effects of bathymetry of sand ridge and tidal channel on the distribution pattern of the fishes were studied, through the analysis of the fish shape features, fish density and the index of relative importance of dominant species and the contribution of dominant species to the total population. Spatially, the distribution patterns of fish were associated with the bathymetry of the tidal channel system. The outer water of the tidal channel in spring was dominated by marine species, including Larimichthys polyactis and Michthys miiuy which migrated to the waters for spawning. Inside the tidal channel, Pholis fangi was predominant migratory fish, M. miiuy was also found in the area. In the sand ridge, it was mostly composed of adult of Thryssa kammalensis and no migratory fishes are found. In autumn, the distribution of fish species is only associated with the terrain of the bathymetry of the tidal channel system, in which it is almost composed of Protosalanx chinensis for shield in autumn. The result also shows that seasonal variation in densities of fish was closely associated with the spawning and nursery of fish community. The density of fish in terms of weight in spring (16.08×10³ ind/km²) was higher than that in autumn (10.74 kg/km²). However, the density in terms of individual in spring (5.36×10³ ind/km²) was lower than that in autumn (16.3×10³ ind/km²). Both average weight and body length of fish in spring were greater than those in autumn, which was probably associated with immigration of the adult of fish to the studied area to spawn during spring (e.g., spawning community of L. polyactisr and Eupleurogrammus muticus). In autumn, it was mainly composed of foraging juveniles (e.g., M. miiuy and P. fangi), due to partial fishes'' finding shelter and feed here. In general, because of the special terrain of North Jiangsu shoal, the sea area becomes the site of spawning in spring while the nursery field in summer and autumn, which is of great significance in fisheries.