黄河口及邻近水域小型鳀鲱鱼类数量分布及其与环境因子的关系

小型鳀鲱鱼类多为浮游生物食性种类；又是多种高营养层次鱼类的饵料生物；作为生态系统中的重要类群；其数量分布对多种生物均具有重要影响。本文根据2013年6月、8月、10月和2014年2月、4月、5月在黄河口及邻近水域进行的渔业资源和环境调查数据；分析了该海域小型鳀鲱鱼类资源数量分布特征；并用广义可加模型研究了其数量分布与时空和环境因子等之间的关系。黄河口及邻近水域小型鳀鲱鱼类相对资源量呈现明显的季节变化；夏、秋季相对资源量明显高于冬、春季。小型鳀鲱鱼类相对资源量具有明显的空间变化；且在不同月份呈现不同的空间分布格局；在4月、5月、6月小型鳀鲱鱼类主要分布于近岸水域；在8月、10月小型鳀鲱鱼类分布外移且范围扩大。GAM分析表明；影响黄河口及邻近水域小型鳀鲱鱼类相对资源量时空分布的主要环境因子包括表层盐度、表层水温、水深和浮游植物丰度等。小型鳀鲱鱼类相对资源量随表层盐度的升高呈现升高的趋势；在盐度达到30时；小型鳀鲱鱼类相对资源量处于最高水平。随表层水温的升高相对资源量有升高趋势；当表层水温达到15℃后；小型鳀鲱鱼类相对资源量增加趋势减缓且丰度较大。小型鳀鲱鱼类相对资源量随浮游植物丰度的增大总体呈现上升趋势；而随水深的变化呈现先降低后升高的趋势。黄河口及邻近水域小型鳀鲱鱼类相对资源量的时空变化与鳀鲱鱼类产卵、索饵和越冬洄游有关；受到季节变化、黄河径流变化以及黄河调水调沙等引起的海洋环境因子变动的影响。

Spatio-temporal distribution of small-sized fish species in Clupeidae and Engraulidae and its relationships with environmental factors in Huanghe River Estuary and its adjacent waters

The small-sized fish species in Clupeidae and Engraulidae are important components in marine ecosystem, as most of them feed on plankton and are food resources for fishes with high trophic levels. Regarding the important ecological roles, their spatiotemporal distribution has an important influence on a variety of organisms. The distribution of this taxon and its relationship with environmental factors was analyzed using generalized additive models (GAM) based on the data collected from the bottom trawl surveys conducted in June, August, October 2013 and February, April, May 2014 in the Huanghe River Estuary and its adjacent waters. The relative abundance of the small-sized fish species in Clupeidae and Engraulidae varied remarkably among seasons, and the relative abundance was higher in summer and autumn and lower in spring and winter. This taxon had significant spatial variation and showed different distribution patterns among months. These species aggregated in the coastal waters of the estuary in April, May and June and moved outward and expanded their distribution in August and October. GAM analysis showed that the spatio-temporal distribution of these species were influenced by several main factors, including sea surface salinity and sea surface temperature, depth and phytoplankton abundance in the Yellow River Estuary. Surface salinity had the most significant effect on the relative abundance of the species in Clupeidae and Engraulidae. The relative abundance was positively corrected with surface salinity and maintained at a high level with surface salinity of 30. The surface water temperature also had a positive effect on the relative abundance of the species in Clupeidae and Engraulidae, and the abundance maintained at a high level when SST was higher than 15℃. The phytoplankton abundance was positively correlated with fish abundance, whereas depth showed a concave-shaped correlation. It is inferred that the distribution of fish species in Clupeidae and Engraulidae could be ascribed to their spawning, feeding behaviors and overwintering migration, driven by the seasonal changes in marine environment and other environmental changes caused by the runoff and sand-washing operation of the Huanghe River.