石首鱼科鱼类小黄鱼（）是吕泗渔场重要的经济鱼种，为了解两者营养价值、摄食习性及食性转变，测定2018年秋季在吕泗渔场采集的46尾小黄鱼和36尾棘头梅童鱼脂肪酸组成，基于脂肪酸标记法进行食性分析。结果显示，小黄鱼和棘头梅童鱼PUFA/SFA比值、n-3/n-6比值在常见水产鱼类中较高，小黄鱼n-3/n-6比值与体长呈显著正相关（<0.01）。小黄鱼体长<70 mm时植物食性贡献较高（P<0.05），体长≥100 mm时植物食性显著减少（<0.05），小黄鱼（2.6~5.9）和棘头梅童鱼（2.6~3.3） DHA/EPA部分重合。研究表明，小黄鱼和棘头梅童鱼营养价值较高，大个体小黄鱼鱼油营养价值更高，小个体棘头梅童鱼则更有利于心血管健康。两者营养级部分重合，食性相似，都是随着体长增加植物食性减少，肉食食性增加且食性转变时的体长相近，因此，两者可能存在一定的食物竞争和生态位重合。

, belonging to the family , are important economic fish species in the Lyusi fishing ground. With the rapid improvement of fishing power and production efficiency, coastal fisheries generally suffer from different degrees of overfishing, and the resources of also suffer from a continuous decline. The purpose of this paper is to provide a reference for the rational development and utilization of resources by analyzing their fatty acid composition, nutritional value, feeding habits, and dietary changes. The fatty acid composition of 46 individuals, collected from the Lyusi fishing ground during autumn 2018, was measured, and a dietary analysis was performed, based on the fatty acid labeling method. The results showed that fatty acid content of (21.77 mg/g); their SFA contents were similar (36.00%); the MUFA content of (15.92%), and the PUFA content of C. lucidus (47.91%). PUFA/SFA and n-3/n-6 of were higher than those found in common aquatic fish. The n-3/n-6 of P<0.05), whereas the PUFA/SFA of P<0.01). The characteristic fatty acids C18:2n6c and C20:5n3 (EPA) of P<0.05) and DHA/EPA had a significantly positive correlation with body length ( had a significantly negative correlation with body length ( had a higher herbivorous diet when the body length was less than 70 mm (<0.05), and a significant decrease in herbivorous diet when the body length was greater than or equal to 120 mm ( had a higher herbivorous diet when the body length was less than 70 mm (<0.05), and a significant decrease in herbivorous diet when the body length was greater than or equal to 100 mm ( (2.6-5.9) partially overlapped with (2.6-3.3). The research indicated that the nutritional values of were very high; the larger individuals' fish oil of had a higher nutritional value, and the smaller individuals of were more beneficial to cardiovascular health. Their trophic levels were partially overlapping, and their feeding habits were similar. As the body length increased, the herbivorous diet decreased and carnivorous diet increased, and the body length was similar when the diet changed. Therefore, they may have a certain niche overlap and food competition.

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江苏省国家级海洋牧场示范项目（D8005-18-0188）；江苏省自然科学基金项目（BK20170438）.