南黄海三种石首鱼类的食性

根据2000—2002年秋季和冬季在南黄海进行的定点底拖网调查，利用多元统计分析方法，研究了黑鳃梅童(Collichthys niveatus)、皮氏叫姑鱼(Jobnius belengerii)和小黄鱼(Pseudosciaena polyactis)的食物组成及其差异，摄食随海区、季节和体长的变化，以及3种石首鱼类摄食器官的形态差异对摄食的影响。结果表明：(1)3种鱼的优势饵料生物各不相同，食物组成存在显著差异；(2)3种鱼的食物组成均随海区和季节的不同而有显著的差异；(3)3种鱼的食物组成和饵料多样性都有明显体长变化，黑鳃梅童和皮氏叫姑鱼的饵料多样性随体长的增大而升高，小黄鱼则相反；(4)黑鳃梅童和小黄鱼种内不同体长问的食物重叠指数较高，而皮氏叫姑鱼则较低，3种鱼的种问食物重叠指数位于0．50～0．56；(5)主成分分析(PCA)表明，黑鳃梅童和小黄鱼摄食器官的形态特征与皮氏叫姑鱼存在一定的差异。

Feeding habits of three sciaenid fishes in the southern Yellow Sea

Based on the bottom trawl surveys conducted in the southern Yellow Sea in autumn and winter from 2000 to 2002, feeding habits of three sciaenid fishes (Collichthys niveatus , Johnius belengerii and Pseudvsciaena polyactis) were studied. The multivariate statistical technique was used to study the seasonal, spatial and ontogenetic variations in the diets of each species and the morphological differences in the feeding apparatus of three species. The results indicate that the food compositions of three species differed significantly from each other. C. niveatus was a planktivorous predator feeding mainly upon euphausiids, shrimps and copepods, whereas J.belengerii was a benthivorous predator consuming primarily benthic shrimps as well as small fish and polychaetes. In comparison with these two species, P. polyactis was a generalist feeding upon both benthic and pelagic preys. Although the diets of J.belengeru and P.polyactis were strongly influenced by habitat type and season, the former variable was more important. The ontogenetic differences in the food composition and dietary diversity were also detected. The dietary diversity increased progressively with increasing body size of C. niveatus and J.belengeru. However, the reverse applied to P,polyactis. The intraspecific values for Schoener' s dietary overlap indexes between each size class of C. niveatus and P. polyactis were relatively high, whereas those of .J. belengeru were lower. The highest intraspecific dietary overlap values of C.niveatus and P. polyactis were recorded between the smaller size classes of both species. The values for interspecific dietary overlap between each size class of the three species were from 0.50 to 0.56. The principal component analysis (PCA) indicates that the morphological characters of the feeding apparatus were similar between C.mveatus and P. polyactis, whereas these two species showed some differences from J.belengerii. The relative lengths of the lower jaw extension and mouth height were smaller for J.belengerii than the other two species.