Abstract:The morphological character is an important external indicator of the value of a large yellow croaker (Larimichthys crocea). Therefore, it has become a hotspot how to improve the morphology of the cultured large yellow croaker in the fishery industry. In this paper, we analyzed the morphological differences among the large yellow croakers cultivated in different environments and fed with different diets. We collected the morphological data of three groups of large yellow croakers, and then applied methods such as cluster analysis, principal component analysis and discriminant analysis to analyze the data. The results showed that there were significant differences in the body height, the caudal peduncle length, the caudal peduncle width and the trunk width between the groups. The environment and the diets also had effects on the frame morphology of D3–4, D3–6, D4–6 and D5–6. The morphological differences primarily existed in anterior trunk of the fish, which indicated that the morphological changes caused by the environment might be associated with the flow velocity. We also speculated that the diet might affect the fish morphology due to different nutrition compositions and accumulation. The cluster analysis showed that the formula diet group and the net-cage group clustered closer than the fresh diet group. Three principal components were extracted by principal component analysis, and it showed that the formula diet group and the net-cage group shared similarity in principal component 1, but were different in principal component 3. The fresh diet group was discrete on each principal component. This finding suggested that the large yellow croaker cultured in the small net cage and fed with fresh diet were more diverse in morphology. We also applied discriminant analysis and established the discriminant functions of the large yellow croaker under different conditions. The cross validation analysis showed that there was no significant difference between the discriminant functions and the expectation, which indicated that the discriminant functions could be used in the morphological identification of the large yellow croaker cultured in different patterns. Our study suggested that the morphological improvement of the large yellow croaker would be achieved to some extent by altering the flow velocity, the size of the cultural space and diets.
