Principal component and discriminant analyses of morphological traits of cultured Konosirus punctatus at different stage

In order to explore the growth pattern and characteristics of phenotypic traits of Konosirus punctatus at different ages, as well as the relationship between traits and month of ages at the best growing season, phenotypic traits data of total length, body length, head length, trunk length, caudal peduncle length, eye diameter, body height, caudal peduncle height, body width, interorbital distance and body mass collected from K. punctatus at two, four, six, eight months old were analyzed by principal component and discriminant analysis in this study. The results showed that there were different degrees of positive correlation among all the phenotypic traits at different ages. The correlation coefficients between body mass and total body length, body height, body width at each month were large. The correlation coefficients between eye diameter and eye spacing and other traits were small, and the correlation coefficients between body weight and other traits at eight months old were less than those at two, four and six months old. The principal components of K. punctatus at different months of age were different. The first principal component was mainly based on the growth of body mass and length increase. The second principal component showed the growth state of body width at two months old, which also showed the growth state of eye diameter at four, six, eight months old. The third principal component showed the growth state of head at two and four months old, as well as the growth state of eye diameter at six months old and that of body width at eight months old. By stepwise discriminant analysis, the discriminant function of each month was established after eliminating three traits. The overall discriminant accuracy was 99.3%, especially the discriminant accuracy of two, four and eight month of age of K. punctatus reached to 100%. The relation equation between body length and body mass of 2-8 months of age was W=0.017L^2.929 (R²=0.981) of K. punctatus. This study proved that total length and body length and body height and body width are the most important morphological traits in the growth stage of K. punctatus. The study established the discriminant function in the different growth stage of K. punctatus, which demonstrated that the growth pattern of K. punctatus is isokinetic growth at two to eight months old. This study provides a theoretical evidence and suggested measure indices for the selection and breeding of K. punctatus.