Principal component and path analysis of morphological traits of selective groups at different month ages of Sebastes schlegeli

In order to research growth characteristics and the effect of morphological traits on body weight of selective groups of Sebastes schlegeli at different month ages, this thesis analyzed the data of body weight, full length, body length, head length, trunk length, body depth, caudal peduncle length and caudal peduncle depth at different month ages, by the methods of principal component, correlation analysis, path analysis and multiple regression analysis. The results showed that notable correlation was found among all the morphological traits of S. schlegeli at different ages, especially between full length and body length. The first principal component always reflects the length and body weight factor of S. schlegeli at different growth phases. However, the second principal component was different and reflected the trunk length factor at 15-month-old and the caudal peduncle factor at 18-month-old, but was not available at 12-month-old. The traits with strongest direct effect on body weight were body length and body depth (0.340, 0.314 and 0.347, 0.324) at 12-month-old and 15-month-old, meanwhile, the full body and body depth (0.498) at 18-month-old. The result of determinant coefficient analysis was consistent with that of path analysis. The growth rate of traits and effect on weight selected traits were not the same because of the different growth stages of S. schlegeli. We proposed that the body length and body depth were the target traits for selective breeding of S. schlegeli at 12-month-old and 15-month-old, We should pay attention to selecting full length at 18-month-age to improve the accuracy of breeding projects. The research provided theoretical evidence and technical parameters for selective breeding of S. schlegeli.