Correlation of growth traits and body mass of spotted sea bass （Lateolabrax maculatus）in different growth stages

【Objective】The aim of this study was to investigate the effects of different growth traits on body weight of Lateolabrax maculatus and provide theoretical support for the selection and breeding standards of different stages in L.maculatus.【Method】The culture experiment was conducted on L.maculatus（average body mass：15.02-599.33 g）using outdoor ponds culture pattern and cultured for about 250 d. Growth traits（including body mass，total length，body length，interorbital diameter，head depth，head length，maxillary length，trunk length，caudal fin length，body depth， tail length，caudal peduncle depth and snout length）were measured every 50 d. The data of growth traits in different growth stages of L.maculatus were analyzed by correlation analysis，path analysis and multiple regression analysis，multiple regression equations were constructed.【Result】Among the 13 growth traits measured，except for snout length， showed an increasing trend with increasing rearing time. Among them，the body mass of the L.maculatus increased from 12.29±2.87 g to 599.33±116.50 g，the body length of the L.maculatus increased from 86.73±7.75 mm to 328.12±21.10 mm. The coefficient of variation fluctuations of body mass and body length of L.maculatus were not greatly changed， ranging from 19.44% to 24.74% and 6.43% to 9.09%，respectively. The growth traits that had significant or extremely significant effects on body weight at different growth stages of L.maculatus were as follows：full length at the first day； body length，head height，and snout length at the 50^th day；the body length and body height at the 100^th day；body length， body height，maxillary length and eye diameter at the 150^th day；body height，body length and trunk length at the 200^th day；body length and head height at the 250^th day. The results of the path analysis showed that the greatest direct effect on the body mass of the L.maculatus on day 1 was the full length（path coefficient 0.894），the direct effect of body length on body mass was the greatest on days 50，100，150 and 250（path coefficients of 0.531，0.663，0.403 and 0.686，respectively），body height had the greatest direct effect on the body mass of L.maculatus on the 200^th day（path coefficient 0.511）.【Conclusion】Growth traits that are significantly or extremely significantly associated with L.maculatus body mass vary across growth stages. The correlation between full length and body mass is the greatest when the mean body mass of the L.maculatus reaches 12.29 g. The correlation between body length and body mass is greater when the body mass of the L.maculatus is in the range of 70.25-599.33 g，and body mass is also correlated with head height and body height. Therefore，body length is the main selection trait in the selection and breeding process of L.maculatus，body height，full length and head height are used as auxiliary.