Mathematical analysis of effects of morphometric attributions on body weight for Paralichthys olivaceus

The total length(X1),body length(X2),head length(X3),snout length(X4),body depth(X5),caudal peduncle length(X6),caudal peduncle depth(X7) and body weight(Y) of 2032 Paralichthys olivaceus were measured at the ages of 5 months and 8 months.The correlation coefficients among the attributions were calculated.Total length(X1) was eliminated from the variable data set because it was co-linear with body length(X2).The 6 morphometric attributions(X2-X7) were used as independent variables and body weight(Y) was used as dependent variable for path analysis.Path coefficients(Pi) and determination coefficients(di) were calculated in path analysis.The result showed that all correlation coefficients between each morphometric attributions and the weight achieved very significant difference levels(P0.01).Body length(X2),body depth(X5) and caudal peduncle depth(X7) which bared strong direct effect were very indicative of determining the body weight,head length(X3),snout length(X4) and caudal peduncle length(X6) had relatively slight direct effect and significant indirect effect on the body weight.The diversification of determination coefficients(di) is consistent with that of path coefficients(Pi).There was significant difference at different months with mathematical analysis.The multiple regression equation of the body length(X2),body depth(X5) and caudal peduncle depth(X7) to the body weight is obtained to estimate body weight.This paper provides theoretical evidence and perfect measure target for breeding of Paralichthys olivaceus in aquaculture.