The Correlation and Path Analysis for Growth-related Traits of GIFT Strain Tilapia(Oreochromis niloticus)

In order to study the effects of morphometric characters on body weight in GIFT Strain Tilapia(Oreochromis niloticus),545 one year old individuals(female:290,male:255)were sampled for measuring the metric traits,including the body length(x1),head length(x2),trunk length(x3),body depth(x4),body width(x5) and body weight(y).The correlation coefficients among the attributes were calculated.The growth-related traits have highly significant difference between female and male fish(P0.01),significant differences were found on body morphometric attributes between female and male fish(P0.05).All 5 morphometric attributes(x1-x5) were used as independent variables,and body weight(y) was used as a dependent variable for path analysis.Path coefficients(Pi),determination coefficients(di) and correnlation(R2) were calculated in path analysis.The results showed that all correlation coefficients between each morphometric attribute and the weight achieved very singnificant difference(P0.01).The path coefficient of body length(x1),trunk length(x3),body depth(x4),body width(x5) to the body weight have all reached a level of significantly.These attributes are very indicative of determining the body weight,among them body depthweighted the most(female,0.378 3* *;male 0.371 4* *) to the body weight,it is a key effective factor,the head lenth(x2) has no significant direct effect to the body weight(P0.05).So that the main variables(x1,x3,x4,x5) have been selected.The multiple regression equation of the body length(x1),trunk length(x3),body depth(x4),body width(x5) to the body weight(y) is obtained to estimate body weight.Female,y=-1 475.72+21.51x1+32.54x3+67.82x4+80.59x5(R2=0.957);male,y=-2 046.40+31.18x1+ 30.20x3+ 96.78x4+81.35x5(R2=0.969),This paper provide atheoretical tool to measure breeding tilapia in aquaculture.