Mathematical analysis of morphological traits and their effects on body weight in the red crab (Charybdis feriata)

The red crab (Charybdis feriata) is one of most important fishery resource in China. In the present study, 17 morphological traits and body weight of C. feriata were first measured and 18 traits were characterized, and then, the effects of morphological traits on body weight were estimated by statistical methods including correlation coefficients, determination coefficients, path coefficients and regression equations. All correlation coefficients between each morphological trait and body weight reached an extremely significant level (P<0.01). Determination and path coefficients analysis revealed the real correlation between the independent variables and the dependent variable. Significant path coefficients were found between three morphological traits (stemum width, X8; meropodite length of pereopod 3, X16; meropodite length of pereopod 4, X17) and body weight, suggesting these three traits were the key factors directly influencing body weight. Multiple correlation index (R2) between the above three morphological traits and body weight was of 0.977, which indicated that the main independent variables influencing body weight had been found. Finally, a best-fit linear regression equation was established as Y = 13.078 X8 + 7.048 X16 - 4.902 X17 - 576.635, which provided an ideal model for better understanding of the feature of morphological traits and body weight of C. feriata. Key words: Charybdis Feriata, morphological traits, correlation analysis, path analysis, regression analysis.