凡纳对虾形态性状对体重的影响效果分析

Mathematical analysis of effects of morphometric attributes on body weight for Penaeus vannamei

选择 6月龄凡纳对虾 176只 ,测定了体长、头胸甲长、胸宽、胸高、额剑上刺数、额剑下刺数、尾长和上市体重共 8个性状 ,采用相关分析和通径分析方法 ,剔除了与体长及头胸甲长有共线性的自变量尾长 ,计算了以形态性状为自变量对体重作依变量的相关系数、通径系数、决定系数及相关指数 ,定量地分析了形态性状对体重的影响效果。结果表明 ,凡纳对虾 5个形态性状与体重的相关系数达到极显著水平 (P<0 .0 1) ;通径分析揭示了多元分析中多个自变量与依变量的真实关系 ,体长、头胸甲长、胸宽、额剑下缘刺数目对体重的通经系数达到显著水平 ,它们是直接影响体重的重要指标 ,其中体长对体重的直接影响(0 .4 2 8* * )最大 ,是影响体重的最主要因素 ,其次为头胸甲长 (0 .2 90 * * )和胸宽 (0 .2 4 5 * * ) ,额剑下缘刺数对体重的直接影响(0 .0 70 * )较小 ;胸高与体重的相关程度很大 (0 .792 3) ,但它与额剑上缘刺数对体重的直接影响都非常小 ,主要通过其他性状间接影响活体重 ,是影响体重的次要因素 ,均被剔除 ;决定系数分析结果与通径分析结果有一致的变化趋势 ;所选形态性状与体重的复相关指数为 R2 =0 .92 13,说明影响体重的主要自变量指标已经找到 ;多元回归分析建立了体长 (X1 )、头胸甲长 (X2 )、胸宽(X3)、

The effects of morphometric attributes on body weight for Penaeus vannamei were analyzed. Data for this study were collected from six-month-old 176 Penaeus vannamei in Banqiao Village of Dongfang City , Hainan Province. The body length ( X _1), carapace length ( X _2), carapace width ( X _3), carapace height ( X _4), number of upper frontal eminence spine ( X _5), number of lower frontal eminence spine ( X _6), tail length ( X _7) and body weight (Y) were measured. The correlation coefficients among the attributes were calculated. Tail length was eliminated from the variable data set because it was co-linear with body length ( X _1) and carapace length ( X _2). The first 6 morphometric attributes( X _1~ X _6) 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 correlation index ( R ~2) were calculated in path analysis. The results showed that all five correlation coefficients between each morphometric attribute and the weight (0.9446, 0.9262, 0.9102, 0.7923, 0.933) achieved very significant difference ( P <0.01) levels. The path coefficient analysis revealed a truthful relationship between the independent variables and the dependent variable. The path coefficients( Pi ) of the body length ( X _1), carapace length ( X _2), carapace width ( X _3) and number of lower frontal eminence spine ( X _6) to the body weight have all reached a level of significance. These attributes are very indicative of determining the body weight, among them body length ( X _1) weighted the most ( P _1=0.428) to the body weight, it is a key effective factor, carapace length ( X _2) and carapace width ( X _3) weighted the second and third ( P _2=0.2902, P _3=0.2453, significant indirect effect 0.6145, 0.6408 respectively). The number of lower frontal eminence spine ( X _6), carapace height ( X _4), number of upper frontal eminence spine ( X _5), and tail length ( X _7) have insignificant direct effect on the body weight and were neglected. The diversification of determination coefficients ( d_i ) is consistent with that of path coefficients( P_i ). Judging from the result of high correlation index ( R ~2=0.921), the main variables ( X _1, X _2, X _3, X _6) have been selected. The multiple regression equation of the body length ( X _1), carapace length ( X _2), carapace width ( X _3) and number of lower frontal eminence spine ( X _6) to the body weight is obtained to estimate body weight. the regression intercept and partial regression coefficients of the equation are -17.994, 1.477, 4.159, 6.197, and 0.4757. This paper provide a theoretical tool to measure breeding shrimps in aquaculture.