星康吉鳗形态性状与体重的通径分析及生长曲线拟合

为探明星康吉鳗（Conger myriaster）形态性状和体重的关系，测定了体重（Y）及全长（X₁）、肛长（X₂）、尾长（X₃）、头长（X₄）、吻长（X₅）、眼径（X₆）、眼后头长（X₇）、背鳍前长（X₈）、躯干长（X₉）、头宽（X₁₀）、眼间距（X₁₁）等11个形态性状，通过相关分析、通径分析、回归分析等方法研究了形态性状对体重的影响；通过曲线拟合获得4个形态性状与体重的最佳拟合模型。结果表明，星康吉鳗各形态性状之间以及形态性状与体重之间均呈极显著正相关关系（P< 0.01）。相关分析发现肛长（X₂）与体重的相关系数最大（0.970）；通径分析发现肛长（X₂）对体重的直接作用最大（0.450），头宽（X₁₀）通过肛长（X₂）对体重的间接作用最大（0.431）；决定系数分析发现，肛长（X₂）对体重的直接决定系数最大（0.203），肛长（X₂）和头宽（X₁₀）的共同决定系数最大（0.172）。形态性状（X）与体重（Y）的多元回归方程为Y=-113.859+6.481X₂+49.213X₆+11.514X₇+20.145X₁₀（R²=0.954）。星康吉鳗肛长（X₂）、眼后头长（X₇）、头宽（X₁₀）与体重的最佳拟合模型为指数函数，模型方程分别为Y=1.466e^0.287X、Y=1.435e^1.328X、Y=1.970e^1.974X，眼径（X₆）与体重的最佳拟合模型为线性，方程为Y=-77.460+222.093X。结论认为，在星康吉鳗选育时，应以肛长（X₂）和头宽（X₁₀）为主要选择性状，以眼径（X₆）和眼后头长（X₇）为辅助选择性状。

Path analysis and growth curve fitting of the morphological traits and body weight of Conger myriaster

Conger myriaster is a fish of high economic and nutritional value in China. It is distributed throughout the Yellow Sea, East China Sea, and Bohai Sea. There have been few studies of this species, focused mainly on fishing, feeding ecology, resource distribution, breeding, and genetics. To explore the relationships between the morphological traits and body weight of C. myriaster, the body weight (Y) and 11 morphological traits were measured, including the total length (X₁), snout-vent length (X₂), tail length (X₃), head length (X₄), snout length (X₅), eye length (X₆), head length behind the eye (X₇), length before the first dorsal fin (X₈), trunk length (X₉), head width (X₁₀), and the interorbital space (X₁₁). The direct and indirect effects of the morphological traits on body weight were studied by correlation and path analyses. A stepwise regression method was used to establish a regression equation in which the morphological traits were independent variables and the body weight was the dependent variable. The best curve models of 4 morphological characters and body weight were obtained by curve fitting. There was a positive correlation between the morphological traits and body weight of C. myriaster, and the correlation coefficients reached extremely significant levels (P<0.01). The correlation coefficient of snout-vent length (X₂) and body weight was the largest (0.970), snout-vent length (X₂) had the largest direct effect on body weight (0.450), and head width (X₁₀) had the largest indirect effect (0.431) on body weight through the snout-vent length (X₂). The direct determinate coefficient of snout-vent length (X₂) on body weight was the largest (0.203) and the largest joint determinate coefficient was for snout-vent length (X₂) and head width (X₁₀) (0.172). The multiple regression equation of the morphological traits and body weigh was Y=-113.859+6.481X₂+49.213X₆+ 11.514X₇+20.145X₁₀ (R²=0.954). The best-fitting models of snout-vent length (X₂), head length behind the eye (X₇), and head width (X₁₀) on body weight were the exponential functions, and the model equations were Y=1.466e^0.287X, Y=1.435e^1.328X, Y=1.970e^1.974X, respectively. The best fit model of eye length (X₆) and body weight was linear, and the equation was Y=-77.460+222.093X. Snout-vent length (X₂) and head width (X₁₀) were the main selective characteristics of C. myriaster, and eye length(X₆) and head length behind the eye (X₇) were auxiliary selective characteristics. These results provide valuable information and a theoretical basis for C. myriaster selection.