不同投喂方式对鳙形态特征的影响

Morphological variations of bighead carp(Aristichthys nobilis)fed by feedstuff

为分析不同投喂方式对鳙形态特征的影响,本研究采用了传统形态度量法和框架分析法构建了31个反映体型的形态比例性状,运用单因素方差分析、聚类分析、主成分分析和判别分析等统计方法对4种投喂方式下,施肥(组A)、施肥+1/2投饲(组B)、施肥+投饲(组C)、投饲(组D)总共56尾鳙的这些性状进行分析比较。方差分析结果显示,不同处理组间头高/体长、4–6/体长、5–6/体长、5–8/体长等7个比例性状无显著差异,其他24个性状差异显著,但头长/体长在组A、组C和组D中无显著差异。聚类分析结果显示,不同处理组分成2支,其中组A单独聚为一支,而组B、组C和组D共同聚为一支。主成分分析构建了7个主成分,累计贡献率达到了94.6%,其散点图显示,组B、组C和组D部分样本重叠在一起,与组A完全分开。以Bayes逐步判别分析方法选用了6个判别效果较好的比例性状,建立了4个种群的判别函数,不同处理组鳙判别准确率分别为92.7%、87.5%、64.3%和87.5%,说明了本结果的可靠性。结果表明,投饲养殖方式下鳙形态特征发生显著变化,但头部相关的主要比例性状无显著差异,头部至背鳍躯干部距离显著增大,形成了头部偏小的假象。本研究首次以数据结果阐释投饲养鳙仍符合人们喜食的大鱼头特征,为该养殖技术奠定了理论基础。

To elucidate the morphological variation of bighead carp （Aristichthys nobilis） fed by feedstuff, 31 morphological proportional characters for four populations （56 specimens） from four treatments as fertilization （group A）, fertilization＋ 1/2 feeding （group B）, fertilization＋ feeding （group C） and feeding （group D） were investigated, using the traditional morphological （one-way analysis of variance, cluster analysis, principal component analysis, and discriminant analysis） and truss network analysis. The four populations of bighead carp differed significantly for 24 morphological proportional characters （e.g., TL/BL, BH/BL, SL/BL）, while there were no differences for other characters as HH/BL, HL/BL, 4-6/BL, 5-6/BL between different groups. A cluster analysis indicated that the group B, group C and group D were more similar compared to group A. The principal component analysis yielded seven principal components with a cumulative contribution ratio of 94.6%. The scatter diagram of major principal components also showed group A completely separated from other three groups, while the latter overlapped together. The discriminant functions of the four populations of bighead carp were established based on 6 morphological characters that differed significantly among the populations. The accuracy of discrimination from four populations was 92.7%, 87.5%, 64.3% and 87.5%, respectively, indicating the reliability of discriminant functions. In summary, the morphological characteristics of bighead carp fed feedstuff changed significantly. However, the morphological characters of fish head have not changed, while the trunk from head to the dorsal fin is significantly increased, hence giving an illusion of smaller head. It is the first study to prove the bighead carp fed feedstuff still have the big head features, laying the theoretical foundation for rearing bighead carp with feedstuff.